Poly /PLLA blend

Poly(Mactide) Blends. In recent years, poly(Z-lactide) (PLLA) received increasing attention because it is produced from renewable recourses and because of its biodegradability. 

To overcome the drawbacks of PVOH/PLA blends (a phase-separated system) and PVAc/PLA blends (a decreased enzymatic degradation of PLA), PLA (M = 367 kDa) was solution blended with a random amorphous copolymer of poly (vinyl acetate-co-vinyl alcohol) (P(VAc-co-VA)) [90]. It was expected that P(VAc-co-VA)/PLA blends could have better miscibility and mechanical properties (obtained from PVAc), including desirable rates of enzymatic and nonen-zymatic degradation (obtained from PVOH) at particular vinyl content [90]. However, the of PLLA blended with P(VAc-co-VA) comprised of 10, 20, and 30 mol% vinyl alcohol were —0.04, 0.029, and 0.007, respectively [90]. Only the blend comprised of 10 wt% P(VAc-co-VA) containing 10 mol% vinyl alcohol had a single Tg [90]. Thus, overall P(VAc -co-VA)/PLA blends are immiscible, whereas partial miscibility seems to occur only with a low vinyl alcohol content. P(VAc-co-VA) was also expelled out of the inter-fibrillar regions of PLA spherulites and did not affect the crystallization behavior of PLA in the blends [90]. 

Poly(L-lactic acid) (PLLA) and poly(e-caprolactone) (PCL), and their films blended with or without 50wt% pofy(etl5rlerte glycol) (PEG), were prepared by solution easting [137]. Porous films were obtained by water extraetion of PEG from solution-cast phase-separated PLLA-blend-PCL-blend-PEG films. Polymer blending as well as pore formation enhanced the enzymatic degradatiort of biodegradable polyester blends. 

Ozaki et al. [106] studied blends of poly(R)-3-hydroxybutyrate) (PHB) and PLLA using FTIR microspectroscopy, and showed that crystalline bands were observed due to PHB, whereas those due to PLLA were hardly observed for all PHB/PLLA blends investigated. On the other hand, some crystalline bands of PLLA were observed in the microinfrared spectra of some spots in the 20/80 PHB-co-HHx/ PLLA blend. Microinfrared spectra also showed a significant difference in the compatibility and crystalline structures between the PHB-co-HHx/PLLA and PHB/PLLA blends. Figure 20.25a and b show microinfrared spectra in the 2000-1000cm region of PHB/PLLA and PHB-co-HHx/PLLA blends with 80/20 and 20/80 blending ratios. The differences in the infrared spectra between neat PHB and PHB-co-HHx lie mainly in the intensities of the crystalline and amorphous bands. The ratios of peak intensities of PHB and PLLA bands were dependent on the measurement points in both blends. In the 80/20 PHB/PLLA blend, the spectra of many spots were similar to the crystalline PHB spectrum, but the main... 

Table 5 Mechanical properties (Young s modulus E, tensile strength cr, elongation at break ) of solvent cast PHBV/poly-L-lactide (PLLA) blends (average standard deviation) [60]...

Y. Li and H. Shimizu, Improvement in toughness of poly(l-lactide) (PLLA) through reactive blending with acrylonitrile-butadiene-styrene copolymer (ABS) Morphology and properties, Eur. Polym. J., 45 (3) 738-746, March 2009. 

Blend films of poly(L-lactide) (PLLA) and poly(vinyl alcohol) (PVA) were synthesized. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid-state NMR. ... 

Furthermore for the formation of a stereocomplex which blends of poly(L-lactide) and poly (D-lactide) could be found the interesting phenomena. The PLA stereocomplex was found to possess a racemic crystalline structure, where PDLA and PLLA chains were packed side hy side with a D monomer unit to L monomer unit... 

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