Weight Polyethylene Powder Research Articles

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.

Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts.

Experiments on Cyclic Impact Compaction (CIC) of UHMWPE powder GUR 4120 were carried out on a laboratory hydro-pneumatic impact device. This device provides impact energies of up to 1 kJ with a frequency of impacts of 9 s−1 and enables producing dense and robust compacts in the form of disks with a diameter of up to 60 mm and a height of up to 24 mm. The optimal parameters of the CIC were determined, which are the preheating temperature of the powder, the impact energy and the number of impacts. The strength, Brinell hardness and elongation of the resulting compacts with a diameter of 40 mm and a height of 15 mm were 37.5 MPa, 49.0 MPa and 470%, respectively. The possibility of activating UHMWPE powder by explosive loading was studied. It was found that the explosive pretreatment reduces the mechanical properties of the resultant compacts. The CIC method is suitable for the manufacture of UHMWPE-based composites with nano-additives, as evidenced by the successful production of compacts containing nanoscale detonation carbon as an additive. The results of the present study show that the CIC method is promising for the industrial production of small-sized UHMWPE parts.

Pelletizing ultra-high molecular weight polyethylene (UHMWPE) powders with a novel tapered die and addition of high density polyethylene (HDPE): Processing, morphology, and properties

The extremely high molecular weight and molecular entanglement have rendered ultra-high molecular weight polyethylene (UHMWPE) superior properties. However, poor inter-particle diffusion makes it difficult to pelletize UHMWPE powders for easy processing/handling. A novel tapered die with air cooling was proposed to pelletize UHMWPE and a UHMWPE blend with 5 wt% high-density polyethylene (HDPE) for compression molding and material characterization. The tensile strength of samples prepared with the tapered die outperformed those by the regular die or from virgin powders. The addition of HDPE further improved the tensile strength. Fourier transform infrared spectroscopy (FTIR) revealed little chain scission and the lowest amount of oxidation from the tapered die. Intrinsic viscosity (IV) measurements confirmed the negligible chain scission and showed an increment in IV for the UHMWPE/HDPE blend. Multi-angle light scattering with size-exclusion chromatography (SEC-MALS) indicated no change in the UHMWPE molecular weight distribution, but some crosslinking in the blend. Polarized optical microscopy (POM) showed that the HDPE and extrusion led to a finer UHMWPE domain size and better fusion between UHMWPE and HDPE. The combined effect of enhanced molecular chain diffusion, improved consolidation, and lower oxidation using the tapered die led to 40% improvement of tensile strength for the UHMWPE/HDPE blend.

Effects of polyethylene microplastics on the microbial community structure of maize rhizosphere soil

The use of agricultural polyethylene films results in polyethylene microplastic accumulation in the soil, causing microplastic pollution, which has attracted the attention of scholars worldwide. To study the effects of polyethylene microplastics on the microbial community structure of crop rhizosphere soil, corn was grown with different polyethylene powders (average molecular weights:2000, 5000, and ≥ 100 000) to simulate microplastic pollution in agricultural soil. There were five treatments in this experiment:planting maize without polyethylene (CK), planting maize with 2000 (T1), 5000 (T2), and ≥ 100 000 (T3) molecular weight polyethylene powder, and non-planting maize without polyethylene (CK0). Differences in mineral element metabolism in different parts of maize plant at the heading stage and variation in the rhizosphere soil microbial community structure were analyzed. The results showed that the mineral element content differed in different parts of maize. Iron and copper were mainly concentrated in the roots; calcium, manganese, and magnesium were most abundant in the leaves; and potassium was mainly concentrated in the stems. After adding the polyethylene microplastics of different molecular weights, the mineral elements in different parts of the plant increased compared with CK; the increase was greatest under the 2000 molecular weight polyethylene treatment. Microbial diversity analysis showed that the polyethylene microplastics had different effects on the microbial community composition in the maize rhizosphere. Except for Proteobacteria and Burkholderiaceae, the abundance of bacteria decreased under the 2000 molecular weight polyethylene treatment compared to CK. The abundance of bacteria and fungi increased under the ≥ 100 000 molecular weight polyethylene treatment compared to CK. In general, the mineral elements contents in different parts of the maize plant increased compared with CK after the addition of polyethylene. Two-thousand molecular weight polyethylene reduced the abundance of bacteria and fungi in the soil, whereas ≥ 100 000 molecular weight polyethylene increased the abundance of bacteria and fungi in the soil; the number of microorganisms related to the degradation of environmental pollutants in each treatment increased, which helped the soil cope with microplastics stress.

