High Molecular Weight Polyethylene Fibers Research Articles

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.

Thermal Conductivity of poly-p-phenylene-2,6-benzobisoxazole Film along the In-Plane Axis in the 10–300 K Temperature Range

The thermal conductivities of compression molded thin films of poly-p-phenylene-2,6-benzobisoxazole (PBO) were measured in directions along an in-plane axis in the 10–300 K temperature range by a steady-state heat flow method, with interest in the use of the material for superconductivity applications. The thermal conductivities of the PBO films increased from 0.3 W/mK to 9.0 W/mK with increasing temperature from 10 K to 300 K and these were much higher than those of polyimide films, epoxy resin and glass fiber reinforced plastics at all temperatures. The 9.0 W/mK at 300 K was 60% of that of stainless steel (SUS304). It was 6 W/mK at 150 K, which was half that of SUS304 and was 3.3 W/mK at 77 K, which was 33% of that of SUS304. The thermal conductivities of the PBO films were lower than those of a cloth of high strength ultrahigh molecular weight polyethylene fiber reinforced plastics in the 30 K–180 K temperature range and were almost equivalent to its values in the 180 K–300 K temperature range. The main contribution to the thermal conduction in the PBO films was from thermal phonon conduction along the molecular chains. Although many kinds of high thermal conductivity polymeric materials have been prepared by a uni-directional drawing process or by adding high thermal conductive additives, the PBO film showed high thermal conductivity without a uni-directional drawing process or high thermal conductive additive.

Study on structures and properties of ultra-hot drawing UHMWPE fibers fabricated via dry spinning method

Abstract High tensile strength ultra high molecular weight polyethylene (UHMWPE) fibers were prepared via the dry spinning method. Raw material was UHMWPE resin with 6 million viscosity-average molecular weight (Mv). Changes of morphology, mechanical properties, thermal properties and crystallization process of the fibers in the ultra-hot drawing process were studied by scanning electron microscopy (SEM), tensile tester, differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD). Results show that there was a maximum value of fracture force at a draw ratio of 40 and excessive draw ratio destroyed crystal structures in fibers and led to a decrease in the fracture force value. A shoulder peak appeared in DSC curves of ultra-drawing samples and its peak value maintained at 154°C in different samples. In addition, three peaks can be observed in all WAXD patterns of drawing samples. The mechanism of microstructural changes during the hot drawing process was elucidated.

Single fiber peel test to assess ultra high molecular weight polyethylene fiber mesostructure interactions

ABSTRACTIn this work, a variable angle, single fiber peel test is developed to analyze the effects of fiber structure on the mixed mode failure within ultra high molecular weight polyethylene fibers. The Mode I and Mode II peel energy release rates are quantified and the effects of fiber meso/nanostructure on these modes are examined. Comparison of the load‐extension curves from the peel test with in‐situ video, and post‐mortem analysis using high‐resolution microscopy techniques indicates that Mode I and Mode II splitting are both significantly influenced by the deformation of nanoscale fibrils within a mesoscale network. The fibrils in the network are placed in tension across the peel/shear interface resulting in elevated values of peel energy release rates with an increasing number of engaged fibrils. The number of engaged fibrils is shown to increase with decreasing peel angle and increasing Mode II failure contribution. A bi‐linear mixed‐mode failure criterion is established. The results, and analysis of the fiber structure are discussed in context of their implications for load pathways in the fiber. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46156.

Uticaj AL2O3 čestica na žilavost hibridnog kompozita sa EVA matricom ojačanog UHMWPE vlaknima

The aim of this paper is to investigate the mechanical properties of hybrid composites with the polymer matrix of the copolymer of ethylene and vinyl acetate (EVA), ultra high molecular weight polyethylene fibers (UHMWPE) and particles based on aluminum oxide. Commercial aluminum oxide nanoparticles and aluminum oxide particles obtained by sol-gel technique were used as fillers in a proportion of 1, 3 and 5 wt. %. Infrared spectroscopy with Fourier Transformation (FTIR) and Scanning Electron Microscopy (SEM) were used to test the chemical structure and microstructure of hybrid composites, respectively. The tensile test showed an increase in the modulus of elasticity and the tensile strength of the obtained hybrid composites. The results of the sample testing showed that the best mechanical properties and toughness of the material shows hybrid composites with 1 mass. % micron particles of aluminum oxide.

