Thermal, physico‐mechanical, and morphological properties of HDPE graft‐copolymerized with polystyrene

Abstract

In this study, polystyrene was graft‐copolymerized onto high‐density polyethylene (HDPE) by in situ polymerization of styrene monomer to change the physico‐mechanical and thermal properties of HDPE. The grafting was carried out in a Brabender‐type static mixer by injecting styrene monomer directly into the molten HDPE in the presence of a free‐radical initiator (lauroyl peroxide or LP). The effect of wt% of styrene and initiator concentrations on thermal, physico‐mechanical, and morphological properties of HDPE was investigated. The neat and modified HDPE was characterized by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and also by tensile strength and contact angle measurements. It was found that the increase in wt% of styrene and LP dosage reduced elongation at break, hygroscopic expansion and also the melting, and the crystallization temperatures of HDPE but increased its tensile strength. The tensile strength was increased from 14.6 MPa for the neat HDPE to 20.6 MPA for the 10 wt% of styrene grafted onto HDPE using 0.8% LP. Scanning electron microscopy results show that there was no phase separation, and the grafted polystyrene became integral part of HDPE. The results demonstrate that styrene could be used in melt compounding to improve various properties of HDPE. Copyright © 2015 John Wiley & Sons, Ltd.

Enhancing the Sound and Thermal Insulation Properties of Polypropylene Foam by Preparing High Melt Strength Polypropylene

“…Compared with pure PP, the crystallinity of each graft‐modified sample decreased, which is mainly caused by the amorphous structure of the St molecular chain and graft chain. [ 33 ]…”

Thermal stability, mechanical properties, impact strength, and uniaxial extensional rheology of reactive blends of PS and SBS polymers

“…Thomann et al found that in the case of SBS/PS blend, SBS with a substantial 'PS softening' effect was found to preferentially form elongated PB lamellar morphologies, which lead to increasing ductility [42]. On the other hand, several researchers reported that grafting of PS onto macromolecular chains of HDPE and polyurethane (PU) copolymer increased the tensile strength of HDPE and PU respectively [1,43]. It was also reported that the addition of a small amount of PP to LDPE in the presence of DCP increased the tensile strength of LDPE [44].…”

“…to convert a low performing polymer into a high performing polymer. For example, the grafting of PS onto high-density polyethylene (HDPE) improves the tensile strength and decreases its hygroscopic expansion [1].…”