A comprehensive study on recycled and virgin PET melt-spun fibers modified by PMDA chain extender

Qu, Muchao; Deng, Hong‐Wen; Wu, Qiang; Han, Lei; Xie, Zixin; Qin, Yijing; Schubert, Dirk W.

doi:10.1016/j.mtcomm.2021.103013

Cited by 9 publications

(10 citation statements)

References 34 publications

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“…Different types of chain extenders by adding reactive functional groups, including trimethyl trimellitate, isocyanates, epoxy-based compounds, bis-oxazolines, and organic phosphites are effective at increasing intrinsic viscosity, molecular mass, and melt strength. The effect of pyromellitic dianhydride (PMDA), as the most commonly used chain extender, on the properties of PET has been comprehensively investigated. − Incorporation of PMDA significantly decreases the carboxyl content, increases the intrinsic melt viscosity, and improves its rheological behavior. These properties are associated with increased molecular weight (MW) and chain entanglement.…”

Section: Introductionmentioning

confidence: 99%

Reactive Blending of Recycled Poly(ethylene terephthalate)/Recycled Polypropylene: Kinetics Modeling of Non-Isothermal Crystallization

et al. 2023

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Plastics were developed to change our world for the better. However, plastic pollution has become a serious global environmental crisis. Thermoplastic polyesters and polyolefins are among the most abundant plastic waste. This work presents an in-depth non-isothermal crystallization kinetics analysis of recycled post-consumer poly(ethylene terephthalate) (rPET) and recycled polypropylene (rPP) blends prepared through reactive compounding. The effect of pyromellitic dianhydride (PMDA) on crystallization kinetics and phase morphology of rPET/rPP blends was investigated by differential scanning calorimetry (DSC) and microscopy techniques. DSC results showed that increasing rPP content accelerated rPET crystallization while reducing crystallinity, which indicates the nucleation effect of the rPP phase in blends. Further, it was found that the incorporation of PMDA increased the degree of crystallinity during non-isothermal crystallization, even though the rate of crystallinity decreased slightly due to its restriction effects. The non-isothermal crystallization kinetics was analyzed based on the theoretical models developed by Jeziorny, Ozawa, Mo, and Tobin. The activation energy of the crystallization process derived from Kissinger, Takhor, and Augis−Bennett models was found to increase in rPET/rPP blends with increasing PMDA due to hindered dynamics of the system. Rheological measurements revealed that rPET melt viscosity is remarkably increased in the presence of PMDA and reactive blending with rPP relevant for processing. Moreover, nanomechanical mapping of the rPP phase dispersed in the rPET matrix demonstrated the broadening of the interfacial domains after reactive blending due to the branching effect of PMDA. Findings from this study are essential for the recycling/ upcycling thermoplastics through non-isothermal fabrication processes, such as extrusion and injection molding, to mitigate the lack of sorting options.

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Section: Introductionmentioning

confidence: 99%

Reactive Blending of Recycled Poly(ethylene terephthalate)/Recycled Polypropylene: Kinetics Modeling of Non-Isothermal Crystallization

et al. 2023

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“…To summarize, each chain extender has successfully increased standard rPET and opaque rPET molar mass and was evaluated via intrinsic viscosity and shear viscosity measurements, as widely described in the literature. − ,− PMDA and JONCRYL are more efficient at a given stoichiometric ratio than BOZ and PBO, especially regarding melt viscosity. However, the viscosity increase is not only due to molar mass improvement but also to the creation of long-chain branched structures.…”

Section: Results and Discussionmentioning

confidence: 99%

“…5,6,16−19 However, a decrease in the degree of crystallinity is often observed. 5,12 The use of chain extenders for fiber spinning production is scarcer in the literature, but Qu et al 19 used PMDA to create longchain branches in PET melt-spun filaments. They have shown that filaments' tenacity was increased at a fixed draw ratio, while crystallinity and the maximal draw ratio achieved in stable conditions are reduced.…”