Tribological performance of self‐lubricating polyurethane elastomer compounding with the modified ultra‐high molecular weight polyethylene

AbstractUltra‐high molecular weight polyethylene (UHMWPE) powder was modified by surface treatment technology, then its wettability, dispersibility, mechanical, and tribological properties in polyurethane elastomer were studied. The testing results showed that after surface treatment, UHMWPE powder could infiltrate and disperse evenly in polyurethane, and build micro cross‐link with the contact surface of polymer substrate, which is conducive to enhancing the internal stress of polymer and improving the mechanical properties. With a small amount of modified UHMWPE being added into the casting polyurethane (CPU) elastomer, the right‐angled tearing strength increases and the abrasion loss decreases. Moreover, the elastomer surface self‐lubricating performance of CPU compounding with modified UHMWPE is enhanced: compared with the neat CPU sample, the average friction coefficient of the CPU samples with 5%, 10%, and 15% of modified UHMWPE is reduced by 46.3%, 41.5%, and 39.0%, respectively, and the surface wear resistance is improved; under the high‐load working condition, the CPU elastomer with 5% of modified UHMWPE has the optimal tribological performance.

Melting kinetics, ultra-drawability and microstructure of nascent ultra-high molecular weight polyethylene powder

For the production of high-performance polyethylene fibers and tapes by ultra drawing, using solid-state processing of disentangled nascent ultra-high molecular weight polyethylene (UHMWPE), the maximum draw ratio is an important design parameter, as it determines the maximum degree of chain alignment and, therewith, the properties of the final product. It would, therefore, be advantageous to have a fast scanning method to estimate the maximum drawability of reactor powders. In the present work, the melting behavior of nascent UHMWPE reactor powder was studied by differential scanning calorimetry, followed by isoconversional analysis to evaluate the apparent activation energy barrier of melting for the different UHMWPE grades of different level of disentanglement. Powder samples were solid-sate processed into tapes at elevated temperature. Ultra drawing of these tapes at the optimum drawing temperature allowed for the evaluation of the maximum draw ratio (λmax) that is determined by the entanglement density. The morphology of the lamellar structure of the nascent powder was studied by small-angle X-ray scattering and by scanning transmission electron microscopy analyses. A correlation between the melting kinetics, the microstructure and the maximum draw ratio was observed for all grades, suggesting that the apparent activation energy of melting can be used as a screening method to estimate the maximum draw ratio.

Optimization of Mechanical Activation Modes for UHMWPE Dry Mixed Powders and Nanomodificators in the Planetary Ball Mill Pulverisette 7

Introduction. Currently, in various technology areas, bronze, cast iron and other antifriction metals are replaced by polymer composites, which extend significantly service life of tribocoupling. An advanced antifriction polymer is ultra-high-molecular-weight polyethylene. The study deals with determining the optimal specific energy consumption for the mechanical activation of the polymer dry mixed powders and nanomodifiers in the planetary ball mill Pulverisette 7, which ensure the best complex of physico-mechanical and rheological properties of nanocomposites. Materials and Methods. In this work, we used GUR 4120 Ticona ultra-high-molecular-weight polyethylene with a molecular weight of 5 million, a Tuball Matrix Beta concentrate of activated carbon nanotubes at a concentration of 0.1%, calculated with reference to carbon nanotubes, and hydrophobic nanocrystalline silicon dioxide with a dispersion of 20 nm at the same concentration. Mechanical co-activation of polymer powders and nanomodifiers, when varying the specific energy consumption, was carried out in the planetary ball mill Pulverisette 7. The production of films from powders, for studying the elastic-strength and rheological characteristics of nanocomposites, was carried out with the use of the hydraulic press Gibitre. Tests were carried out respectively on the tensile testing machine UAI-7000 M and the rheometer Haake MARS III. Results. It has been established that the best physico-mechanical and rheological properties of nanocomposites are with specific energy consumption for mechanical activation of 3,000‒3,200 J/g that allows us to consider them optimal. The mechanical activation of ultra-high molecular weight polyethylene powder, reducing slightly the elasticity modulus and tensile strength of thermally pressed samples, does not affect the dynamic viscosity of melts at an energy consumption of 650‒4,550 J/g. Discussion and Conclusion. The use of carbon nanotubes and nanocrystalline silicon dioxide at a concentration of 0.1% can significantly improve the physical-mechanical and rheological properties of the polymer with energy costs of 3,000‒3,200 J/g for mechanical activation in planetary ball mills. Nanocrystalline silicon dioxide is a more effective modifier that can be explained by its better dispersion in the polymer matrix due to the lower tendency of nanoparticles to agglomerate.

