Acrylonitrial butadiene rubber (NBR)/Polyvinyl chloride (PVC) composites with different PVC content were prepared. The effect of PVC content on the mechanical strength and tribological properties of the NBR/ PVC composites was investigated. The morphologies of the worn traces and debris of NBR/PVC composites and worn traces of mating ball were observed using a scanning electron microscope (SEM). It was found that the friction and wear of NBR/PVC was lower than that of NBR without PVC. The NBR/PVC composite with 30% PVC content showed the best synthetic mechanical and tribological properties. The inferior elastic properties and the lesser deformation under the applied load of composites with PVC resulted in hysteric force and adhesion force decrease, which leading to a lower friction and wear of NBR/PVC composites. The frictional failure unit of NBR70/PVC30 composite being smaller should be an important reason of the wear of the composite being lowest. The lubricating effect of PVC played an important role in decreasing the friction coefficient and wear of NBR/PVC composites.
Based on the acoustic wave field theory, we first study the forward model of seismic data for the case without free surface. Then we consider the case with a reflecting free surface, and derive the forward and inverse models for surface‐related multiple prediction and attenuation. In the physical insight, generation, prediction and attenuation of the wave is also deeply analyzed. The data‐consistence‐based time‐space convolution method is discussed and implemented. The method is formulated by an iterative adaptive procedure. An example with a complex bottom and complex multiple generating system is given to demonstrate its validity and stability of the method which can attenuates multiple energy effectively while keeping the primary events not damaged.
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