Characteristics of Polymer Composites Based on Natural Rubber

This paper presents the obtaining and characterization of new types of polymeric composites based on natural rubber and plasticized starch, crosslinked using peroxide in the presence of a polyfunctional monomer - trimethylolpropane trimethacrylate. Composite variants containing 10 phr, 20 phr, 30 phr, 40 phr and 50 phr starch, respectively were made. Starch was plasticized and then incorporated in natural rubber in the roll mill, and then other ingredients were added; the resulting mixtures were cured in an electrical press. The physico-mechanical characteristics of resulting composites depends on the amount of plasticized starch added to the rubber mixture. The results of liquid action on composites show that it depends on the behaviour of mixture components in immersion media; thus, natural rubber is water resistant (variation of mass and volume in water has very low values) but not resistant to toluene (variation of mass and volume in toluene has high values); starch is hydrophilic – it absorbs water and, with the increased amount of starch in the mixtures, there is also an increase of mass and volume variation in water, but the values obtained are good, with mass and volume variation after 22 h of water immersion being below 8%. In toluene, there is an improvement in the behaviour of composites containing plasticized starch compared to control ones (without plasticized starch). The new polymer composites can be used in various fields such as in the food or pharmaceutical areas that require compositions free of toxic ingredients.