The effect of processing conditions on the rheological properties of blends of ultra high molecular weight polyethylene with high‐density polyethylene

Quan

J of Applied Polymer Sci

et al. 2020

Interface variation in the extraction and drying process of ultra‐high molecular weight polyethylene (UHMWPE) gel fiber results in different shrinkage at different direction. The essence of shrinkage lies in the crystallization of UHMWPE chains under the effect of interface tension. However, UHMWPE gel fiber prepared with different solution concentration has different chain entanglement points density that can hinder the regular stacking for UHMWPE chains. The restriction for axis shrinkage of UHMWPE gel fiber facilitates the orientation of UHMWPE chains that is beneficial to improve the tensile strength of UHMWPE drawn fiber. Combined with multiple methods of Wide angle X‐ray diffraction, Small‐angle X‐ray scattering, Differential scanning calorimetry and sonic orientation, the structural evolution of UHMWPE fiber with different shrinkage ratio and different concentration was investigated. Meanwhile, the suitability for UHMWPE fibers in production was evaluated by final tensile strength of the fibers. Here, a structural evolution model is proposed to elucidate the correlation between the shrinkage and the structure and properties of UHMWPE fibers prepared with different solution concentration.

Section: Resultsmentioning

confidence: 99%

The effect of shrinkage on the structure and properties of ultra‐high molecular weight polyethylene fibers with different concentration

Quan

J of Applied Polymer Sci

et al. 2020

“…The analysis method for the thermorheological behavior was described in detail before [47] and will, therefore, not be repeated here. The results of the numerical analysis of the thermorheological complexity are given in Figure 6a-c.…”

Section: Thermorheological Behaviormentioning

confidence: 99%

“…They found thermorheological complexity but did not evaluate it. Chaudhuri et al [47] melt blended normal HDPE with ultrahigh molecular PE, which was synthesized in a special way that it was unentangled despite the high molar mass in order to facilitate melt blending. This resulted in superior blend quality and improved strain hardening.…”

Section: Introductionmentioning

confidence: 99%

Rheological Behavior of Blends of Metallocene Catalyzed Long-Chain Branched Polyethylenes. Part I: Shear Rheological and Thermorheological Behavior

et al. 2021

Long-chain branched metallocene-catalyzed high-density polyethylenes (LCB-mHDPE) were solution blended to obtain blends with varying degrees of branching. A high molecular LCB-mHDPE was mixed with low molecular LCB-mHDPE at varying concentrations. The rheological behavior of those low molecular LCB-mHDPE is similar but their molar mass and molar mass distribution are significantly different. Those blends were characterized rheologically to study the effects of concentration, molar mass distribution, and long-chain branching level of the low molecular LCB-mHDPE. Owing to the ultra-long relaxation times of the high molecular LCB-mHDPE, the blends exhibited a clearly more long-chain branched behavior than the base materials. The thermorheological complexity analysis showed an apparent increase in the activation energies Ea determined from G′, G″, and especially δ. Ea(δ), which for LCB-mHDPE is a peak function, turned out to produce even more pronounced peaks than observed for LCB-mPE with narrow molar mass distribution and also LCB-mPE with broader molar mass distribution. Thus, it is possible to estimate the molar mass distribution from the details of the thermorheological complexity.

“…Fluidity modification methods of UHMWPE mainly include blending and using rheological modifiers. For the blending method, UHMWPE is usually blended with resins that have good fluidity, such as low-density polyethylene [ 12 , 13 ], high-density polyethylene [ 14 , 15 , 16 ], and polypropylene [ 12 , 17 ]. For the rheological modifier method, the addition of a rheological modifier can decrease the entanglement of molecular chains of UHMWPE and plays the role of lubricant [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Study on Preparation of Ultra-High-Molecular-Weight Polyethylene Pipe of Good Thermal-Mechanical Properties Modified with Organo-Montmorillonite by Screw Extrusion

Guo

Xue

2020

Materials

The study of processing characteristic and property optimization of ultra-high-molecular-weight polyethylene (UHMWPE) pipe is increasingly performed, mainly focusing on difficulties in the melting process and poor thermal-mechanical properties after forming, which have limited the wider engineering application of UHMWPE pipe. In this study, organo-montmorillonite (OMMT)-modified UHMWPE pipe with good thermal-mechanical properties was prepared by screw extrusion molding. First, high-density polyethylene was subjected to fluidity modification so that the screw extrusion molding of UHMWPE pipe was feasible. Then, OMMT-modified UHMWPE pipes under different addition amounts of OMMT were innovatively prepared by extrusion. Furthermore, the effects of the addition amounts of the compatibilizer HDPE-g-MAH and the silane coupling agent γ-(2,3-epoxy propoxy) propyl trimethoxy silane (KH560) on the thermal properties of OMMT-modified UHMWPE pipe were investigated for the first time. Compared with those of pure UHMWPE pipe, the Vicat softening temperature (from 128 to 135.2 °C), thermal deformation temperature (from 84.4 to 133.1 °C), bending strength (from 27.3 to 39.8 MPa), and tensile strength (from 20.8 to 25.1 MPa) of OMMT-modified UHMWPE pipe were greatly increased. OMMT-modified UHMWPE pipe with good thermal-mechanical properties was able to be prepared by extrusion for the first time. The compatibilizer method of HDPE-g-MAH was slightly more effective than the coupling agent method of KH560.