Improving the processibility and mechanical properties of poly(lactic acid)/linear low‐density polyethylene/paraffin wax blends by subcritical gas‐assisted processing

Abstract

Previous studies have shown that paraffin wax (PW) is capable of improving the ductility and fluidity of poly(lactic acid) (PLA) matrices. However, PLA and PW are immiscible, thus the low melting temperature of PW (at around 558C) will pose some processing difficulties and/or practical application limitations on PLA/PW blends. Since linear low-density polyethylene (LLDPE) and PW exhibited miscibility at a 90%/10% weight ratio and a melting temperature of 1238C, LLDPE was added to the PLA/PW blends in order to increase their thermal stability, processability, and elongation-at-break. The blends were prepared by a twin-screw extruder using two different melt compounding processes: conventional melt compounding extrusion and subcritical gas-assisted processing. Then, neat PLA, LLDPE, and the blends were injection molded into tensile bars for evaluation. To observe the effects of the two melt compounding processes, the thermal properties, mechanical properties, and phase morphologies of the various blends were characterized. The physical foaming agent (nitrogen, N 2 ) used in the subcritical gas-assisted processing process also plasticized the melt, thereby reducing the likelihood of thermal degradation and improving the mixing performance. POLYM. ENG. SCI., 00:000-000, 2018.

Durable Polylactic Acid (PLA)-Based Sustainable Engineered Blends and Biocomposites: Recent Developments, Challenges, and Opportunities

“…Chen et al 155 worked on enhancing the processability and mechanical strength of PLA. In this work, paraffin wax (PW) was mixed with PLA to improve the ductility and fluidity of the matrix.…”

Lightweight and tough PVDF foams via high‐pressure foam injection molding with core‐back operation

“…In order to normalize the effect of foaming, following previous studies, the obtained specific property parameters were divided by sample density. [ 4 ] Figure 8A presents the specific tensile strength for the pure PVDF and PVDF 70 blend with different void fractions. Generally, the specific tensile strength of injection‐molded PVDF 70 blend were higher than that of the pure PVDF under any void fractions.…”

“…By changing the core-back distances, different weight reduction of PVDF foams were obtained. [3,4] For instance, to obtain foamed samples with weight reduction of 30%, 40%, and 50%, we shifted a portion of the moveable part of the mold from 0 to 1.25, 2 and 3 mm respectively. Finally, samples in the mold were cooled and shaped to form foamed products.…”

“…In addition, compared with the solid samples, polymeric foams have many distinctive characters, such as the low density, high impact strength, and good thermal and acoustic insulation. [3][4][5] Polyvinylidene fluoride (PVDF) is a polymeric plastic with many excellent benefits, such as corrosion resistance, oxidation resistance, flame retardancy, piezoelectric, and dielectric properties. These merits make it have been widely applied as the membrane material and electronic device, which also attracts people use it as the foaming material.…”

“…In addition, compared with the solid samples, polymeric foams have many distinctive characters, such as the low density, high impact strength, and good thermal and acoustic insulation. [ 3–5 ]…”