Ultra-high Molecular Weight Polyethylene Research Articles

Polymer Physics Behind the Gel-spinning of UHMWPE Fibers.

Gel-spinning of ultra-high molecular weight polyethylene (UHMWPE) fibers has attracted great interest in academia and industry since its birth and commercialization in the 1980s, due to unique properties such as high modulus, low density, and excellent chemical resistance. However, the high viscosity and long relaxation time greatly complicate processing. In industry, solvents like decalin, paraffin oil, etc., usually disentangle the physical networks and promote final drawability. From extruding the polymer solution to post-solid-stretching, many polymer physics problems that accompany high-modulus fiber gel-spinning should be understood and addressed. In this review, by detailed discussions about the effect of entanglements and intracrystalline chain dynamics on the mechanical properties of UHMWPE, we provide theoretical descriptions of the structure formation of disentangled UHMWPE crystals and the origin of high modulus and strength of final fibers. Several physical intrinsic key factors are also discussed, revealing why UHMWPE is an ideal material for producing high-performance fibers. This article is protected by copyright. All rights reserved.

Effect of Nitrate Acid Treated Dolomite on the Tensile Properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) Composites

Ultra-High Molecular Weight Polyethylene (UHMWPE) polymers have been used in biomedical applications due to its biocompatibility, durability, toughness and high wear resistance. To enhance the mechanical properties, various types of minerals are commonly utilized as fillers in UHMWPE. One of the minerals is dolomite, which has been recognized as a valuable mineral with versatile applications, particularly in the field of biomedical applications. This paper presents the tensile properties of UHMWPE composites that filled with dolomite and treated-dolomite at various filler loading (i.e., 1-5 wt.%). Nitric acid and diammonium phosphate were used to treat the dolomite. From the results, the peaks of the FTIR spectrum displays carbonate (CO3–2), phosphate (PO4–3) and hydroxyl (OH–) groups in the ct-dolomite powder sample while the XRD pattern reveals that using dolomite treated with 1M nitric acid resulted in the presence of calcium hydroxide phosphate (Ca10(PO4)5(OH)) and MgO. For tensile strength, UHMWPE/ct-dolomite composites show better tensile strength than the pure UHMWPE composites. Treated improve the dolomite filler and resulted in significantly better matrix-filler interfacial interactions and improve the properties.

“Like binding a book”: Interfacial improvement of pre-melted ultrahigh molecular weight polyethylene by pulse vibration molding

Ultrahigh molecular weight polyethylene (UHMWPE) is widely used in industrial, military, and civilian applications owing to its excellent properties. However, the high entanglement degree of UHMWPE melt leads to great difficulties in diffusion and crystallization, which causes poor interfacial strength and mechanical properties of pre-melted UHMWPE, restricting its high-quality processing and high-value recycling. To this end, we propose a rapid interface stitching technology with a pulsed vibration force driving free volume homogenization and chain segment orientation. For the first time, pulse vibration molding (PVM) is applied for the hot-pressing of pre-melted UHMWPE, successfully realizing the interface stitching and product strengthening. Compared with those of the convention molding (CM) samples at 180 °C, the interfacial adhesive fracture toughness of the adhesive samples processed using PVM is increased by 105.9% and the work of tension of the recycled samples processed using PVM is also increased by 49.09%, respectively. The fracture strength of the PVM recycled samples at 180 °C reaches 91.77% of that of the pure samples and the yield strength is also higher, which significantly enhances the recycling of UHMWPE. The characterization results of the interfacial molecular chain entanglement and crystallization show that PVM strengthens the molecular chain diffusion and induces crystallization by promoting the orientation of chain segments, especially at the interface. Consequently, we believe that the proposed technology can play a significant role in the UHMWPE processing methods that involve surface healing.

Enhancing Wear Resistance of UHMWPE Composites with Micro MoS2 and Nano Graphite: A Taguchi-DOE Approach.

