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  • Study on the crystallization of poly(butylene azelate-co-butylene succinate) copolymers

     Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Thermochimica acta
    Date of publication: 2014-01-10
    Journal article

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    Poly(butylene azelate-co-butylene succinate) samples with different azelate/succinate ratios were synthesized and characterized. Calorimetric data indicate a semicrystalline character for all copolyesters studied and a melting point depression that could be interpreted on the basis of complete exclusion of comonomers from well organized lamellae. Crystallization first occurred through the succinate rich segments, which resulted in a peculiar behavior of copolymers having an intermediate composition. In this case, crystallization of azelate segments was paradoxically enhanced when samples were quenched. Equilibrium melting temperatures significantly decreased with increasing comonomer content compared to those of the corresponding homopolymers. Incorporation of comonomers had a distinct effect on the secondary nucleation constant depending on the composition as deduced from Lauritzen and Hoffman analysis. Thus, azelate units clearly increased the nucleation constant of copolymers rich on succinate units, whereas the incorporation of succinate units had a lower influence on the constant of copolyesters having high azelate content.

    Poly(butylene azelate-co-butylene succinate) samples with different azelate/succinate ratios were synthesized and characterized. Calorimetric data indicate a semicrystalline character for all copolyesters studied and a melting point depression that could be interpreted on the basis of complete exclusion of comonomers from well organized lamellae. Crystallization first occurred through the succinate rich segments, which resulted in a peculiar behavior of copolymers having an intermediate composition. In this case, crystallization of azelate segments was paradoxically enhanced when samples were quenched. Equilibrium melting temperatures significantly decreased with increasing comonomer content compared to those of the corresponding homopolymers. Incorporation of comonomers had a distinct effect on the secondary nucleation constant depending on the composition as deduced from Lauritzen and Hoffman analysis. Thus, azelate units clearly increased the nucleation constant of copolymers rich on succinate units, whereas the incorporation of succinate units had a lower influence on the constant of copolyesters having high azelate content

  • Poly(butylene azelate-co-butylene succinate) copolymers: Crystalline morphologies and degradation

     Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Estrany Coda, Francisco; Del Valle Mendoza, Luis Javier; Puiggali Bellalta, Jorge
    Polymer degradation and stability
    Date of publication: 2014-01
    Journal article

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    Random copolymers derived from 1,4-butanediol and two dicarboxylic units differing in the parity of the number of methylene groups and length of the polymethylene sequence (i.e. succinic and azelaic acids) were studied in terms of thermal properties, crystalline structure and morphology, crystallization kinetics and biodegradability. All samples were semicrystalline and their thermal properties varied in a wide temperature range. Copolymers crystallized according to the monoclinic a-form of polybutylene succinate and the orthorhombic structure postulated for polybutylene azelate depending on the predominant dicarboxylate unit. The behavior of the copolymer with an intermediate composition was complex due to strong dependence of the predominant crystalline form on crystallization and processing conditions. Interestingly, crystallization into the azelate structure was favored when samples were rapidly cooled from the melt, resulting in an unexpected increase in the degree of crystallinity. Spherulitic morphologies were clearly different (i.e. ringed spherulites and axialites) depending on the preferential crystalline structure. Enzymatic degradability of the two homopolyesters was highly different and could be enhanced by incorporation of comonomer units. Preferential enzymatic attack on amorphous regions highlighted the spherulitic morphologies of copolymers having well developed, distinctive ringed structures. © 2013 Elsevier Ltd. All rights reserved.

    Random copolymers derived from 1,4-butanediol and two dicarboxylic units differing in the parity of the number of methylene groups and length of the polymethylene sequence (i.e. succinic and azelaic acids) were studied in terms of thermal properties, crystalline structure and morphology, crystallization kinetics and biodegradability. All samples were semicrystalline and their thermal properties varied in a wide temperature range. Copolymers crystallized according to the monoclinic α-form of polybutylene succinate and the orthorhombic structure postulated for polybutylene azelate depending on the predominant dicarboxylate unit. The behavior of the copolymer with an intermediate composition was complex due to strong dependence of the predominant crystalline form on crystallization and processing conditions. Interestingly, crystallization into the azelate structure was favored when samples were rapidly cooled from the melt, resulting in an unexpected increase in the degree of crystallinity. Spherulitic morphologies were clearly different (i.e. ringed spherulites and axialites) depending on the preferential crystalline structure. Enzymatic degradability of the two homopolyesters was highly different and could be enhanced by incorporation of comonomer units. Preferential enzymatic attack on amorphous regions highlighted the spherulitic morphologies of copolymers having well developed, distinctive ringed structures.

  • Micro-molding with ultrasonic vibration energy: New method to disperse nanoclays in polymer matrices

     Planellas Oates, Marc; Sacristan, Matias; Rey, Lorena; Olmo, Cristian; Aymami Bofarull, Juan; Casas Becerra, M. Teresa; Del Valle Mendoza, Luis Javier; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Ultrasonics sonochemistry
    Date of publication: 2014-07-01
    Journal article

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    Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 001 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent. (C) 2014 Elsevier B.V. All rights reserved.