Experimental studies on micro powder hot embossing for high-aspect-ratio microstructures with ultra-high molecular weight polyethylene powders

High-aspect-ratio microstructures have broad application prospects in many fields. Conventionally, lithography and etching processes are the primary methods for fabricating high-aspect-ratio microstructures on glass or silicon chips. However, as application scenarios have expanded, polymeric microstructures have received increasing attention, due to the low cost and wide ranges of special physical properties of polymers. Hot embossing is a high-efficiency method of processing large-area polymer films, but due to spring back, fabricating high-aspect-ratio microstructures remains a challenge. For this issue, micro powder hot embossing with the advantage of the good fluidity of the powder, is expected to achieve accurate microstructures with a high aspect ratio. In this paper, micro powder hot embossing was studied experimentally with the ultra-high molecular weight polyethylene (UHMWPE) powders which has excellent performances but poor formability. First, the processing window for preparing compact samples was investigated. Two indicators including filling depth and compactness were then proposed to characterize the forming quality of high-aspect-ratio microstructures. Afterwards, the effect of cavity size was also discussed and a ratio of cavity size to powder particle size was suggested to exceed 4 for high-aspect-ratio microstructures. Lastly, influences of process parameters (including temperature, pressure, and sintering duration) were further studied, which recommends a loading pressure greater than 10 MPa and a sintering temperature exceeding 140 °C for the micro powder micro embossing for UHMWPE. Microgrooves with an aspect ratio up to 8.0 were successfully prepared, demonstrating the feasibility of micro powder hot embossing in the fabrication of high-aspect-ratio microstructures with high precision and comprehensive properties.

Fabrication of microplastic parts with a hydrophobic surface by micro ultrasonic powder moulding

Microstructures with hydrophobic surfaces have been widely used in industrial fields such as self-cleaning and drag reduction. With the aim of fabricating microplastic parts with a hydrophobic surface, the paper processed the mould insert with micro-groove arrays from 304 stainless-steel plate through low-speed wire electrical discharge machining (LS-WEDM). And the micro-groove arrays were designed to U shape with bottom radius of 70 μm and depth of 110 μm. Ultra-high molecular weight polyethylene (UHMWPE) powders were used as raw material to fabricate microplastic parts with hydrophobic surface structures by micro ultrasonic powder moulding (micro-UPM). The parameters of the micro-UPM process were obtained by the single-factor test method. Under the ultrasonic energy of 1200 J, welding pressure of 100 kPa and pressure holding time of 8 s, microplastic parts with well surface morphology (Ra =1.36 μm) and replication rate (97.76 %) were successfully fabricated. The surface contact angle of the microplastic part was 135.4°, which indicated well surface hydrophobicity.

Effect of Adhesion on Mechanical and Tribological Properties of Glass Fiber Composites, Based on Ultra-High Molecular Weight Polyethylene Powders with Various Initial Particle Sizes.

The aim of this study was to assess the effect of adhesion between the non-polar, ultra-high molecular weight polyethylene (UHMWPE) matrix and the glass fiber fillers of various lengths treated with the commercially available “KH-550” agent, on the mechanical and tribological properties of the UHMWPE-based composites. The motivation was to find the optimal compositions of the polymer composite, for the compression sintering manufacturing of lining plates for the protection of marine venders and construction vehicles, as well as transport equipment. It was shown that the initial powder size at equal molecular weight determined the distribution patterns of the glass fibers in the matrix, and, as a consequence, the mechanical and tribological properties of the composites. Based on the obtained experimental data and the results of the calculation by a developed computer algorithm, control parameters were determined to give practical recommendations (polymer powder size and glass fiber length), for the production of the UHMWPE-composites having specified mechanical and tribological characteristics. The “GUR4022 + 10% LGF” composite, loaded with the chopped 3 mm glass fibers treated with the “KH-550”, was recommended for severe operating conditions (high loads, including impact and abrasive wear). For mild operating conditions (including cases when the silane coupling agent could not be used), the “GUR2122 + 10% MGF” and “GUR2122 + 10% LGF” composites, based on the fine UHMWPE powder, were recommended. However, the cost and technological efficiency of the filler (flowability, dispersibility) and polymer powder processing should be taken into account, in addition to the specified mechanical and tribological properties.

