The study of the thermomechanical degradation and mechanical properties of PET recycled by industrial-scale elongational processing

Wu, Hao; Lv, Shao-yin; He, Yue; Qu, Jinping

doi:10.1016/j.polymertesting.2019.04.029

Cited by 42 publications

(38 citation statements)

References 26 publications

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“…That is, a small endotherm (indicated by an arrow in Figure 4 a) was detected prior to the prominent double melting peak, which featured two overlapped endotherms. This melting behavior is in line with the literature [ 35 , 37 , 38 , 39 , 40 ] and ascribed to the melting of crystals formed during secondary and primary crystallizations, respectively, and to thickened lamellae formed as a result of the melt-recrystallization process on heating. In the present study, the main difference was in the intensity of the second and third endotherms in order of increasing melting point.…”

Section: Resultssupporting

confidence: 91%

“…That is, a small endotherm (indicated by an arrow in Figure 4a) was detected prior to the prominent double melting peak, which featured two overlapped endotherms. This melting behavior is in line with the literature [35,[37][38][39][40] and ascribed to the melting of crystals formed during secondary and primary crystallizations, respectively, and to thickened lamellae formed as a result of the melt-recrystallization The cooling curve (not shown) of rPET-O showed a well-defined crystallization peak at T c = 198 • C, identical to the cooling behavior of rPET-T. This indicates that both materials exhibited a high crystallization rate, characteristic of rPET materials [35,36].…”

Section: Thermal Properties Of the Rpet Calendered Sheetssupporting

confidence: 92%

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Impact of Titanium Dioxide in the Mechanical Recycling of Post-Consumer Polyethylene Terephthalate Bottle Waste: Tensile and Fracture Behavior

et al. 2021

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This work provides an experimental analysis regarding the fracture behavior of recycled opaque PET (rPET-O) containing titanium dioxide (TiO2) under plane stress conditions. For this purpose, a commercially post-consumer transparent colored/opaque PET flakes mix was processed using a semi-industrial extrusion calendering process. The manufactured rPET-O sheets had a TiO2 content of 1.45 wt.%. The mechanical and fracture properties of unaged and physically aged (1 year) samples were determined through uniaxial tensile experiments and the Essential Work of Fracture (EWF) methodology, respectively, and were compared to those of recycled transparent PET (rPET-T). Under tensile loading, independently of the aging time, rPET-O samples exhibited similar mechanical behavior as rPET-T up to the yield point. The main differences remained in the post-yielding region. The presence of TiO2 particles allowed reducing the strain energy density up to neck formation in aged samples. Regarding the EWF analysis, it is argued that the energy consumed up to the onset of crack propagation (we) for rPET-T was mainly dependent of the molecular mobility. That is, the we value decreased by 26% when rPET-T was physically aged. Interestingly, we values remained independent of the aging time for rPET-O. In fact, it was highlighted that before crack propagation, the EWF response was principally governed by matrix cavitation ahead of the crack tip, which allowed a significant release of the triaxial stress state independently of the molecular mobility. This property enabled rPET-O to exhibit a resistance to crack initiation 17% higher as compared to rPET-T when the material was physically aged. Finally, independently of the aging time, rPET-O exhibited a resistance to crack growth approximately 21% larger than rPET-T due to matrix fibrillation in large scale deformation.

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Section: Resultssupporting

confidence: 91%

“…That is, a small endotherm (indicated by an arrow in Figure 4a) was detected prior to the prominent double melting peak, which featured two overlapped endotherms. This melting behavior is in line with the literature [35,[37][38][39][40] and ascribed to the melting of crystals formed during secondary and primary crystallizations, respectively, and to thickened lamellae formed as a result of the melt-recrystallization The cooling curve (not shown) of rPET-O showed a well-defined crystallization peak at T c = 198 • C, identical to the cooling behavior of rPET-T. This indicates that both materials exhibited a high crystallization rate, characteristic of rPET materials [35,36].…”

