| As excellent non-metallic reinforced material, Glass fibers used in many areas ofthe national economy, national defense construction. In the manufacture of compositematerials and molding process, the wetting properties of the resins on the fibers have avery important influence on the composite interfacial properties that after forming andthe overall performance of the products. Accurately measuring the wetting properties ofthe fiber-resin system and investigating the wetting law have important implications onthe development of new products of fibers or its composite materials and improvementsof manufacturing process. Due to the very fine diameter and single fiber is usually soft；Measuring the wetting performance is so difficult. This thesis is focused on the dynamicwetting system that is suitable for fiber-resin and dynamic contact angle measurementmethods, analysis and discusses the wetting law, the wetting properties of glass fiber-resin system.The main results are shown in the following:①General measuring methods for contact angle: the light reflection method,insertion method, sessile drop method, hanging bubble method, Wilhelmy plate method,capillary method, rotating cylinder method and the static method/dynamic Washburnmethod for the powder/fiber bundle. For fiber materials: the light reflection method,hanging bubble method, capillary method and the rotating cylinder method are difficultto measure their contact angle; the sessile drop method, Wilhelmy plate method and thedynamic Washburn balance method have their own characteristics, the sessile dropmethod can obtain the contact angle less than90°in equilibrium; the dynamicWashburn balance method has a relatively complex operation and can only measure thecontact angle less than90°; The Wilhelmy method reflect the dynamic wetting processby measuring force, compared to others is suitable for fiber materials, especially in asingle fiber contact angle measurement.②In single fiber-resin dynamic contact angle measurements, the expression forthe buoyancy and viscous force are more difficult, This thesis, according to theWilhelmy method, measures the "forward" and "back" contact process force of fiber–resin, obtains single glass fiber-resin dynamic contact angle measurement dataprocessing new method based on studying on dynamic contact, wetting characteristics,force-immersion depth variation: Which gets the force-immersion depth relationship by regression analysis and uses the characteristic that immersion depth is zero,buoyancy, viscous force can be ignored to estimate out the wetting force of the resin onthe fiber. The new method is applied to glass fiber manufacturing enterprise for newfiber product development and manufacturing process improvement, has been fullyrecognized and affirmed.③In the dynamic contact angle measurement of single glass fiber-resin,three-phase contact line movement rate, the fiber immersed in resin depth and resinviscosity have impacts on varying degrees.For relatively high viscosity liquids, such asCYD128/760E epoxy,As the three-phase contact line movement rate increases from0.005mm·s-1/0.01mm·s-1to0.05mm·s-1/0.09mm·s-1in the advancing contact, themeasured dynamic contact angle increases from73.9°/51.31°to170.06°/74.58°.The movement rate of three-phase contact line in measurement should be equal to thecorresponding rate in the manufacturing of fiber-resin composites. The expression ofthe measured contact angle results should be included the rate of movement of thethree-phase contact line. The depth of fiber immersed in the resin has smaller impact onthe contact angle measurement results and can usually be ignored.④Single ECT glass fiber-CYD128epoxy dynamic wetting system is mixedwetting at the rate of0.03mm·s-1and its advancing wetting force is negative, backwetting force positive.⑤The E6, ECT, J202, TM, ER and ECR six kinds of glass fiber have relativelylarge contact angle with CYD128epoxy, wettability is poor and for760E epoxy,contact angle is smaller, wettability is relatively better. For the same kind of resin, ER,E6, ECT have better wettability; TM, ECR, J202have poorer wettability. The relativevalue of the dynamic contact angle between the six kinds of fiber and CYD128epoxy or760E epoxy as follows: E6<ER <ECT <TM <ECR <J202.⑥Glass fiber surface energy has impacts on wetting characteristics of fiber–resin system. High fiber surface energy provides a favorable precondition for goodwetting, but not sufficient condition. |
PDF Full Text Request