Lactides thermal properties

H. Tsuji, Y. Kawashima, H. Takikawa, S. Tanaka, Poly(L-lactide)/nano-structured carbon composites Conductivity, thermal properties, crystallization, and biodegradation., Polymer, vol. 48, pp. 4213-4225, 2007. 

FIGURE 8.24 Chemical structure of poly(ester amide)s derived from L-lactide and characterized by having high thermal properties. 

Stridsberg, K. and Albertsson, A.-C. (2000) Changes in chemictil and thermal properties of the tri-block copolymer poly(L-lactide-b-l,5-dioxepan-2-one-b-L-lactide) during hydrolytic degradation. Polymer, 41, 7321-7330. 

Koyama H, Doi Y (1996) Misdbitity, thermal properties, and enzymatic degradability of binary blends of poly[(J )-3-hydroxybutyric acid] with poly(8-caprolactone-co-lactide). Macromolecules 29 5843-5851... 

Srisa-ard, M. and Baimark, Y. (2010) Effects of arm number and arm length on thermal properties of linear and star-shaped poly(D,L-lactide)s. / Appl. Sci, 10 (17), 1937-1943. 

Vilay, V., Mariatti, M., Ahmad, Z., Pasomsouk, K., and Todo, M. (2009) Characterization of the mechanical and thermal properties and morphological behavior of biodegradable poly(l-lactide)/poly(e-caprolactone) and poly(l-lactide)/ poly(butylene succinate-co-l-lactate) polymeric blends. /. Appl Polym. Sci., 114, 1784-1792. 

Van, S., Yin,)., Yang,)., and Chen, X. (2007) Structural characteristics and thermal properties of plasticized poly(L-lactide)-silica nanocomposites synthesized by sol-gel method. Mater. Lett., 61 (13), 2683-2686. 

Chen, C.X., Yoon, J.S. Morphology and thermal properties of poly(L -lactide)/poly (butylene succinate-co-butylene adipate) compounded with twice functionalized clay. J. Polym. Sci. Part B Polym. Phys. 43, 478-487 (2005)... 

Grijmpa, D.W., Pennings, A.J., 1994. (Co)polymers of L-lactide. 1. Synthesis, thermal properties and hydrolytic degradation. Macromolecular Chemistry and Physics 195, 1633—1647. 

The choice between distillation, crystallization, or novel separation methods such as absorption or membrane separation is determined by the desired stereochemical purity of the product. Crystallization yields highly pure lactide, suitable, for example, for high-melting PLLA homopolymer of high molecular weight. Affordable distillation equipment does not fully remove all mc.yo-lactide, and consequently, a lactide monomer mixture for PLA copolymers with other thermal properties is obtained upon ring-opening polymerization. 

Chitosan is a water-insoluble, nontoxic, edible, biodegradable polymer (polysaccharide) that is obtained commercially from chitin by alkaline deacetylation [103]. Chitosan is the second most abundant biopolymer in nature after cellulose. Since chitosan is a polycationic polymer, its high sensitivity to moisture limits its applications. One way to overcome this drawback is to blend the material with humidity resistant polymers such has PLA. Suyatma et al. [104] combined hydrophilic chitosan with hydrophobic PLA (92% L-lactide and 8% mesolactide, Mw = 49,000 Da) by solution and film mixing, resulting in improved water barrier properties and decreased water sensitivity of the chitosan films. However, testing of mechanical and thermal properties revealed that chitosan and PLA blends are incompatible. 

