jrups
Editorial: Climate Change and Economy of Africa
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Abstract : Properties and Applications of Biodegradable Polymers
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Abstract: Biodegradable materials are one of the major discussable matters in the modern world. To keep and produce environment-friendly products for our daily usage the utilization of degradable materials is increasing at a high rate. The modern world wants sustainable products which will not bring about any harm to the environment. Products made from plastics are sustainable but they cause great harm to our environment due to lack of degradation property. After the end of our usage, these materials can sustain for a long time without any degradation which causes a supreme level of loss to our environment. But if we can produce products by using biodegradable raw materials, they will be degraded by the action of bio-organisms hence our environment will be protected from a great loss. So, it has become a crying need for us to use biodegradable raw materials in our products. The materials which are not biodegradable cause a great pollution especially soil pollution. To protect the world from the cruel humiliation of waste, it has become an overwhelming necessity to manufacture biodegradable products, which can quickly be degraded in the environment, from our daily useable items. The materials contain almost all the properties which are suitable for our environment. Already these materials have been using in several sectors and showing their applications for their friendly properties. Keywords: Degradable, sustainable, bio-organisms, crystallinity, natural, synthetic. |
Abstract : Effect of Ageing on the Mechanical Performance of Thermoset Polymers: A Statistical Approach
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Abstract: The present work investigates the effect of three different ageing processes (natural, 100% relative humidity and salt spray) on the mechanical performance of two thermoset polymers, epoxy and polyester, commonly used as matrix phase in composite materials. A full factorial design is conducted to evaluate the effect of significant factors and interactions on moisture absorption, tensile and compressive strength and modulus of elasticity of the thermosets. Both polymers reveal a decrease in moisture absorption in the saline environment compared to the completely saturated condition (100% RH). Polyester polymers in harsh environments exhibit higher compressive properties compared to those subjected to natural conditioning. In general, polyester polymers, which are most affected by the positive effect of additional cross-linking, have less moisture absorption and superior mechanical properties compared to epoxy, which is more affected by the negative effect of plasticization. Keywords: Epoxy, polyester, salt spray, mechanical properties, moisture absorption, plasticization. |
Abstract : RAFT Polymerization of Styrene with Potassium Ethylxanthate as the Chain Transfer Agent
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Abstract: Using potassium ethylxanthate as the chain transfer agent, 2,2’-azobis(isobutyronitrile) (AIBN) as the initiator, reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene was carried out. The influences of reaction temperature, reaction time, and the amounts of the initiator and chain transfer agent on the RAFT polymerization were investigated in terms of monomer conversion, average number molecular weight (Mn) and molecular weight distribution (Ð) of the obtained polymer. Monomer conversion and the Mn of the obtained polystyrene (PS) improved with an increase in the reaction temperature, and the polymerization kinetics exhibited a highly linear relationship, indicating a first-order reaction. When the amounts of the initiator and chain transfer agent were increased, it led to a decreased Mn of the produced PS. Meanwhile, the Ð of the PS was in a relatively narrow range (1.42-1.89). The chain-end functionality was further demonstrated by adding methyl methacrylate to the PS. Keywords: Potassium ethylxanthate, Styrene, RAFT, Molecular weight, Chain-end functionality. |
