Chain extension reaction in solid‐state polymerization of recycled PET: The influence of 2,2′‐bis‐2‐oxazoline and pyromellitic anhydride

Abstract

in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: Conventional and chain extended-modified solid-state polymerization (SSP) of postconsumer poly(ethylene terephthalate) (PET) from beverage bottles was investigated. SSP was carried out at several temperatures, reaction times, and 2,2 0 -bis-2-oxazoline (OXZ) or pyromellitic anhydride (ANP) concentrations. The OXZ was added by impregnation with chloroform or acetone solution. Higher molecular weights were reached when the reaction was carried out with OXZ, resulting in bimodal distribution. The molecular weights of the flakes reacted at 230 C for 4 h were 85,000, 95,000, and 100,000 for samples impregnated with 0, 0.5, and 1.25 wt % OXZ solution, respectively. In the case of reactions with ANP, branched chains were obtained. The thermal and thermal-mechanical-dynamic properties of these high-molecular-weight recycled PET were determined. For OXZ-reacted samples, the reduction of crystallinity was observed as the reaction time was increased, becoming evident the destruction of the crystalline phase. The chain extended samples did not show changes in thermal relaxations or thermal degradation behavior.

Effect of copolymers synthesized by nitroxide‐mediated polymerization as chain extenders of postconsumer poly(ethylene terephthalate) waste

“…Consequently, there is a need to develop an appropriate technology for improvement of r‐PET properties, to make it suitable for new applications. Several methods, such as the addition of virgin polymers , fillers , compatibilizers , and chain extenders have been described in the literature to compensate for PET degradation by mechanical reprocessing.…”

“…For instance, undesired side reactions taking place when using bis(oxazolines), due to the sensitivity to acidic compounds of oxazoline rings, have been reported. The use of di‐isocyanates is also limited due to their toxicity and product discoloration .…”

Modification of poly(ethylene terephthalate) by combination of reactive extrusion and followed solid‐state polycondensation for melt foaming

“…investigated the effects of SSP reaction temperature and time on the IV of the recycled PET. An increase in the IV from 0.73 to 1.48 dL/g was obtained after SSP at 230°C for 8 h. Recently, Nascimento et al . investigated the chain extended‐modified SSP of recycled PET, in which PET flakes previously impregnated with chain extender were submitted to SSP at different temperatures and for different residence times.…”

Chain extension of poly (ethylene terephthalate) by reactive extrusion with secondary stabilizer

“…These rejects are almost always deposited in land wastes, causing pollution or several others environmental problems 3,5,6 . Many studies have been carried out with the use of chain extenders to recover properties of low molecular weight PET [7][8][9][10][11][12][13][14] . Chemical compounds such as anhydride and organophosphorus are some agents used as chain extender for PET.…”

“…Chemical compounds such as anhydride and organophosphorus are some agents used as chain extender for PET. Chain extenders have two or more reactive sites in molecule, which can react with terminal groups of polymeric chains, bonding each other and increasing molecular weight of the polymer [11][12][13][14][15][16] . In this work was studied the effects of the reactive incorporation of the stabilizer Irgafos 126 (IRG) on the PET wastes, which have showed an action as a chain extender for PET.…”