    Ultrasound technology was proved as an efficient processing technique to obtain micro-molded specimens of polylactide (PLA) and polybutylene succinate (PBS), which were selected as examples of biodegradable polyesters widely employed in commodity and specialty applications. Operational parameters such as amplitude, molding force and processing time were successfully optimized to prepare samples with a decrease in the number average molecular weight lower than 6%. Ultrasonic waves also seemed an ideal energy source to provide effective disaggregation of clay silicate layers, and therefore exfoliated nanocomposites. X-ray diffraction patterns of nanocomposites prepared by direct micro-molding of PLA or PBS powder mixtures with natural montmorillonite or different organo-modified clays showed the disappearance of the 0 0 1 silicate reflection for specimens having up to 6 wt.% clay content. All electron micrographs revealed relatively homogeneous dispersion and sheet nanostructures oriented in the direction of the melt flow. Incorporation of clay particles during processing had practically no influence on PLA characteristics but enhanced PBS degradation when an organo-modifier was employed. This was in agreement with thermal stability data deduced from thermogravimetric analysis. Cold crystallization experiments directly performed on micro-molded PLA specimens pointed to a complex influence of clay particles reflected by the increase or decrease of the overall non-isothermal crystallization rate when compared to the neat polymer. In all cases, the addition of clay led to a clear decrease in the Avrami exponent.

  • Isothermal and non-isothermal crystallization kinetics of a polyglycolide copolymer having a tricomponent middle soft segment

     Marquez Lobato, Yolanda; Franco Garcia, Maria Lourdes; Turon Dols, Pau; Puiggali Bellalta, Jorge
    Thermochimica acta
    Date of publication: 2014-06-10
    Journal article

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    Kinetics of isothermal and non-isothermal crystallization studies of a biodegradable monofilament suture constituted by polyglycolide hard blocks and soft segments derived from glycolide, epsilon-caprolactone and trimethylene carbonate have been undertaken by means of calorimetric methods. This segmented polymer was semicrystalline with melting and crystallization characteristics defined by the polyglycolide hard segments. The amorphous phase had a glass transition temperature highly influenced by thermal processing and the random microstructure of the soft segment. Melting process was complex due to the occurrence of lamellae with different degree of perfection. Equilibrium melting point, determined by the Hoffman-Weeks methodology, became slightly lower than reported for polyglycolide and segmented copolymers having a lower soft segment content.; A heterogeneous nucleation and a three-dimensional crystal growth were characteristic for isothermal crystallizations performed from the melt state, being the Avrami exponent very close to 3 for all experiments. Secondary nucleation constant was evaluated from the overall crystallization rates and by assuming the validity of Lauritzen-Hofmann approach. Results point out a maximum rate for a crystallization temperature of 131 degrees C and probably an underestimated nucleation constant.; Kinetic parameters for non-isothermal crystallization were deduced by Avrami, Ozawa and Caze methods. A good agreement with isothermal parameters was only attained with the last methodology, although results from the other ones were appropriate to simulate the crystallization process. lsoconversional analysis was a good methodology to estimate the secondary nucleation constant from a non-isothermal crystallization. (C) 2014 Elsevier B.V. All rights reserved.

    Kinetics of isothermal and non-isothermal crystallization studies of a biodegradable monofilament suture constituted by polyglycolide hard blocks and soft segments derived from glycolide, epsilon-caprolactone and trimethylene carbonate have been undertaken by means of calorimetric methods. This segmented polymer was semicrystalline with melting and crystallization characteristics defined by the polyglycolide hard segments. The amorphous phase had a glass transition temperature highly influenced by thermal processing and the random microstructure of the soft segment. Melting process was complex due to the occurrence of lamellae with different degree of perfection. Equilibrium melting point, determined by the Hoffman-Weeks methodology, became slightly lower than reported for polyglycolide and segmented copolymers having a lower soft segment content.; A heterogeneous nucleation and a three-dimensional crystal growth were characteristic for isothermal crystallizations performed from the melt state, being the Avrami exponent very close to 3 for all experiments. Secondary nucleation constant was evaluated from the overall crystallization rates and by assuming the validity of Lauritzen-Hofmann approach. Results point out a maximum rate for a crystallization temperature of 131 degrees C and probably an underestimated nucleation constant.; Kinetic parameters for non-isothermal crystallization were deduced by Avrami, Ozawa and Caze methods. A good agreement with isothermal parameters was only attained with the last methodology, although results from the other ones were appropriate to simulate the crystallization process. lsoconversional analysis was a good methodology to estimate the secondary nucleation constant from a non-isothermal crystallization. (C) 2014 Elsevier B.V. All rights reserved.

  • Synthesis and characterization of poly(ester amides)s with a variable ratio of branched odd diamide units

     Murase Fernandez, Sara Keiko; Puiggali Bellalta, Jorge; Del Valle Mendoza, Luis Javier; Franco Garcia, Maria Lourdes
    Journal of applied polymer science
    Date of publication: 2014-04-05
    Journal article

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    The synthesis of a series of poly(ester amide)s constituted by glycolic acid, adipic acid, and different ratios of 1,3-pentanediamine and 1,5-pentanediamine units was studied and the derived copolymers were characterized. Thermal polycondensation between the potassium adipate salt and the appropriate ratio of N,N-bis(chloroacetyl)-1,3-pentanediamine and N,N-bis(chloroacetyl)-1,5-pentanediamine was proved to be effective, proceeded with high yield, and rendered samples with moderate molecular weight for carefully controlled competitive thermal degradation reactions. Physical properties were highly dependent on the final composition. In particular, crystallinity and thermal stability decreased with 1,3-pentanediamine unit content, that is, with the incorporation of lateral ethyl groups into the main chain. The presence of these units also changed solubility in solvents like methanol and degradability in a protease K enzymatic medium. Specifically, incorporation of 1,3-pentanediamine units led to a gradual increase in degradability. All poly(ester amide)s were able to establish intermolecular hydrogen bonding interactions, which in semicrystalline samples pointed to typical sheet structures of polyamides according to X-ray diffraction and infrared spectroscopic data. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40102.

