High Molecular Weight Polyethylene Fibers Research Articles

A universal strategy for rapid and scalable surface modification of ultra high molecular weight polyethylene fiber

The high performance UHMWPE fiber usually demonstrates extremely poor surface adhesion with resin matrix. Therefore, improving the interfacial adhesion property becomes one of the toughest challenges faced by UHMWPE fibers. In this study, a simple and universal surface welding strategy is promoted to effectively modifying UHMWPE fiber with improved surface adhesion in a short time. The surface welding manufacturing approach is realized by the controllable Joule heating generated from the high contact resistance and rapid thermal response of the conductive nano-material layer coated on UHMWPE surface, which can locally melt the UHMWPE fiber surface and weld the nano materials on UHMWE with a strong and robust mechanical bonding. Since the whole welding process is simple and lasts only for a few seconds, it can be easily applied to the current industrial UHMWPE fiber and fabric manufacturing, enabling a continuous, fast, efficiency and scalable roll-to-roll UHMWPE surface modification process.

Strain rate sensitivity of the in-plane mechanical properties of two UHMWPE thin ply composites

The mechanical characterisation of two recent grades of Ultra High Molecular Weight PolyEthylene (UHMWPE) fibres composite is proposed. Used in bulletproof vests, they share the same type of fibres, while composed of different matrices (respectively polyurethane and rubber). The in-plane characterisation is performed through tensile tests on thin layer samples at 0°of the fibres and in-plane shear, in both quasi-static and dynamic conditions. Digital Image Correlation is used for each test to accurately measure strains and evaluate its homogeneity. To study the strain rate effect, various experimental methods were adapted: universal press, drop tower, Split Hopkinson Tensile Bars (SHTB). A significant increase of stiffness with strain rate was observed for both materials At 0°, it transcribed into an increase of 60% for the Young’s modulus, and 40% on failure stress. The in-plane shear modulus was multiplied by two and even eight depending on the considered grade.

Fracture Resistance of Endodontically Treated Maxillary Premolar Teeth Restored with Wallpapering Technique: A Comparative In Vitro Study.

This in vitro study aimed to evaluate and compare the fracture resistance and mode of failure of endodontically treated maxillary premolar teeth restored with different direct composite restorative techniques. Forty freshly extracted maxillary premolar teeth with comparable sizes were used in this in vitro study. Each tooth received mesio-occluso-distal cavity preparation (3 mm width and 6 mm depth) followed by endodontic treatment. Canals were instrumented with RACE EVO rotary files (FKG, Dentaire, Switzerland) up to MAF 25/.06. Canals were obturated using a single cone technique, then the teeth were divided arbitrarily into five groups (n = 8): Group A: direct composite resin only using a centripetal technique, Group B: direct composite resin with glass fiber post, Group C: direct composite resin with short fiber-reinforced composite (everX Flow), Group D: direct composite resin with leno wave ultra high molecular weight polyethylene (LWUHMWPE) fibers placed on cavity floor, and Group E: direct composite resin with LWUHMWPE fibers placed circumferentially around the cavity walls (wallpapering technique). The teeth were then stored in distilled water at 37°C for 24 hr. The fracture resistance of each sample was measured using a universal testing machine in Newton (N). The data were analyzed using one-way analysis of variance (ANOVA) and the Bonferroni test with a significance level of 0.05. Group E recorded the maximum mean of fracture load (2,139.375 N), while Group A recorded the minimum mean of fracture load (689.6250 N). The one-way ANOVA test revealed a significant difference between the groups. The Bonferroni test showed a significant difference between each two groups, with the exception of those between Groups B and C and between Groups D and E, where there were no statistically significant differences (p > 0.05). Restoration of endodontically treated teeth using the wallpapering technique recorded the highest mean of fracture resistance with a repairable mode of fracture.

Combined avulsion fracture of the tibial tubercle and patellar tendon rupture in young athlete: An uncommon injury

