Effect of filler on thermal aging of composites for next-generation power lines

• Published in: Composites. Part A, Applied science and manufacturing Vol. 42; no. 12; pp. 1873 - 1882
• Main Authors: Barjasteh, E., Kar, N., Nutt, S.R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2011; Elsevier
• Subjects: A. Carbon fiber; A. Glass fiber; air; Applied sciences; B. Environmental degradation; carbon fibers; clay; Composites; Degradation; epoxides; Exact sciences and technology; Fillers; Forms of application and semi-finished materials; glass fibers; glass transition temperature; Mathematical models; Oxidation; particles; Polymer industry, paints, wood; prediction; Reaction kinetics; Rods; sampling; Shear; Technology of polymers; Thermal degradation; thermogravimetry; weight loss; A. Glass fiber; B. Environmental degradation; A. Carbon fiber; Thermal degradation; Clay; Thermal ageing; Unidirectional fiber material; Thermooxidative degradation; Epoxy resin; Mechanical properties; Shear strength; Experimental study; Mineral fiber; Modeling; Glass transition temperature; Hybrid composite; Composite material; Thermal stability; Thermal properties; Reaction mechanism; Kinetics; Glass fiber; Carbon fiber; Pultrusion
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2011.08.006

The thermal aging of pultruded composite rods was investigated to determine the effects of filler on oxidation kinetics and degradation mechanisms. The unidirectional hybrid composite rods were comprised of a carbon-fiber core, a glass-fiber shell, and an epoxy matrix filled with clay particles. A reaction-diffusion model was implemented for each of the two hybrid sections to calculate the oxygen-concentration profile and the thickness of the oxidized layer (TOL) within the composite rods, and results were compared with measured oxidation kinetics. The TOL was measured for samples exposed isothermally in air and in vacuum at 200 °C for up to 13,104 h (1.5 year), and the measured values were similar to modeling predictions (within 10%). The domain validity for the reaction-diffusion model was determined from gravimetric experiments (weight-loss measurement), which showed that after prolonged thermal exposure, the degradation mechanism changed from thermal oxidation to thermal degradation. Thermogravimetric analysis (TGA) was performed to determine the thermal degradation and stability of the aged composite. In addition, the effect of thermal aging on glass transition temperature ( T g ) and short beam shear (SBS) strength was determined for isothermal exposures at 180 °C and 200 °C.