    The synthesis of a series of poly(ester amide)s constituted by glycolic acid, adipic acid, and different ratios of 1,3-pentanediamine and 1,5-pentanediamine units was studied and the derived copolymers were characterized. Thermal polycondensation between the potassium adipate salt and the appropriate ratio of N,N-bis(chloroacetyl)-1,3-pentanediamine and N,N-bis(chloroacetyl)-1,5-pentanediamine was proved to be effective, proceeded with high yield, and rendered samples with moderate molecular weight for carefully controlled competitive thermal degradation reactions. Physical properties were highly dependent on the final composition. In particular, crystallinity and thermal stability decreased with 1,3-pentanediamine unit content, that is, with the incorporation of lateral ethyl groups into the main chain. The presence of these units also changed solubility in solvents like methanol and degradability in a protease K enzymatic medium. Specifically, incorporation of 1,3-pentanediamine units led to a gradual increase in degradability. All poly(ester amide)s were able to establish intermolecular hydrogen bonding interactions, which in semicrystalline samples pointed to typical sheet structures of polyamides according to X-ray diffraction and infrared spectroscopic data. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40102.

  • Structural transitions of nylon 47 and clay influence on its crystallization behavior

     Morales Gámez, Laura Teresa; Casas Becerra, M. Teresa; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    European polymer journal
    Date of publication: 2013-06
    Journal article

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    Basic diffraction data on nylon 47 pointed out a peculiar structure of hydrogen bonds along two directions. Nylon 47 showed reversible polymorphic transitions during heating/cooling processes that were analyzed by real time synchrotron WAXD experiments. Results indicated that nylon 47 had a first structural transition at low temperature, followed by a gradual Brill transition towards a pseudohexagonal packing. Nylon 47 crystallized from the melt giving rise to spherulites with different characteristics than those attained with conventional even-even nylons. Interestingly, spherulites crystallized at low supercooling underwent a reversible change in birefringence with temperature. This was due to the reversible structural changes caused by temperature variations and the flat on lamellar morphology. Intercalated and exfoliated nanocomposites based on nylon 47 were prepared by solution intercalation and melt mixing using Cloisites 25A and 30B. The influence of the final silicate layer morphology on the hot crystallization behavior was investigated. Crystallization rates of the neat polymer and its two nanocomposites were significantly different, mainly due to variations in the primary nucleation

  • Study on the hydrolytic degradation of the segmented GL-b-[GL-co-TMC-co-CL] -b-GL copolymer with application as monofilar surgical suture

     Marquez Lobato, Yolanda; Franco Garcia, Maria Lourdes; Turon Dols, Pau; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Polymer degradation and stability
    Date of publication: 2013-12
    Journal article

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    The hydrolytic degradation of Monosyn¿, a segmented copolymer derived from glycolide, trimethylene carbonate and e-caprolactone, has been evaluated in buffered aqueous media at different pH and temperature. Degradation processes have been followed by considering mass loss and molecular weight profiles as well as the changes on 1H NMR and FTIR spectra, morphology and both calorimetric and mechanical properties during exposure to the selected media and temperature. In all cases, the mass and molecular weight evolutions fitted with first order kinetic processes which were indicative of a random chain scission mechanism. Rate constants were found to strongly depend on temperature and pH. A slight deviation towards a backbiting mechanism was only found in the acid medium at long exposure times when degradation progresses through crystalline domains and recombination of ester groups were probable. Amorphous and glycolide rich domains were more susceptible to the hydrolytic attack as revealed from mechanical assays and both spectroscopic and calorimetric data. Morphological changes occurring during degradation were highly dependent on pH and indeed different steps affecting the outer (longitudinal cracks) and inner (transversal cracks) parts of sutures could be distinguished. The high content on amorphous soft segments gave rise to well-defined circumferential cracks that affected the inner part of exposed sutures and were interpreted as a consequence of the hydrolytic attack to intralamellar regions. © 2013 Elsevier Ltd. All rights reserved.

    The hydrolytic degradation of Monosyn™, a segmented copolymer derived from glycolide, trimethylene carbonate and e-caprolactone, has been evaluated in buffered aqueous media at different pH and temperature. Degradation processes have been followed by considering mass loss and molecular weight profiles as well as the changes on 1H NMR and FTIR spectra, morphology and both calorimetric and mechanical properties during exposure to the selected media and temperature. In all cases, the mass and molecular weight evolutions fitted with first order kinetic processes which were indicative of a random chain scission mechanism. Rate constants were found to strongly depend on temperature and pH. A slight deviation towards a backbiting mechanism was only found in the acid medium at long exposure times when degradation progresses through crystalline domains and recombination of ester groups were probable. Amorphous and glycolide rich domains were more susceptible to the hydrolytic attack as revealed from mechanical assays and both spectroscopic and calorimetric data. Morphological changes occurring during degradation were highly dependent on pH and indeed different steps affecting the outer (longitudinal cracks) and inner (transversal cracks) parts of sutures could be distinguished. The high content on amorphous soft segments gave rise to well-defined circumferential cracks that affected the inner part of exposed sutures and were interpreted as a consequence of the hydrolytic attack to intralamellar regions. © 2013 Elsevier Ltd. All rights reserved.