This study presents an in-depth investigation into the wear characteristics of ultrahigh-molecular-weight polyethylene (UHMWPE) composites reinforced with microsized MoS2 and nanosized graphite particles. The objective is to enhance the wear resistance of the UHMWPE by examining the effects of various parameters and optimizing the wear performance. To achieve this goal, wet wear tests were conducted under controlled conditions, and the results were compared between composites with micro MoS2 and nano graphite reinforcements. The Taguchi method was employed to design the experiments (DOE) using an L9 orthogonal array. Four key parameters, namely, reinforcement percentage, load, speed, and track radius, were varied systematically to analyze their impact on wear characteristics, including wear rate, frictional forces, and the coefficient of friction (COF). The data obtained from the experiments were subjected to analysis of variance (ANOVA) to identify the significant factors affecting wear behavior. Subsequently, the optimal wear parameters were determined through regression analysis, allowing for the prediction of wear characteristics under the optimum conditions. This research not only provides insights into the comparative performance of micro MoS2 and nano graphite reinforcements in UHMWPE composites but also offers a comprehensive approach to optimizing wear resistance by employing advanced statistical and experimental techniques. The findings contribute to the development of more durable and wear-resistant materials with potential applications in various industries, such as those investigated in the study, which are commonly employed, such as automotive, aerospace, medical devices, or manufacturing.

Bimodal coaxial fiber sensor for simultaneous strain and temperature sensing for composite manufacturing process

Coaxial structured fibers have gained significant attention in sensor applications due to their design flexibility and ability for multifunctionality. However, the complex and thicker structure of a sensor can lead to stress concentration and signal interference when utilized for strain monitoring in composite manufacturing processes. To address this issue, we propose a bimodal coaxial fiber sensor capable of simultaneous temperature and strain measurement during composite cure and strain monitoring, while preserving the mechanical properties of the fabricated composites. To achieve bimodal sensing, we employ a multi-shell structure consisting of a multi-conductive layer with varying concentrations of multiwalled carbon nanotubes and a PEDOT:PSS layer, applied to a creep-enhanced ultra-high molecular weight polyethylene core fiber using a simple dip-coating method. The bimodal coaxial fiber sensor exhibits a high gauge factor (>4.1), stable cyclic tensile response (>1000 cycles), and linear response to stepwise temperature cycles. Moreover, the sensor demonstrates high sensing accuracy (<3% error) in cure strain monitoring and maintains the fracture toughness of the composite (<1% discrepancy) wherein it is embedded. These results confirm the significant potential of the bimodal coaxial fiber sensor for various applications in the composite industry and other fields.

Experimental study on the synergetic damage of sandwich panel with armored hybrid core under combined blast and fragment loading

Synergetic damage under combined blast and fragment loading drives innovational design of protective structures. In present study, sandwich panel with armored hybrid core was designed, fabricated and finally tested under combined blast and fragment loading. The failure behaviors and the underlying mechanisms were analyzed for the components of sandwich panel. The sandwich panel displayed superior performance over equivalent solid plate. The designability of special interest was exploited by elaborating the effects of face sheet configuration, core material and core sequence on the failure behaviors. Experimental results demonstrate that the same thickness of the front and back faces is beneficial for the constraint of back face deflection. The aluminum foam and ultra-high molecular weight polyethylene (UHMWPE) laminate, adopted as the components of armored hybrid core, cooperated well against combined blast and fragment loading by suffering crushing erosion failure and global bulge deformation, respectively. The potential of armored hybrid core is strongly associated with the core sequence. The ceramic layer supported by the material with high stiffness and the protection of upper bulletproof material for UHMWPE laminate layer would benefit the performance of whole panel. The optimal design of core sequence could markedly reduce back face deflection and even avoid the petalling failure of back face.

Experimental and numerical study of G-HPC slabs rapidly repaired by G-HPC canvas and G-UHPC under contact detonations

The rapid repair of engineering structures damaged due to explosions can enhance the structural impact resistance after an explosion, thereby reducing the potential for casualties and property losses. A novel concrete canvas was firstly proposed based on G-HPC (geopolymer-based high performance concrete), UHMWPEWF（ultra-high molecular weight polyethylene woven fabric), and 3D BFG (basalt fiber grid) to rapidly repair engineering structures and render their blast resistance. A sequence of contact blast tests was systematically conducted to verify the feasibility of the proposed G-HPC canvas. A normal reinforced concrete slab and a steel-wire mesh (SWM) reinforced G-HPC slab were initially damaged by the contact blast loading, afterwards, the damaged concrete slabs were rapidly repaired by G-UHPC (geopolymer-based ultra-high-performance concrete) and the novel G-HPC canvas. The rapidly repaired concrete slabs were subsequently tested by contact blast loading. A precise 3D finite element model was then developed and calibrated based on the experimental results. Eventually, numerical simulations were performed to better understand the contribution of main parameters including repair materials filling the internal slab, steel-wire mesh, G-HPC canvas location and its thickness towards the improvement of the rapidly repaired slabs against the contact blast loading. The experimental and numerical results indicated that the SWM reinforced G-HPC slab has superior blast-resistance compared with the RC slab and the proposed method to rapidly repair the damaged slabs was feasible. The G-HPC canvas should be placed properly since the location of the G-HPC canvas is related to whether fragments are produced on the rear surface of the damaged slab. Increasing the G-HPC canvas thickness and the layers of SWM could significantly reduce the damage area of the repaired slab.