Introduction: Patellar tendon rupture is a rare entity, accounting for 3% of all knee extension system injuries. In some cases, the tear is accompanied with avulsed tibial tubercle. Such concurrent fracture is extremely rare, and only a few previously cases have been described in the literature. We reported a 13-year-old male with combined avulsion fracture of the tibial tubercule and patellar tendon rupture. Case Report: A 13-year-old male junior basketball athlete presenting with left knee pain since 2 days before admission. The patient had previously fell to the ground with his left knee hitting the ground while playing basketball. Physical examination demonstrated swollen left knee. Radiographic examination suggested tibial tubercle avulsion, and magnetic resonance imaging demonstrated partial rupture of distal patellar tendon. The patient then underwent open reduction and internal fixation using single cannulated screw for the avulsed tibial tubercle, and patellar tendon reconstruction using suture anchor with ultra high molecular weight polyethylene fibers. Postoperatively, the patient was placed in a locked straight leg brace. One week after surgery, the patient began range of motion exercises and progression of weight bearing with physical therapy. At 4 months of follow-up, the patient can already weightbear, and he had regained active knee range of motion. Discussion: Combined avulsion fracture of the tibial tubercle and patellar tendon rupture in young athlete is an extremely rare case. As such, there is no guideline regarding the best treatment. In this report, we chose open surgery for anatomical reduction of the tuberosity fragment because we consider the growth plate and direct visualization of the patellar tendon. Rigorous physical therapy is of utmost importance in this patient for return to sport, as he is a young athlete. Conclusions: Open reduction and internal fixation using single cannulated screw, and patellar tendon reconstruction suture anchor might be a treatment of choice for those with combined avulsion fracture of the tibial tubercle and patellar tendon rupture in young patients.

Numerical Investigation of the Elastic Properties of Polypropylene/Ultra High Molecular Weight Polyethylene Fiber inside a Composite Material Based on Its Aspect Ratio and Volume Fraction.

In this study, the characteristics of a composite material composed of polypropylene (PP) and ultrahigh molecular weight polyethylene (UHMWPE) are investigated. The elastic properties of the PP/UHMWPE composite material composed of short UHMWPE fibers with a low aspect ratio and long UHMWPE fibers with a high aspect ratio are compared and analyzed. In addition, the elastic properties of the PP/UHMWPE composite materials are calculated via finite element analysis and the Halpin-Tsai model by changing the volume fraction of the UHMWPE fibers. The results show that when UHMWPE fibers with a low aspect ratio and volume fraction are used, the results of the modulus of elasticity based on the finite element analysis are consistent with those obtained using the Halpin-Tsai model, although the fiber volume fraction of the UHMWPE fibers increases. Meanwhile, the deviation between the results yielded by both methods increases with the aspect ratio of the fiber. In terms of the shear modulus, the Halpin-Tsai model shows a linear trend. The results from the finite element analysis differ significantly from those of the Halpin-Tsai model owing to the random orientation of the UHMWPE fibers inside the fiber. Using a contour graph constructed based on the finite element analysis results, the aspect ratio and volume fraction of the UHMWPE fibers can be inversely calculated based on the elastic properties when synthesizing a PP/UHMWPE fiber composite. In future studies, the interfacial bonding properties of UHMWPE fibers and PP should be compared and analyzed experimentally.

An investigation into the functional properties of Kevlar and Dyneema fabrics used as bulletproof

Bulletproof fabrics are usually used as create jackets to protect the user from being shot. These jackets are varied write as according to the degree of expected risks and required levels of protection. Different types of materials and fibers could be used for achieving many properties and different levels of protections. The type and number of materials were affected on the required protection. The current market is looking to reduce the weight and thickness of these fabrics, in addition to low cost. In all bulletproof protective clothing, there is a certain basic material that contributes to stopping the bullet in a noticeable way. Currently, materials made of high molecular weight polyethylene (UHMWPE) and aramid fibers are widely used for this purpose. Aramid fibers are developed by upgrading ballistic nylon fibers while UHMWPE is developed from polyester. Kevlar 29 and Kevlar 149 are the dominant body armor material belonging to the aramid fibers. Dyneema is another UHMWPE. The molecular formula of this polymer is the same as common polyethylene but differs greatly due to its very high molecular weight, 10 to 100 times higher than that of commercial polyethylene resin.

Development of a Fibrous Adsorbent Prepared Via Green Vapor-Phase Grafting Polymerization for Uranium Extraction.

Owing to many problems of the detriment by large amount of organic reagents, high cost and difficulty of industrialization, development of high-efficiency economical technologies for uranium extraction is an irresistible trend to support steady supply of nuclear energy. Herein, a novel fibrous adsorbent, named as AO-HPE fibers, was prepared by introduction of amidoxime groups using the green vapor-phase grafting polymerization (VPGP) technology of monomer acrylonitrile (AN). Gaseous AN was grafted onto the ultra high molecular weight polyethylene (UHMWPE) fibers at 80 °C in the enclosed evaporation and condensation reflux system. The innovative technology not only endowed synthetic process high monomer utilization ratio but also excellent environmental friendliness. The AO-HPE fibers exhibited an appreciable calculated maximum adsorption capacity (Qm) of 1144.94 mg·g–1 in uranium solution and an adsorption capacity of 14.11 mg·g–1 in simulated seawater. Meanwhile, the higher uranium selectivity than main competing ion vanadium (adsorption mass ratio was almost 5) was achieved. The adsorption process accorded closely with chemisorption mechanism. This work provided a novel idea for the synthetic method of adsorbents for uranium extraction, and inspired the sustainable technologies for grafting polymerization of monomer AN.

