A new method to measure the three-dimensional solubility parameters of acrylate rubber and predict its oil resistance

As people pay more and more attention to environmental protection and the high cost of diesel and gasoline, in order to reduce environmental pollution and use cost, some low-pollution and low-cost components, such as alcohols (ethanol, etc.) and esters (methyl acetate, etc.), are added to diesel and gasoline. Due to the addition of new components, the swelling degree of rubber products will also change. In the literature, this method is often used to test the oil resistance of vulcanizates directly by immersing them in oil. In this paper, a new method is used to predict the oil resistance of vulcanizates. In order to investigate the swelling property of acrylate rubber more comprehensively and predict its oil resistance, the swelling behavior of carboxylic acrylate rubber (AR12) produced by Zeon Corporation (Japan) was measured by swelling method in 24 different organic solvents, and the value of one-dimensional solubility parameter ( δ ) of AR12 was obtained, ranging from 18 to 22 MPa 1/2 . The swelling data were analyzed by Hansen Solubility Parameter in Practice software, and the three-dimensional solubility parameter sphere, two-dimensional solubility parameter graph and three-dimensional solubility parameter of AR12 were thus obtained. The values of the three-dimensional solubility parameter of AR12 were δ d = 18.30 MPa 1/2 , δ p = 7.10 MPa 1/2 and δ h = 5.60 MPa 1/2 , respectively. There is an energy difference (Ra) between AR12 and the 24 solvents, and the swelling ratio ( q ) of AR12 in the 24 solvents presents an inverse “S”-shaped curve as the Ra values between them change. The experimental results proved that the three-dimensional solubility parameters were more accurate in predicting swelling performance than that of one-dimensional solubility parameter. To verify the experimental results, the relationships of Ra, q and δ t values with the volume fractions of two groups of solvent mixtures were established. The experimental results showed the same as those obtained by a single solvent, which further proved the correlation of rubber swelling responses. This new method can be used to predict the oil resistance of rubber, and its advantages compared to traditional methods are using more environmentally friendly and cheaper liquid instead of toxic or expensive liquid. This method can be used not only to evaluate acrylate rubber, but also predict the oil resistance of other polymers.