Flexible, lightweight, high strength and high efficiently hierarchical Gd2O3/PE composites based on the UHMWPE fibers with self-reinforcing strategy for thermal neutron shielding

To tackle the challenge for materials in the fields such as deep space exploration with flexibility, light weight, high strength, and highly efficient neutron shielding properties, a novel organic-inorganic composites has been developed in this study. Based on ultrahigh molecular weight polyethylene (UHMWPE) fibers self-reinforcing linear low-density polyethylene (LLDPE) matrix method and hierarchical scattering and absorption strategy, a flexibly and light-weight multilayer structure has been designed with alternating gadolinium oxide (Gd2O3)/LLDPE layers and UHMWPE fiber layers by stacking hot-pressing to augment the mechanical properties and neutron shielding efficiency of the composites. Moreover, PE, including UHMWPE fibers and LLDPE matrix, and Gd2O3 has been utilized as neutron shielding element to enhance its neutron scattering and absorption capability via an abundance of hydrogen atoms and Gd element. The neutron shielding performance of the multilayer Gd2O3/UHMWPE/LLDPE composite, with a low density of ca. 1 g/cm3, has been verified by neutron shielding test and a simulation method of equivalent Gd areal density (EGdAD). As a result, an ca. 90.0% neutron shielding efficiency can be achieved with only 2 mm thickness of the composites (with 20 wt% Gd2O3), and an EGdAD value of 0.0489 g/cm3 is required to achieve 99% shielding efficiency. Moreover, the composites have a significant improvement in the tensile strength and modulus, with an average increase of 1000% (15.86 MPa–179.95 MPa) and 1238% (230.53 MPa–2787.55 MPa) compared to the Gd2O3/LLDPE composites, respectively. The comprehensive performance of our developed multilayer Gd2O3/UHMWPE/LLDPE composites is superior to previously reported results in the literatures. Therefore, it has great application prospect in the various fields like aerospace.

A viscoelastic-viscoplastic thermo-mechanical model for polymers under hypervelocity impact

In hypervelocity impact (HVI) events, the thermo-mechanical behaviors of polymer materials are significantly influenced by viscous effects, thereby affecting energy absorption and shielding performance. A viscoelastic-viscoplastic thermo-mechanical model was newly developed to simulate the mechanical behavior and heat generation of polymer materials under HVI. The viscoelastic-viscoplastic constitutive equation and the Mie-Grüneisen equation of state (EOS) were applied to describe the deviatoric deformation and strongly nonlinear volumetric compression behavior. Moreover, the heat generation was calculated considering contributions from plastic work, irreversible entropy increase, and viscous dissipation which was not considered in the previous HVI numerical model. The temperature increase was calculated through adopting the apparent heat capacity method. The model was coded and seamlessly integrated into the LS-DYNA program through a user-defined material subroutine. Additionally, the FEM-SPH adaptive method was adopted to accurately simulate the fragmentation which always accompanies in the HVI event, wherein the finite element method (FEM) handles contact and deformation behavior, while the smoothed particle hydrodynamics (SPH) method addresses the formation and motion of debris clouds. Ultra-high molecular weight polyethylene (UHMWPE) was selected as the sample material, and its model parameters were calibrated based on the data from quasi-static and dynamic experiments. Good effectiveness and accuracy have been validated through comparing the simulation results and experimental results from the literatures. A noteworthy feature is that the model has the capability to capture the temperature distribution and various energy components induced by the impact, including viscous dissipation, plastic work, and residual energy. Finally, a comparison was made to explore the influence of viscosity on the impact response of UHMWPE plates. The analysis results indicate that material viscosity significantly improves energy absorption capabilities and overall shielding performance.