  • Bioactive nanomembranes of semiconductor polythiophene and thermoplastic polyurethane: Thermal, nanostructural and nanomechanical properties

     Perez Madrigal, Maria Del Mar; Giannotti, Marina I.; Oncins Marco, Gerard; Franco Garcia, Maria Lourdes; Armelin Diggroc, Elaine; Puiggali Bellalta, Jorge; Sanz Carrasco, Fausto; Del Valle Mendoza, Luis Javier; Aleman Llanso, Carlos Enrique
    Polymer Chemistry
    Date of publication: 2013-02-07
    Journal article

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  • Study on the hydrolytic degradation of glycolide/trimethylene carbonate copolymers having different microstructure and composition

     Diaz Celorio, Elena; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Polymer degradation and stability
    Date of publication: 2013-01
    Journal article

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    Hydrolytic degradation of a series of copolymers synthesized by ring opening polymerization of trimethylene carbonate and glycolide was studied by following the weight loss and changes in molecular weight, polydispersity index and mechanical properties. Analyses of H-1 NMR and FTIR spectra taken during exposure to a pH 7.4 phosphate buffered solution were also performed. Copolymers with different microstructures (i.e. random, triblock and segmented copolymers) were synthesized. Most segmented copolymers studied had identical trimethylene carbonate content but differed in the hard segment content. Composition was also varied to demonstrate the influence of the soft segment composition. Results were consistent with a model where degradation started in the amorphous phases and affected the glycolide units of the less compact soft segments and the regions within lamellar stacks. This degradation step led to a clear decrease of GGG triads (NMR data) and amorphous glycolide content (FTIR data), as well as an increase in Young's modulus. Degradation subsequently proceeded through the crystalline glycolide units belonging to lamellar stacks. The molecular weight of the degraded samples reached always an asymptotic value that corresponded to a solubility limit for fragments with high TMC content and for highly crystalline entities constituted by glycolide rich fragments. Results pointed to the importance of the hard segment content and the composition of the soft segment, which logically influenced the distribution between amorphous and crystalline phases.

  • Influence of microstructure on the crystallization of segmented copolymers constituted by glycolide and trimethylene carbonate units

     Diaz Celorio, Elena; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Express polymer letters
    Date of publication: 2013-02
    Journal article

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  • Nanospheres and nanocapsules of amphiphilic copolymers constituted by methoxypolyethylene glycol cyanoacrylate and hexadecyl cyanoacrylate units

     Valente, Ilaria; Del Valle Mendoza, Luis Javier; Casas Becerra, M. Teresa; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge; Marchisio, D.
    Express polymer letters
    Date of publication: 2013-01
    Journal article

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  • Structural transitions and spherulitic crystallization of even-odd nylons as examples of polyamides able to adopt structures with different hydrogen bonding directions

     Murase Fernandez, Sara Keiko; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    AUSE Conference
    Presentation's date: 2013-09-04
    Presentation of work at congresses

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  • Study on the crystallization of segmented copolymers constituted by polyglycolide hard segments and poly8glycolide-co-trimethylene carbonate)soft segments

     Marquez Lobato, Yolanda; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    International Symposium Frontiers in Polymer Science
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • Study on the crystallization behaviour of poly(butylene succinate-co-butylene azelate) copolymers

     Diaz Andrade, Angelica Maria; Casas Becerra, M. Teresa; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    International Symposium Frontiers in Polymer Science
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • Study on the hydrolytic degradation of a segmented copolymers constituted by polyglycolide hard segments and a middle poly(glycolide-co-trimethylene carbonate-co-caprolactone)soft segment (Monosyn)

     Marquez Lobato, Yolanda; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    International Symposium Frontiers in Polymer Science
    Presentation's date: 2013-05
    Presentation of work at congresses

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  • Thermal degradation studies of poly(trimethylene carbonate)blends with either polylactide or polycaprolactone

     Marquez Lobato, Yolanda; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Thermochimica acta
    Date of publication: 2012-10-04
    Journal article

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    The thermal stability and degradation kinetics of poly(trimethylene carbonate) (PTMC) blends with different ratios of polylactide (PLA) and alternatively polycaprolactone (PCL) were investigated by thermogravimetric analysis under a nitrogen atmosphere. These studies were extended to the single components (i.e. PCL and PLA). In all cases, the derivative thermogravimetric curves indicated a complex decomposition process with at least two degradation steps. The kinetic parameters of the main step, including activation energy, reaction model and pre-exponential factor, were evaluated by the Kissinger, isoconversional (Friedman and KAS) and Coats¿Redfern methods. Data of the main decomposition process were obtained by mathematical deconvolution of experimental DTG curves acquired at heating rates ranging from 2 to 40 °C/min. It was demonstrated that degradation of blends did not correspond to a mere superposition of the characteristic decomposition processes of the two involved polymers. Furthermore, PCL and PLA influenced the decomposition of the less thermally stable PTMC component in a different way. Thus, PLA modified the degradation of PTMC, and specifically led to thermal stabilization and a new decomposition process characterized by a higher activation energy. On the other hand, PCL favored the degradation of PTMC by enhancing a typical minor decomposition process that occurred in the single component at a lower temperature. The main decomposition step of PTMC, PLA, PCL and the studied blends always followed an Avrami model but with significant differences in their exponents (i.e. from 2 to 7

