Inhalations can be divided into two types: specific and nonspecific. The former such as dust mites, pollen, fungi, animal dander and so on. Nonspecific inhalants, such as sulfuric acid, sulfur dioxide, chloramine, etc. Specific inhalants for occupational asthma, such as toluene diisocyanate, phthalic anhydride, ethylenediamine, penicillin, protease, amylase, silk, animal dander or excrement, etc. In addition, nonspecific ones include formaldehyde and formic acid. The formation and attack of asthma are related to repeated respiratory infections. There may be specific IgE such as bacteria, viruses and mycoplasma in asthma patients. Inhalation with the corresponding anti-principle can stimulate asthma. After virus infection, it can directly damage the respiratory epithelium, leading to increased respiratory reactivity.
It is suggested not to underestimate the harm of environmental factors to the body.
glass fibre
Glass fiber is an inorganic nonmetallic material with excellent performance. The original English name is: glass fiber. It is made of glass balls or waste glass through high temperature melting, drawing, winding and weaving. Finally, various products are formed. The diameter of glass fiber monofilament varies from a few microns to more than 20 meters microns, which is equivalent to 1/20- 1/5 of a hair filament. Each bundle of fiber precursor is composed of hundreds or even thousands of monofilaments, which are usually used as reinforcing materials, electrical insulation materials, thermal insulation materials, circuit boards and so on in composite materials, and are widely used in various fields of national economy.
Characteristics of glass fiber:
Generally speaking, glass is a hard and fragile object, which is not suitable for structural materials. However, if it is drawn into silk, its strength will be greatly increased, and it will be flexible. After being shaped with resin, it will eventually become an excellent structural material. As the diameter of glass fiber decreases, its strength increases. As a reinforcing material, glass fiber has the following characteristics, which makes the use of glass fiber far wider than other kinds of fibers, and its development speed is far ahead. These features are as follows:
(1) has high tensile strength and low elongation (3%).
(2) High elastic coefficient and good rigidity.
(3) It has large elongation and high tensile strength within the elastic limit, so it absorbs large impact energy.
(4) It is an inorganic fiber with incombustibility and good chemical resistance.
(5) Low water absorption.
(6) Good dimensional stability and heat resistance.
(7) Good processability, and can be made into different forms of products such as strips, bundles, felts and weaves.
(8) transparent and light-transmitting.
(9) The development of surface treatment agent with good adhesion to resin was completed.
(10) is cheap.
Classification of glass fiber:
Glass fiber can be divided into continuous fiber, fixed length fiber and glass wool according to its shape and length. According to the composition of glass, it can be divided into alkali-free, chemical-resistant, high alkali, medium alkali, high strength, high elastic modulus and alkali-resistant glass fibers.