Valorization of poly(butylene terephthalate) wastes by blending with virgin polypropylene: Effect of the composition and the compatibilization

Abstract

Blends of recycled poly(butylene terephthalate) (PBT) parts obtained from scrapped cars, and virgin polypropylene (PP), were prepared in a twin‐screw extruder at different compositions. Selected compositions were also prepared with the presence of ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA) compatibilizers. The effect of the composition and the type of compatibilizer, as well as the mixing conditions, on the morphology phase, thermal, viscoelastic behavior, and mechanical properties of the blends has been investigated. Blends PP/PBT of various composition exhibit a coarse morphology and a poor adherence between both phases, resulting in the decrease of ductility, whereas at weak deformation, PBT reinforced the tensile properties of PP. Addition of E‐GMA and E‐MA‐GMA to the PP/PBT blend exhibited a significant change in morphology and improved ductility because of interfacial reactions between PBT end chains and epoxy groups of GMA that generate EG‐g‐PBT copolymer. Moreover, thermal and viscoelastic study indicated that the miscibility of PP and PBT has been improved further and the reactions were identified. The E‐MA‐GMA results in the best improvement of ductility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Compatibilization of polypropylene/ poly(3‐hydroxybutyrate) blends

“…As expected, PHB presented the lowest value of impact strength and elongation, whereas the PP/PHB blend without compatibilizer presented intermediary properties between those of pure PP and PHB. When any of the compatibilizers was incorporated, the impact strength and elongation of the ternary blends increased significantly when compared to the PP/PHB blend, which is a typical result found in the literature when an elastomeric compatibilizer is added to a mixture 4, 7, 9–11, 13, 16, 23, 39. This result could be due to toughening by addition of a material with elastomeric character and/or the occurrence of effective compatibilization.…”

“…The efficiency of P(E–MA) as a compatibilizer for the PP/PHB system could also be attributed to physical effects, and it was greater than PP–MAH, possibly because of the higher amount of functional groups contained in P(E–MA) (29 vs 2 wt %, see Table I). Transesterification reactions were unlikely to have occurred between acrylate and polyester as they are very slow kinetically and can be neglected unless long residence times or catalysts are employed 10, 14, 23. In fact, in a previous study of PBT/P(E–MA) blends, the authors could not find the existence of grafted PBT, which indicated the absence of a reaction in this system 48.…”

“…The most applied compatibilization technique in these systems is the use of compatibilizers containing groups able to react with polyester end groups (COOH and OH). Among these compatibilizers, the most frequently used are the ones with glycidyl methacrylate (GMA), [3][4][5][6][7][8][9][10][11][12][13][14][15][16] oxazoline, [17][18][19] and maleic anhydride (MAH) [11][12][13][14][15][16][20][21][22][23][24][25][26] functions grafted in polymers such as PP, polyethylene, and styrene-ethylene/butylenestyrene rubber (SEBS). The GMA group contains an epoxy moiety at the end of its chain, which is highly reactive with the polyester COOH end group and also able to react with the polyester OH end group, although the reaction with COOH occurs primarily and is 10-20 times faster.…”

“…There are also a few works in which compatibilizers used for polyolefin/polyester system were copolymers containing only acrylate groups, such as methyl acrylate (MA), ethyl acrylate, and butyl acrylate, 14,16 and copolymers containing acrylate together with GMA and MAH groups. 9,10,15 Although it is possible that acrylate and polyester undergo transesterification reactions, it has already been pointed out that these reactions are unlikely to occur and are less predominant than the epoxy/COOH reaction. 28 Some studies have compared the efficiency between GMA, MAH, and acrylate groups; they all converged in indicating the better performance of the epoxy-containing molecule.…”

Preparation and characterization of nanocomposites with polyphenylene oxide

“…In some cases, their addition even weakens the mechanical properties (Li et al, 2010;Barhoumi et al, 2008). First, copolymers themselves offer little benefit to the strength and stiffness of polymer blends because they tend to be "soft" materials.…”