Surface functional modification of ultrahigh molecular weight polyethylene fiber by atom transfer radical polymerization

In order to improve the bonding between Ultra High Molecular Weight Polyethylene fiber (UHMWPE) and resin, the fiber surface need to be modified with functional groups. In the paper, the UHMWPE fiber was chlorinated by NaClO and then grafted with 2-hydroxyethyl methacrylate by Atom Transfer Radical Polymerization. After chlorination and grafting, the surface tensions of fibers achieved to 36.5mN/m and 49.5mN/m, respectively. FTIR-ATR and XPS confirmed that the surface of UHMWPE fiber has been functional modified by hydroxyl and ester function of grafted polyhydroxyethylmethacrylate. Further, it can be seen from SEM that the surface of functional modified UHMWPE fiber was not damaged. Compared to unmodified UHMWPE fiber, the mechanical property of functional modified UHMWPE fiber and epoxy resin composite was greatly improved.

高強度化学繊維によるワイヤ駆動のための基礎的検討

Synthetic fiber ropes, which are lightweight and have high tensile strength and flexibility, have attracted attention as an alternative to stainless steel wire rope. This study clarifies various physical characteristics of synthetic fiber ropes to design a tendon-driven mechanism and this paper focuses on creep of ropes. We first designed and constructed a creep testing machine for ropes. Second, we performed experiments with three types of synthetic fiber ropes and one stainless steel wire rope. As a result, in stainless steel wire rope, creep was not observed. In addition, Polyarylate(PAR) fiber rope and Poly-phenylene-Benzobisoxazole(PBO) fiber rope have much higher creep resistance than Ultra High molecular weight Polyethylene(UHPE) fiber rope.

An Amidoximated-UHMEPE Fiber for Selective and High Efficient Removal of Uranyl and Thorium from Acid Aqueous Solution

High efficient removal and recovery of uranium and thorium from nuclear waste solution are essential for environmental preservation and fuel recycle. A new polymer fiber adsorbent (UHMEPE-g-PAO fiber), prepared by amidoximation of grafted polyacrylonitrile onto Ultra High Molecular Weight Polyethylene (UHMWPE) fiber, was used to remove the uranyl and thorium ions from acid aqueous solutions and its performance was carefully investigated. It was found that uranyl ion can penetrate the fiber through the connected pore structures, forming (UO2) (R-C(NH2)-NO)2 chelates with the amidoxime groups within the fiber. Two amidoxime groups (U-N and U-Oeq) and two water molecules (U-Oeq2) are bound to uranyl ion in the fiber. On the contrary, thorium ions are adsorbed mainly on the fiber surface in the form of Th(OH)4 precipitate that blocks the entrance of Th4+ ion into fiber pores. The maximum included other two capacities of uranyl and thorium ions were estimated to be 262.01 mg/g and 160 mg/g at room temperature with pH 3.0, respectively. The results also indicate that the UHMWPE-g-PAO fiber has higher adsorption selectivity for uranyl ion than thorium ion. Uranium and thorium oxide particles were obtained as the ultimate product after sintering of the fiber adsorbent. This novel and environmentally friendly adsorption process is feasible to extract uranium or thorium from acidic aqueous solution.

