# Sealing Performance of Phenyl-Silicone Rubber Based on Constitutive Model Under Thermo-Oxidative Aging

## TL;DR

This study examines how aging affects the sealing performance of phenyl-silicone rubber at extreme temperatures, providing a model to predict its reliability over time.

## Contribution

The paper introduces a novel framework linking thermo-oxidative aging to sealing reliability using mechanical tests and simulations.

## Key findings

- Compression set increases with aging time and temperature, with an Arrhenius model predicting storage life at 25 °C.
- Finite element simulations show contact pressure peaks at lateral necks but decreases with aging due to displacement loss.
- Even under severe aging, predicted contact pressure remains above the leak-tightness criterion at cryogenic temperatures.

## Abstract

Phenyl-silicone rubber is the elastomer of choice for cryogenic and high-temperature static seals, yet quantitative links between thermo-oxidative aging and sealing reliability are still lacking. Here, sub-ambient (−70 °C to 25 °C) and room-temperature mechanical tests, compression set aging, SEM, FT-IR, and finite-element simulations are integrated to trace how aging translates into contact-pressure decay of an Omega-profile gasket. Compression set rises monotonically with time and temperature; an Arrhenius model derived from 80 to 140 °C data predicts 34 d (10% set) and 286 d (45% set) of storage life at 25 °C. SEM reveals a progressive shift from ductile dimple fracture to brittle, honeycomb porosity, while FT-IR confirms limited surface oxidation without bulk chain scission. Finite element analyses show that contact pressure always peaks at the two lateral necks; short-term aging increases in the shear modulus C10 from 1.87 to 2.27 MPa, raising CPRESS by 8~21%, yet this benefit is ultimately offset by displacement loss from compression set (8.0 mm to 6.1 mm), yielding a net pressure reduction of 0.006 MPa. Critically, even under the most severe coupled condition (56 days aging with compression set), the predicted CPRESS remains above the 0.1 MPa leak-tightness criterion across the entire cryogenic service envelope. This framework provides deterministic boundaries for temperature, aging duration, and allowable preload relaxation, enabling risk-informed maintenance and replacement scheduling for safety-critical phenyl-silicone seals.