Development of lightweight and highly efficient fast neutrons composites shields based on epoxy, UHMWPE fibres and boron carbide particles

In a vision to design wearable and lightweight protective thermal neutrons shields, a new hybrid composite was developed from Ultra High Molecular Weight Polyethylene (UHMWPE) fibres, epoxy and boron carbide (B4C) particles. The hybrid constituents were selected in a way to maximize both the shielding performances and the overall mechanical behaviour. Indeed, two first constituents of the hybrid attenuate the incident neutrons through scattering, while the B4C particles mainly interact with neutrons by absorption. More importantly, the UHMWPE fibres, as one of the strongest polymeric fibres, were also chosen to sustain the mechanical loads and provide the requested flexibility. The measurements were performed using an optimized experimental setup at NUR research reactor, Algiers. The effect of the amount of the B4C particles was also studied to maximize the shielding ability. The obtained results confirmed the high shielding efficiency of all the developed materials. Meanwhile, the best performance was recorded at B4C amount of 10 wt% with a macroscopic cross-section (Σ) of 0.188 cm−1 equivalent to a mean free path (λ) of 3.7 cm. In general, the developed materials performed better than the traditional neutrons shields and can be seen as promising materials for the intended use.

Yarn on yarn abrasion failure mechanism of ultrahigh molecular weight polyethylene fiber

Yarns of fiber assemblies such as ropes would abrade with each other during repeated stretching or bending. The yarn on yarn abrasion failure is a main reason for the final assembly failure as the result of the relative movement to each other. To explore the influencing factors and failure mechanism, this work, taking the Ultra High Molecular Weight Polyethylene Fiber (UHMWPE) as the research object, discussed the influences of abrading frequency and the yarn tension on its abrasion life. Based on the observation and analysis of the rising temperatures from abrasion, the abrasion fragments, and morphology of failed yarns, the heating failure and crack propagation mechanisms were proposed, which provide insights into a variety of UHMWPE product designs and applications.

Synthesis of an Acid-gas Sensing Fluorescence Dye Showing Change of Both Color and Fluorescence Emission Spectrum inside Polyethylenic Fiber on Exposure to Gas Phase Strong Acid for Application to Washable Textile Sensors

A halochromic fluorescence dye was synthesized to fabricate acid-gas sensing textiles. The dye has a maximum absorption at 436 nm and stokes shift of 54 nm in ethanol, which means that it exhibits a typical fluorescence color of greenish yellow. The dye was designed to have good substantivity toward hydrophobic and chemical resistant polyethylenic fibers, such as high molecular weight polyethylene (HMWPE) fibers, by introducing di-butyl and t-butyl groups on coumarin and benzoxazole moieties of the chromophore, respectively. The fluorescence dye showed the change of both color and fluorescence emission properties not only in a solution by addition of hydrochloric acid but also inside the HMWPE fiber on exposure to gas phase hydrogen chloride even at relatively low concentrations. From the repeat test, the sensing performance was maintained reversibly even after 20 repeat cycles of adsorption and desorption of gas phase hydrogen chloride. The HMWPE fabrics dyed with the fluorescence dye can be washable by showing fastness of rating 4–5 to washing.

Effects of silane surface modified alumina nanoparticles on the mechanical, thermomechanical, and ballistic impact performances of epoxy/oxidized UHMWPE composites

AbstractIn this study, a new kind of hybrid material was prepared from various amounts of silane surface modified alumina nanoparticles, oxidized ultra high molecular weight polyethylene (UHMWPE) fibers, and epoxy resin. The reinforcing phases were selectively treated to achieve a fully connected network aiming an effective stress transfer between the constituents. The efficiency of the grafting mechanisms was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The developed hybrid materials were tested for their mechanical, thermomechanical, and ballistic performances. The mechanical results, namely tensile and bending, confirmed the positive effects of increasing the nanofillers amounts up to 5 wt%. The thermochemical properties analyzed by dynamic mechanical analysis (DMA) revealed consequent improvements in the storage modulus and glass transition temperature upon the addition of the nanophase. In the meantime, the ballistic tests evaluated under the National Institute of Justice standard (NIJ standard‐0101.06‐IIA) also highlighted an improved kinetic energy absorption following the increase in the amounts of the discontinuous phase. Subsequent experimentations precisely quantified the required number of plies for an effective projectile stopping under the chosen standard. Overall, this study unraveled for the first time ever the benefits obtained from a fully connected hybrid network under both static and dynamic loads.

