Poly(lactic acid) (PLA) toughening is often associated with significant modulus and/or strength losses making it unsuitable for many consumer and biomedical applications. The major objective of this research was to toughen PLA without significant loss in modulus and strength and to introduce reactive acid groups using reactive blending of PLA with a combination of polymers. PLA was reactive blended with poly(acrylic acid) (PAA) followed by physical blending with poly(ethylene glycol) (PEG) in solution. The modified PLA was extruded into films using a co‐rotating twin‐screw extruder and characterized using tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA). This technology resulted in films with a ten‐fold increase in toughness compared to neat PLA with little or no decrease in strength and modulus.
A novel approach to PLA toughening is proposed in this study. Poly(lactic acid) (PLA) is toughened using poly(ethylene‐n‐butylene‐acrylate‐co‐glycydyl methacrylate) (EBA‐GMA) as a reactive compatibilizer with the aid of an epoxy‐based chain extender. It is found that the toughening effect of EBA‐GMA in the binary blend investigated is strongly influenced by blending temperature. Blending at high temperatures which are non‐typical for PLA processing (over 250 °C) allows toughness to be increased by an order of magnitude when compared to the toughness of blends prepared at low temperatures (below 200 °C). This effect is attributed to a combination of factors, namely an increasing rate of reactive bonding between PLA and EBA‐GMA at elevated temperatures and enhanced interfacial adhesion between PLA and EBA‐GMA phases. DSC studies show that PLA/EBA‐GMA bonding on the interface acts as an efficient nucleator for PLA. The nucleation ability of the PLA/EBA‐GMA interface strongly depends on blend processing temperature and gradually increases with increasing blending temperature. The PLA/EBA‐GMA interface shows its highest nucleation ability at 250 °C.
This research focuses on brittleness improvement of biodegradable poly(lactic acid) (PLA) by reactive melt blending with poly(trimethylene terephthalate) (PTT). First, PLA is simultaneously blended with PTT and a reactive compatibilizer, poly(ethylene‐co‐glycidyl methacrylate) (PEGMA), (one‐step blending procedure). In the PLA/PTT/PEGMA blend, PEGMA mainly disperses in the PLA matrix phase, and the blend shows unimproved tensile properties. To increase the reaction between PTT and PEGMA, PEGMA is sequentially blended with PTT then PLA (two‐step blending procedure). This procedure is effective in drastically enhancing elongation at break of the blend. The strain at break of the blend formed by two‐step blending is significantly improved because the blending procedure affects the blend morphology. PLA‐g‐PEGMA‐g‐PTT graft copolymer is formed at the interface between PLA and PTT during reactive melt blending with PEGMA when the two‐step blending procedure is employed as a blending method which is confirmed by Fourier transform infrared spectroscopy and viscosity measurement. Such features bring about craze formation during tensile test and this is the reason why the toughening is achieved by the two‐step blending procedure. 相似文献
The modification of polypropylene (PP) fibers via blending with recycled poly(lactic) acid (r-PLA) flakes by a melt spinning method was investigated. Mechanical and morphological properties, biodegradability, differential scanning calorimetery (DSC) analysis, and dyeing behavior were carried out for physical and structural characterization of the fiber samples. The results showed that the PP/r-PLA blend fibers with the different blend ratios could be successfully melt spun along with suitable continuity. Acceptable tenacity and initial modulus and suitable biodegradability were obtained for the modified PP fibers. Dye uptake of the modified PP fiber samples was improved and the washing and light fastness of some them were excellent. 相似文献