Crystal morphology and corresponding physical properties of nascent ultra-high molecular weight polyethylene powder with short-branched chains

Due to the linear and ultra-long molecular chains, ultra-high molecular weight polyethylene (UHMWPE) has been playing a vital role in many fields. Based on more and more demands for special UHMWPE resins, the relationship between microstructure of nascent powder and its corresponding physical properties was investigated in this work, and one special powder with high degree of short-chain branch was fully contrasted with one general-purpose UHMWPE resin. Based on series characterization results, it revealed that short-branched chains led to a decrease on the entanglement density and brought a significant increase in the processing performance and mechanical properties. In addition, the short-branched chains also made a huge difference on crystal morphology of nascent UHMWPE powders. By correlating high-resolution scanning electron microscopy, DSC curves and Raman spectroscopy characteristics, the slurry polymerization mechanism of UHMWPE was deduced, and the corresponding performance of nascent UHMWPE powders was fully explained.

Effect of Various Infrared Heaters on Sintering Behavior of UHMWPE in Selective Inhibition Sintering Process

Selective inhibition sintering (SIS) is an emerging powder-based additive manufacturing technology that creates polymer or metal based parts through adhesion of layer-by-layer from three-dimensional computer-aided design model. Replacement of costly laser system in selective laser sintering tremendously reduces the cost of manufacturing. SIS attempts to incorporate low cost heaters to achieve efficient sintering for production of high quality parts. However, SIS demands uniform heating of each layer for effective sintering. The present study focused on examining the heating characteristics of three different types of infrared heaters with respect to various layer thickness and determining the optimal distance between the heating surface and the powder bed. Experiments are conducted using the low-cost heaters to obtain uniform distribution of heat energy across the ultra-high molecular weight polyethylene (UHMWPE) powder surface. The thermal and optical images are captured to observe the temperature distribution on the powder and the surface roughness. Tensile and compressive specimens were fabricated and their corresponding strength was determined and surface roughness was measured to study the surface characteristics of the parts.

Injection and injection compression molding of ultra‐high‐molecular weight polyethylene powder

Ultra‐high‐molecular weight polyethylene (UHMWPE) powder was processed using injection molding (IM) with different cavity thicknesses and injection‐compression molding (ICM). The processing parameters of feeding the powders were optimized to ensure proper dosage and avoid jeopardizing the UHMWPE molecular structure. Dynamic mechanical analysis (DMA) and Fourier‐transform infrared spectroscopy tests confirmed that the thermal and oxidative degradations of the material were avoided but crosslinking was induced during melt processing. Tensile tests and impact tests showed that the ICM samples were superior to those of IM. Increased cavity thickness and ICM were helpful for reducing the injection pressure and improving the mechanical properties due to effective packing of the material. Short shot molding showed that the UHMWPE melt did not exhibit the typical progressive and smooth melt front advancements. Due to its highly entangled polymer chains structure, it entered the cavity as an irregular porous‐like structure, as shown by short shots and micro‐computed tomography scans. A delamination skin layer (around 300‐μm thick and independent of cavity thickness) was formed on all IM sample surfaces while it was absent in the ICM samples, suggesting two different flow behaviors between IM and ICM during the packing phase. POLYM. ENG. SCI., 59:E170–E179, 2019. © 2018 Society of Plastics Engineers

Cyclic impact compaction of ultra high molecular weight polyethylene powder

Bulk specimens of GUR 4150 ultra-high-molecular-weight polyethylene with a molar mass of 9.2 · 106 g/mol are obtained by cyclic impact compaction. During compaction, the material remains in the solid state, which ensures the preservation of the crystalline phase with a volume fraction of up to 66%. The strength properties of the specimens are not inferior to those of the products obtained using the industrial hot molding process. It is shown that the method described here is suitable for producing compacts with micro- and nanosized additives.