Direct measure of crystalline domain size, distribution, and orientation in polyethylene fibers

High performance ultra high molecular weight polyethylene (UHMWPE) fibers are primarily composed of extended chain (shish) and lamellae (kebab) crystalline domains. Characterization of these architectures commonly utilizes x-ray scattering techniques, which rely upon models to transform from inverse scattering space to real space. Scattering models for lamellae and straight chain crystalline domains were developed and intended for use in ideal scattering scenarios; ie. purely extended chain or purely lamellae. Simultaneous implementation of both models with real (non-ideal) fibers takes for granted the validity of either model in the presence of the other crystalline feature. In this work, we utilize atomic force microscopy (AFM) to directly couple real space stiffness measurements to the analysis of scattering data. The validity of scattering models is tested against real space image analysis and conclusions are drawn regarding the analysis of scattering data to quantify crystalline domain sizes. We find that the lamellae long spacing estimated from scattering data is consistent with real space image analysis. Whereas significant differences are observed for the analysis of lamellae diameter. The characteristic size of extended chain crystalline domains is measured via the streak analysis method on both SAXS 2D scattering data and the Fast Fourier Transform (FFT) of AFM stiffness maps. The streak analysis results in comparable length scales when applied to SAXS and FFT AFM images. A comparison of the streak analysis with novel filtered AFM images suggest that the streak analysis is capturing continuity of straight chain crystalline domains.

RETRACTED: Interfacial microstructure and properties between epoxy resin and novel organic hybrid graphene oxide modification ultra high molecular weight polyethylene fiber

Abstract An efficient chemical grafting method was developed to enhance interfacial properties of ultra high molecular weight polyethylene (UHMWPE) fiber reinforced composites. Novel organic hybrid graphene oxide (NOHGO) was successfully prepared via grafting polyetheramine (PEA) on graphene oxide (GO) surface with (3-glycidyloxypropyl) trimethoxysilan (GLYMO) as coupling agent. Even if in the extremely dilute suspension, ideal interfacial modification effect was still easily achieved via efficiently grafting NOHGOs on the surface of UHMWPE fiber. The results revealed NOHGOs were of amino groups and almost unfolding structure. NOHGOs were adhered closely on the surface of UHMWPE fiber, which seems to form a uniform tree-rings-like interfacial structure. This type of interfacial structure benefits to reduce defects of the modified fiber surface, to enhance chemical bonding at weak region (between NOHGO and fiber) in interface, and to make the propagation paths of cracks complication, as to the extremely improvement of interfacial properties. Compared with conventional organic hybrid graphene oxide (OHGO), as many as 14.9% enhancement of the interfacial shear strength (IFSS) and higher energy absorption at the interface region were found via microbond test.

Fiber tortuosity and its effects on shock transfer characteristics of Ultra High Molecular Weight Polyethylene (UHMWPE) fibers embedded in a polyurethane composite structure

Low density, high strength, and flexibility of ultra-high molecular weight polyethylene (UHMWPE) fibers have made them a topic of intensive research in many fields. More specifically, UHMWPE has been extensively used in shock damping applications. However, little is known about the effects of fiber tortuosity and fiber wetting on the shock transfer characteristics of these fibers. Herein, focus is placed on studying the effects of tortuosity and fiber wetting on the shock transfer characteristics of UHMWPE fiber braid embedded in a polyurethane matrix. Shock transfer characteristics of these fibers are identified by generating a longitudinal shock on one end of the fiber, while simultaneously measuring the transferred force overtime on the other side of the fiber. From the experiments it is found that the force versus time response of these structures show an underdamped response. Analyzing the maximum force transfer and the rate of decay, it is seen that tortuosity has a significant effect on the shock transfer characteristics of these structures. Given the nature of these results, it is strongly believed that the presented work provides a creative strategy for designing, developing, and characterizing, new composite structures with improved impact attenuation characteristics.