    The thermal stability and degradation kinetics of poly(trimethylene carbonate) (PTMC) blends with different ratios of polylactide (PLA) and alternatively polycaprolactone (PCL) were investigated by thermogravimetric analysis under a nitrogen atmosphere. These studies were extended to the single components (i.e. PCL and PLA). In all cases, the derivative thermogravimetric curves indicated a complex decomposition process with at least two degradation steps. The kinetic parameters of the main step, including activation energy, reaction model and pre-exponential factor, were evaluated by the Kissinger, isoconversional (Friedman and KAS) and Coats–Redfern methods. Data of the main decomposition process were obtained by mathematical deconvolution of experimental DTG curves acquired at heating rates ranging from 2 to 40 °C/min. It was demonstrated that degradation of blends did not correspond to a mere superposition of the characteristic decomposition processes of the two involved polymers. Furthermore, PCL and PLA influenced the decomposition of the less thermally stable PTMC component in a different way. Thus, PLA modified the degradation of PTMC, and specifically led to thermal stabilization and a new decomposition process characterized by a higher activation energy. On the other hand, PCL favored the degradation of PTMC by enhancing a typical minor decomposition process that occurred in the single component at a lower temperature. The main decomposition step of PTMC, PLA, PCL and the studied blends always followed an Avrami model but with significant differences in their exponents (i.e. from 2 to 7).

  • New Sulfonated Polystyrene and Styrene¿Ethylene/Butylene¿Styrene Block Copolymers for Applications in Electrodialysis

     Müller, Franciélli; Ferreira, Carlos Arthur; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge; Aleman Llanso, Carlos Enrique; Armelin Diggroc, Elaine
    Journal of physical chemistry B
    Date of publication: 2012-09
    Journal article

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  • Copolymerization of potassium chloroacetate and potassium N-chloroacetyl-6-aminohexanoate

     Murase Fernandez, Sara Keiko; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Journal of applied polymer science
    Date of publication: 2012-11-15
    Journal article

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  • Biodegradable free-standing nanomembranes of conducting polymer:polyester blends as bioactive platforms for tissue engineering

     Armelin Diggroc, Elaine; Gomes, Alex Linardi; Perez Madrigal, Maria Del Mar; Puiggali Bellalta, Jorge; Franco Garcia, Maria Lourdes; Del Valle Mendoza, Luis Javier; Rodriguez Galan, Rafael Alfonso; Campos, J.S.D.C.; Ferrer Anglada, Nuria; Aleman Llanso, Carlos Enrique
    Journal of materials chemistry B
    Date of publication: 2012-01-14
    Journal article

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  • Thermal degradation studies on homopolymers and copolymers based on trimethylene carbonate and glycolide units

     Diaz Celorio, Elena; Franco Garcia, Maria Lourdes; Marquez, Yolanda; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Thermochimica acta
    Date of publication: 2012-01-20
    Journal article

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    The non-isothermal degradation kinetics of poly(trimethylene carbonate) (PTMC) and polyglycolide (PGL) was investigated by thermogravimetric (TG and DTG) analysis in the temperature range between 50 and 550 °C at different heating rates (0.5–40 °C/min). Both homopolymers showed a complex multi-step degradation process. Kinetic analysis was successfully performed for the main degradation steps using the isoconversional Kissinger–Akahira–Sunose and Friedman methods. Activation energies of these steps were practically independent of the degree of conversion. The true kinetic triplets (E, A, f(α)) were determined by the Coats–Redfern method. The results clearly indicated that the two homopolymers mainly degraded by quite different mechanisms, i.e. A3 and F1, which may be associated with different depolymerization processes (e.g. decarboxylation or unzipping). Degradation of copolymers of trimethylene carbonate and glycolide with different chemical microstructures (i.e. random, blocky and segmented) and of blends with different percentages of both homopolymers was also studied. Interestingly, a deceleration and an acceleration for the decomposition of trimethylene carbonate and glycolide segments were observed, respectively. Specifically, the two-step degradation process of the blend with 50 wt% of each homopolymer was analyzed by the above methodologies. Kinetic data indicated that the main degradation process involved a different mechanism from that previously determined for PTMC and PGL, and that the activation energy was intermediate (i.e. EPTMC < EBlend < EPGL).

  • Synthesis of glycolide/trimethylene carbonate copolymers: influence of microstructure on properties

     Diaz Celorio, Elena; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    European polymer journal
    Date of publication: 2012-01
    Journal article

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    Copolymers of glycolide and trimethylene carbonate with different compositions and microstructures (i.e. random, blocky and segmented) were synthesized by two-step ring opening polymerization. NMR analyses revealed that transesterification reactions took place during the first step, which corresponded to the synthesis of soft segments, and mainly when the trimethylene carbonate content of the reaction medium was high. The transesterification percentage did not significantly change with the addition of hard blocks in the second reaction step. Infrared spectroscopy was a complementary, highly effective tool to evaluate the hard segment length, crystallinity and glycolide percentage incorporated into the crystalline phase for all studied samples. Calorimetric analyses showed dependency of properties on the length of the polyglycolide hard segment and also good miscibility between glycolide and trimethylene carbonate rich phases. Crystalline morphologies attained with segmented and random copolymers were significantly different, although in all cases a positive birefringence was detected. Thermogravimetric analyses indicated that all studied copolymers had a similar degradation behavior, which was intermediate between those observed in the corresponding homopolymers. Samples with a significant glycolide unit content showed a stabilizing effect for the degradation of poly(trimethylene carbonate) blocks.

