The Research Of Effect Of Immobilized Rubber On Dynamic Mechanical Property Of Silicone Rubber

Silicone rubber is a kind of special rubber with good weather resistance, biocompatibility, wide temperature range and thermal stability, but it has a weakness of mechanical property which restricts the application in the aerospace, hospital, construction and automobile industries. Nowadays, reinforced silicone rubber is used widely. Silica is one of the good reinforced fillers with obvious reinforcing effect and it cannot affect the other good properties.Immobilized rubber including bound rubber and trapped rubber is formed when reinforced filler is added into silicone rubber. The mobility of immobilized rubber is between the mobility of filler and free silicone rubber. Immobilized rubber has the similar characteristic with glassy-like structure and it is one of the reasons to affect the mechanical property of rubber. Therefore, study of the influence of immobilized rubber on the mechanical property of filled rubber is benefit for researching and predicting the mechanical property and its development during use. We can control the structure of silicone rubber better. In this paper, we adopted some methods to analyze the distribution of grain size, morphology and contents of silica and its corresponding bound rubber. We also study the influence of silica and its corresponding bound rubber on the vulcanization property and mechanical property. Rubber is always in the dynamic conditions along with the using expansion of rubber. Considering the using restriction and life-span of rubber in many dynamic conditions, the mechanical property of rubber in the dynamic conditions is one of the research hotspots. In this paper, we have mainly studied the dynamic mechanical property of silicone rubber in strain sweeps and frequency sweeps. In the study of the strain sweeps, we have inflicted the sinusoidal strains on the filled rubber, and the storage modulus is decreased with the increasing strains. The loss modulus appeared a peak when the strain in about 0.1. This phenomenon results from the breakage of filler network which is formed by both direct contacts of filler aggregates and immobilized rubber. In our study, we have find that the amount of immobilized rubber is decreased with the increasing temperature, and the immobilized rubber has a critical value to affect this phenomenon which is verified by Maier-G?ritz model. In the study of the frequency sweeps, we research the mechanical property of fumed silica filled rubber, precipitated silica filled rubber and sol-gel silica filled rubber at different temperature and obtain the mechanical property in a broad frequency range by Arrhenius time-temperature conversion. It is find that the pure silicone rubber is insensitive to the frequency of this range due to that there is not a filler network in pure silicone rubber. As for 40 phr fumed silica filled rubber and 40 phr precipitated silica filled rubber, strong filler-filler and filler-rubber interactions exist in samples, and they can form the stronger filler network which makes the storage modulus of material be sensitive to frequency. In the silicone rubber filled with 40 phr sol-gel silica, there is only an incomplete filler network exist in material due to the weak filler-filler and filler-rubber interactions, so the storage modulus at different temperature changes slightly which is close to the characteristics of pure rubber.