scholarly journals Gamma Rays Induced Modification in Ultrahigh Molecular Weight Polyethylene (UHMWPE)

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Suveda Aarya ◽  
Pawan Kumar ◽  
Mamta Bhatia ◽  
Sanjeev Kumar ◽  
Jyotsna Sharma ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gamma Ray ◽  
Polymeric Materials ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Oscillatory Behavior ◽  
Morphological Properties ◽  
Polymeric Chain ◽  
X Ray Diffraction ◽  
Ultrahigh Molecular Weight ◽  
Radiation Induced

Modifications taking place in ultrahigh molecular weight polyethylene (UHMWPE) films due to gamma ray radiation-induced and investigated in correlation with the applied doses. Films were irradiated in a vacuum at room temperature by a 1.25 MeV Co60 a source with doses ranging from 0 to 300 kGg. The optical, chemical, structural, and surface morphological properties of the irradiated and unirradiated UHMWPE films were investigated by UV-Visible, FTIR, XRD, and SEM, respectively. The band gap E g decreases with increasing radiation dose and coloration effects have been seen at higher doses. FTIR spectra show an oscillatory behavior in the transmittance intensities without affecting in their peak positions. Number of small absorption peaks can be seen clearly which may be due to the cross-linking of the polymeric chain. No significant change in crystalline peak has been found in the X-ray diffraction pattern indicating the structural stability of the polymer. The morphology of the smooth topography of the polymer samples to change rougher one polymeric sample shows the formation of microvoids on the surface of the polymeric materials with the increase of the doses from 0 to 300 kGy.

On the mechanical and morphological properties of highly performant composite laminates based on epoxy resin and oxidized ultrahigh-molecular-weight polyethylene fibers

2020 ◽  
Vol 32 (9) ◽  
pp. 992-1000 ◽  
Author(s):  
Raouf Belgacemi ◽  
Mehdi Derradji ◽  
Abdelrazak Mouloud ◽  
Djalal Trache ◽  
Abdeldjalil Zegaoui ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Epoxy Resin ◽  
Composite Laminates ◽  
High Performance ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Cost Effective ◽  
Polymeric Matrix ◽  
Morphological Properties ◽  
Ultrahigh Molecular Weight ◽  
Uhmwpe Fibers

In this study, new high-performance composite laminates were prepared from epoxy resin and surface modified ultrahigh-molecular-weight polyethylene (UHMWPE) fibers. The UHMWPE fibers underwent two types of chemical modifications, namely through chromic acid and potassium permanganate oxidations. The adopted chemical procedure aimed the grafting of polar groups on the outer surface of fibers for an improved chemical and physical compatibility with the polymeric matrix. The efficiency of the grafting methodology was confirmed by vibrational, thermal, and morphological analyses, and the grafting mechanism was thoroughly discussed. Furthermore, composite laminates were prepared to study the effects of chemical treatments on the mechanical and morphological properties of the resulting composites. The grafting techniques allowed consequent improvements in the tensile and bending properties, up to 34% and 23% for the tensile and flexural strengths, respectively. The study of the fractured surfaces confirmed the exceptional compatibility between the fillers and the polymeric matrix and further corroborated the mechanical findings. Finally, the adopted modification techniques can be regarded as cost-effective and highly suitable for the manufacturing of structural composites for advanced applications.

scholarly journals Enhancing Chain Mobility of Ultrahigh Molecular Weight Polyethylene by Regulating Residence Time under a Consecutive Elongational Flow for Improved Processability

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2192
Author(s):  
Xiaochuan Chen ◽  
Xiaotong Wang ◽  
Yanhong Feng ◽  
Jinping Qu ◽  
Dingshan Yu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Molecular Weight ◽  
Residence Time ◽  
Elongational Flow ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polymeric Chain ◽  
Thermal Oxidative Degradation ◽  
Chain Entanglement ◽  
Chain Mobility ◽  
Ultrahigh Molecular Weight

Improving the processability of ultrahigh molecular weight polyethylene (UHMWPE) and understanding the effect of the polymeric chain mobility has long been a challenging task. Herein, we show that UHMWPE without any processing aids can be processed at a lower temperature of 180 °C compared to conventional processing temperatures (~250 °C) under a continuous elongational flow (CEF) by using an eccentric rotor extruder (ERE). By probing the effect of the residence time of UHMWPE samples under a CEF on the morphology, rheological behavior and molecular orientation, we find that the long polymer chains of UHMWPE are apt to orientate under a consecutive volume elongational deformation, thereby leading to a higher residual stress for the extruded sample. Meanwhile, the residence time of samples can regulate the polymeric chain mobility, giving rise to the simultaneous decrease of the melting defects and residual stress as well as Hermans orientation function with increasing residence time from 0 to 60 s. This also engenders the enhanced diffusion of UHMWPE segments, resulting in a defect-free morphology and higher entanglement with lower crystallinity but without causing obvious thermal oxidative degradation of UHMWPE. This interesting result could originate from the fast chain entanglement and particle welding enabled by a desirably short residence time, which could be explained by the empirical, entropy-driven melting explosion mechanism.

scholarly journals Тепловой эффект перехода моноклинной фазы в орторомбическую в сверхвысокомолекулярном полиэтилене

2019 ◽  
Vol 61 (10) ◽  
pp. 1965 ◽  
Author(s):  
В.М. Егоров ◽  
В.А. Марихин ◽  
Л.П. Мясникова ◽  
А.К. Борисов ◽  
Е.М. Иванькова ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Solid State ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Effects ◽  
Ultrahigh Molecular Weight

AbstractWe analyze heat effects associated with the solid-state phase transition in ultrahigh molecular weight polyethylene from the unstable monoclinic phase into thermodynamically stable orthorhombic phase. The model proposed here for the structure of supramolecular formations of monoclinic phase does not contradict to earlier X-ray diffraction data for this polymer.

scholarly journals A Novel Ziegler–Natta-Type Catalytic System—TiCl4/2,2′-Dimethoxy-1,1′-Binaphthalene/Et3Al2Cl3/Bu2Mg for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solvent-Free Processing

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1281 ◽  
Author(s):  
Olga Serenko ◽  
Mikhail Buzin ◽  
Vladislav Tuskaev ◽  
Svetlana Gagieva ◽  
Nikolay Kolosov ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic System ◽  
High Strength ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Melting Behavior ◽  
Solvent Free ◽  
X Ray Diffraction ◽  
Molecular Weights ◽  
Ultrahigh Molecular Weight ◽  
Different Temperatures

A series of ultrahigh molecular weight polyethylenes with viscosity-average molecular weights in the range of 1.6–5.6 × 106 have been prepared by using a novel Ziegler–Natta-type catalytic system—TiCl4/2,2′-dimethoxy-1,1′-binaphthalene/Et3Al2Cl3/Bu2Mg at different temperatures (Tpoly) in the range between 10 and 70 °C in toluene. The morphology of the nascent reactor powders has been studied by scanning electron microscopy, wide-angle X-ray diffraction, and the DSC melting behavior. Polymers are suitable for the modern processing methods—the solvent-free solid-state formation of super high-strength (tensile strength over 1.8–2.5 GPa) and high-modulus (elastic modulus up to 136 GPa) oriented film tapes. With decrease of Tpoly, the drawability of the reactor powders increased significantly.

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