Titanium Nitride Coatings on CoCrMo and Ti6Al4V Alloys: Effects on Wear and Ion Release

While titanium nitride (TiN) coatings are well known for their biocompatibility and excellent mechanical properties, their wear particle and debris release in orthopedic implants remains a matter of active investigation. This study addresses the efficacy of TiN coatings on CoCrMo and Ti6Al4V alloys to enhance wear resistance and reduce ion release from prosthetic implants. Three different coating variants were utilized: one variant deposited using arc evaporation (Arc) followed by post-treatment, and two variants deposited using high-power impulse magnetron sputtering (HiPIMS) with or without post-treatment. The coatings’ performance was assessed through standard wear testing against ultra-high-molecular-weight polyethylene (UHMWPE) in bovine serum lubricant, and in the presence of abrasive PMMA bone cement particles in the lubricant. The results indicated that Arc and HiPIMS with post-treatment significantly reduced wear and eliminated detectable metal ion release, suggesting that these coatings could extend implant longevity and minimize adverse biological responses. Further long-term simulator and in vivo studies are recommended to validate these promising findings.

Synergistically improving interface behavior by designing physical twisting structure and “rigid-flexible” interface layer on ultra-high molecular weight polyethylene (UHMWPE) fiber surface

The application limitations of Ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composites in different fields can be attributed to their surface chemical inertness and weak interfacial adhesion. Herein, we developed a novel method for preparation of a stable biomimetic layer surface treatment, via the combination use of physical twisting structure and “rigid-flexible” interface layer. Unlike the conventional methods under special conditions, in this method, the UHMWPE fibers were converted into twisting structure, and the efficient nanoparticle deposition facilitated on the fiber surface in the presence of reductive dopamine coating. Moreover, the multi-structured synergy promotes the roughness of the T-UHMWPE fiber, which improves the interface bonding strength of the fibers-reinforced composites. The effectiveness of the modified treatment was evaluated by Fourier transform infrared spectroscopy (FT-IR), microscopic confocal laser Raman spectrometer (Raman), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), contact angle and surface free energy. The surface morphology and interfacial properties of the treatment was evaluated using field emission scanning electron microscopes (FE-SEM) and energy dispersive spectrometry (EDS). The experimental results demonstrated that the interfacial shear strength (IFSS) of the modified T-UHMWPE was improved by 218 %, compared with those of the unmodified UHWMPE fibers. This innovative approach, combining physical twisting structure and “rigid-flexible” interface layer, would provide a valuable potential for the preparation of advanced UHMWPE reenforced composites with high interfacial bond strength.

Experimental and numerical studies of ballistic resistance of hybrid sandwich composite body armor

Abstract Defense mechanisms remain important and indispensable due to the different types of pistols and ordnance besides many guns. Hybrid composite sandwich panels are an attractive focus because of their ingrained characteristics, such as high stuffiness and high energy absorption. Hybrid composite sandwich panels are among the most important in armoring various structures. Despite the high density of these panels, they have significant qualities that qualify them to be the first selection for use in armored vehicles or body armor. Recently, there have been several types of structures, and selecting the appropriate structure as armor against the projectiles is very important. The study subjected three samples to the ballistic impact test using a 7.62 × 39 mm bullet. The first sample, S1, consists of ultra high molecular weight polyethylene (UHMWPE)/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, and UHMWPE/epoxy; the second sample, S2, comprises Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, and UHMWPE/epoxy, and the third sample, S3, comprises Al2O3, Kevlar/epoxy, unfilled honeycomb core, carbon/epoxy, unfilled honeycomb core, and carbon/epoxy. ABAQUS software was used to evaluate the ballistic impact numerically, and after that, the study examined the same armor samples experimentally. The results manifested that only the armor S3 succeeded in stopping the bullet. This is attributed to the structure of the cores, which helps compress and accumulate the cells under the projectile. The speeds of the bullet after penetration (residual velocity; VR) were 748.5 and 715.3 m/s for S1 and S2 armors, respectively, where the back face signature for S3 was 1.5 mm, which is optimum and within the allowed range. The total energy absorption of these armors S1, S2, and S3 is 344.65, 539.04, and 2585.66 J. Furthermore, the highest deviation between numerical and experimental approaches is about 2.04% in the VR.

Study on the synergistic effect of additives on the processing performance of UHMWPE/HDPE blends

AbstractThe challenging melt processing of ultrahigh‐molecular‐weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high‐density polyethylene (HDPE), this article studies the effects of CaSt2, polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt2 and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as‐spun filaments of UHMWPE/HDPE blends modified with CaSt2/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%.

