Aggregation And Dispersion Of Nano-powder In The Rubber Matrix

This thesis contains two parts: Firstly, the research works focus on the agglomeration kinetics of nano-inorganic powders filled rubber composites, the relationship of the dispersion of filler and the reinforcement, and the application of nano-silica filled EPDM compounds in the tank-tracked pad. The relationship of dispersion of nano-titania and antimicrobial property of rubber composites are also investigated. Secondly, the research works focus on the reinforcement of short fibers in the microcellular rubber foams.The agglomeration kinetics of nano-silica filled rubber:The properties such as modulus of nanofiller filled rubber compounds are remarkably influenced by the extent of the filler microdispersion. The present work focuses on the microstructure evolution of nanofiller filled rubber composites during thermal annealing. It is found that the modulus at small strain amplitude and low frequency Go' can be used to evaluate the microstructure of nanofiller filled rubber composites since it is sensitive to the microstructure. Times of wide-range strain sweeps technique is applied before the modulus kinetics testing to avoid the various dispersions of nanofillers in the rubber matrix. Experiment techniques such as transmission electron microscopy, bound rubber measurement are also applied to confirm the change of microdispersion of the nanofiller in the rubber matrix and nanofiller-polymer interactions. The experiment results show that the logarithm of the modulus Go' grows linearly with the logarithm of time at the initial thousands of seconds. The correlation between the bound rubber and flocculation of nanofiller is also studied. The experiment results indicate that the agglomeration of nano-silica aggregates and the increasing bound rubber are responsible for the modulus recovery of nanofiller filled rubber matrix during thermal annealing. A filler networking mechanism, wherein the silica aggregate bridged by the immobilized shell layer and free polymer chains and the filler-filler network densified by nanofiller's agglomeration, is proposed to explain the experiment results observed.The dispersion and reinforcement of nano-silica filled EDPM:As silica easily agglomerates in nonpolar rubber due to the strong filler-filler and weak filler-rubber interactions, a dispersant-an alphatic salt containing amine groups and carboxylic groups is used to study effect of the filler-filler and filler-rubber interactions on the reinforcement of silica as well as the dynamic properties of the compounds, in comparison with a traditional silane coupling agent-bis(triethoxysilylpropyl) tetrasulphide (TESPT). The experimental results indicate that incorporation of the dispersant leads to a reduction in the extent of particle agglomeration but also lowers the modulus of the composites by decreasing the adhesion between filler and rubber, while the introduction of TESPT improves the dispersion of silica but also strengthens filler-rubber interactions, therefore leads to a increase in reinforcing potential of the filler. Greater improvement in the dispersion of filler and filler-rubber interactions is obtained when TESPT is adopted to modify silica together with the dispersant. The results also suggest that the strengthened interfacial interaction are the primary contributor to the improved wet traction of the composites, and that both the improved dispersion of filler and the strengthened filler-rubber interactions are mainly responsible for the lowered rolling resistance.The application of nano-silica filled EPDM rubber composites in tank-tracked rubber pads:Tank-tracked rubber pad (TTRP) with excellent mechanical properties, which well meets with the requirement of the novel tanks, is obtained using the formula of nano-silica filled ethylene-propylene-diene terpolymer (EPDM) "in-situ" modified by silane coupling agent. The EPDM rubber composites have good bonded with the metal pad by incorporating dimethacrylic acid zinc salt.The dispersion and antimicrobial properties of nano-titana filled rubber composites...