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Abstract : Modification and Characterization of Biodegradable Chitosan/ Starch-Based Films with Monomer 1,4-Butanediol Diacrylate (BDDA) by Gamma Radiation
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Abstract: Chitosan reinforced starch-based biodegradable films were prepared by solution casting. Tensile strength (TS), tensile modulus (TM), elongation at break (%), and water vapor permeability (WVP) of the 50% chitosan containing starch-based films were found to be 47 MPa, 550 MPa, 16%, and 2.45 g·mm/m2·day·kPa, respectively.Monomer 1,4 butanediol diacrylate (BDDA) was added (0.25-1% by wt) to the starch/chitosan (50:50) based film formulation. Then, films were cast and gamma irradiated from a radiation dose varied from 1 kGy to 25 kGy. Then mechanical and barrier properties were evaluated. The highest TS (80 MPa) and TM (880 MPa) of the films were found by using 0.5% monomer at 5 kGy dose. The WVP of the films were found to be 1.50 g·mm/m2·day·kPa which is 38.77% lower than control starch/chitosan-based films. Molecular interactions due to incorporation of BDDA were supported by Fourier transform infra red (FTIR) spectroscopy. The water uptake of the films pointed out better hydrophobic character due to incorporation of BDDA in starch/chitosan-based films. Surface morphologies of BDDA treated films were examined by scanning electron microscope (SEM) and suggested better morphologies due to BDDA treatment with starch/chitosan-based biodegradable films. Keywords: Starch, chitosan, biopolymer, monomer, biodegradable, gamma radiation.Download Full Article |
Abstract : Three-Dimensional Simulation of the Shrinkage Behavior of Injection-Molded Poly Lactic Acid (PLA): Effects of Temperature, Shear Rate and Part Thickness
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Abstract: The effects of injection temperature, shear and part thickness on the linear shrinkage of injection-molded poly (lactic acid) (PLA) were intensively analyzed using the Autodesk Moldflow software. The obtained results showed that both melt temperature and shear rate had obvious effects on the linear shrinkage of PLA, i.e., the linear shrinkage of PLA increases significantly with the increase of melt temperature and shear rate. In addition, the shrinkage of high-crystallinity PLA was remarkably larger than that of low-crystallinity PLA, and thin-walled parts was larger than thick-walled ones in shrinkage.. Keywords: 3D simulation, poly (lactic acid), temperature, shear rate, thickness, shrinkage.Download Full Article |
Abstract : Computational Simulation of the Random Depolymerization of Linear Polymers Obtained by Step-Polymerization of AB-type Monomers
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Abstract: This paper presents evaluation results of a computational algorithm developed to simulate the random depolymerization process of a linear polymer having an initial distribution of molecular weights similar to polymers obtained by polycondensation of AB-type monomers, i.e., Flory-Schultz or most probable distribution. Starting from fundamental definitions of this system, as the initial values of the degree of polymerization and chain number (Xno and No, respectively) and the percentage of cleaved bonds (%E), it is confirmed that our algorithm adequately describes the random depolymerization process. Results obtained during the computational simulation indicate that the algorithm properly predicts, among other things, that the inverse of the final polymerization degree (1/Xnf) increases linearly with the applied %E while polydispersity after depolymerization (Df) decreases linearly when the latter parameter increases. Keywords: Depolymerization computational simulation, Flory-Schultz distribution, polydispersity index, random scission.Download Full Article |
