Effect of unsaturated polyester resin on the mechanical and ultrasonic properties of SBR and NBR

An unsaturated polyester resin is prepared by the ester interchange between p-carbethoxy phthalanilic acid and maleic anhydride with ethylene glycol i n the ratio of (1:1:2.1 mel). The structure of this polyester was establish ed by studying its IR and NMR spectra and the acid number was determined. T he effect of 5 phr polyester on the mechanical and physical properties of t wo types of rubber namely styrene-butadiene rubber (SBR) and acrylonitrile- butadiene rubber (NBR) was studied. The ultrasonic velocity and attenuation have been investigated for both types of rubber with and without the polye ster resin at 2 and 5 MHz in the temperature range between 180 and 346 K. F or each type of rubber two relaxation peaks are observed in these temperatu re and frequency ranges, a main peak and a secondary one. The addition of t he polyester resin is found to affect the position and height of the main p eak in SBR but not in NBR. It was found that the apparent activation energy of the main relaxation process is temperature dependent and increases with the addition of the polyester resin in both types of rubber. (C) 2000 Else vier Science Ltd. All rights reserved.