  • Influence Of Composition And Microstructure On Properties Of New Trimethylene Carbonate/Glycolide Copolymers With Biomedical Applications

     Díaz Celorio, Elena
    Defense's date: 2012-07-23
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Study of Nanocomposites Prepared from Polyamides and Biodegradable Polyesters and Poly(ester amide)s  Open access

     Morales Gámez, Laura Teresa
    Defense's date: 2012-01-23
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    Polymer clay nanocomposites of polyamides and biodegradable polymers with three kinds of organomodified clays were prepared by different techniques (in situ polymerization, solution casting, and melt mixing). The polymers used in this research were nylons 56, 65 and 47 and the biodegradable polymers: poly (glycolic acid-alt-6-hydrohexanoic acid) and poly(glycolic acid-alt-6-aminohexanoic acid). The development of biodegradable nanocomposites with improved or modified material properties is an interesting topic since these new materials are expected to replace already existing biodegradable and non-biodegradable commodity plastics in some specific applications.This project aims to study the influence of clay particles incorporated in a polymer matrix on the crystallization processes, the study of the in situ polymerization kinetics of mixtures of clays and monomers of biodegradable polymers, as well as the influence of nanoparticles on the thermal behavior and morphologic parameters. Even-odd, and odd-even polyamides were chosen to study the Brill transition and to prepare nanocomposites with organomodified clays. These polyamides have a peculiar structure where hydrogen bonds are established along two different directions. X-ray diffraction as well as SAXS-WAXD synchrotron experiments were employed to study the structural changes induced by temperature, during heating and cooling. Different organomodified clays were used to prepare nanocomposites, which final structure was found to be dependent on the preparation method. Nanocomposites derived from biodegradable polymers were characterized by means of X-ray diffraction and transmission electron microscopy. Morphological studies showed that the extent of clay dispersion depended on the clay type and on the preparation technique. Hence, exfoliated and intercalated nanocomposites could be obtained. The final nanocomposite structure was found to have a great influence on both cold and hot crystallization processes. Hence, the crystallization rate increased and decreased with respect to the neat polymer when intercalated and exfoliated structures were respectively obtained. The kinetics of the polymerization process was also studied by means of FTIR and SAXS-WAXD. The results indicate that the presence of the organomodified clay had a remarkable effect on the kinetic parameters.

  • Thermal stability studies on clay nanocomposites prepared from a degradable poly(ester amide) constituted by glycolic acid and 6-aminohexanoic acid

     Morales Gámez, Laura Teresa; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Thermochimica acta
    Date of publication: 2011-01
    Journal article

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    An intercalated nanocomposite of the organically modified montmorillonite Cloisite C25A and a degradable poly(ester amide) based on glycolic acid and 6-aminohexanoic acid units (poly(glc-alt-amh)) was prepared using a twin-screw co-rotating extruder. The non-isothermal degradation kinetics was investigated by thermogravimetric analysis (TG and DTG) in the temperature range of 50–600 ◦C at five heating rates (2, 5, 10, 20 and 40 ◦C/min) and compared with the neat polymer. Significant differences were found since the nanocomposite showed three degradation steps instead of the two decomposition processes detected in the pristine sample. The onset mass loss temperature decreased in the nanocomposite due to the presence of the organo-modifier compound, but the presence of the silicate layers significantly decreased the degradation rate at the last stages of decomposition. Kinetic analysis was performed using the Kissinger method and the isoconversional (Kissinger–Akahira–Sunose and Friedman) methods. The true kinetic triplets (E, A, f(˛)) were determined for the first two steps of degradation through the Coats–Redfern and the Invariant Kinetic Parameters methods. The results clearly indicated that the presence of the organo-modified clay modified the mechanisms of degradation.

  • Electrospinning of polylactide and polycaprolactone mixtures for preparation of materials with tunable drug release properties

     Del Valle Mendoza, Luis Javier; Camps, Roger; Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Journal of polymer research
    Date of publication: 2011-11
    Journal article

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    Nanocomposites of new biodegradable poliesters and polyesteramides  Open access

     Puiggali Bellalta, Jorge; Morales Gámez, Laura Teresa; Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Del Valle Mendoza, Luis Javier; Rodriguez Galan, Rafael Alfonso
    Plastics research online
    Date of publication: 2011-03-16
    Journal article

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    Polymers are easily prepared by bulk polycondensation based on metal-halide salt formation, while crystallization is strongly influenced by incorporation and distribution of silicate nanoparticles.

  • Poly(ester amide) nanocomposites by in situ polymerization: Kinetic studies on polycondensation and crystallization

     Morales Gámez, Laura Teresa; Jones, Ignacio; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Express polymer letters
    Date of publication: 2011
    Journal article

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  • New biodegradable poly(ester amide)s: study of polymerization, crystallization and degradation processes

     Botines Mas, Maria Emma
    Defense's date: 2011-09-30
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Crystallization studies on a clay nanocomposite prepared from a degradable poly(ester amide) constituted by glycolic acid and 6-aminahexanoic acid

     Morales Gámez, Laura Teresa; Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge
    Polymer engineering and science
    Date of publication: 2011-08
    Journal article

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  • Preparation and release study of ibuprofen-loaded porous matrices of a biodegradable poly(ester amide) derived from L -alanine units

     Del Valle Mendoza, Luis Javier; Roca, Diana; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge; Rodriguez Galan, Rafael Alfonso
    Journal of applied polymer science
    Date of publication: 2011-11
    Journal article

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    Scaffolds of a biodegradable poly(ester amide)constituted of L-alanine, sebacic acid, and 1,12-dodecanediol units (abbreviated as PADAS) were prepared by the compression-molding/particulate-leaching method. The influence of the type, size, and percentage of salt on the scaffold porosity and morphology was evaluated. The thermal behavior and crystallinity were also studied for samples obtained under different processing conditions. PADAS scaffolds were not cytotoxic because they showed good cell viability and supported cell growth at a similar ratio to that observed for the biocompatible materials used as a reference. The use of PADAS scaffolds as a drug-delivery system was also evaluated by the employment of ibuprofen, a drug with well known anti-inflammatory effects. Different drug-loading methods were considered, and their influence on the release in a so¨rensen’s medium was evaluated as well as the influence of the scaffold morphology. A sustained release of ibuprofen could be attained without the production of a negative effect on the cell viability. The release kinetics of samples loaded before melt processing was well described by the combined Higuchi/first-order model. This allowed the estimation of the diffusion coefficients, which ranged between 3x10‾14 and 5x10‾13 m2/ s. Samples loaded by immersion in ibuprofen solutions showed a rapid release that could be delayed by the addition of polycaprolactone to the immersion medium (i.e., the release rate decreased from 0.027 to 0.015 h‾1).

