Study of LLDPE/chitosan blend with LLDPE-g-AAm as compatibilizer using infrared spectroscopy and molecular modeling.

Caracas

Congreso; XIII International Congress of Numerical Method in Engineering and Applied Sciences (2016).; 2017

Sociedad Venezolana de Métodos Numéricos en Ingeniería

The study of biodegradable plastics from natural sources such as chitosan (Ch), is one of the challenges today. Chitosan is of great interest because has the advantages of being biodegradable and biocompatible. Polymer blends have been the focus of attention over many years, allowing the development of new materials with improved properties. However, these blends generally are immiscibles. These limitations can be overcome by means of the functionalization. The polar groups are incorporated to obtain a compatibilizing agent. In this study blends of linear low density polyethylene (LLDPE) with Ch or LLDPE, Ch and linear low density polyethylene-graft-Acrylamide (LLDPE-g-AAm) as a compatibilizing agent were evaluated by infrared spectroscopy with a FTIR Perkin Elmer a model Frontier, in an attenuated total reflectance device (ATR) and molecular modeling through geometry optimizations and vibrational frequency calculations. Calculation of the electronic structure of lowest energy in the components of the mixtures was carried out using the Density Functional Theory (DFT) and absorption bands were obtained from calculations of frequencies (harmonics) using mechanical quantum and statistical mechanics for the partition functions of species, allowing to assign peaks observed in the FTIR and understanding of the specific interactions that occur between the polymers. Comparing the experimental blends in the presence and absence of the compatibilizing agent displacing some bands of C=O, OH and N-H at lower frequencies is observed, suggesting the formation of new hydrogen bonds between the OH and NH2 chitosan groups and C=O and NH2 amide grafted in LLDPE. Through molecular modeling is inferred that the gradual change in bands of theoretical blends at lower frequencies may be favored due to the interaction between the carbonyl (C=O) acrylamide and amine (NH2) chitosan and interaction between NH2 of amide and OH of chitosan as, shown in optimized structures. It demonstrated that incorporation of the compatibilizer in the ternary blend, promotesintermolecular interactions with Ch by means of hydrogen bonds. Finally, the results obtained for molecular modeling confirm FTIR-ATR analysis of blends and helps predict the types of interactions that occur, opening new perspectives in the study of biocompatible polymeric materials.