Thermoplastic composites from maleic anhydride modified post‐consumer plastics

Abstract

In attempts to identify potential applications for refined commingled postconsumer plastics, a feedstock containing about 80% polyethylene (PE) and lesser amounts of poly(ethylene terephthalate) (PET), polystyrene (PS), polypropylene (PP), and poly(vinyl chloride) (PVC) was modified through functionalization with maleic anhydride in a co‐rotating intermeshing twin‐screw extruder. The modified and unmodified blends were compounded with various fillers and reinforcements such as glass fibers, mica flakes, talc, and calcium carbonate. Injection molded composites based on the modified matrix had, in general, superior mechanical and thermal properties. These findings are discussed in view of the improved adhesion resulting from reactions and/or enhanced polar interactions at phase boundaries. Several compounds prepared in this work had overall property data comparable to, or approaching those, of equivalent commercial HDPE molding compounds that are commonly used in “durable” applications.

Recycling Polymer Blends

“…Of course, an appropriate compatibilizer must be used to improve the phase adhesion and dispersion between all these polymers that form highly incompatible systems. One of the first materials used as general compatibilizing agent was chlorinated polyethylene (Paul et al 1972(Paul et al , 1973aPark et al 1996a) followed by several other polymers modified with carboxyl or other polar groups, styrene block copolymers (Paul et al 1973a;Nosker et al 1990;La Mantia 1992b, 1993bHope et al 1994;Xanthos et al 1994Xanthos et al , 1995, or maleated polymers (Martinez et al 2008). The main effect of adding such compatibilizers is a general improvement of the mechanical properties and especially of impact strength and elongation at break.…”

Talc

“…The major benefits of incorporating talc into plastics are summarized in Table 12-4 according to its primary and secondary functions, with examples obtained from refs. [1,2,3,8,13,17,21]. Primary reasons for using talc include improvements in mechanical properties such as heat def lection temperature (HDT), rigidity, creep resistance, and sometimes impact resistance, as well as lower shrinkage.…”

“…Primary reasons for using talc include improvements in mechanical properties such as heat def lection temperature (HDT), rigidity, creep resistance, and sometimes impact resistance, as well as lower shrinkage. Additional secondary benefits, because of the f laky nature of talc, include improvements in dimensional stability (as it orients along f low lines during molding) and lower permeability; other benefits are reduced coefficient of thermal expansion (CLTE), increased brightness, shortening of the injection molding cycle due to nucleation, and its use as an anti-block additive [7,8,10,13,14]. Adverse effects include reduction in toughness and elongation at break in certain polymers, reduced weld line strength, and for certain polymer/stabilizer package combinations a reduction in long-term thermal ageing and UV resistance.…”

“…It has been shown that a maleic anhydride based coupling agent can increase tensile and f lexural properties [13]. For 20 and 40% talcfilled PP, levels of 20 wt.…”

A review on composite materials based on recycled thermoplastics and glass fibres

“…9 Several methods of upgrading recycled plastics have been reported; mainly involving blending recyclate with virgin polymers, restabilisation using specialised additive formulations, compatibilisation of mixed plastics, or addition of elastomers and fillers. In particular, reinforcing recycled polymers with glass fibres (GFs) or natural fibres can lead to a composite material with a more favourable and more consistent set of properties (as reported for example by Xanthos et al 10,11 ). However, despite much industrial work on the subject, as testified by patents and publications in trade magazines, scientific literature on recycled polymer composites is still fragmentary.…”