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In order to improve the electromagnetic interference (EMI) shielding performance of poly(vinylidene fluoride) (PVDF), both carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) as functional fillers were chosen and employed in this work. The PVDF‐based composites were prepared through melt blending and the hybrid fillers exhibited fine interaction with PVDF matrix. CNTs and GNPs could act as heterogeneous nucleation agents for PVDF matrix, thus increased the crystallization peak temperature. The gradual formation of interconnected conductive network of hybrid fillers could improve the conductivity and rheological properties of PVDF effectively. Especially, in contrast to those of pure PVDF, about four orders of magnitude increment for their storage modulus and complex viscosity of PVDF/GNPs/CNTs composite as well as approximate 10 orders of magnitude improvement in their electrical conductivity were obtained. Adding 2 wt% CNTs in PVDF matrix could generate the conductive network and further GNPs addition was helpful to obtain higher EMI shielding effectiveness. The new PVDF samples would possess wide applications as electromagnetic shielding materials, on account of their simple processing, low‐cost and without use of organic solvent characteristics.

In order to improve the viscoelasticity and foamability, poly (butylene succinate) (PBS) was modified through reactive melt mixing with chain extender (CE) having multi epoxy-groups. Subsequently, the prepared chain extended PBS (CEPBS) was foamed in a high pressure stainless steel autoclave using CO 2 as physical blowing agent. The molecular weight, thermal properties, rheological properties, and foam properties of various PBS samples were characterized using gel permeation chromatography, differential scanning calorimetry, rotational rheometer, and scanning electron microscope, respectively. With the introduction of CE, the molecular weight, the crystallization temperature, the complex viscosity and storage modulus of PBS were increased and the crystallization degree of PBS was decreased. At the CE content of 0.75 phr, the cross-linking structure was formed and the expansion volume ratio increased to nearly 15 times, which meant the chain extension played an important role in the foaming process of PBS. POLYM. ENG. SCI., 55:988-994, 2015.

High breakdown strength and low dielectric loss are necessary for the outdoor insulator using silicone rubber (SR) composites. In this work, polydopamine coated mica (mica-PDA) was synthesized via bioinspired dopamine self-polymerization, and mica-PDA-filled SR composite (SR/mica-PDA-VTMS) was prepared using vinyl tri-methoxysilane (VTMS) as a silane coupling agent which serves as the molecular bridges between the organic rubber and the inorganic filler. The SR/mica-PDA-VTMS composite demonstrated dense and uniform morphology where the filler was well dispersed. Due to the strong interfacial interactions between filler and rubber, the SR/mica-PDA-VTMS composite exhibits much lower dielectric loss compared to the other mica-filled SR composites, which was comparable to the prepared alumina-tri-hydrate-filled SR composites. Moreover, the breakdown strength of ~31.7 kV/mm and tensile strength of 5.4 MPa were achieved for the SR/mica-PDA-VTMS composite, much higher than those of the other as-prepared SR composites.

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Different content of dicumyl peroxide (DCP) acting as a crosslinking agent was mixed with high-density polyethylene (HDPE) in a Haake internal mixer to improve the viscoelasticity and foamability of HDPE. The crosslinked HDPE samples were foamed in a high pressure stainless steel autoclave using CO 2 as the physical blowing agent. The molecular weight, crystallization behavior and rheological properties of various HDPE samples were examined by gel permeation chromatography, differential scanning calorimetry, rotational rheometer, and torque rheometer, respectively. The foaming properties of various samples were characterized by scanning electron microscope and densimeter. It was found that with the increasing content of DCP, the molecular weight, crystallization temperature, complex viscosity, and storage modulus of HDPE increased and the crystallization degree of HDPE decreased. When 0.2 phr of DCP was introduced into HDPE, the expansion volume ratio of HDPE showed the highest value, which could be more than 7 times.

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