Search

ABSTRACT: The polylactide (PLA) was blended with poly(1,2‐propylene glycol adipate) (PPA) and poly(butylene carbonate) (PBC). Then the extruded PLA/PPA/PBC blends were processed in the form of blown films. All of the ingredients used in the films are biodegradable. The miscibility, fracture surface morphology, and rheological properties of the PLA/PPA/PBC blends, further thermal properties, the tear‐fracture surface morphology, crystalline morphology, and mechanical and optical properties of the blown films were investigated. PPA did not enhance the miscibility between PLA and PBC. From SEM micrographs of the cryogenically fracture surfaces, PBC particles evenly dispersed in the PLA matrix. It could increase the nucleating density of the spherulites and decrease the size of the spherulites of PLA. The results indicated that the 85.5/9.5/5 PLA/PPA/PBC film had excellent tensile strength, elongation at break, tear strength, and transmittancy. The shear yielding induced by cavitation of PBC particles was the major tearing mechanism during the film tear test. The enzymatic degradation of PLA was slightly retarded in the presence of both PPA and PBC. These findings contribute new knowledge to the additives area and give important implications for manufacturing biodegradable polymer packaging materials. [ABSTRACT FROM AUTHOR]

Blends of poly(butylene terephthalate) (PBT)/thermoplastic polyurethane (TPU) were prepared by melt compounding. The miscibility, crystallization behaviors and toughening mechanism of the PBT/TPU blends were studied. Dynamic mechanical analysis results demonstrated that PBT was immiscible with TPU. Differential scanning calorimetry and wide angle X-ray diffraction results showed that the crystallinity of PBT decreased with increasing TPU content. Furthermore, blending with TPU did not modify the crystal structure of PBT. The small angle X-ray scattering results indicated that the crystal layer thickness decreased and the amorphous layer thickness increased with increasing TPU content, indicating that TPU mainly resided in the interlamellar region of PBT spherulites in the blends. An obvious improvement in toughness of PBT was achieved with addition of TPU. Neat PBT had elongation at break and impact strength of about 15 % and 2.9 kJ/m, respectively. However, the elongation at break and impact strength of the 70/30 PBT/TPU blend reached 410 % and 62.9 kJ/m, respectively. The morphology of the PBT/TPU blends after tensile and impact tests was investigated, and the corresponding toughening mechanism is discussed. It was found that the PBT showed obvious shear yielding in the blend during the tensile and impact tests, which induced dissipation of energy and, therefore, led to the improvement in toughness of the PBT/TPU blends. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]