Section: Introductionmentioning

confidence: 99%

“…Di-epoxides, bis-oxazolines, and diisocyanate are commonly used for linear chain extension, and anhydride-based or epoxy-based compounds are commonly used for branched structures. , Among them, the most widely used and studied compounds for branched structures are a multifunctional epoxide oligomer named JONCRYL and a tetrafunctional modifier pyromellitic anhydride (PMDA). − The use of these additives leads to an increase in intrinsic viscosity, molar mass distribution, and long-chain branching, resulting in higher melt elasticity and shear-thinning behavior. Regarding linear chain extension, 2,2′-bis(2-oxazoline) (BOZ) and 1,3-phenylene-bis-oxazoline (PBO) are commonly used to improve the molar mass and reduce the carboxylic content of PET. ,,− However, a decrease in the degree of crystallinity is often observed. , The use of chain extenders for fiber spinning production is scarcer in the literature, but Qu et al used PMDA to create long-chain branches in PET melt-spun filaments. They have shown that filaments’ tenacity was increased at a fixed draw ratio, while crystallinity and the maximal draw ratio achieved in stable conditions are reduced.…”

Section: Introductionmentioning

confidence: 99%

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

Odet

Ylla

Delage

et al. 2022

ACS Appl. Polym. Mater.

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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.

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“…This coupling reaction yields polyesters of high M w and high melt viscosities. , A key advantage of chain extension is that it can be readily performed during reactive extrusion with short reaction times (∼2–4 min), and thus, it is compatible with high-speed industrial polymer processes. , The utilization of these CEs as compatibilizers and stabilizing agents during the processing of recycled and foamy polymer, which improves melt and rheological characteristics, is one of their most potential application . Several CEs, including diisocyanates, dianhydrides, bisoxazolines, carbodiimides, phthalimides, and epoxides, as well as copolymers with epoxy functionalized have been successfully tested with various polyesters. ,− Epoxides are the most widely used CEs in the melt-processing of polyesters. Epoxides react preferentially with carboxyl groups to form stable ester linkages and with the hydroxyl end-groups of PET to create ether linkages. , At high temperatures, the main reaction is between carboxylic acid and epoxide groups, while hydroxide groups that are formed during the reaction between carboxylic acid and epoxide groups also participate in reactions, leading to the formation of branched and cross-linked structures. , Epoxies are easily produced and can be readily integrated with PET via melt-processing in extruders.…”

Section: Introductionmentioning

confidence: 99%

Polystyrene-Free Chain Extenders for Recycled Poly(ethylene terephthalate)

Abdelwahab

Khan

Matuana

et al. 2022

ACS Appl. Polym. Mater.

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Chain extenders are additives introduced to economically and efficiently restore the performance of recycled condensation polymers such as poly(ethylene terephthalate). The most widely used commercial chain extenders for recycled poly(ethylene terephthalate) (rPET) is the Joncryl ADR (ADR) family of copolymers which are composed of styrene, glycidyl methacrylate (GMA), and butyl acrylate (BA). However, polystyrene is prone to degradation at higher temperatures. Thus, the aim of this study was to create polystyrene-free chain extenders for rPET recycling. Polystyrene-free chain extenders were synthesized via free radical polymerization from GMA, BA, and acetylated hydroxyethyl methacrylate (HEMA-Ac) or benzoylated hydroxyethyl methacrylate (HEMA-Bz) to enhance the thermal and mechanical properties of rPET. These chain extenders were analyzed by 1H NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. The chain extender (1 phr) was then blended with rPET by melt reactive extrusion, resulting in mechanical and thermal properties comparable to those of the commercial chain extender ADR. These additives offer safe alternatives to ADR and will enable the recycling of large volumes of rPET and other condensation polymers without generating any harmful residual styrene.

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A comprehensive study on recycled and virgin PET melt-spun fibers modified by PMDA chain extender

Cited by 9 publications

References 34 publications

Reactive Blending of Recycled Poly(ethylene terephthalate)/Recycled Polypropylene: Kinetics Modeling of Non-Isothermal Crystallization

Reactive Blending of Recycled Poly(ethylene terephthalate)/Recycled Polypropylene: Kinetics Modeling of Non-Isothermal Crystallization

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

Polystyrene-Free Chain Extenders for Recycled Poly(ethylene terephthalate)

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