Documents published in Scipedia

• Investigating the effect of cure schedules and cure initiators on sustainable composites for large offshore structures

  J. Pothnis, K. Vélon, G. Bhatia, A. Hejjaji, A. Comer, A. Hejjaji

  Investigating the effect of cure schedules and cure initiators on sustainable composites for large offshore structures (2024).

  
  

  Abstract

  This study evaluates the effect of post-cure schedules and cure initiator form on the mechanical properties of Glass fibre reinforced polymer (GFRP) laminates manufactured using an infusible reactive thermoplastic resin. Tensile, flexural, shear and dynamic mechanical analysis tests were conducted. Fractography was also performed. Specimens fabricated using liquid cure initiator and subjected to an elevated temperature post-cure were the control specimens. Ambient cured specimens decreased by no more than 12% in the case of tensile properties (modulus of 90◦ specimens) and by < 14.3% in the case of flexural properties (also modulus in 90◦ specimens). Furthermore, the difference in mechanical properties of 0◦ specimens fabricated using a powder cure initiator was observed to be within ≈ 7% of respective properties of control specimens. In the context of fabricating thick laminates for large-size offshore structures, the results suggest that an extended ambient post-cure cycle in conjunction with an initiator in powder form can be employed instead of an elevated temperature post-cure schedule with initiator in liquid form. This is economically beneficial since it eliminates infrastructure required for elevated temperature curing/post-curing. The risk of porosity induced due to liquid-based initiators is also avoided.

  Abstract
  This study evaluates the effect of post-cure schedules and cure initiator form on the mechanical properties of Glass fibre reinforced polymer (GFRP) laminates manufactured [...]

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• In-situ polymerizable thermoplastic and bio-epoxy based composites for offshore renewable energy applications.

  G. Bhatia, A. Hejjaji, J. Pothnis, A. Portela, A. Comer

  Fibregy OA (2024). Vol. Open Access Papers, 15

  
  

  Abstract

  This study evaluates various quasi-static mechanical properties of an in-situ polymerizable thermoplastic and a bio-based thermosetting composite comprising of non-crimp fabric reinforcement for potential use in the next generation of Offshore Wind and Tidal Power platforms. Mechanical properties are characterized under tensile, flexural, in-plane shear and interlaminar shear loading. Results reveal that the evaluated properties differ based upon matrix type. Fractographic evidence from scanning electron microscopy is used to explain the differences observed and was generally consistent in terms of revealing cohesive failure at the fiber-matrix interface for the thermoplastic composite and contrasting adhesive failure for the thermosetting composite. For glass fibre reinforcement, the thermoplastic composite is superior in terms of flexural 90° properties (+20%) while the thermosetting composite performed better in flexure 0° in terms of both strength (+15%) and modulus (+25%). In terms of interlaminar shear, the thermosetting composite exhibited higher strength (+14%) while Tensile and in-plane shear properties are similar for composites of both resin systems. Overall, neither matrix is superior in terms of overall mechanical properties and both matrices show promise as a stepping stone towards the use of more sustainable constituents in offshore structures.

  Abstract
  This study evaluates various quasi-static mechanical properties of an in-situ polymerizable thermoplastic and a bio-based thermosetting composite comprising of non-crimp fabric [...]

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• Compression characteristics and fractography of in-situ polymerisable thermoplastic and bio-epoxy based noncrimp carbon and glass fibre composites

  G. Bhatia, K. Fahey, A. Hejjaji, J. Pothnis, A. Comer

  (2024).

  
  

  Abstract

  This experimental work involves characterization and fractography of a bio-based epoxy and an in-situ polymerisable thermoplastic polymer matrix based non-crimp glass and carbon fibre composites under compressive loading. The laminates are characterized under compression loading using a combined loading compression (CLC) fixture. Laminates made using the thermoplastic matrix exhibit higher compressive strength (approx. 20% along fibre direction) compared to the bio-epoxy based laminates. Further, both composites exhibit comparable compressive modulus characteristics. The tested composites are subjected to fractography analysis using Scanning Electron Microscopy (SEM) and Computed tomography (CT). SEM results indicate a difference in fibre-matrix interface characteristics between the thermoplastic matrix and the bio-epoxy matrix. Additionally, the CT scans reveal a difference in failure modes due to fibre orientations. A difference between failure mode of the exterior and interior plies of the specimens was also noticed. However, no specific influence of matrix type was observed on the overall macroscopic failure behavior.

  Abstract
  This experimental work involves characterization and fractography of a bio-based epoxy and an in-situ polymerisable thermoplastic polymer matrix based non-crimp glass and [...]

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