Rheological properties of HDPE/chitosan composites modified with PE- g -MA
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enate M.R. Wellen Department of Materials Engineering, Federal University of Paraíba, João Pessoa, PB 58051-900, Brazil
Eduardo L. Canedo and Suédina M.L. Silvaa) Department of Materials Engineering, Federal University of Campina Grande, Campina Grande, PB 58429-900, Brazil (Received 24 August 2016; accepted 19 December 2016)
The rheological behavior of composites made with high-density polyethylene (HDPE) and chitosan was studied. Composites were prepared by melt processing in a laboratory internal mixer. Maleic anhydride grafted HDPE (PE-g-MA) was used as compatibilizer to enhance the dispersion of chitosan in the HDPE matrix. Different percentages of chitosan and compatibilizer (up to a maximum of 25 phr) were added into HDPE to prepare composites. Characterization of the composites with parallel plate rheometer and laboratory internal mixer revealed that the presence of chitosan increases the complex viscosity, loss modulus, storage modulus and the torque (i.e., melt viscosity), and the combination chitosan/compatibilizer has a similar, if slighter, effect. At higher filler levels it is clear that the PE-g-MA affected the microstructure of the compounds, possibly increasing matrix–filler interactions and acting as an effective compatibilizer. I. INTRODUCTION
High density polyethylene (HDPE) is a versatile material that offers a high cost/benefit ratio compared to other polymers and alternative materials such as glass, metal or paper. It is widely used in high volume for short term applications such as biaxially oriented films for packaging, blown molded bottles for food, carrier bags, food wrapping material and so on.1–3 Although HDPE can offer a combination of characteristics that are ideally suited to various applications, such as good flow, good thermal stability, and excellent chemical resistance, this polymer decompose after long periods of time in natural environments; so, it is a source of pollution and social concern when disposed as solid waste.4–9 Still, HDPE packaging has poor antimicrobial and antifungal activities and little bivalent metal chelating ability.2,3,10–13 The incorporation of fillers from renewable resources as functional additives (such as chitosan, starch, cellulose and their derivatives) into synthetic polymers, has been reported in many publications and has been considered
Contributing Editor: Sarah Morgan a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.519
one of the best routes for preparing new materials with useful properties, partially or totally biodegradable.14–24 Chitosan is a natural polyaminosaccharide, composed by N-acetyl-D-glucosamine and D-glucosamine units linked by b glycosidic bonds. It is obtained from the deacetylation of chitin, one of the world’s most plentiful, renewable organic resources (a major constituent of the shells of crustaceans, the exoskeletons of insects and the cell walls of fungi), and has a great potential as filler. This is due to its biodegradability, biocompatibility, antimicrobial activity, no
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