Experimental study on uniaxial tensile and welding performance of a new coated fabric for airship envelopes

This paper investigated the mechanical properties of GQ-6 subjected to a tremendous amount of uniaxial tests. Such material is a new kind of ultra high molecular weight polyethylene fiber and aimed to be adopted in stratospheric airship. To begin with, mono-uniaxial tensile tests were conducted. The cycling-uniaxial tensile experiments were then carried out on the basis of the mono-uniaxial tensile tests data. Finally, performances of welding seams were thoroughly investigated with forty welding specimens. Results of mono-uniaxial tensile tests revealed that such woven fabric possesses high tensile strength and low elongation ratio at break. Meanwhile, the stress–strain behaviors were fitted by the Ogden model and a good agreement between such model and experimental data was obtained. Influences of the uniaxial loading cycle on such woven stiffness were discussed and the elastic moduli were defined with a standard hysteresis loop. For the welding tests, four types of overlapping welding failures were discovered. Compared with intact specimens, an appropriate welding width of 60 mm and an approximate 15% discount of the ultimate tensile stress on the intact textile were obtained.

Effect of Surface Modification and Hybridization of UHMWPE Fibers on Performance of their Composites with Epoxy Resin

Ultra high molecular weight polyethylene (UHMWPE) fibers possess outstanding properties such as high tensile strength and low density. However, their low surface polarity and poor heat resistance restrict the application of UHMWPE fibers as a reinforcing material for high performance composites. These shortcomings of UHMWPE fibers can be overcome by ultraviolet (UV) assisted grafting treatment and hybridization with aramid fibers. Results show that UHMWPE fibers could firstly be modified by means of an UV radiation assisted one step grafting process with acetone as solvent and acrylic acid as monomers, then the mechanical properties of composites of epoxy resin with the modified UHMWPE fibers was greatly enhanced; with the increasing monomer content in the acetone solvent, the tensile strength of UHMWPE fibers/epoxy resin composites increased obviously, while there was no significant change of flexural strength and impact strength. In order to further improve the heat resistance of UHMWPE fibers/epoxy resin composites, UHMWPE fibers were hybridized with aramid fibers and then the hybrid fibers were used as reinforcing material to produce hybrid fibers/epoxy resin composites. As a result, the deformation of the hybrid fibers/epoxy resin composites decreased by 66.7% at 90°C compared to that of UHMWPE fibers/epoxy resin composites. The result proves that the pre-hybridization of UHMWPE fibers is an effective means to enhance the heat resistance of UHMWPE fibers/epoxy resin composites .

Effect of Accelerated Ageing on Ballistic Textiles Modified By Plasma-Assisted Chemical Vapour Deposition (PACVD)

The functionalisation of textile products and materials using the low temperature plasma technique is increasingly used in industrial practice, mainly because of the many benefits, often unattainable with the use of other techniques. The study focused on the modification of the composite textile materials - sheets of Ultra High Molecular Weight Polyethylene (UHMWPE) fibres (Dyneema ® SB51) by applying the surface deposition of silicone-like polymer in an environment of low temperature plasma. The aim of this study was to evaluate changes in the mechanical and physical properties of modified ballistic textiles un der simulated storage conditions in accelerated time. Based on experiences in planning the research on accelerated aging, a test programme was developed for the assessment of changes during the aging process in ballistic fibrous materials under various environmen tal conditions. The process of low temperature plasma modification affected the mechani cal properties of the ballistic composite textile materials during the accelerated ageing using temperature or temperature and humidity. The effect of the modification varied with the mechanical properties investigated.

Extended Chain Crystals of Ultra High Molecular Weight Polyethylene Fiber Prepared by Melt Spinning

The extended-chain crystal structure of the UHMWPE fibers prepared by melt spinning method was studied with WAXD, DSC and SEM. At draw ratio (DR) values higher than 24, double melting peaks were observed from the DSC thermograms, the corresponding temperatures being 137.1–142°C and 142–145°C, respectively. With the increase of DR values, the lengths in a and b axis of the unit cell shortened, and the unit cell remained orthorhombic even if the DR values increased to 60. At DR values lower than 24, the crystallinity and orientation degree of the UHMWPE fibers affected the tensile strength of fibers markedly. At DR values were higher than 24, the abundantly produced extended-chain crystals mainly dominated the improvement of tensile strength of the UHMWPE fibers.

