JEC COMPOSITES MAGAZINE - Issue #63 - March 2011 - 86

medical/biocomposite

Tab.2: IFSS results for carbon fibres/PCL composites with different treatments and processes

More information: http://www.nottingham.ac.uk/~eazwww/composite/ Contact: Rawaa.Habeb@nottingham.ac.uk Acknowledgments The authors wish to thank the EPSRC, via the Platform Grant GR/T18578/01, and the Royal Society via International Incoming Short Visits Scheme Fellowship R1 2005. References 1. A. U. Daniels, M. K. Chang, K. P. Andriano, Mechanical Properties of Biodegradable Polymers and Composites Proposed for Internal Fixation of Bone. J Appl Biomater 1990; 1:57-8. 2. M. Elst, A. Dijkema, C. Klein, P. Patka, H. Haarman, Tissue Reaction on PLLA versus Stainless Steel Interlocking Nails for Fracture Fixation: an Animal Study. Biomaterials 1995; 16; 103-06. 3. C. A. Scotchford, M. Garle, J. Batchelor, J. Bradley, D. M. Grant, Use of Novel Carbon Fibre Composite of a THR System: In Vitro Biological Assessment. J Biomaterials 2003; 24:4871-79. 4. R. R. Habeb, G. S. Walker, I. A. Jones, C. D. Rudd, Fabrication Effects on Properties of Composites for Medical Applications: 1 Composite Preparation and Characterisation. Accepted by the Journal of Reinforced Plastics and Composites 2008. 5. J. Middleton, A. Tipton, Synthetic Biodegradable Polymers as Orthopaedic Devices. Biomaterials 2000; 21: 2335-46. 6. M. J. Lodeiro, Single-Fibre Fragmentation Test for the Characterisation of Interfacial Phenomena in PMCs. MATC(MN)07, 16 pages. 7. F. Jones, D. Tripathi, N. Lopattananon, A Technological Solution to the Testing and Data Reduction of Single Fibre Fragmentation Test. Composites Part A 1998; 29A, 1099109. 8. H. L. Yip, S. J. Pickering, C. D. Rudd, Characterisation of Carbon Fibres Recycled From Scrap Composites Using Fluidised Bed Process, Plastics Rubber and Composites, 2002; 31 (6), 278-82. 9. Z. Y. Wan, Y. L. Wang, Q.Y. Li, X. H. Dong, Influence of Surface Treatment of Carbon Fibres on Interfacial Adhesion Strength and Mechanical Properties of PLA-Based Composites. Applied Polymer Science 2001; 80: 367-76. 10. J. L. Thomason, The Interface Region in Glass Fibrereinforced Epoxy Resin Composites: 3.Characterisation of Fibre Surface Coatings and the Interphase. Composites 1995; V26: 487-98.

Specimen preparation Fibre Heat treated (HT) only HT only HT plus chloroform wash HT plus 24 hours in caprolactone (99% pure) at 120˚Croform wash HT plus 24 hours in CL at 120˚C and chloroform wash Composite ISP FS FS

Average Samples tested no. of breaks 10 10 5 29.4 21.4 23.6

IFSS (MPa)
21.79 ± 2.41 14.98 ± 1.17 16.81 ± 1.27

24.6

17.70 ± 0.97

25.5

18.42 ± 2.02

those of the in-situ polymerised samples. Even chloroform treatment appears effective (it was evaporated before the laminating procedure) in cleaning the fibre surface. Further light may be shed on this effect via surface analysis of the fibre prior to laminating and also through repeating the caprolactone experiments with distilled monomer in order to eliminate any moisture interaction at the fibre surface (where evaporated material could be trapped inside the laminate and form a void).

jec composites magazine / No63 March 2011

Other studies [9,10] report the effectiveness of fibre surface treatment in improving the mechanical properties of composites. Surface treatment can increase fibre surface area, leading to greater fibre/matrix interface area and thus strengthening mechanical interlocking. It may further improve the surface free energy of fibres, thus promoting wettability and increasing the reactive species, resulting in enhanced interfacial bonding.

Conclusions

The single-fibre fragmentation test results discussed here show the capability of the in-situ polymerisation method to maintain a better interface between carbon fibres and polycaprolactone in comparison to the film stacking approach. The SFFT test procedure has identified pretreatment methods for improving bonding effectiveness in melt-processed composites. The degradation tests of film stacking and in situ polymerisation samples were also carried out with ageing up to 33 days and SEM observations. These tests and SFFT demonstrated the consistency between the two methods for examining laminate durability in a hydrolytic environment. n

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JEC COMPOSITES MAGAZINE - Issue #63 - March 2011

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