Recycled poly(ethylene terephthalate)/linear low‐density polyethylene blends through physical processing

Abstract

Poly(styrene-ethylene/butylene-styrene) (SEBS) was used as a compatibilizer to improve the thermal and mechanical properties of recycled poly(ethylene terephthalate)/linear low-density polyethylene (R-PET/LLDPE) blends. The blends compatibilized with 0-20 wt % SEBS were prepared by low-temperature solid-state extrusion. The effect of SEBS content was investigated using scanning electron microscope, differential scanning calorimeter, dynamic mechanical analysis (DMA), and mechanical property testing. Morphology observation showed that the addition of 10 wt % SEBS led to the deformation of dispersed phase from spherical to fibrous structure, and microfibrils were formed at the interface between two phases in the compatibilized blends. Both differential scanning calorimeter and DMA results revealed that the blend with 20 wt % SEBS showed better compatibility between PET and LLDPE than other blends studied. The addition of 20 wt % of SEBS obviously improved the crystallizibility of PET as well as the modulus of the blends. DMA analysis also showed that the interaction between SEBS and two other components enhanced at high temperature above 130 C. The impact strength of the blend with 20 wt % SEBS increased of 93.2% with respect to the blend without SEBS, accompanied by only a 28.7% tensile strength decrease.

Recycling Polymer Blends

“…The best compatibility was found when 20 wt% of maleated SEBS with positive effects on the elastic modulus and impact strength in agreement with the other studies (Zhang et al 2008;Jeziórska 2006). SEBS-g-MA was also used as compatibilizer impact modifier for blends of r-PET with different polyethylenes (LLDPE, LDPE, m-PE) to evaluate the influence of the structural differences of the PE phase on the properties of the material (Zhang et al 2011). In the work, moreover, the effect of the molecular weight of LLDPE was also evaluated.…”

“…In a study, SEBS-g-MA was used to improve the thermal stability and the mechanical properties of r-PET/LLDPE blends (Zhang et al 2009). In this case, therefore, instead of using distinct compounds -namely, the maleated one and the impact modifier -the functions of compatibilization and impact modification are committed to only one additive.…”

Recycling of poly(ethylene terephthalate) – A review focusing on chemical methods

“…Besides such additives, the addition of other polymers (e. g. polyethylene, polypropylene) or inorganic materials (clay minerals) has been applied for thermomechanical PET recycling to improve mechanical properties of the recyclate [81][82][83][84][85][86][87][88][89][90][91][92][93][94]. In addition to blending PET with a second polymer, the use of compatibilizers such as ethylene vinyl acetate, ethylenebutyl acrylate-glycidyl methacrylate copolymer, poly (styrene-ethylene/butylene-styrene) and epoxy-chain extenders has been applied to further improve mechanical properties [82][83][84][85][86]. Although the use of additives to PET can improve properties of thermo-mechanically recycled PET, it ultimately leads to a downcycling of the material, since this material becomes increasingly difficult to be recycled again due to the heterogeneous and inherent composition of PET with the other components.…”

Melt rheology and properties of compatibilized recycled poly(ethylene terephthalate)/(styrene‐ethylene‐ethylene‐propylene‐styrene) block copolymer blends

“…Melt blending has been thought to be a practical and economic approach to improve the properties of the notch-sensitive polymers [10][11][12]. Recently, several studies have been done to improve the toughness of R-PET by blending or compounding with different polymers, such as polycarbonate [13], acrylonitrile-butadiene-styrene [14,15], high-density polyethylene [16][17][18], linear low-density polyethylene [19,20], polypropylene [21,22], poly(ethyleneoctene) [23,24], styrene-ethylene-butadiene-styrene (SEBS) [25], and ethylene-glycidyl methacrylate copolymer [26]. Among them, elastomer modification is generally recognized to be a feasible choice to improve the toughness of R-PET based on the finer dispersion of small elastomer particles in the R-PET matrix.…”