  • Nonisothermal crystallization behavior of a biodegradable segmented copolymer constituted by glycolide and trimethylene carbonate units

     Díaz Celorio, Elena; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Journal of applied polymer science
    Date of publication: 2011-02-05
    Journal article

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  • Crystallization studies on clay nanocomposites of nylon 47

     Franco Garcia, Maria Lourdes; Morales Gámez, Laura Teresa; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge
    European Polymer Congress
    Presentation's date: 2011
    Presentation of work at congresses

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    Aliphatic polyester and Poly(ester amide) Clay nanocomposites by In-situ Polymerization  Open access

     Morales Gámez, Laura Teresa; Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Date of publication: 2011
    Book chapter

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  • Handbook of Biodegradable Polymers

     Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Date of publication: 2011
    Book chapter

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    Biodegradable Poly(Ester Amide)s: Synthesis and Applications  Open access

     Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Date of publication: 2011
    Book chapter

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  • Copolymers of trimethylene carbonate and glycolide: synthesis and relationship between microstructure and properties

     Díaz Celorio, Elena; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    European Polymer Congress
    Presentation's date: 2011
    Presentation of work at congresses

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  • Study on the copolymerization of potassium chloroacetate and potassium n-chloroacetyl-6-aminohexanoate

     Murase Fernandez, Sara Keiko; Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    European Polymer Congress
    Presentation's date: 2011
    Presentation of work at congresses

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  • Study on the crystallization of poly(nonamethylene azelate) and its copolymers incorporating pimelate moieties

     Diaz Andrade, Angelica Maria; Franco Garcia, Maria Lourdes; Díaz Rodríguez, Raúl; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge
    European Polymer Congress
    Presentation's date: 2011
    Presentation of work at congresses

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  • Electrospinning of polylactide and polycaprolactone mixtures for preparation of materials with tunable drug release properties

     Del Valle Mendoza, Luis Javier; Camps, Roger; Díaz, Angélica; Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    International Symposium Frontiers in Polymer Science
    Presentation's date: 2011-05
    Presentation of work at congresses

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  • Poly(ester amide) nanocomposites by in situ polymerization: kinetic studies on polycondensation and crystallization

     Morales Gámez, Laura Teresa; Jones Camacho, Ignacio; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    International Symposium Frontiers in Polymer Science
    Presentation's date: 2011-05
    Presentation of work at congresses

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  • Crystallization Behavior of Clay Nanocomposites Prepared from a Degradable Alternating Copolyester Constituted by Glycolic Acid and 6-Hydroxyhexanoic Acid

     Morales Gámez, Laura Teresa; Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge
    Journal of polymer science. Part B, polymer physics
    Date of publication: 2010-01
    Journal article

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  • Isothermal crystallization study on a biodegradable segmented copolymer constituted by glycolide and trimethylene carbonate units

     Diaz Celorio, Elena; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Journal of applied polymer science
    Date of publication: 2010-04-05
    Journal article

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    The isothermal crystallization behavior of a segmented copolymer constituted by hard blocks of polyglycolide and soft segments derived from the copolymerization of glycolide and trimethylene carbonate was investigated. This polymer has applied relevance because it is one of the most widely used for bioabsorbable surgical sutures. Calorimetric, optical microscopy, and infrared techniques were combined to understand the thermal properties and the different factors that influence the crystallization process. Basically, only the hard blocks crystallized, although certain processing conditions allowed performing an additional crystallization associated with small lamellar domains of the soft segment. Crystallization from both the melt and the glass state rendered positive spherulites with a fibrillar texture. The observed unusual sign of birefringence was a consequence of the close packing structure of polyglycolide, which was also corroborated by electron diffraction patterns. Crystallization was characterized by an athermal nucleation, which allowed accurate estimation of the secondary nucleation parameter by using the calorimetric data only. Significant differences in the Avrami exponent (from 2.32 to 1.45) were found between the cold and hot isothermal crystallizations. The stronger geometric constraints observed in the crystallization from the glass state were also corroborated by FTIR analyses

  • Influence of degradation on the crystallization behaviour of a biodegradable segmented copolymer constituted by glycolide and trimethylene carbonate units

     Franco Garcia, Maria Lourdes; Rodriguez Galan, Rafael Alfonso; Puiggali Bellalta, Jorge
    Polymer degradation and stability
    Date of publication: 2010-12
    Journal article

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    The influence of degradation on non-isothermal crystallization from the melt of a segmented copolymer constituted of glycolide and trimethylene carbonate units and used as a bioabsorbable surgical suture was studied by optical microscopy, differential scanning calorimetry and time-resolved X-ray diffraction. Fibrillar positive spherulites were obtained with slightly degraded samples but new axialitic morphologies were detected when samples had a molecular weight, Mw, lower than 29,000 g/mol and the crystallization started at a high temperature. Crystal growth kinetics of samples degraded under different conditions was evaluated over a wide temperature range by a non-isothermal method. Two crystallization regimes (I and II) were determined for the more degraded samples (i.e., those able to crystallize according to axialitic and spherulitic morphologies), whereas only regime II was found for samples of higher molecular weights. Primary nucleation density decreased with the extent of degradation provided no morphological changes occurred, and so did the regularity of lamellar stacking, as shown by synchrotron measurements, although the morphological parameters remained practically constant.

