High Temperature Resistant Flexible Silicone Laminate for Thermal and Structural Applications in the Composite Structure
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ORIGINAL ARTICLE
High Temperature Resistant Flexible Silicone Laminate for Thermal and Structural Applications in the Composite Structures of Launch Vehicles K. Indulekha1 · M. A. Shahina1 · C. Suchithra2 · N. Supriya2 · R. S. Rajeev1 · Dona Mathew1 Received: 22 June 2020 / Accepted: 31 August 2020 © Indian National Academy of Engineering 2020
Abstract High temperature resistant and flexible polymeric laminates are highly desirable as thermal and structural back-up to prevent through—delaminations from growing in to a burn—through in the composite structures of launch vehicles. Phenylated silicones are promising high temperature resistant polymers. However, limited work has been reported on the development of fibre-reinforced and room temperature curable silicone laminates that exhibit high temperature resistance characteristics based on silicone polymers. Hence, an attempt is made herein to develop flexible and high temperature resistant silicone laminates based on phenylated silicone polymer and E-glass fabric and to evaluate its high temperature properties. Herein, high molecular weight vinyl terminated poly (dimethyl-co-diphenyl)siloxane polymer (V-PDMPS) has been reinforced with mixed inorganic fillers, catalyst and the cross linker, trimethylsilyl terminated poly (dimethyl-co-methylhydrogen-codiphenyl)siloxane, (TMS-PDMHS) and laminate has been prepared using two layers of E-glass fabrics as the reinforcement, followed by curing under ambient to form the silicone laminate. Isothermal TGA analysis of the laminate at 300 °C for 30 min shows negligible mass loss. Furthermore, the laminate exhibits good mechanical and adhesive strength over wide temperature range from RT to + 300 °C proving its high temperature resistant characteristics. Keywords Silicone · Laminate · E-glass fabric · Hydrosilylation · High temperature resistance
Introduction The introduction of rigid groups into the molecular backbone can improve the thermal stability of the silicones, as the rigid units can hinder the intra-chain rearrangements that result in the polymer degradation at higher temperatures (Dvornic and Lenz 1990, 1994; Wang et al. 1993a, b; Zhang et al. 1997Li and Kawakami 1999; Kawakita et al. 2001). Another way to improve the thermal stability is through close-packed polymer network formation. Similar to the previous case, the usual thermal degradation mechanisms are minimized in polymer networks, due to higher restriction of the rearrangements and suppression of reactive end blocks * R. S. Rajeev [email protected] 1
Polymers and Special Chemicals Division, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, India
Analytical and Spectroscopy Division, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, India
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(Michalczyk et al. 1993). Another approach to improve the thermal stability of silicones is the incorporation of methylphenyl siloxane unit or diphenyl siloxane unit as a copolymer with PDMS, which can increase the onset temperature of degradation to nearly 400 °C from 300–350 °C of PDMS (
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