scholarly journals Ultra-high molecular weight elastomeric polyethylene using an electronically and sterically enhanced nickel catalyst

2017 ◽  
Vol 8 (41) ◽  
pp. 6416-6430 ◽  
Author(s):  
Qaiser Mahmood ◽  
Yanning Zeng ◽  
Erlin Yue ◽  
Gregory A. Solan ◽  
Tongling Liang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Nickel Catalyst ◽  
High Tensile Strength ◽  
Elongation At Break ◽  
Highly Active ◽  
High Elongation ◽  
Ultra High Molecular Weight ◽  
Shape Fixity

Highly active para-t-Bu-containing 1,2-bis(imino)acenaphthene-Ni(ii) catalysts are disclosed which afford hyper-branched PEs with Mw's up to 3.1 × 106 g mol−1; high tensile strength, excellent shape fixity as well as high elongation at break are a feature.

scholarly journals Melt- vs. Non-Melt Blending of Complexly Processable Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 404
Author(s):  
Nur Sharmila Sharip ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Yoshito Andou ◽  
Yuki Shirosaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Yield Strength ◽  
Young’S Modulus ◽  
High Molecular Weight ◽  
Melt Processing ◽  
Cellulose Nanofiber ◽  
Melt Blending ◽  
Ultra High Molecular Weight

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young’s modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young’s modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.

Synthesis of Cyclic Polysulfides and their Properties as Curing Agents

2004 ◽  
Vol 77 (2) ◽  
pp. 380-390
Author(s):  
Wonmun Choi ◽  
Tomoyuki Matsumura
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Mass Spectra ◽  
Elongation At Break ◽  
Molecular Weights ◽  
Aging Properties ◽  
Curing Agents ◽  
Polysulfide Polymer

Abstract The reactions of dichloroalkanes and sodium tetra-sulfide (Na2S4) were carried out in a mixture of water and toluene to produce corresponding cyclic polysulfides and polysulfide polymer. The low molecular weights of cyclic sulfides were obtained by the reaction at 90 °C, while the high molecular weight of polysulfide polymer was obtained by the reaction at 50 °C. GPC chromatograms and Mass spectra revealed that the structures of cyclic polysulfide were 1:1, 2:2, and 3:3 adducts of dichloroalkane and sodium tetra-sulfide. The mechanical properties of vulcanized NR at 148 °C with cyclic sulfides were similar to that with sulfur. However, both tensile strength and elongation at break of vulcanized NR at 170 °C with cyclic sulfides are much higher than that with sulfur. The aging properties of vulcanized NR at 148 °C or 170 °C with cyclic polysulfides indicate better stability.

The effect of simultaneous fiber surface treatment and matrix modification on mechanical properties of unidirectional ultra-high molecular weight polyethylene fiber/epoxy/nanoclay nanocomposites

2018 ◽  
Vol 52 (21) ◽  
pp. 2961-2972 ◽  
Author(s):  
Mohammad Mohammadalipour ◽  
Mahmood Masoomi ◽  
Mojtaba Ahmadi ◽  
Zahra Kazemi
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Glycidyl Methacrylate ◽  
Interfacial Adhesion ◽  
Fiber Surface ◽  
Cohesive Failure ◽  
Polyethylene Fiber ◽  
Ultra High Molecular Weight

Nonpolar structure of ultra-high molecular weight polyethylene fiber leads to a weak interfacial adhesion in ultra-high molecular weight polyethylene fiber reinforced epoxy composite. Herein, synchronized fiber and matrix modifications were utilized so as to improve the interfacial adhesion, resulting in promoting mechanical properties of these composites. For this purpose, the surface of ultra-high molecular weight polyethylene fiber was chemically treated with glycidyl methacrylate and the epoxy resin was modified through incorporation of different contents of nanoclay. The mechanical properties results showed that individual modification, either fiber or matrix, can just lead to improvements around 36.74% and 10.54% in tensile strength as well as 14.28% and 4.27% in tensile modulus, respectively. However, the ultimate outcome of the study revealed that much higher improvement can be achieved in synergistic attitude. The highest enhancement around 48.31% and 26.76% in tensile strength and modulus were seen for the sample containing glycidyl methacrylate-treated ultra-high molecular weight polyethylene fibers as reinforcement and nano epoxy modified with 1 wt.% of nanoclay. Such observation could be attributed to the mechanical interlocking and chemical reaction which were arising from incorporation of nanoclay in matrix and chemical treatment of fiber surface, correspondingly. In this regard, fiber roughness and chemical bonds formed between treated fiber and modified matrix play a key role in improving interfacial adhesion. Moreover, the fractured surface of such composites studied by scanning electron microscope confirmed the mechanical results and showed that much more matrix was adhered to the fiber surface after treatment, indicating cohesive failure.

