Multiscale characterisation of randomly oriented board strand composites from re-used prepreg scrap

The aim of this project is to develop manufacturing upcycling technologies to re-use prepreg scrap and determine the resultant mechanical properties. This project mitigates the environmental impact of conventional composite manufacturing processes reducing air emissions and energy consumption. It also contributes towards a sustainable economy reducing the waste disposal fees paid by commercial companies and recovering commercial value from the composite scrap. 

This project aims to develop novel recycled composites based on prepreg scrap. The prepreg scrap can be cut in short strands that can be distributed over the mould surfaces with different orientation. Different manufacturing processes have been analysed and the equivalent mechanical properties have been compared against the performance of equivalent quasi-isotropic continuous carbon fibre laminates. The influence of defects such as discontinuous tow ends, fibre curvature and resin pockets have been analysed by high-speed imaging and Digital Image Correlation. 

This manufacturing method has an inherently low cost and suits the specifications of sectors such as the automotive industry. It provides a random fibre distribution with equivalent stiffness to those of conventional quasi-isotropic panels, but half the strength. Still, the mechanical properties are superior in specific terms to those of aluminium and steel alloys. This methodology also provides notch-insensitive laminates, reducing the safety factors of components including metallic inserts for future assembly operations.


[1] A. B. Ibrahim. Manufacturing and testing of randomly oriented strand board composites from scrap prepreg. MEng dissertation. The University of Edinburgh. 2020


Collaborators: University Carlos III Madrid

Funding: The Royal Society. RGS\R2\180091

Manufacturing process of recycled composite laminates
Manufacturing process of recycled composite laminates. (a) and (b) hand lay-up of randomly oriented platelets and (c) mould for hot plate press.
Mechanical properties
Mechanical response of open hole specimens. (a) Equivalent stiffness and (b) Equivalent Strength. The dashed line stands for the mechanical properties of benchmark quasi-isotropic laminates.
Evolution of full-field strain with deformation. Strand orientations are marked with yellow lines on the first image.

Principal Investigator: 

Francisca Martinez Hergueta

Postgraduate Researchers: 


Afif Bin Ibrahim, 

Rutger Kok 

Research Institutes: 

  • Infrastructure and Environment

Research Themes: 

  • Structural Engineering

Last modified: 

Monday, June 22, 2020 - 09:40