Remarkable mechanical enhancement achieved by interfacial strengthening of organic/inorganic/fiber composites

In this study, a series of organic/inorganic composites were fabricated by melt-mixing ultra-high molecular weight polyethylene (UHMWPE) powder with a mixture of magnesia, potassium di-hydrogen phosphate and water. The microstructure and chemical composition of the composites were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Three point bending tests showed that the flexural strength and toughness of the composites were improved with the increase of polymer content. The flexural strength of the composite with 25.0wt% UHMWPE was 7.7MPa, and can be dramatically enhanced to 21.1MPa by incorporating only 0.1vol% of oriented thermotropic liquid crystalline copolyester (TLCP) fibers. The improvement is due to the enhanced interfacial bonding between the polymer and fibers, which was much stronger than that between the inorganic phase and fibers, making the fibers adequately contribute to the mechanical strength of the three-component composite. Our results demonstrated that the interfacial strengthening between fiber and inorganic matrix achieved by interpenetrated organic phase helps to establish a strong composite system.

Mechanism of cement paste reinforced by ultra-high molecular weight polyethylene powder and thermotropic liquid crystalline copolyester fiber with enhanced mechanical properties

In this study, a series of cementitious composites with high toughness and flexural strength was obtained by melt-dispersing ultra-high molecular weight polyethylene (UHMWPE) into a cement matrix followed by water immersion. The structure and chemical composition of the composites were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Three point bending tests showed that the flexural strengths of the composites were improved from 5.5 MPa to 18.2 MPa with the presence of 25 wt% UHMWPE, and could be further enhanced to 28.1 MPa with the addition of only 0.1 vol% oriented thermotropic liquid crystalline copolyester (TLCP) fibers. An adhesive test revealed that the interfacial binding force between polymer and fiber was much stronger than that between cement and fiber. Our findings provide a simple way for utilizing polymer to improve the interface between the fibers and cement matrix, consequently achieving a dramatic increase in the flexural strength and toughness.

Porous UHMWPE Membranes and Composites Filled with Carbon Nanotubes: Permeability, Mechanical, and Electrical Properties

Application of electric fields as a mechanism against membrane fouling is an emerging cleaning process for membranes. Sintering of ultrahigh molecular weight polyethylene powder particles decorated with multiwalled carbon nanotubes (MWCNT) is performed to produce electrically conductive porous filtration membranes. The contact of the molten particle surfaces leads to their fusion through neck formation during sintering. As the MWCNT only cover the surface of the powder particles, they form a conductive network with a high number of inter‐MWCNT contacts in pathways through the polymer matrix. Membranes with an electrical conductivity of 0.9 S m−1 at a MWCNT concentration of 5.0 wt% are prepared. Additionally, a comparison of sintered and compression molded samples shows that after the heating interval, crystallization during cooling strongly influences the formation of the MWCNT network. The study reveals that electrically conductive, porous polymer membranes for microfiltration applications can be prepared using a solvent‐free process. image

More wear‐resistant and ductile UHMWPE composite prepared by the addition of radiation crosslinked UHMWPE powder

ABSTRACTRadiation crosslinked ultrahigh molecular weight polyethylene (X‐UHMWPE) powder was prepared by γ‐ray irradiation under nitrogen atmosphere with a dose of 50–200 kGy at a dose rate of 7 kGy/h and further annealing in vacuum at 120 °C for 4 h. The crosslinked powder was characterized by FT‐IR spectroscopy, gel content, and hot‐press molding. Then, X‐UHMWPE was added to pristine UHMWPE to prepare a composite with 0–25 wt % filler. The morphology, wear resistance, and tensile property of the composite were investigated. Using X‐UHMWPE as a filler could sufficiently improve the wear resistance of the composite. Adding 25 wt % X‐UHMWPE (dose: 150 kGy) improved wear resistance by 130% and retained approximately 90% tensile strength and 70% ductility. Wear‐resistant and ductile UHMWPE composite may be potentially used for artificial joint replacement and engineering devices. The proposed route is useful in fabricating UHMWPE material with excellent comprehensive performance or functional polymer composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44643.

