Activated calcium silicate/natural rubber composites prepared via latex compounding: Static and dynamic mechanical properties

Activated calcium silicate (ACS) is a solid byproduct of alumina extraction from high-alumina fly ash. Because of the excellent properties of ACS, the effective utilization of the material has attracted considerable research interest. In this study, we prepared a series of natural rubber (NR) composites via a latex compounding method using ACS. The effects of ACS content and particle size on the processing properties, network structure, and static and dynamic mechanical properties of the composites were investigated. The ACS particles were found to be chemically absorbed on the rubber macromolecules. Lower ACS particle sizes and higher ACS content promoted vulcanization, caused the formation of shorter rubber chains, and increased the cross-linking density. The tensile strength of the composite reached 22.32 MPa (163% greater than that of pure NR) at an ACS average particle size of 2.92 μm (D90) with a loading of 40 phr (mass parts per hundred parts of rubber), whereas further increasing the ACS content led to agglomeration. Overall satisfactory performance was achieved at an optimal ACS particle size of 2.92 μm (D90) with a loading of 30 phr in the NR matrix. Thus, this approach both enhances the performance of NR and effectively utilizes ACS waste.