Effect of silane coupling agent and air plasma treatment on interfacial shear strength
Silane coupling agent bears alkoxysilane groups and a large number of functional groups which ensure a good compatibility between the reinforcing element and the polymer matrix. There are only a few articles relating to the influences of silane coupling agent on the interfacial shear strength and mechanical performance of carbon fiber reinforced polymer composites, especially for the CF/PPS composites. In this study, CF was first modified by surface coating of silane coupling agent to improve the interfacial adhesion between carbon fiber and PPS resin. Microbond, tensile and flexural tests were conducted to verify the effects of silane coupling agent on the CF/PPS interfacial adhesion and mechanical properties.
The effect of silane coupling agent on τapp values of the CF/PPS composites is presented in Figure 2. The average shear strength τ¯app of CF/PPS with coupling agent treated carbon fiber is 35.6 ± 4.9 MPa, which is 13.2% higher than that of the untreated samples which illustrates that the positive effect of the coupling agent on the interface bonding between carbon fiber and PPS resin.
Meanwhile, the corresponding tensile and flextural properties of PPS/CF composites were tested by a universal testing machine (AG-10TA, Seiko), according to Chinese Standard GB/T1040-1992 and GB/T9341-2000, respectively, at 20 °C. As shown in figure 3(a), for the 20 wt% CF reinforced composites, the tensile strength was improved from 129.1 MPa to 174.7 MPa when 3% coupling agent was added. Meanwhile, the tensile modulus was also increased from 3.4GPa to 4.3GPa. Figure 3(b) shows that the flexural strength and modulus were also increases by 23.2% and 15.7%, respectively, at the presence of the coupling agent.
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