Yu Jianying

Microstructure and Properties of Desulfurized Crumb Rubber Modified Bitumen

The microstructures of general crumb rubber (CR), dynamic desulfurized crumb rubber (DD-CR) and high speed agitation desulfurized crumb rubber (HSADCR) modified bitumens were investigated by a fluorescence microscope, and the physical properties of these three modified bitumens were studied. The results show that the dynamic desulfuration can improve the swelling capacity of crumb rubber in bitumen by destroying the sulfuratized bond of the crumb rubber, but the reunion of rubber particles during dynamic desulfuration also makes the swelling and the DDCR in bitumen difficult, so properties of the DDCR modified bitumen are not superior to the general crumb rubber modified bitumen. However, high speed agitation desulfuration can not only improve the swelling capacity of crumb rubber in bitumen, but also avoid the reunion of rubber particles, so some properties of bitumen can be improved by the modification of HSADCR.

Self-healing action of permeable crystalline coating on pores and cracks in cement-based materials

The self-healing action of a permeable crystalline coating on the porous mortar was investigated by two times impermeability test. Moreover, the self-healing mechanism of cement-based materials with the permeable crystalline coating was studied by SEM. The results indicate that the permeable crystalline coating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or cracks produced by freeze-thaw cycles. Therefore, cement-based materials can be improved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great quantity of non-soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.

Influence of an optimized fibre coating on interfacial and mechanical properties of glass fibre/polypropylene composites

The influence of pretreatment of fibre on interfacial and mechanical properties of glass fibre/polypropylene composites was investigated. Firstly, the glass fibres were coated with the blends of m-IPP (maleic anhydride grafting isotatic polypropylene) and m-APP (maleic anhydride grafting amorphous polypropylene) in different ratios. Secondly, the interfacial reaction of the coated composites was analysed by FTIR, which shows that the interfacial chemical reaction between m-IPP/m-APP in the fibre coating and the fibre surface-bound coupling agent is in existence. Thirdly, the microstructure of the coated composites was studied by SEM. The results indicate that the coating treatment is effective on improving interfacial adhesion of the fibre-matrix and the right amount of m-APP added to the coat impels the plastic deformation surrounding the point of cracks, which makes cracks turn to region and prevents from further interface debonding. Lastly, the mechanical properties were evaluated by measurement of the flexural strength and impact strength of the composites. It was found that the flexural strength and impact strength of the composites with coating fibre are higher than those of uncoating fibre composite. The results of these investigations draw the conclusion that the pretreatment of fibre with m-IPP/m-APP blends can form an optimize interlayer between the fibre and the PP matrix, which improves both the strength and toughness of the composites.

Preparation and properties of phenolic resin/montmorillonite intercalation nanocomposites

Phenolic resin/montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation. Properties and structure of the composites were investigated by using XRD, TG and test of softening point. It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/ organo-montmorillonite intercalation nanocomposites. Compared with phenolic resin, the intercalation nanocomposites have better heat-resistance, higher decomposition temperatures and less thermal weight-loss. However, these two intercalation methods have different effects on the softening point of the intercalation nanocomposites. Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites, while melt intercalation significantly increases the softening point of the intercalation nanocomposites, probably due to the chemical actions happening in the process of melt intercalation.