硅烷偶联剂改性硅藻土及其对天然橡胶/丁苯橡胶补强效果的影响

Surface Modification of Diatomite by Silane Coupling Agent and Its Effects on the Reinforcing Efficiency of NR/SBR Blend

用不同的硅烷偶联剂对硅藻土进行表面改性,并将改性前后的硅藻土替代白炭黑添加到天然橡胶/丁苯橡胶并用胶中,研究了改性工艺、机理及其对橡胶补强效果的影响规律。结果表明,偶联剂硅烷KH570或Si69的最佳用量均为1.2%,改性后硅藻土颗粒表面呈现一定的疏水性。未改性硅藻土替代白炭黑后填充在天然胶橡/丁苯橡胶中后材料的抗拉强度为14.9MPa,撕裂强度32.5kN/m,300%定伸应力5.0MPa。两种硅烷偶联剂改性硅藻土后均能提高材料的撕裂强度、抗拉强度和300%定伸应力,但是不利于提高材料的扯断伸长率。填充1.2%偶联剂硅烷KH570改性硅藻土制得的橡胶样片撕裂强度提高了7.4%,300%定伸应力提高了62%,抗拉强度提高了18.1%,但扯断伸长率降低了17.4%。填充1.2%偶联剂硅烷Si69改性硅藻土制得的橡胶样片撕裂强度提高了21.8%,300%定伸应力提高了68%,抗拉强度提高了9.2%,同样扯断伸长率降低了24.5%。机理分析表明,硅烷偶联剂与硅藻土颗粒表面的吸附方式为化学吸附。

Diatomite was surface modified by silane coupling agent. The effects of modification process and mechanism on the efficiency of natural rubber/styrene butadiene rubber blends (NR/SBR) were investigated by adding modified diatomite into NR/SBR blend as a replace agent of amorphous silica. The results indicate that the optimal dosage of KH570 or Si69 is 1.2% (mass fraction) of diatomite. The surface of modified diatomite particles is hydrophobic to some extent. The tensile strength, tearing strength and 300% stretching stress of NR/SBR with unmodified diatomite are up to 14.9 MPa, 32.5 kN/m and 5.0 MPa, respectively. The tearing strength, tensile strength and 300% stretching stress of diatomite modified by KH570 and Si69 can also be improved but elongation at break. When 1.2% KH570 is used, the tearing strength, 300% stretching stress and tensile strength of NR/SBR are increased by 7.4%, 62.0% and 18.1%, respectively, while the elongation at break is decreased by 17.4%. When 1.2% Si69 is used, the tearing strength, 300% stretching stress and tensile strength of NR/SBR are increased by 21.8%, 68.0% and 9.2%, respectively, while the elongation at break is decreased by 24.5%. The analysis shows that the adsorption type between silane coupling agent and diatomite is chemistry adsorption.