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Melt blending with poly(ether-b-amide) copolymer (PEBA) was found to significantly enhance the toughness of poly(lactic acid) (PLA). The miscibility, morphology, thermal behavior, mechanical properties and rheological behavior of the blends were investigated. DMA and DSC analysis revealed that the PLA/PEBA blends were immiscible. A clear, phase-separated morphology was observed from SEM results. The addition of PEBA enhanced the cold crystallization of the PLA in the blends and accelerated the crystallization rate due to the interfacial function between PLA and PEBA phases. Significant enhancement of the toughness of PLA was achieved by the incorporation of PEBA copolymer. The optimum impact modification of the PLA was obtained by blending with 20 wt% PEBA, with an elongation at break of 300% as compared to 5% for pure PLA. The impact strength was ten times higher than that of the pure PLA. SEM results showed that the interfacial cavitation followed by a massive shear yielding of the matrix contributed to the increased toughening effect in the blends. The rheological measurement revealed an interaction between PLA and PEBA in the melt state.

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The influence of spinning temperature on ultrahigh-molecular-weight polyethylene/high-density polyethylene as-spun blend filaments and the influence of drawing temperature on ultrahigh-molecular-weight polyethylene/high-density polyethylene-blend fibers were investigated. The results showed that the optimum spinning and hot-drawing temperatures were 310℃ and 85℃, respectively, and blending with high-density polyethylene improved the orienting ability of the molecular chains and the crystallization ability. The blend filaments spun at 310℃ had the best molecular chain orientation, crystallinity and crystal orientation of the filaments examined; both lower and higher spinning temperatures were detrimental to the crystal structure growth of the as-spun blend filaments. The optimum drawing temperature of the blend fibers was 85℃, which resulted in blend fibers with the best molecular chain orientation, crystallization, and crystal orientation as well as the thinnest grains of the fibers examined. The highest tensile strength and initial modulus were 1204 MPa and 20.4 GPa, respectively; these high values can be attributed to the fibrillar structure, which consisted of extended molecular chains and thin grains. The results in this paper can help disclose the effect mechanism of formation temperature on the melt spinning method used to produce high-strength ultrahigh-molecular-weight polyethylene fibers.