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Ultra-high molecular weight polyethylene (UHMWPE) acquires excellent properties while possessing poor processability. Blending low molecular weight polyethylene disentangles the molecular chain of UHMWPE and improves its processability, improving fiber productivity. In the present study, UHMWPE and its HDPE-blended fibers were produced by a high-temperature electrospinning process, and the effect of HDPE content on fiber properties was investigated in depth. Analysis of fiber surface morphology revealed the formation of uniformly distributed nano- to microscopic pores/pits, wrinkles, and grooves on the surface of blended fibers, unlike neat UHMWPE fibers containing irregular surface bulges and pits. It suggested that the blending of HDPE affected the surface topography and the thermal and mechanical properties of electrospun fibers. The tensile strength and Young's modulus of UHMWPE fiber improved by 142 and 102% at a 67:33 mass ratio of UHMWPE and HDPE and by 84 and 132% in the case of a 50:50 composition ratio, respectively. [ABSTRACT FROM AUTHOR]

Defence structures are under high threat of blast loading in recent years due to rising terrorist activities. Protection of defence structures against blast conditions has received a huge interest in the past few years. Blast mitigation requires to study the behavior of various metals under supersonic shock loading. An experimental study was carried out using in-house developed shock tube apparatus to understand effect of shock loading on mild steel and aluminum sheets. A limitation of current study is 1-D loading occurring in shock tube which is unlike 3-D loading occurring in a blast event. Experiments reveal that the properties of thin sheets in through-thickness direction plays an essential role in the shock transfer, which affects considerably the failure and final deformed shape of the sheet. The study showed that metallic thin sheets absorbed shock energy via plastic deformation and failed via a tensile failure mode. Results from this study indicate that aluminum sheets and mild steel sheets can offer shock-resistant properties and mitigate more energy via absorption and plastic deformation. Aluminum and mild steel sheets can therefore be used as a face and back sheet for the development of any sandwich composites. [ABSTRACT FROM AUTHOR]

Nano-micron size fiber formation of UHMWPE (ultra-high molecular weight polyethylene) can be carried out by a high temperature (130 °C) electrospinning method. In this work, the effect of solution parameters on fiber formation by the electrospinning method is discussed. Two different grades of UHMWPE having a molecular weight (Mw) of 2.21 million g/mole (UM2.21) and 4.43 million g/mole (UM4.43) were chosen for the analysis. The solution properties of UHMWPE were investigated via rheology, which allowed the identification of the entanglement concentration before conducting the electrospinning process. The entanglement concentration (ce) for UM2.21 was 1.5 wt.%, while that for UM4.43 was 0.8 wt.%, respectively. The concentration exponent in semi dilute unentangled, and semi dilute entangled regimes was 1.23 and 2.59 for UM2.21 and 0.45 and 2.57 for UM4.43, respectively, in-line with de-Gennes's scaling theory. SEM of the electrospun product revealed that defect-free smooth fiber morphology could only be obtained when the concentration of the solution is around 1.5-2.5 times the entanglement concentration. [ABSTRACT FROM AUTHOR]