四川大学高分子研究所 四川省橡塑材料复合成型技术工程实验室 成都
The reactive enhanced filler zinc methacrylate (ZDMA) can give EPDM high hardness, high elasticity, low internal friction, high strength and high elongation characteristics. However, the specific composition of EPDM/ZDMA and the structural changes of crosslinked network under the action of tensile, compression forces or high temperature are still not clear. Therefore, in this paper, differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were used to confirm that the total crosslinked network of EPDM/ZDMA composite is mainly composed of ionic crosslinked network and covalent crosslinked network. The changes of covalent bond crosslinking density (vr1) and ionic bond crosslinking density (vr2) in EPDM/ZDMA composite under tensile, compression forces and aging at different temperatures were studied through the combination of swelling equilibrium and acid extraction method. The results indicated that both vr1 and vr2 decreased in different degrees under tensile stress. When ZDMA content was low, vr1 decreased greatly, while vr2 decreased more when ZDMA content was higher. At the initial stage of compression stress, both vr1 and vr2 decreased greatly, but with the extension of compression time, the ionic crosslinked network continued to be destroyed, while the covalent crosslinked network was maintained. The ionic bond crosslinking network of EPDM/ZDMA composite system had a sensitive temperature between 90℃ and 120℃. When the temperature is lower than 90℃, the ionic bond crosslinking density had almost no effect after 24 hours aging. However, when the temperature was higher than 120℃, the ionic bond crosslinking density decreased rapidly after 24 hours aging.