Recycling poly(ethylene terephtalate) wastes: Properties of poly(ethylene terephtalate)/polycarbonate blends and the effect of a transesterification catalyst

Abstract

The article addresses the issue of recycling of poly(ethylene terephtalate) (PET) by melt blending with polycarbonate (PC). PET/PC blends containing various amounts of the immiscible polymers were prepared in a twin-screw extruder. Selected compositions were also prepared in the presence of an Sn-based catalyst to assess the influence of transesterification during melt mixing. The degree of miscibility in the blends was studied using differential scanning calorimetry, scanning electron microscopy, and mechanical testing. PET/PC blends exhibit enhanced tensile properties in comparison to neat components for compositions of PET higher than 50% and these properties are improved by the addition of a transesterification catalyst. The PET/PC blend containing 20 wt% of PC, prepared with stannous octoate, shows the smallest size of the dispersed phase because of transesterification reactions that generate copolymer molecules at the interface between the immiscible polymers. The melting temperature of PET is decreased with the increase of the PC content in blends extruded in the presence of the catalyst. Also, the temperatures of the cold crystallization of PET are higher than those of similar blends without added catalyst. Both features give rise to better molding properties because of a shortening of the cooling time in the range of 50-90 wt% of PET

Effects of composition and transesterification catalysts on the physico-chemical and dynamic properties of PC/PET blends rich in PC

“…PC90 blend has the finest dispersed phase compared with PC80 or PC70 that have a less uniform dispersion with a higher number average particle size. Significantly, the number average particle size of dispersed phases that are mentioned here are in the same range that has been cited by other works for blends containing equal or more than 10% by weight of PET [27][28][29][30].…”

“…There is a shift in curves to make space between them and so the maximum and width peak of the peaks appear clearer components especially in the presence of catalysts. This copolymer may reduce the mobility of the PET chains on the crystal surface because of the constraints from the high T g PC domains and the copolymer chains will also act as defects during chain folding [27]. In addition, the reduced particle size and the well distribution of these particles could play an important rule in the T cc shifting.…”

Properties of Recycled-Polyethylene Terephthalate/Polycarbonate Blend Fabricated by Vented Barrel Injection Molding

“…A co-continuous morphology with small droplets can be found only in 50% PC as shown in Figure 2(b). Mbarek et al have also reported that a cocontinuous morphology is only found in a 50/50 blend composition of PET/PC [22].…”

Reciclagem de rejeitos de poli(tereftalato de etileno) (PET) e de poliamida (PA) por meio de extrusão reativa para a preparação de blendas

“…Para a preparação das blendas, a primeira etapa foi a pré-mistura dos dois polímeros nas quantidades de PET/PA de 1500/0 (PET), 1125/375 (PA25), 750/750 (PA50), 375/1125 (PA75) e 0/1500 (PA) em gramas juntamente com 1,5 mL do catalisador 2-etilexanoato de estanho (II) para cada amostra, medidos em uma pipeta volumétrica. O catalisador tem como função auxiliar na compatibilidade das blendas durante a etapa seguinte de extrusão, por meio da catálise de trans-reações entre o PET e a PA [13] .…”