Highly hydrophilic ultra-high molecular weight polyethylene powder and film prepared by radiation grafting of acrylic acid

The surface properties of ultra-high molecular weight polyethylene (UHMWPE) are very important for its use in engineering or composites. In this work, hydrophilic UHMWPE powder and film were prepared by γ-ray pre-irradiation grafting of acrylic acid (AA) and further neutralization with sodium hydroxide solution. Variations in the chemical structure, grafting yield and hydrophilicity were investigated and compared. FT-IR and XPS analysis results showed that AA was successfully grafted onto UHMWPE powder and film; the powder was more suitable for the grafting reaction in 1wt% AA solution than the film. Given a dose of 300kGy, the grafting yield of AA was ∼5.7% for the powder but ∼0.8% for the film under identical conditions. Radiation grafting of a small amount of AA significantly improved the hydrophilicity of UHMWPE. The water contact angle of the UHMWPE-g-PAA powder with a grafting yield of AA at ∼5.7% decreased from 110.2° to 68.2°. Moreover, the grafting powder (UHMWPE-g-PAA) exhibited good dispersion ability in water.

Evolution of tensile properties of UHMWPE after short residence times in the melt state followed by high pressure molding

Event Abstract Back to Event Evolution of tensile properties of UHMWPE after short residence times in the melt state followed by high pressure molding Beatrice Yeung1, Pierangiola Bracco2, Thomas S. Thornhill1 and Anuj Bellare1 1 Brigham & Women's Hospital, Harvard Medical School, Department of Orthopedic Surgery, United States 2 University of Turin, Department of Chemistry, Italy Introduction: Consolidation of ultra-high molecular weight polyethylene (UHMWPE) powder during molding has received considerable attention due to damage associated with incomplete UHMWPE fusion in total joint replacement prostheses components [1],[2]. In this study, we studied the early stage fusion of UHMWPE powder in the melt state using a unique high pressure process that enables the polymer to be maintained in the melt state for very short times. Figure 1 outlines the phase diagram of polyethylene and the path taken to enable UHMWPE to reside in the melt state for specific time intervals. This is possible since the polymer enters the melt state isothermally via depressurization at elevated temperature compared to conventional compression molding wherein melting occurs via increase in temperature at moderate pressures, which is a slow process due to the low thermal conductivity of UHMWPE. We measured the tensile properties of the resulting UHMWPE to evaluate fusion of the consolidated polymer. Materials and Methods: GUR 1020 UHMWPE powder (Celanese, Oberhausen, Germany) was compression molded at 180˚C and 10 MPa pressure for 2 hours, and served as the control. A high pressure cell was used to apply 300 MPa pressure to the UHMWPE powder, heated to 180˚C, depressurized and maintained in the melt state for 5, 30 and 60 minutes respectively (HP-5min, HP-30min and HP-60min, respectively), re-pressurized to 300 MPa, cooled and depressurized. ASTM 638 type V specimens were prepared (n=5) and subjected to tensile testing at 10mm/min crosshead speed. The tensile modulus, yield stress, maximum strain and tensile strength were measured. A Differential scanning calorimeter (DSC) was used to measure the degree of crystallinity using a heat of fusion of 293 J/g (n=3). Results: DSC revealed a crystallinity of 53.1 ± 0.9%, 66.4 ± 0.3%, 71.1 ± 3.3%, 71.5 ± 2.5% and 70.0 ± 1.8% for Control UHMWPE, UHMWPE powder, HP-5min, HP-30min and HP-60min, respectively. There was no statistically significant difference in crystallinity for the HP UHMWPEs (p>0.05, ANOVA). The tensile modulus of the Control UHMWPE was approximately three times lower than those of the HP group (see Table 1). The HP UHMWPEs also had a higher yield stress and UTS compared to the Control but there was no statistically significant difference among the HP UHMWPEs. The maximum strain of HPE-5min and HP-10min was significantly lower than that of the Control but this was not the case for HP-60min. Discussion: This study showed that it took 60 minutes of melt fusion for the maximum strain of UHMWPE to attain a value close to that of the control, in which the polymer resided in the melt state for 2 hours. Such a rapid evolution of tensile properties indicates that co-crystallization of polymer chains across powder boundaries must play a significant role in consolidation since diffusion of chains across powder boundaries would likely take several hours to days. The study also shows that high pressure molding provided a high modulus UHMWPE with high yield stress, tensile strength and comparable maximum strain at 60 minutes of residence time in the melt state. Conclusions: The fusion of UHMWPE resin powder in the melt state results in rapid evolution of tensile properties during high pressure molding providing a UHMWPE with high tensile properties compared to conventional molding. Figure 1. Phase diagram of polyethylene indicating processing route. Table 1. Tensile properties of UHMWPEs