Section: Thermal Properties Of the Rpet Calendered Sheetssupporting

confidence: 92%

Impact of Titanium Dioxide in the Mechanical Recycling of Post-Consumer Polyethylene Terephthalate Bottle Waste: Tensile and Fracture Behavior

et al. 2021

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“…Recently, Wu et al [ 35 ] investigated the melting and crystalline behaviors of recycled poly(ethylene terephthalate) (PET) and comparative analysis was made between ERE and conventional TSE. The molar mass of TSE-processed PET samples decreased significantly more than that of ERE-processed samples, due to longer residence time and much stronger shear component in the flow field, and the laminar thickness of the primary crystallization for ERE-processed PET samples is higher than that for virgin PET samples.…”

Section: Applications Of Elongational Flow Dominated Plasticizing and Convey Devicesmentioning

confidence: 99%

Recent Advances in Elongational Flow Dominated Polymer Processing Technologies

Yuan

Chen

2021

Polymers

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The continuous development of plasticizing conveying methods and devices has been carried out to meet the needs of the polymer processing industry. As compared to the conventional shear-flow-dominated plasticizing and conveying techniques, a new method for processing polymers based on elongational flow was proposed. This new method and the related devices such as vane extruders, eccentric rotor extruders and so on, exhibited multiple advantages including shorter processing time, higher mixing effectiveness, improved product performance and better adaptability to various material systems. The development of new techniques in the field of polymer material processing has opened up a broad space for the development of new plastic products, improved product performance and reduced processing costs. In this review, recent advances concerning the processing techniques based on elongational flow are summarized, and the broad applications in polymer processing as well as some future opportunities and challenges in this vibrant area are elucidated in detail.

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“…On the other hand, the molecular weights show acceptable correlation with the IV values. As the IV value is widely used in the literature and shows strong correlation with the average molecular weight [36,37], the IV value was decided to be used hereinafter for characterization of the PET materials. Figure 3 shows a typical group of DSC curves obtained from original PET samples with an IV value of 0.80 dl/g.…”

Section: Molecular Weight Analysismentioning

confidence: 99%

Melting temperature versus crystallinity: new way for identification and analysis of multiple endotherms of poly(ethylene terephthalate)

et al. 2020

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Poly(ethylene terephthalate) (PET) materials with different molecular weights were isothermally crystallized from melt by systematically varying the temperature and duration of the treatment performed in the differential scanning calorimeter (DSC). Multiple endotherm peaks were observed on the subsequent heating thermograms that were separated from each other on the basis of their melting temperature versus crystallization temperature and melting temperature versus crystallinity function. By this new approach five sub-peak sets were identified and then comprehensively characterised. Wide-Angle X-Ray Diffraction (WAXD) analyses revealed that the identified sub-peak sets do not differ in crystalline forms. By analysing the crystallinity and the melting temperature of the sub-peak sets as a function of crystallization time, crystallization temperature and intrinsic viscosity, it was concluded that below the crystallization temperature of 460 K the sub-peak sets that were formed during primary or secondary crystallization transform partially or completely to a third sub-peak set during the heating run of the measurement, while above this temperature, the sub-peak set formed during primary crystallization gradually transforms to a more stable structure, with higher melting temperature. These formations and transformations are described with mathematically defined parameters as well.

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The study of the thermomechanical degradation and mechanical properties of PET recycled by industrial-scale elongational processing

Cited by 42 publications

References 26 publications

Impact of Titanium Dioxide in the Mechanical Recycling of Post-Consumer Polyethylene Terephthalate Bottle Waste: Tensile and Fracture Behavior

Impact of Titanium Dioxide in the Mechanical Recycling of Post-Consumer Polyethylene Terephthalate Bottle Waste: Tensile and Fracture Behavior

Recent Advances in Elongational Flow Dominated Polymer Processing Technologies

Melting temperature versus crystallinity: new way for identification and analysis of multiple endotherms of poly(ethylene terephthalate)

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