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Environmental degradation of unidirectional polmer matrix composites: an interim report.

Broughton, W R; Lodeiro, M J; Maudgal, S (1999) Environmental degradation of unidirectional polmer matrix composites: an interim report. NPL Report. CMMT(A)187

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This report provides an interim assessment of accelerated test methods evaluated within the Composites Performance and Design (CPD) Project “Life Assessment and Prediction” for characterising long-term properties and residual life/strength of glass and carbon fibre-reinforced composites exposed to aggressive environments and static loads. The report considers convenient methods for obtaining basic strength-time data for unconditioned and moisture conditioned fibre bundles and continuous aligned fibre-reinforced rods and laminates. These test methods require relatively short conditioning times and relatively low manufacturing and testing costs in comparison with current practices.
The report considers: (i) tensile testing of moisture pre-conditioned fibre bundles and glass fibre-reinforced polyester rods; (ii) static fatigue testing of unconditioned glass fibre bundles and unidirectional glass fibre-reinforced rods and laminates; (iii) flexural properties of moisture pre-conditioned unidirectional laminates at ambient and elevated temperatures; and (iv) autoclave conditioning of flexural specimens manufactured from carbon fibre-reinforced laminates. Moisture pre-conditioning involved immersion in deionised water at elevated temperatures ranging from 23 ºC to 70 º C for up to 42 days, whereas autoclave conditioning involved exposure of composite specimens to a steam environment at 136 ºC and 2.2 bar for periods no longer than 24 hours.
The principal conclusions that can be drawn from the results to-date are: (i) fibre tows and small diameter (i.e. 1.5 mm) composite rods are suitable for accelerated testing under combined static loads and hostile environments with fibre tows offering a relatively rapid method for evaluating fibre sensitivity to chemical attack; (ii) transverse flexural properties are particularly sensitive to the combined effect of moisture and elevated temperature; and (iii) autoclave conditioning can accelerate moisture absorption by a factor of 100 and is suitable for use with materials designed for hot/wet conditions. The report provides a summary of the results, including recommendations on preparation and testing of fibre bundles and composite rods, and concludes with comments relating to future work.

Item Type: Report/Guide (NPL Report)
NPL Report No.: CMMT(A)187
Subjects: Advanced Materials
Advanced Materials > Composites
Last Modified: 02 Feb 2018 13:18
URI: http://eprintspublications.npl.co.uk/id/eprint/1157

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