Adding fibers to polymer mortar to improve the comprehensive performance of mortar has become a common and feasible method. The commonly used fibers are as follows
Alkali-resistant fiberglass?
Glass fiber is made by melting silicon dioxide, oxides containing aluminum, calcium, boron and other elements, and a small amount of processing aids such as sodium oxide and potassium oxide into glass balls, and then melting and drawing the glass balls in a crucible. Each thread drawn from the crucible is called a monofilament, and all the monofilaments drawn from a crucible are assembled into a raw yarn (tow) after passing through the soaking tank. After the tow is cut, it can be used in polymer mortar.
The performance characteristics of glass fiber are high strength, low modulus, high elongation, low linear expansion coefficient, and low thermal conductivity. The tensile strength of glass fiber far exceeds the strength of various steel materials (1010-1815 MPa).
Velen fiber?
The main component of vinylon is polyvinyl alcohol, but vinyl alcohol is unstable. Generally, vinyl alcohol acetate (vinyl acetate) with stable performance is used as a monomer to polymerize, and then the resulting polyvinyl acetate is alcoholylated to obtain polyvinyl alcohol. After the silk is treated with formaldehyde, the hot water resistant vinylon can be obtained. The melting temperature (225-230C) of polyvinyl alcohol is higher than the decomposition temperature (200-220C), so it is spun by solution spinning.
Vinylon has strong hygroscopicity and is the most hygroscopic variety among synthetic fibers, which is close to cotton (8%). Vinylon is slightly stronger than cotton and much stronger than wool. Corrosion resistance and light resistance: insoluble in general organic acids, alcohols, esters and petroleum lamp solvents, not easy to mould, and the strength loss is not large when exposed to sunlight. The disadvantage is that the hot water resistance is not good enough and the elasticity is poor.
Acrylic fiber?
It refers to the synthetic fiber made by wet spinning or dry spinning with more than 85% of the copolymer of acrylonitrile and the second and third monomers.
Acrylic fiber has excellent light resistance and weather resistance, which is the best among common textile fibers. When acrylic fiber is exposed to the sun for one year, its strength will only decrease by 20%. Acrylic fiber has good chemical stability, acid resistance, weak alkali resistance, oxidation resistance and organic solvent resistance. However, acrylic fibers will turn yellow in lye, and macromolecules will break. The quasi-crystalline structure of acrylic fiber makes the fiber thermoelastic. In addition, acrylic fiber has good heat resistance, no mildew, and is not afraid of insects, but has poor wear resistance and poor dimensional stability.
Polypropylene fibers?
A polyolefin fiber made from stereoregular isotactic polypropylene polymer by melt spinning. The relative density is the smallest among synthetic fibers, the dry and wet strength are equal, and the chemical corrosion resistance is good. But the sun aging is poor. When the polypropylene mesh fiber is put into the mortar, during the mixing process of the mortar, the transverse connection between the fiber monofilaments is destroyed by the rubbing and friction of the mortar itself, and the fiber monofilament or network structure is fully opened, so as to realize the quantity The effect of many polypropylene fibers evenly mixed into concrete.
Nylon fiber?
Polyamide, commonly known as nylon, is a general term for thermoplastic resins containing repeated amide groups—[NHCO]—on the main molecular chain.
Nylon has high mechanical strength, high softening point, heat resistance, low friction coefficient, wear resistance, self-lubrication, shock absorption and noise reduction, oil resistance, weak acid resistance, alkali resistance and general solvents, good electrical insulation, has Self-extinguishing, non-toxic, odorless, good weather resistance, poor dyeing. The disadvantage is that it has high water absorption, which affects dimensional stability and electrical properties. Fiber reinforcement can reduce the water absorption of the resin, so that it can work under high temperature and high humidity. Nylon has a very good affinity with glass fibers.
Polyethylene fiber?
Polyolefin fibers spun from linear polyethylene (high-density polyethylene) by melt spinning. The device features are:
(1) Fiber strength and elongation are close to those of polypropylene;
(2) The moisture absorption capacity is similar to that of polypropylene, and the moisture regain rate is zero under normal atmospheric conditions;
(3) It has relatively stable chemical properties, good chemical resistance and corrosion resistance;
(4) The heat resistance is poor, but the heat and humidity resistance is better, its melting point is 110-120 ° C, which is lower than other fibers, and the resistance to melting holes is very poor;
(5) It has good electrical insulation. The light resistance is poor, and it is easy to age under the irradiation of light.
Aramid fiber?
The main chain of the polymer macromolecule is composed of aromatic rings and amide bonds, and at least 85% of the amide groups are directly bonded to the aromatic rings; the nitrogen atoms and carbonyl groups in the amide groups of each repeating unit are directly bonded to the aromatic rings The polymer in which carbon atoms are connected and replaces one of the hydrogen atoms is called aramid resin, and the fibers spun from it are collectively called aramid fibers.
Aramid fiber has excellent mechanical and dynamic properties such as high tensile strength, high tensile modulus, low density, good energy absorption and shock absorption, wear resistance, impact resistance, fatigue resistance, and dimensional stability. Chemical corrosion, high heat resistance, low expansion, low thermal conductivity, non-combustible, non-melting and other outstanding thermal properties and excellent dielectric properties.
wood fiber?
Wood fiber refers to the mechanical tissue composed of lignified thickened cell wall and fiber cells with fine crack-like pits, and is one of the main components of xylem.
Wood fiber is a natural fiber that absorbs water and is insoluble in water. It has excellent flexibility and dispersibility.