Tracing the antioxidant effect of vitamin E on ultra-high molecular weight polyethylene

The antioxidant effect of vitamin E on ultra-high molecular weight polyethylene (UHMWPE) during radiation oxidation and post-irradiation oxidation process was investigated using electron paramagnetic resonance spectroscopy (EPR) and fourier transform infrared microscopy (FTIR). EPR results showed that the free radical concentration of UHMWPE induced by γ-rays irradiation decreased with increasing vitamin E content both in air and nitrogen atmosphere. FTIR results indicated that the irradiated samples underwent a continuous oxidation reaction, and the higher the vitamin E content, the lower the oxidation reaction. However, radiation oxidation also occurred inevitably to the vitamin E-stabilized UHMWPE indicating vitamin E could only partially prevent oxidation. Further investigation suggested that ozone can rapidly oxidize the vitamin E-stabilized UHMWPE, that is, vitamin E cannot prevent ozone from oxidizing UHMWPE. Then radiation oxidation schematic presentation of vitamin E-stabilized UHMWPE was described. This work would provide more comprehensive understanding on the radiation oxidation and post-irradiation oxidation of vitamin E-stabilized UHMWPE.

Influence and mechanism of ultra-high molecular weight polyethylene on mechanical and electromagnetic shielding properties of alkali-activated composite mortar based on magnesium slag, blast-furnace slag and silica fume

Addressing the environmental impact of the magnesium industry's waste, our study presents a sustainable solution by repurposing magnesium slag, blast-furnace slag, and silica fume to create an innovative alkali-activated mortar (MBS-AAM). This research further explores enhancing electromagnetic (EM) shielding capabilities by incorporating ultra-high molecular weight polyethylene (UHMWPE) powder into MBS-AAM. The addition of 0.5 wt% UHMWPE significantly improves the EM shielding effectiveness of the MBS-AAM composite. Specifically, the modified MBS-AAM demonstrates compressive and flexural strengths of 55.0 MPa and 8.5 MPa, respectively, along with a 148.68% increase in EM shielding effectiveness compared to conventional cement mortar. This advancement is attributed to the optimized pore structure, featuring a higher proportion of smaller pores and reduced overall porosity. Our findings highlight a dual benefit: effective waste utilization and enhanced material functionality for EM shielding, offering a promising approach to sustainable construction and waste management within the magnesium industry.

Polymer Composites with Carbon Fillers Based on Coal Pitch and Petroleum Pitch Cokes: Structure, Electrical, Thermal, and Mechanical Properties.

The effect of particle size and oxidation degree of new carbon microfillers, based on coal pitch (CP) and petroleum pitch (PET) cokes, on the structure as well as thermal, mechanical, and electrical properties of the composites based on ultrahigh molecular weight polyethylene (UHMWPE) was investigated. The composites studied have a segregated structure of filler particle distribution in the UHMWPE matrix. It was found that composite with smaller CP grain fraction has the highest Young's modulus and electrical conductivity compared to the other composites studied, which can be the result of a large contribution of flake-shaped particles. Additionally, conductivity of this composite turned out to be similar to composites with well-known carbon nanofillers, such as graphene, carbon black, and CNTs. Additionally, the relationship between electrical conductivity and Young's modulus values of composites studied was revealed, which indicates that electrical conductivity is very sensitive to the structure of the filler phase in the polymer matrix. In general, it was established that the properties, especially the electrical conductivity, of the composites studied strongly depends on the size, shape, and oxidative treatment of CP and PET filler particles, and that the CP coke of appropriately small particle sizes and flake shape has significant potential as a conductive filler for polymer composites.

Irradiation Behavior of Analgesic and Nonsteroidal Anti-Inflammatory Drug-Loaded UHMWPE for Joint Replacement.

Local delivery of pain medication can be a beneficial strategy to address pain management after joint replacement, as it can decrease systemic opioid usage, leading to less side and long-term effects. In this study, we used ultrahigh molecular weight polyethylene (UHMWPE), commonly employed as a bearing material for joint implants, to deliver a wide set of analgesics and the nonsteroidal anti-inflammatory drug tolfenamic acid. We blended the drugs with UHMWPE and processed the blend by compression molding and sterilization by low-dose gamma irradiation. We studied the chemical stability of the eluted drugs, drug elution, tensile properties, and wear resistance of the polymer blends before and after sterilization. The incorporation of bupivacaine hydrochloride and tolfenamic acid in UHMWPE resulted in either single- or dual-drug loaded materials that can be sterilized by gamma irradiation. These compositions were found to be promising for the development of clinically relevant drug-eluting implants for joint replacement.

