Influence of SiO2 fillers on the irradiation ageing of silicone rubbers

• Published in: Polymer (Guilford) Vol. 42; no. 22; pp. 9287 - 9292
• Main Authors: STEVENSON, I, DAVID, L, GAUTHIER, C, ARAMBOURG, L, DAVENAS, J, VIGIER, G
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.10.2001
• Subjects: Applied sciences; Engineering Sciences; Exact sciences and technology; Materials; Physical properties; Polymer industry, paints, wood; Properties and testing; Radiation influence; Technology of polymers; Dimethylsiloxane polymer; Crosslink density; Electron beam; Mechanical properties; Dispersion reinforced material; Crystallinity; Experimental study; Molecular relaxation; Silica; Transformation temperature; Crosslinked polymer; Radiation effect; Silicone elastomer
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(01)00470-0

The effects of irradiation on the viscoelastic properties of peroxide-crosslinked polydimethyl siloxane (PDMS) elastomers (EVC) without filler, filled with 30% untreated nanoscopic SiO2 and with 30% surface modified silica were investigated. Electron irradiation in air using a high dose rate allowing homogeneous irradiation at different doses ranging from 25 to 500 kGy led to additional crosslinking of these three types of silicone rubbers making them become more rigid and brittle. The apparent crosslink density is higher for filled elastomers since links at the polymer-silica interfaces are created as a result of irradiation. A further crosslink density enhancement is obtained for the surface treated silica fillers. Differential scanning calorimetry (DSC) measurements confirm that crystallization is limited by the formation of a higher number of crosslinks, and that this effect is amplified for filled PDMS samples. A study of mechanical hysteresis at high strains (Mullins effect) shows an increase of the associated dissipative phenomena due to the induced polymer/silica bonds. (Original abstract - amended)