Microcracking in resins and matrices; Progress towards understanding the relative influence of carbon fibre properties and sizing

Bronwyn L. Fox, Nisa V. Salim, Nishar Hameed, Srinivas Nunna, Claudia Creighton, Minoo Naebe, Peter Lynch, Nicole Stanford, Jiangting Wang, Sahar Naghashian

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther


Matrix micro-cracking in carbon fibre composites is a problematic defect that often occurs at the interface between the fibre and the resin. When a composite material is placed under a load, micro-cracking may propagate through the matrix with these cracks joining up to form macroscopic cracks resulting in a deterioration of mechanical properties. A number of studies have focussed on the effect of interfacial adhesion on the formation of micro-cracks in laminates, leading to the reasoning that the fibre sizing is important in determining whether micro-cracks are present. Other studies have noted that the micro-cracking is mostly prevalent in composite materials that have been reinforced with high modulus fibres and not intermediate and standard modulus fibres. It has been postulated that this is due to the structural characteristics of the fibres leading to a greater difference in the coefficient of thermal expansion (CTE) between the fibre and the matrix. However the linear CTE was not related to the micro and nanoscale properties of the fibre and the critical property, the radial CTE of the fibre has not yet been reliably measured. The relative importance of the roles of carbon fibre sizing and modulus in the formation of micro-cracks remains unclear. In this paper, the structure and morphology of three different grades of carbon fibres; high modulus (M46J), intermediate modulus (IM7) and low modulus (BS24) were analysed using electron microscopy and SAXS-WAXS experiments leading to a greater understanding of the relationship of carbon fibre modulus to microstructure.

Original languageEnglish
Title of host publicationCAMX 2015 - Composites and Advanced Materials Expo
PublisherThe Composites and Advanced Materials Expo (CAMX)
Number of pages8
Publication statusPublished - 2015
Externally publishedYes
EventAnnual Composites and Advanced Materials Expo 2015 - Dallas Convention Center, Dallas, United States of America
Duration: 26 Oct 201529 Oct 2015
Conference number: 2nd


ConferenceAnnual Composites and Advanced Materials Expo 2015
Abbreviated titleCAMX 2015
Country/TerritoryUnited States of America

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