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

Yan, Haichao; Yuan, Haitao; Gao, Feng; Zhao, Liang; Liu, Tao

doi:10.1002/app.42708

Cited by 30 publications

(37 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In other words, the reaction did occur, but the product of this reaction was not a long chain structure and, therefore, could not cease the degradation. Despite the high reactivity between PMDA and PET, due to the weakness of the ester bond in PLA, degradation in this polyester may occur more readily. Increments in number‐average and weight‐average molecular weights were observed in samples containing both chain extenders compared to pure PLA.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Yahyaee

Javadi

Garmabi

et al. 2019

Macro Materials & Eng

View full text Add to dashboard Cite

polymer in processes involving melt stretching (film extrusion, blow molding, foaming, and the like) have been limited due to disadvantages such as intrinsic brittleness, slow crystallization rate, low melt strength, narrow processing window, and low thermal stability. [7][8][9][10][11][12][13] The low melt strength of PLA is due to the inherent degradation behavior of polyesters. PLA degrades at temperatures above its melting point, similar to other polyesters. The degradation reactions include hydrolysis, inter-chain transesterification, and depolymerization by back-biting (intramolecular transesterification). Depending on the process conditions, one of these undesirable reactions overcomes the others. For example, the chain scission, at temperatures above the melting point, is responsible for the degradation of the polymer that leads to a decrease in molecular weight and rheological properties. [1,14,15] To obtain a wider processing window for PLA and thus make the range of its applications broader, improved melt strength is postulated. [16,17] For increasing the melt strength, the modification of PLA is an effective method to achieve a branched high molecular weight structure. Several ways exist for the branching of PLA, including solution polymerization, using the free radical initiator, and functional groups reaction. Due to environmental problems, high costs, low effectiveness, and issues associated with process convenience, solution reactions are not the best choices. Furthermore, as the free radical reaction is a random one, it is more difficult to control the molecular weight when utilizing this method. On the contrary, compared to the free radical branching, reactions of functional groups tend to give rise to long chain branching (LCB) more readily, leading to controlled structures. [18] Chainextension reactions are exploited to increase the melt strength of linear polymers. The advantage of using the chain extenders with functional groups includes re-bonding the degraded chains together and as a result, increasing the molecular weight and the melt strength. For polyesters such as PET and PLA, chain-extension occurs by increasing the molecular weight due to bridging the hydroxyl or carboxyl reactive-end groups using bi-or multi-functional molecules. [1,9] Some researchers have investigated the effect of different chain extenders with different functional groups such as diand multi-functional epoxides, [19][20][21][22][23][24][25][26][27] diisocyanate, [28][29][30] dianhydride, [31][32][33] and so forth. Among these, chain extenders constituted of multi-functional epoxy groups such as Joncryl are highly This research considers a two-step chain extension reaction in the presence of two chain extenders, Joncryl and Pyromellitic dianhydride (PMDA), as a solution for poor melt properties of poly (lactic acid) (PLA). The aim of adding PMDA is to increase the carboxyl groups via the anhydride ring-opening reaction so that the reaction between PLA and Joncryl could be facilitated since the reactivity between t...

show abstract

Section: Resultsmentioning

confidence: 99%

“…Some researchers have investigated the effect of different chain extenders with different functional groups such as di‐ and multi‐functional epoxides, diisocyanate, dianhydride, and so forth. Among these, chain extenders constituted of multi‐functional epoxy groups such as Joncryl are highly favorable.…”

Section: Introductionmentioning

confidence: 99%

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Yahyaee

Javadi

Garmabi

et al. 2019

Macro Materials & Eng

View full text Add to dashboard Cite

show abstract

“…Further advances are needed, however, to ensure the production of recycled PET (r-PET) products, which maintain the properties required for market application. [1][2][3][4][5][6] Reduction in molecular weight occurs when postconsumer PET is recycled in a normal extrusion scheme, due both to thermal and hydrolytic degradation, resulting in the loss of molecular weight (commonly measured indirect as intrinsic viscosity [IV] [η]) and loss of overall mechanical properties. The presence of retained moisture (hydrolysis) and contamination by poly(vinyl chloride) (hydrogen chloride) generation are two key reasons for polymer degradation during processing of r-PET.…”

Section: Introductionmentioning

confidence: 99%

Thermo‐rheological analysis of various chain extended recycled poly(ethylene terephthalate)

Pandey

Seese

Maia

et al. 2020

Polymer Engineering & Sci

View full text Add to dashboard Cite

Three chain extenders, pyromellitic dianhydride (PMDA), ethylene carbonate (EC), and a polymeric-epoxide, were investigated for improving recycled p(ethylene terephthalate) (r-PET) properties with melt extrusion. The amount of additives and processing temperatures were also varied to check for melt degradation. Small amplitude oscillatory shear experiments were performed to probe rheological changes with different chain extenders. Capillary rheometry with haul-off was also performed to measure extensional viscosity and melt strength. Higher loadings of the chain extenders were found to improve properties of r-PET. These chain extenders definitely increased melt viscosities when incorporated at the higher level of the ranges examined, matching that of virgin PET. EC addition resulted in high shear thinning of the polymer.

show abstract

“…In the extrusion process, the polymer molecules are melted and mixed. Once melted, the reaction of PET end groups with the chain‐extension compound can then take place …”

Section: Introductionmentioning

confidence: 99%

Recycling of poly(ethylene terephthalate) by chain extension during reactive extrusion using functionalized block copolymers synthesized by RAFT polymerization

Benvenuta‐Tapia

González-Coronel

Soriano‐Moro

et al. 2018

J of Applied Polymer Sci

View full text Add to dashboard Cite

In this study, a series of reactive block copolymers of glycidyl methacrylate (G), styrene (S), and maleic anhydride (MA) (GS-SMA-GS), with well-defined properties and high number average functionalities, is presented. They were synthesized through reversible addition-fragmentation chain transfer polymerization (RAFT) and evaluated as chain extenders in reactive extrusion recycling of poly(ethylene terephthalate) (rPET). Modification of the process using GS-SMA-GS results in increased melt flow and intrinsic viscosities higher than those of conventional rPET. Results show that increasing epoxide content makes chain organization in rPET difficult and promotes lower crystallization rates and lower degrees of crystallinity, both of which are characteristics suited to produce preforms with the desired clarity. Chain-extended rPET exhibits improved rheological characteristics with increasing glycidyl methacrylate content. Chain-extended rPET using GS-SMA-GS shows enhanced complex viscosity; elastic and viscous modules, which are indicative of high melt elasticity, improved mechanical properties, and processability.Recycling processes include thermal and hydrolytic degradation of PET, which reduces its molar mass, intrinsic viscosity, and mechanical properties. This degradation limits its processability and leads to undesirable properties and inferior performance of Additional Supporting Information may be found in the online version of this article.

show abstract

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

Cited by 30 publications

References 36 publications

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Effect of Two‐Step Chain Extension using Joncryl and PMDA on the Rheological Properties of Poly (lactic acid)

Thermo‐rheological analysis of various chain extended recycled poly(ethylene terephthalate)

Recycling of poly(ethylene terephthalate) by chain extension during reactive extrusion using functionalized block copolymers synthesized by RAFT polymerization

Contact Info

Product

Resources

About