Low Temperature Studies on DC745U Pressure Pads
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
DC745U is a silica-filled solid silicone elastomer used to manufacture pressure pads for a variety of applications. The material is proprietary to Dow Corning and thus very little information on its composition and properties is available. A considerable amount of characterization work has been conducted (Denisse Ortiz-Acosta W-1-TR-0098U/ LA-UR-12-23612) on DC745U. Based on these studies an estimate of the composition of the polymer was obtained. DC745U is composed of ≤ 100 wt% dimethyl siloxane repeat units, ≤1.5 wt% of methylphenyl siloxane, and ≤ 1 wt% methylvinyl siloxane groups. The methylvinyl siloxane groups are used as crosslink sites. The polymer is cured using a vinyl-specific peroxide, Varox DBPH-50, at 160ºC to form a polymer network. The structure and composition of this polymer network provide DC745U its unique properties. The methylphenyl siloxane repeat unit was added to improve DC745U’s thermal properties when compared to polydimethylsiloxane (PDMS). PDMS has a glass transition temperature of -120ºC and a melting temperature of -40ºC. It is believed that the phenyl group in DC745U improves thermal properties by inhibiting crystallization. This report describes the results obtained from low temperature thermal, mechanical and molecular characterization. These studies were conducted to improve our understanding of low temperature crystallization kinetics and thermal kinetics under compression strain and to determine if the pad undergoes stress deformations under these extreme conditions. Results described herein address several knowledge gaps previously stated in the report W-1-TR-0098U. Experiments described here include Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), Nuclear Magnetic Resonance (NMR), and mechanical (stress/strain) tests.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1088888
- Report Number(s):
- LA-UR--13-25885
- Country of Publication:
- United States
- Language:
- English
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