Martyn Douglas Wakeman

Biographie

Dr. Martyn Wakeman is a seasoned professional in advanced composites with a proven record of 20 yrs, spanning academia and global corporations. He has worked in M&A deep dive projects in the Advanced Composites Space and has a proven publication (80 ) and patent (30) history in the development of continuous fibre thermoplastic composites from formulation, processing, to applications. He is currently attached at 50% to the Laboratory for Processing of Advanced Composites at the EPFL focused on 3D printing and advanced composites and also available as an independent consultant. Prior to this role he worked at DuPont from 2007-2016 in Geneva, Switzerland where he worked to drive the development strategy and led research of the DuPont Vizilon thermoplastic composites offer including continuous carbon and glass reinforced composites. From 1997 to 2007 he was a Scientific Collaborator at the Swiss Federal Institute of Technology, EPFL, in which he was Head of the Composite and Polymer Laboratory's "Industrial implementation group", located in the EPFL science park, focused on the automotive industry both in Europe and North America. He has a PhD in mechanical engineering focused on composites.

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https://people.epfl.ch/martyn.wakeman?lang=fr

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Domaines de recherche associés (24)

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Publications associées (63)

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Personnes menant des recherches similaires (98)

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Screening method for the onset of bonding of molten polyamide resin layers to continuous fiber reinforced laminate sheets

Martyn Douglas Wakeman

Thermoplastic polymer composites (TPC) with multiple fabric layers of continuous fiber reinforcement are laminate sheets designed to be thermally stamped and overmolded leading to low cycle times and thus high volume composite parts. Injection over-molding is one way to combine the high processability of thermoplastic melts with the less processable TPC sheets, for complex part making. To simulate the adhesion development during processes like over-molding, a non-isothermal screening method for bonding molten polyamide (PA) to a solid TPC surface has been developed and applied to evaluate differences in the threshold temperatures for good bond formation as a function of TPC matrix composition. Pure PA66 and aromatic high temperature nylons (PPA) in addition to miscible PPA blends comprising different ratios of PA66, were used as TPC matrices, and retain most of the very high melting point of 100% PPA. We have devised experiments to address two critical aspects: The first is to develop a screening test that probes very short timescales relevant to practical part making. The second is to investigate various miscible semi-crystalline blend ratios as matrices for the TPC where both blend species are crystalline. This allows us to explore a practical improvement of a lower required bonding temperature without substantially decreasing the high melting point of the PPA. DSC was also used to correlate the various blend melting transitions with the temperature required for the onset of bonding. The interfaces are shown to develop high strength partly because of substantial surface melting of certain blend components of the initially solid TPC, and this quickly allows interpenetration and inter-diffusion across the interface, which then crystallizes and strengthens during cooling.

2016

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Consolidation of net-shape random fiber thermoplastic composite preforms

Patrick Blanchard, Simon Jespersen, Jan-Anders Månson, Véronique Michaud, Martyn Douglas Wakeman

A novel thermoplastic composite preforming process has been developed. This thermoplastic programmable powdered preforming process (TP-P4) uses commingled glass and polypropylene yarns, which are chopped to a desired length and deposited onto a vacuum screen. The as-placed fibers are then heat-set for improved handling, before potential preconsolidation, and final conversion with preheating and press forming. This work investigated the effect of using either a double belt lamination preconsolidation stage or using an improved heat-setting stage. Polymer degradation was examined using gel permeation chromatography analysis, and the void content evolution tracked using image analysis techniques from the heat setting stage until the final part. It was shown that without preconsolidation, preforms prepared for a 2 mm thick final pressed part could be compression molded into a substantially void free, non degraded part. By using the lamination route, this limit could be increased to 4 mm, but without allowing local thickness changes in the preform. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers

2010

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Polypropylene/montmorillonite (iPP/MMT) has been investigated as an alternative to isotactic polypropylene (iPP) as a matrix for glass mat thermoplastic (GMT) composites. The melt viscosity increased significantly on MMT addition, but iPP/5.9wt% MMT-based hybrid GMT preforms were fully impregnated after 30 s of compression molding, which is consistent with GMT industrial cycle times. The flexural modulus and strength increased monotonically with MMT content in consolidated hybrid GMT specimens prepared by compression molding, although the impact strength decreased. Moreover, the increases in the flexural modulus were greater than predicted from a conventional rule of mixtures taking into the measured Young’s moduli of the iPP/MMT matrices. Possible reasons for this are discussed.

2010

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