Ultra-high-molecular-weight polyethylene fiber reinforced dental composites: Effect of fiber surface treatment on mechanical properties of the composites

ObjectivesPoor interfacial adhesion between the fibers and resin matrix in the ultra high molecular weight polyethylene (UHMWPE) fiber reinforced composites (FRCs) is the main drawback of the composites. This study aims to evaluate the effect of corona and silane surface treatment of the fibers on the mechanical properties of the UHMWPE FRCs. MethodsUHMWPE fibers were exposed to corona discharges for different periods of time (0s, 5s, 7s). The surface characteristics of the UHMWPE fibers were investigated by attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and nanoindentation technique. The flexural strength and flexural modulus of the FRCs made of the treated fibers were determined on 2mm×2mm×25mm specimens. The fracture toughness (the critical stress intensity factor, KIC) of the composites was also evaluated using a three-point single edge notch beam (SENB) bending technique. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. The fiber-resin interface and the fracture surface were investigated using SEM. ResultsThe change in the surface mechanical properties and chemistry of the corona treated UHMWPE fibers were monitored. The fibers exposed to corona for 5s showed higher surface nanohardness. In the FRCs, the specimens reinforced with 5s corona treated silanized fibers showed higher mechanical properties (flexural modulus, flexural strength, and fracture toughness), SEM images revealed a better adhesion between the resin and fibers after 5s fiber corona treatment and silanization. SignificanceCorona and silane treatment of UHMWPE fibers provide dental FRCs with improved mechanical properties.

Structural hierarchy and surface morphology of highly drawn ultra high molecular weight polyethylene fibers studied by atomic force microscopy and wide angle X-ray diffraction

The meso/nanostructure of UHMWPE fibers manufactured using different processing conditions is explored through atomic force microscopy (AFM) and wide-angle X-ray diffraction (WAXD). Characteristic dimensions of sub-filament microstructure are quantified at the fiber surface and the fiber interior. These measurements are compared to crystalline parameters determined using WAXD. Observation of junctions between microfibrils suggests the original gel network from which the fiber was drawn remain in the final product. For fibers having undergone greater drawing, the fiber surface reveals the presence of large-scale epitaxial features oriented perpendicular to the direction of drawing. Annealing experiments show that epitaxial structures undergo thickening at temperatures >120 °C. Examining fiber cross-sections reveals a network of microfibrils that appear to undergo consolidation with increased drawing. The evolution of the structural hierarchy of these fibers is discussed in the context of its implications for optimization of processing both fibers and their composites.

Low Velocity Impact Behaviour of Aramid and UHMWPE Composites

The most popular method to produce composites for ballistic applications is to use aramid and ultra high molecular weight polyethylene (UHMWPE) fibers as reinforcement materi als in different matrices. The composite materials used in this type of application, especially those used as armoring materials for explosions, are subjected to a very high level of energy. In this study, the effect of the reinforcement material type and cross-plied condition of reinforcement were examined using high-level impact tests. The impact tests were performed at low speed but high energy, and thus the behaviour of the composite materials that were exposed to high-level impact energy could be examined. According to the results, the UD aramid composite produced the best results with respect to high-level impact tests. In addition, mass optimisation could be achieved without the loss of the high-level impact energy by preparing a hybrid composite with UD UHMWPE and UD aramid fibers.

알킬아닐린을 디아조성분으로 활용한 디스아조계 초소수성 적색염료의 합성

Novel super hydrophobic disazo red dyes were synthesized to improve light fastness of the primary monoazo red dye of previous study on polyolefin fibers such as polypropylene and ultra high molecular weight polyethylene fibers. 4-Alkylanilines were diazotized and then coupled to 2,5-dimethylaniline to produce dye intermediates which were then further used to synthesize final disazo red dyes by diazoization and coupling to β-naphthol. Considering both affinity of the dyes toward both polyolefin fibers and color fastnesses, the decyl-substituted dye was determined as the optimum dye. The decyl-substituted disazo red dye exhibited good dyeability on both polyolefin fibes and almost the same color values as the previous primary monoazo red dye. Light fastness on ultra high molecular weight polyethylene fibers was improved up to rating 3~4 compared to rating 2~3 of the previous primary monoazo red dye.

