Mastication is the technique widely used to reduce viscosity of natural rubber and the higher mastication speed leads to lower NR viscosity. The optimum viscosity of NR that could provide high impact strength for the blends depends largely on the blending time and method. This study is focused on the enhancement of impact strength of polylactic acid (PLA) blended with masticated natural rubber (NR) using sorbitan ester (SE), a biodegradable food additive, as a compatibilizer. The effects of NR mastication, compatibilizer and NR contents and the mixture’s viscosity on the morphological, thermal and impact properties of PLA/NR blends were investigated in relation to the changes in the morphology, thermal properties and impact strength of PLA/NR blends. It was found that the optimum viscosity of NR that provided the highest impact strength to the blends was achieved when NR was masticated at 40 rpm for 15 min. The highest impact strength corresponded well not only with the small NR phase size, but also with the highest crystallization rate. For the effect of compatibilizer, it was found that a small amount of SE could more than double the impact strength of the blends, where the optimum compatibilizer content was 0.5 wt%. Interestingly, the high impact strength of the blends in all cases was accompanied by short interparticle distance and slightly higher percent crystallinity. 相似文献
Summary: In order to produce nanometer‐sized fibers at an industrial scale, not only the morphology but also the production rate of fibers is important. The effect of solvent properties and functionality on the production rate of electrospun PS nanofibers was investigated using eighteen different solvents. The solution concentration was varied between 10 and 30% w/v. Electrospinning of PS solutions was carried out at various applied voltages and tip‐to‐collector distances The production rate of the obtained PS nanofibers was quantified in terms of electrospinnability. We found that the chance for the resulting PS solution to be spinnable is greater for solvents with high dipole moment and low viscosity. The solvent that provided the highest electrospinnability for polystyrene was DMF and the functionalities that promoted high dipole moment and thus high spinnability were the carbonyl group and the nitrogen group with free electrons. General guidelines for choosing suitable solvents for successful production of electrospun nanofibers have also been proposed.
SEM image of PS 685D at 200× magnification and the %‐coverage of the fibers obtained by using DMF, chloroform, and 1,4‐dioxane. 相似文献