Study Of Filled Thermal Conductive Silicone Rubber Composite Via Admicellar-polymerizated Treatment

Accordingly in this article, admicellar polymerization was used to coat a nano- layer of Polypyrrole(PPy) on the surface of Al2O3, CF, Zn O and Al. Then thermal conductive fillers(PPy-Al2O3,PPy-CF,PPy-Zn O,PPy-Al) and crosslinking agent were dispersed in poly(vinylmethyl siloxane) using a two-roll mill, and then cured in a mould under pressure to obtain the thermal conductive silicone rubber with good mechanical properties. The effects of modification, fillers, content, morphology, particle size, combined contribution on the mechanical, thermal and electric properties of silicone rubber(MVQ) composites were studied using cure-curves, fourier transform infrared(FT-IR), scanning electron microscopy(SEM),differential scanning calorimetry(DSC), thermogravimetric analyzer(TGA),mechanical properties test. The study found that:1) Compared with the non-modified fillers(Al2O3, Al,CF), PPy nanolayer could improve the interfacial compatibity between the fillers and MVQ matrix, increase the loading amount, reduce the interface thermal resistance between the fillers and matrix, improve the thermal stability of the composites. Due to the reinforcing effect of Zn O and non-reinforcing effect of PPy-Zn O, the modification of Zn O did not show the same effect as the others. In PPy-Al/Zn O(100 phr) system, the modification could improve the mechanical properties and thermal conductivity of the composite dramatically without damaging the electrical insulating property of the composites. At fixed 300 phr, the tensile strength, elongation, shore A hardness, thermal conductivity, volume resistivity and surface resistivity of the composites with PPy-Al/Zn O system were 4.7 MPa,76%,83, 2.13 W/(m·K),1010Ω·cm and 1015Ω/m,respectively.2) Although PPy itself is intrinsic conductive polymers, but its impact on the electrical insulating property of the composites is not obvious. At fixed 400 phr of PPy-Zn O system, the volume resistivity of the composites dropped from 1014 Ω·cm to 1011 Ω·cm, while the effect on the volume resistivity of composites with other modified fil ers were less than 102.3) Compared with the single particle filler, the hybride particles can form tight thermal conductive chain at lower loadings, thereby enhancing the thermal conductivity of the composite material. When 200 nm,1μm, 40μm PPy- Al2O3 mass ratio was 20:1:4 and the total dosage was 500 phr, the tensile strength, elongation, shore A hardness, thermal conductivity, volume resistivity and surface resistivity of the composites was 2.9 MPa, 63%, 89, 1.96 W/(m·K), 8.02×1012 Ω·cm and 4.78×1010 Ω/m, respectively.4) Compared with the single shape filler, the combination of different shape fillers could complete the thermal conductive chain and improve the thermal conductivity without damaging the other properties of the composites.a) In PPy-Al2O3/PPy-CF system, PPy-CF was acted as the ―bridge‖ to enlarge thethermal conductive network in the composite filled with 300 phr of PPy- Al2O3. Whenthe loading amount of PPy-CF was 10 phr, the thermal conductivity of the compositeswas 1.82 W/(m·K).b) In the PPy-Al(needle-like)/Zn O(100 phr random)system, When 1μm, 20μm PPy-Almass ratio was 1:4 and the total dosage was 300 phr, the tensile strength, elongation,shore A hardness, thermal conductivity, volume resistivity and surface resistivity of thecomposites was 4.7 MPa, 76%, 83, 2.13 W/(m·K), 5.21×1010 Ω·cm and 8.52×1015 Ω/m,respectively.