Toughening effects of interleaved nylon veils on glass fabric/low‐styrene‐emission unsaturated polyester resin composites

Abstract

The effectiveness of using interleaved nylon veils to increase the interlaminar toughness of glass fiber reinforced, low‐styrene emission unsaturated polyester resin composites has been investigated. Samples were manufactured by a hand lay‐up technique followed by compression moulding. Nylon 66 veils were used, with the veil content varying from 0% to 4% by weight. Double cantilever beam, short beam shear, and three point bend tests were performed. The increasing levels of nylon veil content improved the interlaminar toughness of the composites, which was characterized by critical strain energy release rate (GIC). The maximum GIC for crack propagation of a nylon interleaved composite increased by almost 170% over the baseline glass fiber reinforced composite. Dynamic Mechanical Analysis revealed an increase in the damping parameter of up to 117%. Image analysis via Digital Image Correlation and Scanning Electron Microscopy revealed increased fiber bridging between adjacent plies as a key reason for these improvements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41462.

PET interleaving veils for improved fracture toughness of glass fibre/low‐styrene‐emission unsaturated polyester resin composites

“…The PET veil between the two glass fiber plies being flexible in nature and being strongly bonded with the adjacent plies, takes part in energy absorption under shear and improves the ILSS. However, a 25% drop in ILSS was seen in GPETPETG with two PET veils in the interlaminar region, which is similar to our findings on polyamide veils in the same glass/resin system . It is apparent from the results that the interlaminar region between the two adjacent PET veils, both being flexible in nature, might act as a weak point under shear stress and the ILSS is reduced.…”

“…Such an increase in flexural strength can be attributed to the similar chemical nature of the veil and the matrix resin which helped them to strongly interact with one another. Note that a drop in flexural strength, up to 23%, was evident in our previous work with a similar GF/unsaturated polyester resin system with interleaving polyamide veils . The enhancement in flexural strength observed here reflects the additional advantage of using chemically similar interleaving veils with the matrix resin.…”

“…This value compares well with the flexural strength of a similar GF/unsaturated polyester resin composite reported by O'Donovan et al . (466 MPa) and Velmuruganet et al . (378 MPa) .…”

“…The specimens were tested at a constant rate of 5 mm/min. The crack growth was tracked visually and also with the use of a LaVision two‐dimensional (2D) Digital Image Correlation (DIC) camera, with results analyzed via LaVis 7.4 processing software . Five specimens of were tested from each set.…”

“…In our previous work we reported on the use of polyamide veils as interleaving materials in glass fiber composites, with a low styrene emission grade of unsaturated polyester resin. A laminate containing two layers of polyamide veils between each glass layer exhibited an increase of up to 170% in G IC over the values obtained for the all‐glass fiber composite.…”