Mono- and bi-nuclear phosphine-phenolate neutral nickel catalysts via simple Schiff-Base condensation for ethylene polymerization

In catalytic olefin polymerization, a significant amount of effort has been invested to modify either phosphine substituent or ligand backbone in recently advanced phosphine-phenolate [P,O] neutral nickel catalysts. Unlike other commonly used ligands like phenoxy-imines [N,O] and α-diimines [N,N], [P,O] ligands often require a laborious synthesis technique, which has hindered the rational design of ligand structures and the development of new catalysts. Here we present a novel and effective strategy for creating catalysts using [N,O,P] hybrid ligands. The substituent adjacent to the phenoxy group can be efficiently modified through straightforward Schiff-base condensation reactions with various amines that have established synthetic routes and diverse structures. This process results in the preparation of a series of highly active [P,O] nickel catalysts (up to 1.7 × 107 g mol-1h−1) that are capable of producing ultrahigh molecular weight polyethylene (UHMWPE) (Mw = 243.7 × 104 g/mol) in ethylene polymerization. The additional binding site greatly facilitates modulation of catalytic properties by additives, and parameters such as catalytic activity, polymer molecular weight, and polymer branching can be tuned in this way. Furthermore, binuclear [P,O] neutral nickel catalysts for olefin polymerization are synthesized for the first time using a sequence of diamines. The strategy presented in this work greatly improves the efficiency for the design and synthesis of [P,O] nickel and related catalysts. These findings will be advantageous for future catalyst design and screening.

Characterization of Extruded Ultra-High Molecular Weight Polyethylene (UHMWPE) Filament Prepared for 3D Printing

Fused filament fabrication (FFF) has nowadays become a popular 3-dimensional (3D) printing technique for the fabrication of polymeric components with customized and complex-shape design, including biomedical implants. However, the use of this technique is often constrained by the limited number of polymeric materials that can be printed to form the final product. Despite excellent wear resistance and widely used as the acetabular component of a joint prosthesis, ultra-high molecular weight polyethylene (UHMWPE) is among such the rarely-found filament material in the market. In this research, preliminary work to fabricate UHMWPE filament for the FFF processing is carried out by using extrusion. The influences of extrusion temperature, addition of polyethylene glycol (PEG), and rotational speed of the extruder’s screw on the physical, chemical, and mechanical properties of the extruded UHMWPE filament were determined. The result demonstrated no change in the chemical compositions of the filament due to the processing parameters applied, as noted from the FTIR spectra. The result of the tensile test showed that the highest tensile strength of UHMWPE filaments could reach 23.5 MPa.

Tensile Strength Statistics and Fracture Mechanism of Ultrahigh Molecular Weight Polyethylene Fibers: On the Weibull Distribution.

To study the distribution of ultrahigh molecular weight polyethylene fiber (UHMWPE) strength, three groups of UHMWPE fibers were spun by the gel spinning method, which was undrafted raw fibers (with high strain at break) and fibers with different prespinning and postspinning draw ratios. It is found that even when the strain at break (εb) > 46%, the tensile strength of the fiber still obeys the Weibull distribution. The draw ratio has a great influence on the distribution of fiber strength, especially the draw ratios of the spinneret in the prespinning process. It may be that different drafting processes affect the fracture mechanism of the fibers. This paper analyzes and discusses that and proves it by differential scanning calorimetry and the taut tie molecules (TTMs) fractions. The parameters of the Weibull distribution suggest the quality of the fiber. The Weibull modulus is closely related to the dispersion of the fiber properties and processing parameters. The characteristic strength is similar to the test average strength, which is more suitable for the judgment of fiber reliability in actual use. At the same time, the normality of the samples was tested by Kolmogorov-Smirnov, Shapiro-Wilk, Jarque-Bera test, and quantile-quantile (Q-Q) plots, and the strength distribution was visually displayed by the bell curve. The results show that the Gaussian distribution is not so suitable to describe the strength distribution of the stretched fiber compared to the Weibull distribution.