Studies of non-isothermal crystallization and melting of ultra high molecular weight polyethylene

Zhu, Yan; Chang, Linkai; Yu, Shouzhi

doi:10.1007/bf02548697

Cited by 14 publications

(2 citation statements)

References 2 publications

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“…(a) and Table that with increasing UHMWPE content, the blends exhibited a slightly raised crystallization onset temperature ( T o ) and melting temperature ( T m ) and decreased crystallinity ( χ c ). The raised T o and T m might be attributed to the increase in molecular weight . The decrease of χ c might be attributed to that UHMWPE crystallizes to a much smaller extent than HDPE, and the UHMWPE long chains are more difficult to move than HDPE short chains, indicating the existence of UHMWPE long molecular chains in crystals corresponding to the increase in molecular weight .…”

Section: Resultsmentioning

confidence: 98%

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Lin

Yang

2019

Polymer International

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As linear polyethylenes, ultrahigh‐molecular‐weight polyethylene (UHMWPE) and high‐density polyethylene (HDPE) have the same molecular structure, but the large difference in viscosity between them makes it difficult to obtain well‐mixed blends. An innovative eccentric rotor extruder (ERE) generating an elongational flow was used to prepare HDPE/UHMWPE blends within short processing times. Compared with the obvious two‐phase morphology of a sample from a twin‐screw extruder observed with a scanning electron microscope, few small UHMWPE particles were observed in the HDPE matrix for a sample from the ERE, indicating the good mixing on a molecular level of HDPE/UHMWPE blends achieved by the ERE during short processing times. The morphological changes of blends prepared using the ERE evidenced the good integration of HDPE and UHMWPE even though the UHMWPE content is up to 50 wt% in the blends. Moreover, all blends retained most of the intrinsic molecular weight. The good mixing was further confirmed from the thermal, crystallization and rheological behaviors determined using differential scanning calorimetry and dynamic rheological measurements. Importantly, the 50/50 blend presented improved mechanical properties, especially super‐impact strength of 151.9 kJ m−2 with incomplete‐break fracture state. The strengthening and great toughening effects of UHMWPE on the blends were attributed to the addition of unwrapped UHMWPE long molecular chains. The effective disentanglement mechanism of UHMWPE chains under elongational flow was explained schematically by a non‐parallel three‐plate model. © 2019 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 98%

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Lin

Yang

2019

Polymer International

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“…This implies that plasticization occurred at entangled chains in between the crystalline regions. [35][36][37]…”

Section: Thermal Transitions and Crystallizing Behavior Of P-uhmwpesmentioning

confidence: 99%

Processability and physico‐mechanical properties of ultrahigh‐molecular‐weight polyethylene using low‐molecular‐weight olefin wax

Bakshi

Ghosh

2022

Polymer Engineering & Sci

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The influence of molecular weight of olefin wax as a plasticizer on the processability and properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) was thoroughly investigated in this study. Two different grades of olefin wax (H5 and 210P) were used separately to plasticize UHMWPE. Comparative results were analyzed based on mixing torque, mechanical, thermal, thermo‐mechanical, and morphological aspects. The Gaussian mathematical model was applied to the internal thermo‐shear batch mixing torque data to predict processability and plasticization of the resulting compounds. A decrease in the peak torque value with increase in wax content revealed the plasticization effect. Across both types of wax (H5 and 210P) at 4, 8, and 10 phr content, the 10 phr H5 wax plasticized UHMWPE batch showed a minimum peak torque of 4.5 Nm with a broad mixing temperature window (∆T) of 32.4°C. The relatively low‐molecular‐weight wax (H5) seemed to be more efficient at uncoiling the entanglements among the amorphous phase of UHMWPE, perhaps because of its smooth interpenetration between ties. The lowest degree of crystallinity range (34%–40%) and the highest nucleation rate (0.9 min−1) were found with 10 phr H5 wax plasticized UHMWPE. The tensile strength of 30.5 MPa and elastic modulus of 127 MPa, achieved by the addition of H5 wax at 10 phr loading, confirmed the optimum effect of plasticization. The plasticization effect was also established from the loss moduli and Cole–Cole plots (log loss modulus vs. log storage modulus). A smaller number of multiple stress‐induced overshoots and the inclining approach toward the viscous dominant regime with temperature sweep were observed in the case of 10 phr H5 wax composition. Scanning electron microscopy (SEM) analysis revealed disappearance of interfacial crazing and interparticle boundaries progressively with the increase in H5 wax content. Overall, plasticized UHMWPE with 10 phr content of H5 wax showed the optimum processability and properties.

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Mechanical properties of an ultrahigh‐molecular‐weight polyethylene/polypropylene blend containing poly(ethylene glycol) additives

Xie

2008

J of Applied Polymer Sci

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It was recently reported that poly(ethylene glycol) (PEG) additives (PEG and its hybrids with inorganic fillers) could significantly improve the processability of ultrahigh-molecular-weight polyethylene (UPE)/polypropylene (PP) blends. The influence of PEG additives on the mechanical properties of UPE/PP blends was investigated in this study. With the addition of small amounts of PEG additives, the tensile properties of UPE/PP blends were little affected, whereas the loss in impact strength was relatively noticeable; however, the toughness was maintained at a high level. Stress-relaxation and stressstrain tests showed that the PEG additives acted mainly in the amorphous phase, reducing the entanglement density of the blends.

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Studies of non-isothermal crystallization and melting of ultra high molecular weight polyethylene

Cited by 14 publications

References 2 publications

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Processability and physico‐mechanical properties of ultrahigh‐molecular‐weight polyethylene using low‐molecular‐weight olefin wax

Mechanical properties of an ultrahigh‐molecular‐weight polyethylene/polypropylene blend containing poly(ethylene glycol) additives

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