Thermal characterization of polylactides

Jamshidi, K.; Hyon, Suong‐Hyu; Ikada, Yoshito

doi:10.1016/0032-3861(88)90116-4

Cited by 643 publications

(465 citation statements)

References 20 publications

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“…As can be seen, the glass transition temperature (T g ) of PEA-5 is about 6°C lower than that of the pure PLA because of its lower molecular weight [14]. The PEAs display a lower cold crystallization temperature but far smaller crystallinity than that of the pure PLA.…”

Section: Thermal Propertiesmentioning

confidence: 95%

Synthesis and characterization of poly(ester amide) from remewable resources through melt polycondensation

Ge¹,

Yuan²,

Luo³

et al. 2014

Express Polym. Lett.

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Abstract. Biodegradable poly(ester amide)s (PEAs) were synthesized from lactic acid and 11-aminoundecanoic acid via melt polycondensation. Molecular weights, chemical structures and thermal properties of the poly(ester amide)s were characterized in terms of gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), 1 H nuclear magnetic resonance ( 1 H NMR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The PEAs have low molecular weights and display a lower cold crystallization temperature as well as smaller crystallinity by comparison with the pure poly(lactic acid) (PLA). The incorporation of the 11-aminoundecanoic acid into the PLA chain not only improved the thermal stability but changed the decomposition process.

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Section: Thermal Propertiesmentioning

confidence: 95%

Synthesis and characterization of poly(ester amide) from remewable resources through melt polycondensation

Ge¹,

Yuan²,

Luo³

et al. 2014

Express Polym. Lett.

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“…Kale et al [16] applied Fox-Flory equation to demonstrate the reduction of the T g with the decrease of the number average molecular weight ( -M n ) of commercial PLA products during degradation in a compost. Based on this relation, which has also been applied a couple of years earlier [22], we can associate the decrease of the T g of PLA with the reduction of its molecular weight due to hydrolysis. Perhaps there was a molecular weight degradation during water absorption that would be associated with the cleavage of the chain at -C-O-ester group by water molecules due to hydrolysis.…”

Section: Thermal Propertiesmentioning

confidence: 97%

Characterization of hydrolytic degradation of polylactic acid/rice hulls composites in water at different temperatures

Ndazi¹,

Karlsson²

2011

Express Polym. Lett.

144

107

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Abstract. Hydrolytic degradations of polylactic acid/rice hulls (PLA/RH) composites with various rice hulls contents due to water absorptions at 23, 51 and 69°C were investigated by studying the thermal properties, chemical composition, molecular weight, and morphology of the degraded products. The results have attested that the stability of PLA/RH composites in water depends slightly on rice hulls contents but it is significantly influenced by water temperature. Water absorption in 30 days at 23°C was between 0.87 and 9.25% depending on rice hull contents. However, at thermophilic temperatures, the water absorption and degradation of these products were increased significantly. Saturations were achieved in less than 25 and 9 days at 51°C and 69°C, respectively, while hydrolytic degradation was demonstrated by an increase in fragility and development of crystallinity. At 69°C, there were significant reductions of the decomposition and glass transition temperatures of the polymer by 13°C. These changes were associated with the reduction of the molecular weight of PLA from 153.1 kDa to !10.7 kDa due to hydrolysis of its ester group.

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“…Despite the possibility of producing PLA and its copolymers of controlled molecular weight and chemical composition from the lactide/glycolide monomers by ring-opening polymerization (ROP), 9-13 these materials do not always show suitable or optimal properties for all the desired applications. For example, the PLA/PLGA polymers usually have a glass transition temperature of around 40-608C, 14,15 and therefore are not applicable on their own for injectable drug delivery systems. Injectable polymers themselves are receiving increased attention 16,17 as alternatives to emulsions, liposomes, or microsphere injectable drug delivery systems.…”

Section: Introductionmentioning

confidence: 99%

Poly(hexyl‐substituted lactides): Novel injectable hydrophobic drug delivery systems

Trimaille

Gurny

Möller

2006

J Biomedical Materials Res

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Poly(hexyl-substituted lactides) (PHLA) as new hydrophobic polyesters with controlled molecular weights and narrow distributions were synthesized by ring-opening polymerization (ROP) using tin(II) 2-ethylhexanoate (Sn(Oct) 2 ) and benzyl alcohol as catalyst and initiator. Glass transition temperatures (T g ) and zero shear viscosities (g 0 ) at 258C could be modulated from T g ¼ À428C to À108C and 40 to 4850 Pa s, respectively, by varying the polymer molecular weight and the number of hexyl groups along the polymer chain. Degradation studies were performed in terms of both mass and molecular weight loss in the course of time. The degradation mechanism is shown to be of the ''bulk erosion'' type, and comparable to standard poly(D,L-lactide) (PLA). Despite the increased steric hindrance in the poly(monohexyl-substituted lactide) (PmHLA) due to the hexyl side groups, its degradation rate at pH 7.4 and 378C was found to be slightly higher than observed for the analogue standard PLA. This could be attributed to the flexible rubbery state of the hexyl-substituted polymer (T g *À158C) at the physiological temperature, which is favoring the degradation in comparison to the rigid and glassy standard PLA (T g *408C). In contrast, degradation studies performed at 608C, where both polymers are above their glass transition temperature, confirmed that the degradation rate is lower for the sterically more hindered PmHLA. The degradation products were analyzed by ESI-MS. Hydrolysis lead first to the corresponding oligo-ester fragments and finally to the nontoxic 2-hydroxyoctanoic acid and lactic acid. Tetracycline was tested as a model drug for release studies. This drug was found to be released faster and in higher amounts in its active form from the PHLA matrix than from standard PLA. The results presented in this work demonstrate the potential of these hydrophobic polylactide-based semisolid materials as an alternative to conventional PLA/PLGA for injectable drug delivery systems. 2006 Wiley Periodicals, Inc. J Biomed Mater Res 80A: [55][56][57][58][59][60][61][62][63][64][65] 2007

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Thermal characterization of polylactides

Cited by 643 publications

References 20 publications

Synthesis and characterization of poly(ester amide) from remewable resources through melt polycondensation

Synthesis and characterization of poly(ester amide) from remewable resources through melt polycondensation

Characterization of hydrolytic degradation of polylactic acid/rice hulls composites in water at different temperatures

Poly(hexyl‐substituted lactides): Novel injectable hydrophobic drug delivery systems

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