Effect of High-Density Polyethylene Nanocomposite Compatibilizer Type on the Interfacial Adhesion and Mechanical Properties of Polyethylene Nano-Homocomposites

In this paper, the effect of nanocomposite compatibilizer type on the interfacial adhesion and mechanical properties of new class of polyethylene (PE) homocomposites, comprising PE/clay nanocomposites as matrix and ultra high molecular weight polyethylene (UHMWPE) fibers as reinforcement, was investigated. These were manufactured by a combination of powder impregnation and film stacking methods, introduced in previous research. Three types of high-density polyethylene (HDPE) Nanocomposites were prepared based on the various compatibilizers used: (i) nanocomposites containing HDPE-grafted maleic anhydride (HDPE-g-MA) as compatibilizer of clay and HDPE matrix, (ii) linear low-density polyethylene-grafted maleic anhydride (LLDPE-g-MA) used as compatibilizer, and (iii) nanocomposites without any compatibilizer. The effects of the presence and compatibilizer type on the quality of clay dispersion, and also the interface features of HDPE-nanocomposite and UHMWPE fibers were investigated and compared with each other. The results demonstrated that the kind of compatibilizer was an important factor determining the dispersion state of clay platelets, and influenced the UHMWPE fiber–PE matrix interface adhesion and the mechanical properties of the PE nano-homocomposites.

Modelling microbuckling failure of a composite cantilever beam made from ultra high molecular-weight polyethylene fibres

Experimental results have shown that composite cantilever beams with ultra high molecular-weight polyethylene fibres are collapsed by a new mode of microbuckling, which involves elastic bending and shearing of the plies, and plastic shear of the interfaces. Different finite element modelling strategies were employed in this study. Simulation results reveal that an enough number of interfacial cohesive layers, accurate partition of the shear stiffness between plies and interfaces, and accurate partition of the flexural stiffness between plies are important in predicting the collapse responses. The sensitivity of the predicted microbuckling responses to the overall effective shear modulus and interlaminar shear strength of long composite beams are also investigated.

450-500nm의 최대흡수를 가지는 순수 폴리올레핀 소재용 초소수성 오렌지 염료의 합성

Novel super hydrophobic orange dyes having maximum absorption band at 450-500nm were synthesized to dye polyolefin fibers such as polypropylene and ultra high molecular weight polyethylene fibers, using 4-alkylanilines and β-naphthol. Their absorption spectra at visible range showed almost the same, which meant that the alkyl substituents introduced to chromophore did not affect on color appearance of the dyes. Considering both color strength and wash fastness, the decyl-substituted dye was determined as the optimum one practically. From the dyeing results at various conditions, the optimum dyeing was 130℃ for 1 hour with 5% owf of dyes. The good fastness ratings to washing, rubbing were obtained showing 4-5 for both fibers. Light fastness was also acceptable giving rating 3-4 for polypropylene fibers and rating 3 for ultra high molecular weight polyethylene fibers.

A study of mechanical behavior and morphology of carbon nanotube reinforced UHMWPE/Nylon 6 hybrid polymer nanocomposite fiber

We report a phenomenal increase in strength, modulus, and fracture strain of ultra high molecular weight polyethylene (UHMWPE) fiber by 103 %, 219 %, and 108 %, respectively through hybridizing this fiber with Nylon 6 as a minor phase and simultaneously reinforcing it with single-walled carbon nanotubes (SWCNTs). Loading of Nylon 6 and SWCNTs into UHMWPE was 20.0 wt% and 2.0 wt%, respectively. Hybridized fibers were processed using a solution spinning method coupled with melt mixing and extrusion. We claim that the enhancement in strain-to-failure of the nanocomposites is due to induced plasticity in the hybridized Nylon 6-UHMWPE polymers. The enhancement in strength and stiffness in the nanocomposites is attributed to the load sharing of the SWCNTs during deformation. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) studies showed that changes in percent crystallinity, rate of crystallization, crystallite size, alignment of nanotubes, sliding of polymer interfaces and strong adhesion of CNT/polymer blends were responsible for such enhancements.