Improved processibility of silicone composites by MQ silicone resins

ABSTRACT Processibilities of silicone composites were always a problem for their high content of SiO 2 powders. This article found that the substitution of silicone resins for linear polydimethylsiloxanes (PDMS) made processibilities easier. Three silicone resins (MQ1.0, MQ1.1, and MQ1.2) with clarified chemical structures (by FT IR, 29 Si NMR, and GPC) were adopted. Their shearing viscosities [η( )] were greatly higher than PDMS with higher molecular weight, which could be assigned to stronger molecular interactions as surface tension and flowing activation energy Δ E indicated. On the contrary, η( ) of MQ‐PDMS binary blends greatly decreased to that even lower than either components (about 85% utmost decrease comparing to PDMS), for the variation of molecular interaction rather than dilution effect. Furtherly, when PDMS were partly replaced with MQ resins, process time of PDMS–SiO 2 silicone composites were greatly shortened (from >6 to 2 h), while with better SiO 2 dispersion (Mooney viscosity greatly decreased from 30.0 to 5.0 MU). Better dispersion of SiO 2 fillers in composites could be confirmed by SEM and mechanical properties. For the better dispersion, mechanical properties of composites were improved with higher elastic modulus, higher tensile strength, and higher hardness, especially with higher elongation at break (utmost increased from 190% to 277%). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46445.