An effective surface modification of UHMWPE fiber for improving the interfacial adhesion of epoxy resin composites

AbstractUltra high molecular weight polyethylene (UHMWPE) fiber composite was reinforced by coating a functional layer on the surface of the UHMWPE fiber to improve interfacial adhesion between the fiber and the resin matrix. In this work, tannic acid (TA)‐Na+ composite modified UHMWPE fiber was used to improve moisture wettability and adhesion between the fiber and the resin. This approach had the advantages of being green, sustainable, lossless, low‐cost, and industrialized. The surface characteristics of UHMWPE fiber were investigated by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The results show that the TA coating can improve the surface roughness, wettability, and adhesion of UHMWPE fiber, thereby improving the interface properties between fiber and resin. The tensile strength of interfacial shear strength and macro‐composites of TA coating UHMWPE fiber increased by 43.3% and 28%, respectively.

Enhancement of interfacial adhesion in UHMWPE fiber/HDPE composites by electrophoretic deposition of graphene oxide on UHMWPE fibers

In contrast to the conventional methods of improving interface and performances of UHMWPE fiber composites throughfibre surface modification, this paper has reported a novel approach to deposit graphene oxide (GO) to increase thefiber/matrix interfacial shear strength (IFSS) of ultra high molecular weight polyethylene fibers (UHMWPE fiber)reinforced high density polyethylene (HDPE) composites. To validate our argument, GO has been synthesized and depositedover UHMWPE fiber through electrophoretic deposition. Tuned voltage lead to different thickness of deposited GO steadilyincreasing with the electric field up to 10 V/cm. Coated fibers have been aligned in a mold and an HDPE matrix has beenused to create a single-fiber microcomposite. This latter has resulted to be muchhigher than the ILSS thus proving theefficiency of the new GO coating method here proposed for producing advanced graphene based composites. The failure ofthe composite at the GO/matrix rather than at the GO/UHMWPE fiber interface has been also confirmed by scanningelectron microscopy observation of the fracture surfaces of microcomposites.

Soft Wearable Skin-Stretch Device for Haptic Feedback Using Twisted and Coiled Polymer Actuators.

Soft and integrated design can enable wearable haptic devices to augment natural human taction. This paper proposes a novel, soft, haptic finger-worn wearable device based on compliant and adhesive silicone skin and lightweight twisted and coiled polymer (TCP) actuators using ultra high molecular weight polyethylene (UHMWPE) fibers to provide lateral skin stretch sensations. Recently, silicone elastomers have been used in wearable sensors and in haptic applications for their high compliance or adhesion. TCP actuators have also demonstrated high power to weight ratios, large stroke length, simple mechanism, and inherent softness. Lateral skin stretch is sensitive to small motions and has been used for intuitive proprioceptive feedback applications. We combined these characteristics to design and manufacture a wearable, functional haptic prototype. Prototype performance was evaluated using an optical tracking system, a force gauge test bench, and compared to vibrotactile haptic feedback in a experiment with 14 healthy participants. Results showed that participant mean reaction times were comparable to those of a vibrotactile feedback system, though task completion times were longer. This paper is the first to employ TCP actuators for haptic stimulation and could serve as a foundation for future applications involving soft wearable haptics in gaming, health, and virtual reality.

Temperature Regulation in Colored Infrared-Transparent Polyethylene Textiles

Summary Effectively regulating heat flow between the human body and its environment not only increases thermal comfort but also presents a novel and potentially cost-effective approach to reducing building energy consumption. Infrared property-engineered textiles have been shown to passively regulate radiative heat dissipation for effective cooling and warming of the human body. However, a lack of dyes that can tune the textile color without compromising the infrared properties remains a major impediment to textile commercialization. Here, we report a new strategy utilizing inorganic nanoparticles as a coloring component for scalable brightly colored, infrared-transparent textiles. The as-fabricated composite textiles not only show a high infrared transparency of ∼80% and a passive cooling effect of ∼1.6°C–1.8°C but also exhibit intense visible colors with good stability against washing. This facile coloration approach will promote the commercialization of radiative cooling textiles in temperature-regulating wearable applications for effective energy savings.

Body armour – New materials, new systems

This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve – a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in on-going developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.

A general approach for the study of kink band broadening in fibre composites and layered materials

The progressive non-linear mode of deformation known as steady-state kink band broadening is analysed for fibre composites and layered materials. The mode of deformation is investigated using an analytical, a semi-analytical model and a finite-element model. The semi-analytical model is based on a constitutive model, where independent material behaviour can be given for two constituents. The analytical model assumes rigid fibres and results in a transcendental equation for the kink band broadening state. Both the analytical and semi-analytical model use a Maxwell construction to determine the steady-state, which is done by equating the internal and external work. The influence of size-effects are explored and two case studies are performed; in the first case study the finite element model and semi-analytical model are used upon a carbon fibre-reinforced PEEK composite. The second case study is on a layered composite made from ultra high molecular-weight polyethylene fibres with a kink band developing on ply level.