In this study, acrylate (ACR) copolymer was used to toughen polylactide (PLA). Dynamic mechanical analysis and differential scanning calorimetry results showed that PLA was partially miscible with ACR. Isothermal crystalline behavior indicated that the incorporation of ACR significantly prevented the crystallization of PLA. The transmission electron micrograph showed that ACR was uniformly dispersed in PLA matrix. The mechanical properties of PLA could be improved by the addition of ACR. The analysis of yield stress indicated mild interfacial adhesion between PLA and ACR. Scanning electron micrograph of PLA/ACR blends revealed that the major toughening mechanism was matrix shear yield and plastic flow. Complex viscosity values of PLA/ACR blends were remarkably improved with the incorporation of ACR. Moreover, the van Gurp–Palmen plot, the rheological percolation threshold for the blends was lower than 15 wt%. The incorporation of ACR decreased the absorption coefficient (α), which was caused decreasing transmittance of PLA. POLYM. ENG. SCI., 55:386–396, 2015. © 2014 Society of Plastics Engineers

Poly(lactic acid) (PLA) was plasticized with acetyl tributyl citrate (ATBC). The plasticized PLA was further blended with poly(ethylene octene) grafted with glycidyl methacrylate (POE-g-GMA denoted as GPOE) using a twin-screw extruder and the extruded samples were blown using the blown thin film technique. Both ATBC and GPOE significantly influenced the physical properties of the films. Compared to neat PLA, the elongation at break and tear strength of the films were significantly improved. The cavitation and large plastic deformation observed in films subjected to the tear test were the important energy-dissipation process, which led to a torn PLA film. Moreover, the PLA/ATBC/GPOE blown films had better transparency and water tolerance than that of neat PLA. GPOE could act as a tear resistance modifier for PLA blown films. These findings contributed new knowledge to the additives area and gave important implications for designing and manufacturing polymer packaging materials. POLYM. ENG. SCI., 55:2801–2813, 2015. © 2015 Society of Plastics Engineers

Glycidyl methacrylate-functionalized methyl methacrylate–butadiene (MB-g-GMA) copolymers were prepared via an emulsion polymerization process. These functionalized copolymers were blended with polylactide (PLA). Dynamic mechanical analysis and differential scanning calorimetry results showed that the addition of MB-g-GMA did not result in a marked change in the glass transition temperature of PLA. With an increase of MB-g-GMA content, the tensile strength of the blends decreased; however, the elongation at break and impact strength increased significantly. From scanning electron micrographs, there was large plastic deformation (shear yielding) in blends subjected to impact tests, which was an important energy-dissipation process and led to a toughened polymer. Rheological investigation demonstrated that there was a significant dependence of viscosity on composition. When the MB-g-GMA content increased, the viscosity began to increase. © 2013 Society of Chemical Industry

Polylactide (PLA) is an attractive candidate for replacing petrochemical polymers because it is biodegradable. In this study, a specific PLA 2002D was melt-mixed with a new plasticizer: glycerol monostearate (GMS). The PLA/GMS blends with different ratios were analyzed by dynamic mechanical analysis and differential scanning calorimetry. Although a slightly phase separation can be seen in DSC curves, the SEM micrographs of the impact fracture surfaces of PLA/GMS blends had a relatively good separation and this phenomenon was in good agreement with their higher impact strength. The result showed that the adding of GMS has enhanced the flexibility of PLA/GMS blends as compared to neat PLA. The relationship between complex viscosity and angular frequency of the PLA/GMS blends exhibits that the melt viscosity substantially lower than that of neat PLA. For example, at 10 rad/s, the melt viscosity of PLA/GMS (85/15) was reduced by about 7.2% compared to that of neat PLA. The impact strength was changed from 4.7 KJ/m² for neat PLA to 48.2 KJ/m² for 70/30 PLA/GMS blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Biodegradable stereocomplex-type poly(l-lactide) (PLLA)/poly(d-lactide) (PDLA)/multiwalled carbon nanotubes (MWCNTs) nanocomposites are prepared via simple melt blending method at PDLA loadings from 5 to 20 wt %. Formation of the stereocomplex crystals in the nanocomposites is confirmed by the phase transition in the differential scanning calorimetric profiles. Field emission scanning electron microscopy observation indicates that MWCNTs are nicely dispersed in the PLLA/PDLA/MWCNTs ternary blends with 20 wt % PDLA loading due to the increased shear stress in the melt-compounding with presence of PDLA. The overall crystallization rates are faster in the PLLA/PDLA/MWCNTs nanocomposites than in PLLA/MWCNTs nanocomposite; however, the crystallization mechanism and crystal structure of these nanocomposites remain unchanged despite the presence of PDLA. The storage modulus above glass transition temperature has been apparently improved in the PLLA/PDLA/MWCNTs nanocomposites with respect to PLLA/MWCNTs nanocomposite. It is interesting to find that the hydrolytic degradation rates have been enhanced obviously in the PLLA/PDLA/MWCNTs nanocomposites than in PLLA/MWCNTs nanocomposite, which may be of great use and importance for the wider practical application of PLLA/MWCNTs nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3919–3929, 2013