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        Introduction to raw materials of rubber
        Source: | Author:zywenju | Published time: 2021-07-24 | 538 Views | Share:
        high elastic polymer material with reversible deformation. It is elastic at room temperature and can produce large deformation under the action of small external force.

        The raw materials of rubber are rubber or plastic, sulfur, vegetable oil and gravel.

        Rubber: high elastic polymer material with reversible deformation. It is elastic at room temperature and can produce large deformation under the action of small external force. It can be restored to its original state after removing the external force and is not conductive. Rubber is a completely amorphous polymer. Its glass transition temperature (TG) is low and its molecular weight is often large, more than hundreds of thousands.

        The word rubber comes from the Indian cau uchu, which means "tearful tree". Natural rubber is made from the latex flowing out during rubber cutting of clover rubber tree after solidification and drying. In 1770, the British chemist J. Priestley found that rubber could be used to erase pencil handwriting. At that time, the material for this purpose was called rubber, which has been used today. The molecular chain of rubber can be crosslinked. When the crosslinked rubber deforms under external force, it has the ability of rapid recovery, and has good physical and mechanical properties and chemical stability. Rubber is the basic raw material of rubber industry. It is widely used in the manufacture of tires, rubber hoses, tape, cables and other rubber products.

        Rubber is divided into natural rubber and synthetic rubber according to raw materials. It can be divided into block raw rubber, latex, liquid rubber and powder rubber. Latex is colloidal aqueous dispersion of rubber; Liquid rubber is an oligomer of rubber, which is generally viscous liquid before vulcanization; Powdered rubber is to process latex into powder to facilitate batching and processing. The thermoplastic rubber developed in the 1960s is formed by the processing method of thermoplastic without chemical vulcanization. Rubber can be divided into general type and special type.

        plastic cement

        Concept of plastic raw materials

        1. The main component of plastic raw materials is resin.

        2. Plastic raw material: it is a kind of material with polymer synthetic resin (polymer) as the main component and infiltrated into various auxiliary materials or additives. It has plasticity and fluidity under specific temperature and pressure. It can be molded into a certain shape and keep the shape unchanged under certain conditions.

        3. Polymer: refers to the pure material or polymeric material produced by the polymerization process. Both natural resin and synthetic resin belong to polymer, which is referred to as polymer for short.

        4. Plastic has good insulation to electricity, heat and sound: excellent electrical insulation, arc resistance, thermal insulation, sound insulation, sound absorption, vibration absorption and noise elimination.

        Most of the plastic raw materials are extracted from some oils. The most familiar part of PC material is extracted from oil. PC material has a smell of gasoline when burning; ABS is extracted from coal. When ABS is burned out, it will be in the form of soot; POM is extracted from natural gas. When POM is burned, it will have a very smelly gas smell.

        Characteristics of general plastic raw materials:

        a. Plastic raw materials expand when heated, and the linear expansion coefficient is much larger than that of metal;



        b. The rigidity of general plastic raw materials is one order of magnitude lower than that of metal;

        c. The mechanical properties of plastic raw materials will decrease significantly under long-term heating;

        d. General plastic raw materials will have permanent deformation under long-term stress at room temperature and stress lower than its yield strength;

        e. Plastic materials are very sensitive to notch damage;

        f. The mechanical properties of plastic raw materials are usually much lower than those of metals, but the specific strength and specific modulus of some composites are higher than those of metals. If the product design is reasonable, it will give full play to its advantages;

        g. Generally, the mechanical properties of reinforced plastic raw materials are different;

        h. Some plastic materials will absorb moisture and cause changes in size and properties;

        i. Some plastics are flammable;

        j. At present, the fatigue data of plastic raw materials are very few, which should be considered according to the use requirements.

        Classification of plastic raw materials:

        According to the molecular structure of synthetic resin, plastic raw materials are mainly divided into thermoplastic and thermosetting plastics; For thermoplastics, it refers to plastics with plasticity after repeated heating: mainly PE / PP / PVC / PS / ABS / PMMA / POM / PC / PA and other common raw materials. Thermosetting plastics mainly refer to the plastics made of heat hardened synthetic resin, such as some phenolic plastics and amino plastics, which are not commonly used.

        According to the scope of application, there are mainly general plastics, such as PE / PP / PVC / PS. Engineering plastics such as ABS / POM / PC / PA are commonly used. In addition, there are some special plastics, such as high temperature, high humidity and corrosion resistance, and other plastics modified for special purposes.

        Material utilization and color treatment:

        1. Most of the plastic raw materials can be recycled, but because the reused plastic (nozzle material) is more brittle than ordinary raw materials, it can only be mixed with new materials (raw materials), and the maximum proportion shall not exceed 25%, which shall be based on the standard required by customers. Various types of plastic materials are subject to different injection pressure due to different melting points, so they must not be confused in production.

        2. Because plastic products should match with color, plastic raw materials can be divided into: granulated materials, toner materials, color seed materials, and the recent addition of liquid to color in plastic raw materials. The granulation raw material is that the pigment has been mixed into the raw material, and each plastic material has been colored, so the color of the product is stable and uniform. Toner material and color seed material are used by mixing color seed or toner with raw materials, which has low cost and does not need to store a large number of colored raw materials. However, the color is unstable and it is difficult to control the unity in production.