A Modification Method of Polyvinyl Alcohol Fiber for Strain Hardening Cementitious Composite

Abstract

The invention discloses a modification method of polyvinyl alcohol fiber for a strain-hardening cement-based composite material. According to the method, the surface of the polyvinyl alcohol fiber asa raw material is coated with a layer of interface epoxy resin, and the surface of an epoxy resin coating is coated with a layer of nano graphite powder. By means of the method, the interfacial properties of the polyvinyl alcohol fiber and a cement matrix can be well regulated, the stability of the coating can be guaranteed, and no damage can be caused to the fiber.

Description

technical field [0001] The invention relates to the technical field of modification of composite materials, in particular to a method for modifying polyvinyl alcohol fibers on the surface of epoxy resin-nanometer graphite coatings of strain-hardened cement-based composite materials. Background technique [0002] In 1992, a paper jointly published by Victor Li of the University of Michigan and Christopher Leung of the Massachusetts Institute of Technology theoretically demonstrated the tensile properties of SHCC, established the physical basis and design criteria for designing cement-based composite materials, and thus opened the research on SHCC materials. and apply. Strain Hardening Cementitious Composites (SHCC) has the characteristics of strain hardening and multi-micro crack cracking under uniaxial tensile load, and the ultimate tensile strain can reach 3%~7%. Its superior tensile properties and super toughness have significantly changed the defects of high brittleness ...

AI Technical Summary

Problems solved by technology

[0004] At present, most of the fibers used in strain hardening cement-based composite materials are PE fibers and PVA fibers. Because PE fibers are more expensive and their long-term mechanical properties decline, PVA fibers are used more. However, because the surface of polyvinyl alcohol fibers contains a large number of hydroxyl groups , has a strong affinity with cement, and under tension, due to the strong adhesion with the cement matrix, the polyvinyl alcohol fiber is pulled out during the pull-out process instead of being pulled out; resulting in The properties of strain hardened cementitious composites will be severely affected

[0005] At present, in order to adjust the interface performance between polyvinyl alcohol fiber and cement matrix, the surface of polyvinyl alcohol fiber is generally coated with oil agent (such as Chinese patent application number 201210468413.3). On the one hand, the oil agent is easy to enter the cement matrix and affect the performance of the cement matrix. On the one hand, the oil film coating on the surface of the fiber is easy to fall off during the molding and stirring process; another example (Chinese Patent Application No. 201610375068.7) uses a strong oxidant, potassium permanganate, to oxidize the surface of the polyvinyl alcohol fiber to make the polyvinyl alcohol fiber After the surface is rough, apply a layer of hydrophobic substance. On the one hand, it will damage the surface of the polyvinyl alcohol fiber and reduce the performance of the fiber. At the same time, the hydrophobic coating only depends on the physical adsorption force between the coating and the fiber surface, and the stability cannot be guaranteed.

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