The influence of nano‐PS particle on structure evolution and electrical properties of PP/PS

Abstract

The polypropylene‐g‐polystyrene (PP‐g‐PS) copolymers with different grafting ratios are used as compatibilizers to control the size of polystyrene (PS) particles at nanometer scale in polypropylene (PP) matrix. Then the PP/PS insulating nanocomposites (containing 10 wt % PS calculated from PS and PP‐g‐PS) are manufactured. With the increase in grafting ratio of PP‐g‐PS, the size of PS particle is reduced and the interfacial adhesion is enhanced. Meanwhile, the dielectric properties, DC breakdown strength and volume resistivity are increased with the decreasing of PS particle size. The spherulite size of PP is decreased and the boundary between crystals and amorphous regions is blurred or even disappears due to the presence of PS nanoparticles. This evolution of PP structure is attributed to the serious entanglements of PP and PS molecular chains. Finally, the correlation between morphological structure and electrical properties is ultimately established based on the in‐depth understanding of the molecular chain movement, crystal structure, and phase morphology. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 706–717

Enhanced High-Temperature DC Dielectric Performance of Crosslinked Polyethylene with a Polystyrene Pinning Structure

“…With the aim of characterizing the interface between XLPE and PS, SEM photographs of cryogenically fractured cross sections of samples are shown in Figure 8. XLPE with PS shows a phase separation and PS dispersed into the matrix of XLPE as spherical particles with a dimension of micrometers, thus forming a typical sea-island structure, which is similar to PP/PS blends reported by Q. Guo et al [21]. When PS is blended with LDPE, interfaces have been introduced between LDPE and PS particles and because of incompatibility, gaps and voids can be generated in the interfacial area.…”

“…Basically, carrier transfer in polymers usually occurs at the amorphous region including the spherulite boundary, and the conductivity relies on the concentration of charge carriers, the quantity of charge carriers, and mobility of charge carriers. As presented in Figure 9, PS particles distribute in the amorphous area including the spherulite boundaries and PS has a positive effect on decreasing the carrier mobility [21]. PS particles can impede the transport of charge carriers, thus DC conductivity of XLPE is decreased by the addition of PS particles.…”

Crosslinking Dependence of Direct Current Breakdown Performance for XLPE-PS Composites at Different Temperatures

“…The role of dispersed PS particles in XLPE-PS composites may be embodied in two aspects. On one hand, the existence of benzene rings could absorb the energy of high-energy electrons, reducing the risk of breakdown [ 29 ]. On the other hand, the crosslinking between PS and polyethylene improves their compatibility, leading to the decrease of defects in the interfacial area of PS and polyethylene.…”

Enhanced electrical insulating properties of polyethylene by incorporating polyethylene‐g‐polystyrene graft copolymers

“…As LLDPE‐ g ‐PS is added, the T c of the blends is located at a higher temperature and gradually increases with increasing PS content from 107.9 °C of LLDPE to 110.1 °C of S20; LLDPE‐ g ‐PS has the highest T c (110.7 °C). This is because the PS side chains play the role of heterogeneous nucleation agents in the blends, which accelerates the crystallization rate of LLDPE 8,43 . In terms of the melting temperature ( T m ) of LLDPE‐ g ‐PS and LLDPE/LLDPE‐ g ‐PS blends, no obvious changes are found compared to pure LLDPE.…”

“…Blending is a low‐cost and practical modification method. Many polymers such as polyolefin elastomer, 6,7 polystyrene (PS) 8,9 and high density polyethylene 10 are proved to be effective in improving the electrical properties of PP or low density polyethylene (LDPE). Wang et al .…”