Effect of Water Absorption on Some Mechanical Properties of Unsaturated Polyester Resin/Natural Rubber Blends

Binary polymer blend (UPE/ NR) with a weight ratio of (95/5)% was prepared by mixing of unsaturated polyester resin (UPE) with natural rubber (NR). Standard dimensions of specimens were prepared from the polymer blend. Compression, bending and impact tests were carried out on the prepared specimens. This investigation was conducted before and after the immersion of the specimens into three types of water (distilled, tap and rain water) for different periods of time (1, 2... 5 weeks). The (stressstrain) curves were obtained from compression test; while the Young s modulus values (E) were obtained from three-point bending test. The impact strengths (I.S.) were found from the impact test before and after immersion into water. The results have exhibited that the mechanical behavior of the prepared blend is affected by the nature of water and immersion time. In general, the strain rates and the impact strength of the polymer blend have increased after immersion; while the Young s modulus has decreased at the same conditions.