Properties and Applications of Biodegradable Polymers  - Pages 32-41

M.A. Sayed Patwary, S.M. Surid and M.A. Gafur

DOI: https://doi.org/10.6000/1929-5995.2020.09.03

Published: 05 August 2020

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.

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RAFT Polymerization of Styrene with Potassium Ethylxanthate as the Chain Transfer Agent  - Pages 50-57

Xinmeng Xu, Xiang Xu, Yanning Zeng and Faai Zhang

DOI: https://doi.org/10.6000/1929-5995.2020.09.05

Published: 09 October 2020

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.

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Quaternized and Unmodified Chitosans: Hydrodynamic Properties
Pages 31-41
N.P. Yevlampieva, A.S. Gubarev, M. Yu. Gorshkova, B.M. Okrugin and E.I. Ryumtsev

DOI: http://dx.doi.org/10.6000/1929-5995.2015.04.01.4

Published: 17 April 2015

Abstract: Molecular properties of N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan (modified chitosan) series with the averaged quaternization degree 90% have been studied in comparison with the unmodified chitosan series by the method of translation isothermal diffusion, viscometry and static light scattering in dilute solutions in 0.33М СН₃СООН+0.2М CH₃СООNa at pH 3.54. Molecular mass, translation diffusion coefficient, and hydrodynamic size of the homologues samples in the modified/unnmodified series have been determined as well as their chain rigidity and Mark-Kuhn-Houwink equations at acidic pH. It was established that the size of modified chitosan molecules might be smaller than the initial polysaccharide of an equal polymerization degree in the same solvent, which was explained by the change of thermodynamic conditions and the change of the ratio of thermodynamic/electrostatic contributions to the total chain rigidity. Quaternized chitosan molecules displayed the different hydrodynamic behavior in 0.33М СН₃СООН+0.2М CH₃СООNa and in 0.2M NaCl (neutral pH). Solution properties of quaternized chitosan at neutral pH had been identified as the concentration dependent. The threshold influence of the secondary amino group protonation on the hydrodynamic properties of modified chitosan molecules was detected in 0.2M NaCl at the solute concentration range 0.001-0.004 g/cm³.

Recent Advances in Biodegradable Polymers - Pages 33-71

Sunil Dhamaniya, Virendrakumar Gupta and Rucha Kakatkar

DOI: https://doi.org/10.6000/1929-5995.2018.07.02.3

Published: 10 July 2018

Abstract: Biodegradable polymers are important as an alternative to conventional non-degradable polymers for sustainable eco-system. The recent trends indicate that the new developments in biodegradable polymers focus on novel polymer systems that can cater the need of biomedical and packaging applications in-terms of performance and economics. The new interest is rapidly moving toward reducing carbon footprint through utilization of carbon dioxide and developing new methods of manufacturing such as 3D printing for specific purposes. This review focus on the present state-of-art and recent developments in biodegradable polymers covering their sources, synthetic methodologies, salient properties, degradation patterns, polymer blends and nanocomposites. As well as biodegradable polymers as a 3D printing material and the use of carbon dioxide as a renewable raw material for biomedical and packaging applications.

Keywords: Biodegradable polymers, polymer blends, 3D printing, carbon dioxide, renewable resources.