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Sealing strip construction industry has high reversible deformation of elastic polymer material. Elastic, at room temperature under external force at an early age can generate large deformation, can recover after removal of the external force. Rubber belongs to complete the amorphous polymer, and its low glass transition temperature (T g), molecular weight often large, more than hundreds of thousands of. Rubber is a word derived from the Indian cau - uchu, meaning "and" tree. Natural rubber is made by hevea when tapping outflow of latex after solidification, drying and made. In 1770, the British chemist j. Priestley discovered rubber pencil marks can be used to wipe away, at that time, will the use of material, called rubber, the term has been in use today.
Rubber molecular chain can crosslinking, and crosslinked rubber due to the interaction between the external force and deformation, has the ability of quick recovery, and has good physical and mechanical properties and chemical stability. The basic materials of rubber is rubber industry, widely used in the manufacture of tires, rubber hose, adhesive tape, cable and other rubber products. Natural rubber is made by latex, latex in the part of the rubber component stay solid natural rubber. General in the natural rubber rubber hydrocarbon containing 92% ~ 95%, rather than rubber hydrocarbon (5% ~ 5%. Due to different process, producing area different rubber and adopt different season, the proportion of the ingredients may have differences, but basically within the range. Protein can promote rubber vulcanization, delay aging. Protein, on the other hand, has the strong water imbibition, can cause rubber damp mildewy, insulation, protein and increased heating shortcoming. Acetone extract is senior fatty acids and sterols substances, including some role natural protective agent and accelerator, and can help powder compound in the process of mixing dispersion and raw rubber softening effect. In the ash mainly containing magnesium phosphate and calcium phosphate salts, have a very small amount of copper, manganese, iron and other metal compounds, because the base metal ions can promote the rubber aging, so their content should be controlled. Moisture in the dry glue not more than 1%, in the process of machining can be volatile, but when moisture content is too much, not only can make the rubber easy mold storage process, but also affects the rubber processing, such as mixed compound easy cluster; Bubbles, calendering, extruding process sulfide in the process of bubble or a cavernous, etc. Provide the most commercial rubber hevea.
It hurt (such as stem bark was cut open) will produce a large number of SAP containing rubber emulsion. In addition, the FIG tree and some euphorbiaceae plants can also provide rubber. Germany during the second world war because the rubber supply is cut off, tried to obtained from these plant rubber, but later changed to the production of artificial rubber. The original rubber trees grow in South America, but after artificial grafts, southeast Asia also has a lot of kinds of rubber tree. In fact, Asia has become the most important source of rubber. Made of silver chrysanthemum gum rubber can reduce the sensitivity.