Combining the respective advantages of PVA and shell in wastewater treatment, poly(vinyl alcohol)/shell powder (PVA/SP) porous composite suitable for the removal of heavy metal ions from wastewater was prepared via thermoplastic foaming technology using water as both plasticizer and physical blowing agent. The effects of SP content on the thermoplastic foaming mechanism including interactions among components, water states and water evaporation behaviors, as well as cell structure and Pb2+ adsorption property of the porous composite were studied. The results showed that SP could form different hydrogen bonding or coordination interactions with water and PVA, making free water in system reduced and nonfreezing water increased, thus realizing the controllable foaming of water and avoiding the formation of the big cells caused by intensive evaporation of water. SP particles could also act as heterogeneous nucleating agents to effectively increase the number of heterogeneous nucleating points in the system, resulting in the formation of denser and more uniform cells. With the increase of SP content, the adsorption capacity of porous composite on Pb2+ increased, and reached the maximum at 10 wt%, that is, 31.1 mg/g, higher than that of pure SP powders, that is, 23.4 mg/g, ascribing to the good dispersion of SP in PVA matrix as well as the high hydrophilicity of PVA porous material.

Lightweight, high-strength, and multifunctional polymer composite foams are urgently needed in various high-tech areas. Herein, we proposed a facile, clean, and energy-saving strategy to prepare the microcellular polystyrene/carbon nanotubes (PS/CNTs)...

Formation of a segregated structure in conductive polymer composites is one of the most effective strategies for achieving good electrical conductivity and electromagnetic interference (EMI) shielding performance. Nevertheless, for low-melt-viscosity poly(lactic acid) (PLA), intense molecular motion occurs at the molding temperature, which is detrimental to the fixation of the conductive networks. In this study, a novel molding technique assisted by microwave heating was proposed to construct a segregated structure in a PLA/carbon nanotube (CNT) composite. The coating layer of CNTs acted as the microwave absorber and caused intense localized heating of PLA surfaces upon microwave irradiation. The surface temperature of the PLA granule was precisely regulated by adjusting the coated CNT content, microwave power, and irradiation time. Thus, the coated granules were softened and fused at an optimal sintering zone, which effectively hindered the excessive migration of CNT strips into the interior of PLA phases, and a majority retained the original CNT network in the molded composite. Meanwhile, benefiting from microwave sintering, sufficient chain diffusion and entanglement occurred in the interfacial regions, enhancing the adhesion strength among the neighboring PLA phases. The prepared PLA/CNT composite with only 5.0 wt % CNTs exhibited a high electrical conductivity of 16.3 S/m and an excellent EMI shielding effectiveness (EMI SE) of 36.7 dB at a frequency of 10.0 GHz. The results indicate that microwave-assisted sintering might be a promising alternative for constructing a segregated structure in low-melt-viscosity polymers.