  • Study on the brill transition and melt crystallization of nylon 65: A polymer able to adopt a structure with two hydrogen-bonding directions

     Morales Gámez, Laura Teresa; Ricart López, Albert; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    European polymer journal
    Date of publication: 2010-11
    Journal article

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    Degradable Poly(ester amide)s for biomedical aplications  Open access

     Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Polymers
    Date of publication: 2010-12-27
    Journal article

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    Poly(ester amide)s are an emerging group of biodegradable polymers that may cover both commodity and speciality applications. These polymers have ester and amide groups on their chemical structure which are of a degradable character and provide good thermal and mechanical properties. In this sense, the strong hydrogen‑bonding interactions between amide groups may counter some typical weaknesses of aliphatic polyesters like for example poly(e-caprolactone). Poly(ester amide)s can be prepared from different monomers and following different synthetic methodologies which lead to polymers with random, blocky and ordered microstructures. Properties like hydrophilic/hydrophobic ratio and biodegradability can easily be tuned. During the last decade a great effort has been made to get functionalized poly(ester amide)s by incorporation of a-amino acids with hydroxyl, carboxyl and amine pendant groups and also by incorporation of carbon-carbon double bonds in both the polymer main chain and the side groups. Specific applications of these materials in the biomedical field are just being developed and are reviewed in this work (e.g., controlled drug delivery systems, hydrogels, tissue engineering and other uses like adhesives and smart materials) together with the main families of functionalized poly(ester amide)s that have been developed to date.

  • Brill transition and melt crystallization of nylon 56: An odd¿even polyamide with two hydrogen-bonding directions

     Morales Gámez, Laura Teresa; Soto, David X.; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Polymer
    Date of publication: 2010-11-12
    Journal article

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    Brill transition and crystallization behaviour of nylon 56, a representative polymer of odd–even polyamides, were investigated by simultaneous WAXD and SAXS synchrotron radiation. Nylon 56 crystallized from solution into a peculiar structure where hydrogen bonds were established along the two directions. Nylon 56 experimented on heating a Brill transition that lead to a pseudohexagonal packing and lately to a monoclinic unit cell where neighbouring molecular segments were shifted along the chain axis direction. In disagreement with conventional polyamides, the Brill transition of nylon 56 was not reversible since on cooling the pseudohexagonal arrangement was mainly attained. Optical microscopy studies performed under both isothermal and non-isothermal conditions demonstrated that nylon 56 spherulites had different optical properties than even–even nylons having conventional sheet structures. The birefringence sign changed in the sequence positive–negative–positive when crystallization temperature was decreased.

  • MATERIALES BASADOS EN UNIDADES DE TRIMETILENCARBONATO. NANOCOMPUESTOS DE POLIESTERES Y POLIESTERAMIDAS CON APLICACIONES COMMODITIES

     Franco Garcia, Maria Lourdes; Del Valle Mendoza, Luis Javier; Rodriguez Galan, Rafael Alfonso; Casas Becerra, M. Teresa; Urpi Garriga, Lourdes; Puiggali Bellalta, Jorge
    Participation in a competitive project

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  • Sequence analysis of glycolide and p-dioxanone copolymers

     Rodriguez Galan, Rafael Alfonso; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    Journal of polymer science. Part A, polymer chemistry
    Date of publication: 2009-11
    Journal article

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    Low and medium molecular weight copolymers constituted by glycolide and p-dioxanone units have been synthesized by a ring-opening polymerization. The p-dioxanone monomer was obtained from (2-hydroxyethoxy)acetate or by thermal depolymerization of poly(p-dioxanone). 1H and 13C NMR spectra were highly sensitive to the chemical sequences, which were effectively assigned by considering the data from samples with different compositions, and the acquisition of heteronuclear 1H and 13C NMR-correlated spectra. End groups were also identified, allowing methylene protons of sequences involving up to two glycolide units to be distinguished. These data seem basic to analyze degradation products or the influence of thermal treatments in chain microstructure. Glycolide/p-dioxanone copolymers are an interesting system because changes on chemical sequences can easily occur due to a depolymerization reaction that eliminates p-dioxanone residues. Furthermore, depending on the polymerization conditions, the occurrence of transesterification reactions may be highly significant. These reactions have a great impact in properties such as the melting temperature and can be easily quantified by NMR spectroscopy because of the occurrence of a new chemical sequence

  • Degradable polyoctamethylene suberate/clay nanocomposites. Crystallization studies by DSC and simultaneous SAXS/WAXD synchrotron radiation

     Gestí, S; Zanetti, M; Lazzari, M; Franco Garcia, Maria Lourdes; Puiggali Bellalta, Jorge
    European polymer journal
    Date of publication: 2009-02
    Journal article

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  • Poly(ester amide)/Clay Nanocomposites Prepared by In Situ Polymerization of the Sodium Salt of N-Chloroacetyl-6-Aminohexanoic Acid

     Morales Gámez, Laura Teresa; Franco Garcia, Maria Lourdes; Casas Becerra, M. Teresa; Puiggali Bellalta, Jorge
    Journal of polymer science. Part A, polymer chemistry
    Date of publication: 2009-07
    Journal article

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