Wetting Behavior of Elastomer-Modified Glass Fibers

Abstract

Interfacial properties of glass fibers coated by admicellar polymerization with a styrene−isoprene copolymer thin film have been investigated. Advancing and receding contact angles on single glass fibers as small as 6.2 μm in diameter were measured at slow meniscus velocities (2.0 μm/s) by using the Wilhelmy method with probe liquids of various hydrophobic/hydrophilic characteristics. Distinctly different contact angles were obtained from the dynamic wetting of fibers with different surface treatments. In water, the average advancing contact angle for admicellar-modified fibers was high (θadv ≈ 65−75°), suggesting an increased hydrophobicity as compared to that of the fully wettable desized fibers. Furthermore, it was found that both fibers with silane coupling agents and admicellar-coated fibers are chemically heterogeneous on their surfaces. Contact line pinning behavior induced by regions of different surface energy, as well as high hysteresis values, indicates that the ultrathin styrene−isoprene film is not uniform throughout the glass on a macroscopic length scale. However, when assessed with an epoxy resin (e.g. EPON 815C), the admicellar polymerization treatment produced fibers with statistically identical wetting characteristics to those of fibers containing a proprietary sizing. Good adhesional wetting of the elastomer-modified fibers by an epoxy resin may be indicative of an adequate interaction between fiber and matrix in large-scale composite fabrication.

Porosity Reduction in the High-Speed Processing of Glass-Fiber Composites by Resin Transfer Molding (RTM)

“…Therefore, herein all calculations involving the modified capillary number include the advancing contact angles measured for the pure epoxy resin and fibers from the random-mat preform. These advancing contact angles have been already presented elsewhere [28]. It is worth noting that the fibers were relatively small in diameter (e.g.…”

Effects of electrochemical oxidation of carbon fibers on interfacial shear strength using a micro-bond method

“…The contact angles of water and diiodomethane on the epoxy matrix were measured using the sessile drop method [33]. W ad can be estimated by applying Fowke's theory [34] and the Young-Dupré equation [35] according to the geometric mean method, as given in the following eq (4): (4) where g s is the surface energetic of the CFs listed in Table 1, g L is the surface energetic of the epoxy matrix used and = 37.5 mN/m and = 5.8 mN/m [36].…”

Analysis of the resin transfer molding (RTM) process for FRP and its process simulation fundamentals

“…Literature only describes few values and reproduceable data is hard to obtain. Measurements were conducted by means of the Wilhelmy method with values of 34°±5° [6]. In this method the fibers are dipped into a drop of the resin.…”