Fibre-reinforced polymer matrix composites find use in most transport applications, chemical plant, renewable energy systems, pipelines and a variety of other industries. These applications often require a surface finish for cosmetic and/or durability reasons. The coating is usually polyester or vinyl-ester gel-coat painted or sprayed onto the mould tool before the structural composite is laminated. Alternatively a (typically polyurea) coating may be sprayed onto the surface of the cured composite part. The process may emit vapours (normally volatile organic compounds, VOC) into the workplace and the environment. This review paper will consider the potential for in-mould gel-coating as a route to improved workplace conditions and reduced environmental impact. It will also address measurement of quality by adhesion, surface characterisation, and long-term durability. Customer satisfaction is the key driver for gel-coated products.

Surface coatings (gel-coats) are often used on commercial composite mouldings for cosmetic and/or durability reasons. They have traditionally been prepared in open moulds with styrene vapour allowed to escape to the workspace and environment. This paper considers the development of in-mould gel-coating processes. A Double Glass Plate Mould (DGPM) was used to prepare flat composite test panels. Laminates were manufactured by liquid composite moulding processes. Conventional hand painted gel-coat, innovative In-Mould Gel-Coating with a trilayer separator fabric (IMGC) or In-Mould Surfacing with a silicone shim (IMS) were studied. The surface quality of the final products was measured using a Wave-Scan device while the adhesion of the gel-coat was characterised by pull-off tests. The new processes offer reasonable properties in a cleaner, more controlled process.

Self-heating of nanocomposite materials based on the joule heating effect is suitable for numerous engineering applications. In this study, a highefficiency self-heating nanocomposite, using high conductive multi-walled carbon nanotubes (MWCNTs)-based phenolic resin, was fabricated with a hot press method. The microstructure and the thermal stability of self-heating nanocomposite were studied by X-ray diffraction, scanning electronic microscopy, and thermogravimetric tests. Electromechanical and thermal performance tests were conducted to investigate their potential as a self-heating application. Results showed that the compressive strength, modulus, and the piezo-resistive behaviour were higher after adding MWCNTs to the phenolic resin, indicating better load transfer and self-damage sensing as well. Moreover, at 4.0 wt% of MWCNTs concentration, the electrical conductivity of a self-heating nanocomposite showed a higher value of 13.26 S/m which was also found to be proportionally increased with the thickness of the samples, it was ≈25.5 and ≈12.8 S/m for 10 and 3 mm, respectively. In addition, a steady-state temperature of ≈110°C could be reached at low applied volts (8 V) as well as its heating performance was significantly dependent on the input power and the thickness of the sample. This is also confirmed by statistical results between the sample with thicknesses of 3 and 10 mm in terms of power consumption with P value ≈ .0001. Furthermore, the influence of Joule heating was estimated analytically based on the one-dimensional heat transfer equation in companying with other previous models. The estimated distributed temperatures values were in good agreement with the experimental results. The selfheating nanocomposite described in this study has the potential to be used in various industrial applications and a wide range of sectors due to its ability to self-damage sensing, easy fabrication, and high heating efficiency at low power consumption.

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