Free radical photopolymerization process for fiber‐reinforced polymer: Effect on the mechanical properties

Abstract

Glass–fiber‐reinforced polymers were manufactured either through a room temperature thermal curing or under ultraviolet (UV) light from a LED. The thermal system yields high performances when a post‐curing process at 65°C is applied. The photochemical curing leads to a composite in a faster timescale, albeit at the extent of the mechanical properties. It is found that in this case, impregnation and vacuum steps are too fast to allow a good wetting of the fibers, thereby leading to mechanical weaknesses and larger void volume. However, when applying longer vacuum and impregnation steps, the mechanical properties of the photochemically cured sample match the best thermally cured one. As a conclusion, it is shown that photochemical curing of glass–fiber‐reinforced polymer can lead to high performance composite provided that the preparation steps are well controlled.

Frontal free‐radical photopolymerization of thick samples: Applications to LED‐induced fiber‐reinforced polymers

“…The values measured vary between 8.8 MPa for the laminate with the lowest content of TPO and 42 MPa for the laminate with a TPO concentration of 2 wt %. The high value of 42 MPa is close to that recently reported in the literature for similar composites . This validates UV technology as a viable process in composites manufacturing, capable of competing with existing products.…”

“…This illustrates how difficult it can be to compare two systems and to come up with a reasonable conclusion. Recently, the mechanical properties of six layers glass fibers/UP laminates obtained with a 100% UV process were investigated . They were compared to two thermally initiated composites, one with a postcuring step at 65 °C for 12 h and one without.…”

“…The viability of light to cure thick composite parts having already been demonstrated, this work offers to study the key parameters influencing the frontal photopolymerization of thick samples such as fiber‐reinforced polymers. Acyl phosphine oxides have been proven to be suitable photoinitiators for photocomposites in the aforementioned works . On this basis, glass fiber/unsaturated polyester (UP) laminates formulated with various amounts of an acylphosphine photoinitiator were manufactured.…”

Multifunctional biphenyl derivatives as photosensitisers in various types of photopolymerization processes, including IPN formation, 3D printing of photocurable multiwalled carbon nanotubes (MWCNTs) fluorescent composites

“…35,36 The morphology of so obtained composites is signicant: the more homogeneously dispersed is the nanoller in the polymer matrix, the higher is the reinforcement of the polymer. 37 There are two common methods for producing polymeric nanocomposites. The in situ technique requires the dispersion of a nanoadditive in a monomeric mixture containing an initiator or an initiating system.…”

Influence of the Fibre Content, Exposure Time, and Compaction Pressure on the Mechanical Properties of Ultraviolet-Cured Composites

“…This means that the UV prepreg storage does not require special conditions, such as in the case of traditional prepregs.The UV curing leads to composite manufacturing in a faster timescale. However, this curing technique is usually limited to thin composite structures, because thicker parts require a longer curing period to fully penetrate the radiation, thereby reducing the efficiency of the production [7]. Moreover, it is reported that UV-curable composites suffer from low conversion due to the low penetration depth of the radiation as a result of the absorption of light by fibres and fillers, resulting in poor mechanical properties [8,9].…”