Five types of polyurea elastomers were synthesized by changing the isocyanate component and the mechanical properties of polyurea materials were measured. Fiber-reinforced cement boards(FRCB)strengthened by polyurea w...Five types of polyurea elastomers were synthesized by changing the isocyanate component and the mechanical properties of polyurea materials were measured. Fiber-reinforced cement boards(FRCB)strengthened by polyurea with different formulations were processed, and a series of experiments were carried out on the specimens with gas explosion devices. The results showed that the conventional mechanical properties of different types of polyureas had their own advantages. Based on the gas explosion overpressure criterion, the blast resistances of reinforced plates were quantitatively evaluated,and the best polyurea was selected to guide the formulation design. The three typical failure modes of polyurea-reinforced FRCBs were flexural, shear, and flexural-shear failure. Dynamic thermodynamics and shock wave spectral analysis revealed that the polyurea did not undergo a glass transition in the gas explosion tests but retained its elastic properties, allowing it to effectively wrap the fragments formed by the brittle substrates.展开更多
Straw fiber-reinforced cement board made from straw fiber and cement was prepared by semi-dry processing technology to investigate the effects of alkali treatment on the mechanical properties of the board.The results ...Straw fiber-reinforced cement board made from straw fiber and cement was prepared by semi-dry processing technology to investigate the effects of alkali treatment on the mechanical properties of the board.The results indicate that the board fibers were treated with 1%alkali solution showed obvious improvements in mechanical properties.After alkali treatment,hemi-celluloses of straw fiber were hydrolyzed and dissolved,which avoided hemi-celluloses hydrolyzing into monosaccharide to hinder the solidifying of cement. The fibers surface became rough,which increased the mechanical interweaving force between cement and fibers.Thereby the board’s mechanical properties were improved.At the same time,the increase of tensile strength and aspect ratio of the fibers improved the mechanical properties.展开更多
基金funded by National Natural Science Foundation of China(No.12002392).
文摘Five types of polyurea elastomers were synthesized by changing the isocyanate component and the mechanical properties of polyurea materials were measured. Fiber-reinforced cement boards(FRCB)strengthened by polyurea with different formulations were processed, and a series of experiments were carried out on the specimens with gas explosion devices. The results showed that the conventional mechanical properties of different types of polyureas had their own advantages. Based on the gas explosion overpressure criterion, the blast resistances of reinforced plates were quantitatively evaluated,and the best polyurea was selected to guide the formulation design. The three typical failure modes of polyurea-reinforced FRCBs were flexural, shear, and flexural-shear failure. Dynamic thermodynamics and shock wave spectral analysis revealed that the polyurea did not undergo a glass transition in the gas explosion tests but retained its elastic properties, allowing it to effectively wrap the fragments formed by the brittle substrates.
文摘Straw fiber-reinforced cement board made from straw fiber and cement was prepared by semi-dry processing technology to investigate the effects of alkali treatment on the mechanical properties of the board.The results indicate that the board fibers were treated with 1%alkali solution showed obvious improvements in mechanical properties.After alkali treatment,hemi-celluloses of straw fiber were hydrolyzed and dissolved,which avoided hemi-celluloses hydrolyzing into monosaccharide to hinder the solidifying of cement. The fibers surface became rough,which increased the mechanical interweaving force between cement and fibers.Thereby the board’s mechanical properties were improved.At the same time,the increase of tensile strength and aspect ratio of the fibers improved the mechanical properties.