Until 2003, Chen s [28], Qu s [29-31], and Hu s [32] groups independently reported nanocomposites with polymeric matrices for the first time the. In Hsueh and Chen s work, exfoUated polyimide/LDH was prepared by in situ polymerization of a mixture of aminobenzoate-modified Mg-Al LDH and polyamic acid (polyimide precursor) in N,N-dimethylactamide [28]. In other work, Chen and Qu successfully synthesized exfoliated polyethylene-g-maleic anhydride (PE-g-MA)/LDH nanocomposites by refluxing in a nonpolar xylene solution of PE-g-MA [29,30]. Then, Li et al. prepared polyfmethyl methacrylate) (PMMA)/MgAl LDH by exfoliation/adsorption with acetone as cosolvent [32]. Since then, polymer/LDH nanocomposites have attracted extensive interest. The wide variety of polymers used for nanocomposite preparation include polyethylene (PE) [29, 30, 33 9], polystyrene (PS) [48, 50-58], poly(propylene carbonate) [59], poly(3-hydroxybutyrate) [60-62], poly(vinyl chloride) [63], syndiotactic polystyrene [64], polyurethane [65], poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] [66], polypropylene (PP) [48, 67-70], nylon 6 [9,71,72], ethylene vinyl acetate copolymer (EVA) [73-77], poly(L-lactide) [78], poly(ethylene terephthalate) [79, 80], poly(caprolactone) [81], poly(p-dioxanone) [82], poly(vinyl alcohol) [83], PMMA [32,47, 48, 57, 84-93], poly(2-hydroxyethyl methacrylate) [94], poly(styrene-co-methyl methacrylate) [95], polyimide [28], and epoxy [96-98]. These nanocomposites often exhibit enhanced mechanical, thermal, optical, and electrical properties and flame retardancy. Among them, the thermal properties and flame retardancy are the most interesting and will be discussed in the following sections. 

Hiroshi Urayama, Chenghuan Ma, Yoshiharu Kimura. Mechanical and thermal properties of poly(l-lactide) incorporating various inorganic fillers with particle and whisker shapes. Macromolecular Materials and Eneineerine. 2P,Wy.5h2-56S, 2003. 

Ahmed, J., Zhang, J., Song, Z., Varshnet, S.K., 2009. Thermal properties of polylactides effect of molar mass and nature of lactide isomer. J. Therm. Anal. Calorim. 95, 957—964. 

Table 7.6 Thermal Properties of Hydrolytically Degraded Poly(L-lactide) (Tsuji et al., 2008)...

In this study, lactide was polymerized by Sn-oct in the presence of polyfunctional alcohols such as glycerol or pentaerythritol. The resulting PLA had multi-armed chains to yield a star-shaped architecture. The microstructure, thermal properties, and degradation behaviour were studied to compare the effect of the different architecture, linear PLA with starshaped one. In addition, it was very beneficial to study the effect of various chain end groups on the thermal and hydrolytic stability of this multi-armed PLA. Therefore, OH terminal groups of PLA were converted into Cl, NH2 or COOH groups. 

This chapter aims at reviewing the production of such aliphatic polyester layered silicate nanocomposites and the related improvements in terms of physical, mechanical, and thermal properties. Special attention will be focused on a selected polyester, i.e., poly(e-caprolactone) (PCL), considered as a model of the family of aliphatic polyesters. These results will be then briefly extrapolated to another well-known polyester, poly(lactide) (PLA). Materials performances will be discussed and analyzed in terms of the investigated production process and related nanostructural morphology. 

The two isomers of lactic acid can give rise to three lactides 1-, d-, and meso. The fermentation process makes /-lactic acid exclusively. The chemical processing steps allow us to racemize small amounts of 1-lactic acid to d-lactic acid. This provides us with three dimers for polymerization. Figures 11.7 and 11.8 are cartoon representations of the polymer structures we can achieve from the three lactides. By varying the amount and sequence of rf-lactic units in the polymer backbone, we can change product properties, such as melt behavior, thermal properties, barrier properties, and ductility. ... 

Poly(lactide)-Poly(ethylene oxide)-Poly(lactide) Triblock Copolymers Synthesis and Thermal Properties... 

Renewable sources such as starch-made PLAs are biodegradable and compostable. They usually have very low or no toxicity but possess high mechanical performance compared to those of commercial pol5miers. However, the thermal stability of PLAs is not sufficiently high enough to use them as an alternative in many commercial pol5nner applications. Various PIA hlends have been studied to improve their thermal properties. A stereocomplex is formed from enantiomeric PLAs, poly(L-lactic acid) (PLIA), and poly(D-lactide) (PDLA) due to the strong interaction between PLLA and PDLA chains. 

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