Abstract:Polymer Phase change material (PCM's) are materials used to store Energy for a broad range of Applications.Unlike conventional storage materials, PCM absorbs and release heat at a nearly constant temperature. They store 5-14 times more heat per unit volume than sensible storage materials. Increasing demand in solar engineering and spacecraft thermal control applications; require the continuous development of such materials to maximize its efficiency. One of the options is to develop energy storage devices, which are as important as developing new sources of energy. In This paper we can show that combination of low Density Polyethylene (LDPE) paraffin wax and glycerin is an alternative material that can be used as PCM's. Differential Scanning Calorimeter (DSC); Melt Flow Index test and FTIR technique were used to characterize the new developed Compound. Results obtained indicate that a reduction of more than 10°C in melting temperature (Tm) of the pure LDPE-resin was achieved.
The inclusion of CaCO<sub>3</sub> and kaolin in polyvinyl chloride (PVC) polymer matrices greatly enhances the physical and mechanical properties of the composite. In this study, the effects of kaolin and surface treatment of CaCO<sub>3</sub> and kaolin particles on the microstructure and mechanical properties of PVC composites filled with kaolin particles via melt blending method were studied by means of SEM, tensile, Charpy impact testing, and FTIR. Treated and untreated kao-lin particles were dispersed in matrices of PVC resin at different concentrations up to 30 wt percentage. The tensile strength, elastic modulus, strain to failure and morphology of the resulting composites were measured for various filler loadings. Uniform dispersion of the fillers into the matrix proved to be a critical factor. SEM images revealed that small sized particles were more agglomerated than micron-sized particles and the amount of agglomerates increased with increasing particle content. Silane treated Kaolin-CaCO<sub>3</sub>/PVC composites had superior tensile and impact strengths to untreated kaolin-CaCO<sub>3</sub>/PVC composites. The Young’s modulus of all composites increased with increasing particle content up to maximum at 10% filler loading followed by gradually decreasing as content increased
Epoxy adhesives (single and two components) modified with SiO 2 nano-particles were used in this investigation to glue aluminum alloy and also two types of high strength steel (dip-galvanized steel DP 600 and micro-alloyed steel ZStE340). To improve the adhesion between metal surfaces and adhesives, the metal surfaces were pretreated with: a self-indicating pretreatment (SIP * ); corundum blasting; corundum blasting + a SIP coating; and a Pyrosil ® treatment + SurALink ® primer (PG 15 for epoxy adhesive). A single-lap shear tension test, done in accordance to DIN EN 1465, was used to determine the adhesive strength. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) analysis were used to analyze fractures that took place in the samples. The results showed that the adhesion strength of glued samples, containing the nano-particles modified adhesive, had significantly higher strength than unmodified ones. Pretreatment of the metal surfaces affected the adhesion, using nano-adhesives, only slightly. The adhesive strength values for single component epoxy resins were higher than those for two component epoxy resins. It was found that steel samples fractured adhesively at the steel surfaces. Aluminum treated samples indicated after pretreatment an increase in adhesive strength and the fracture occurred adhesively at the aluminum surfaces. Aluminum glued with two-component adhesives and pretreated with corundum blasting plus a SIP coating showed a mixed fracture mode; adhesively at the aluminum surface and cohesively in the adhesive layer.
The effect of aluminium billets and H13 steels qualities on the mechanical failure of the extrusion dies was investigated. Secondary AA6063 billets were homogenised at 570 and 580°C for 6 h then cooled by water, fan, and air. The step cooling method was also applied by quenching from 570 to 275°C. It was found that the quality of the secondary billet, in terms of hardness and microstructure, would be comparable to the primary ones when homogenised at 570°C for 6 h and then water-quenched. The quality of H13 steels in terms of wear resistance was improved through cyanidation. It was performed in KCN for 2, 2.5, and 3 h with a cyanide layer of 60, 87, and 115 μm, respectively.
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