Effects of electron beam irradiation on structure and properties of ultra-high molecular weight polyethylene fiber

2017 ◽  
Vol 47 (6) ◽  
pp. 1357-1377 ◽  
Author(s):  
Dongliang Dai ◽  
Meiwu Shi
Keyword(s):  
Molecular Weight ◽  
Electron Beam ◽  
High Molecular Weight ◽  
Electron Beam Irradiation ◽  
Breaking Strength ◽  
Beam Irradiation ◽  
Elongation At Break ◽  
Gel Content ◽  
Ultra High Molecular Weight ◽  
Polyethylene Fibers

This study introduced trimethylolpropane trimethacrylate into ultra-high molecular weight polyethylene fibers through supercritical CO2 pretreatment before the fibers were irradiated under an electron beam. Significant differences, emerging in the ultra-high molecular weight polyethylene fibers’ gel content, mechanical properties, and creep property according to their different irradiation doses, were studied through one-way analysis of variance. Regression equations were established between the irradiation dose and the gel content, breaking strength, elongation at break, and creep rate by regression analysis. A reasonable irradiation dosage range was determined after a verification experiment and the impact trends were analyzed; additionally, the sensitized irradiation crosslinking mechanism of ultra-high molecular weight polyethylene fibers was preliminarily examined. Then the surface morphology, chemical structures, thermal properties, and crystal properties of treated ultra-high molecular weight polyethylene fibers were measured. The results showed that as the irradiation dose increased, the gel content first rose and then declined; the breaking strength decreased continuously; the elongation at break increased at first and then decreased; and the creep rate originally fell and then rose before finally declining slowly. Electron beam irradiation had a significant etching effect on the fibers’ surface, and both the melting point and crystallinity decreased slightly.

Weibull statistics of tensile strength distribution of gel-cast ultra-oriented film threads of ultra-high-molecular-weight polyethylene

2016 ◽  
Vol 52 (3) ◽  
pp. 1727-1735 ◽  
Author(s):  
Yu. M. Boiko ◽  
V. A. Marikhin ◽  
L. P. Myasnikova ◽  
O. A. Moskalyuk ◽  
E. I. Radovanova
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Strength Distribution ◽  
Weibull Statistics ◽  
Oriented Film ◽  
Ultra High Molecular Weight

Natural fiber-reinforced high-density polyethylene composite hybridized with ultra-high molecular weight polyethylene

2019 ◽  
Vol 53 (15) ◽  
pp. 2119-2129 ◽  
Author(s):  
Haibin Ning ◽  
Selvum Pillay ◽  
Na Lu ◽  
Shaik Zainuddin ◽  
Yongzhe Yan
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Hybrid Material ◽  
High Density Polyethylene ◽  
Natural Fiber ◽  
High Density ◽  
Low Density ◽  
Fiber Reinforced ◽  
Ultra High Molecular Weight

A great deal of research and development work has been recently conducted on natural fiber-reinforced polymer matrix composite for its abundancy, low density, excellent damping characteristic, and good mechanical properties. However, the low strength of natural fiber composite has limited its use to only low stress applications. The purpose of this work is to develop a natural fiber hybrid material with both enhanced strength and failure strain using a novel approach and study the effect of the processing temperature on its microstructure and performance. High-strength ultra-high molecular weight polyethylene fabrics are co-molded onto the surfaces of a kenaf fiber high-density polyethylene-based composite material by single-step compression molding. The status of the ultra-high molecular weight polyethylene fabrics at different processing temperatures is investigated using microscopic analysis. The tensile strength and impact strength of the hybrid material are evaluated. It is found that its tensile strength is increased by more than 90% with only 8% ultra-high molecular weight polyethylene fiber reinforcement added and its low density is maintained.

scholarly journals Embedding Ultra-High-Molecular-Weight Polyethylene Fibers in 3D-Printed Polylactic Acid (PLA) Parts

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1825 ◽  
Author(s):  
Amza ◽  
Zapciu ◽  
Eyþórsdóttir ◽  
Björnsdóttir ◽  
Borg
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
3D Printing ◽  
High Molecular Weight ◽  
Polylactic Acid ◽  
Strength Tests ◽  
Raster Angle ◽  
Uhmwpe Fibers ◽  
3D Printed ◽  
Ultra High Molecular Weight

This study aims to assess whether ultra-high-molecular-weight polyethylene (UHMWPE) fibers can be successfully embedded in a polylactic acid (PLA) matrix in a material extrusion 3D printing (ME3DP) process, despite the apparent thermal incompatibility between the two materials. The work started with assessing the maximum PLA extrusion temperatures at which UHMWPE fibers withstand the 3D printing process without melting or severe degradation. After testing various fiber orientations and extrusion temperatures, it has been found that the maximum extrusion temperature depends on fiber orientation relative to extrusion pathing and varies between 175 °C and 185 °C at an ambient temperature of 25 °C. Multiple specimens with embedded strands of UHMWPE fibers have been 3D printed and following tensile strength tests on the fabricated specimens, it has been found that adding even a small number of fiber strands laid in the same direction as the load increased tensile strength by 12% to 23% depending on the raster angle, even when taking into account the decrease in tensile strength due to reduced performance of the PLA substrate caused by lower extrusion temperatures.

scholarly journals Evaluation of the Tensile Strength of Electron Beam Irradiated Powdered Ultra High Molecular Weight-Polyethylene (UHMWPE) Prior to Sintering

2015 ◽  
Vol 56 (9) ◽  
pp. 1505-1508 ◽  
Author(s):  
Masae Kanda ◽  
Tiana Deplancke ◽  
Olivier Lame ◽  
Yoshitake Nishi ◽  
Jean-Yves Cavaille
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Electron Beam ◽  
High Molecular Weight ◽  
Ultra High Molecular Weight
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