Influence of Chain Extenders on Recycled Standard and Opaque PET Rheology and Melt-Spun Filament Properties

Abstract

This work aims to evaluate the spinnability of recycled poly­(ethylene terephthalate) (rPET) modified by chain extenders. Pyromellitic anhydride (PMDA), JONCRYL ADR 4400, 2,2′-bis­(2-oxazoline) (BOZ), and 1,3-phenylene-bis-oxazoline (PBO) were used from 0.1 to 1 wt% on transparent postconsumer PET bottle flakes and opaque rPET flakes containing TiO2 particles. The created molecular architectures were characterized in the first section. Second, their spinnability was assessed via a pilot high-speed spinning process. The corresponding shear rheology, intrinsic viscosity, and elongational rheology were reported. It was observed that PMDA and JONCRYL induce a more drastic increase in melt strength and melt elasticity than BOZ and PBO due to chain branching. In a second step, melt-spun filaments were produced with a low content of chain extenders on standard rPET and opaque rPET matrices. Finally, their degree of crystallinity, molecular orientation, and mechanical properties were determined. PMDA and JONCRYL strongly decrease the spinnability and, consequently, the properties of filaments. However, BOZ improves the opaque rPET filaments’ tenacity while decreasing their degree of crystallinity.

Influence of Branching on the Rheology, Filmability and Mechanical and Optical Properties of a Biodegradable and Compostable Co-Polyester

“…In particular, this behavior can be observed in the presence of long chain branching as short branches do not impart this rheological behavior to linear polymers [40]. This behavior was expected since the presence of long chain branches increases the elongational viscosity and decreases the deformability of the melt [37][38][39].…”

Rheology of Recycled PET

“…Joncryl is a multifunctional epoxide oligomer that is widely used in industry [38]. During chain extension, the reaction of the epoxy group with the carboxyl end group of the PET linear chain is favored; nevertheless, interaction with the terminal hydroxyl group also takes place.…”

“…The intrinsic viscosity is obtained by measuring the viscosity of polymer solutions in a dilute regime. To this end, either Ubbelohde-type viscometers [38,61,64] or automated falling-ball (or rolling-ball) viscometers [66] were used. The first apparatus consists of a vertical capillary tube of known geometry, and the solution flows under the effect of gravity.…”

Flow-Induced Polymer Crystallization under Pressure and Its Engineering Application in “Structuring” Polymer Processing

“…The scientific achievements of the above research topics have already gained economic returns from the polymer industry. For example, a crystallized PET bottle with spherulite morphology is opaque and brittle, while flow-induced crystallization of PET occurs in injection stretch blow molding, which makes transparent and toughened soft drink bottles. − Ultrahigh molecular weight polyethylene (UHMWPE) with spherulitic morphology has a low strength; once the highly oriented shish-kebab structure forms through high-speed melt spinning, the UHMWPE fiber can be strong enough to make a bulletproof vest. − In addition, iPP, a typical commodity plastic, can be processed into microporous membrane by stretching processing where the cavitation is induced by β-to-α phase transition; thus, it can be used as high value-added battery separator . In light of the above discussion, one can see a huge opportunity to achieve high performance or novel function of well-commercialized semicrystalline polymers through controllable processing fields without modification of the molecular structure of raw materials.…”