Plastics heat-sensitive

In contrast, most equipment can safely tolerate higher degrees of heat density than those defined for personnel. However, if anything vulnerable to overheating problems is involved, such as low melting point construction materials (e.g., aluminum or plastic), heat-sensitive streams, flammable vapor spaces, or electrical equipment, then the effect of radiant heat on them may need to be evaluated. When this evaluation is required, the necessary heat balance is performed to determine the resulting surface temperature, for comparison with acceptable temperatures for the equipment. 

Typical Use Nichrome wires, conductive plastics. Heat-sensitive materials. Also glass, metals, plastics and ceramics. 

For plastics, heat capacity is usually reported during constant pressure heating. Plastics differ from traditional engineering materials because their specific heat is temperature sensitive. 

This technique is used for the production of radiation-cured coatings, adhesives, and inks. The process is not accompanied by the release of heat, which is particularly important in the case of heat-sensitive materials, e.g., wood, cardboard, paper, plastics, etc. Various radiation sources are used for this technique, among which UV and EB are most useful. 

Polyester c Esters, diacetone Heat-sensitive plastics, vehicles, home appliances, wood... 

Preassembled parts Preassembled parts may contain components made from heat-sensitive substrates (e.g., plastic inserts, wiring). In contrast to the conventional method, where individual components are coated prior to assembly to avoid heat damage, UV powder coating permits the manufacturer to fully assemble a part prior to coating. 

Conventional tin and glass containers can be satisfactorily treated by steam or hot air. Paper, cardboard, and heat-sensitive plastics require subtler techniques. Experiments with Co60 gamma rays indicate that 200,000 r. are sufficient to inactivate vegetative contaminants, while the customary 2 X 10 r. are required for spore formers. These doses are considerably below those that would be expected to have any effect on the physical properties of these materials (Sec. IIIC5). 

Self-Adhesive or Pressure-Sensitive Labels. It is preferable to call these pressure-sensitive labels, as both the pregummed and heat-sensitive labels are self-adhesive (i.e., the adhesive is already there). They consist of a suitable label facing material (usually paper or polymer), the reverse side of which is coated with a permanently tacky adhesive that is in contact with a backing paper (occasionally plastic) that protects it prior to use. The backing paper is coated with a special release coating that permits the label to be removed easily. Labels may be provided on roll or sheet form both can have the label laid on that is, the unprinted area has been cut and removed. 

Also propellant charges for rockets and guns have also been developed by compounding solid explosives such as nitramines (e.g. -> Cy-clonite) with plastics. Plastic explosives and plastic propellants are of interest, if low thermal and impact sensitivity is needed (- LOVA -> Armor Plate Impact Test -> Friction Sensitivity -> Heat Sensitivity - Impact Sensitivity -> Projectile Impact Sensitifity - Susan Test). 

They are extensively used for plastic compounding that includes heat-sensitive materials such as PVC, processing of difficult-to-feed materials (such as certain powders), reactive processing,197 and for plastic devola-... 

Conversely, mills with impact and attrition modes often do poorly with heat-sensitive materials where the materials become ductile as they heat up. Impact and attrition mills cause significant heating at the point of impact, and it is not uncommon for heat-sensitive materials (e.g., plastics) to stick to the device rather than being ground. In the worst cases, cryogenic grinding can be necessary for highly ductile or heat-sensitive materials. 

Use Pressure-sensitive and hot-melt adhesives, bonding of paper to polyethylene, laminating adhesive, tackifier and plasticizer for coatings, heat sensitizer for rubber latex, pigment binder in textile finishing and printing inks, protective colloid in emulsions. 

Heat-sensitive materials may be sterilized by radiation, providing the product and its container are not radiation sensitive. It is particularly used with plastics, and more widely used with containers than with products. An alternative is ethylene oxide gas. This presents problems in that the gas must be brought into contact with the cell walls of contaminating bacteria. Ethylene oxide is highly reactive and can only be used when it can be proved not to react with the product. 

The specified factors indicate that high-strength structural steel of 30CrMnSiNi2Mo grade as heat treated works at a limit of its capabilities, without a reserve of plasticity is sensitive to presence of surface defects, has low corrosion resistance and is not the best material for the loaded units with long term of operation. 

Polyvinyl acetate polymer is generally a soft, flexible and low melting polymer. Copolymers with vinyl chloride combine the properties of the softness of PVA with the hardness of the former. PVA and copolymers find use as an adhesive (labelling paper to metal or plastic), and a heat sensitive base. 

Exchange between product and pack can occur in both directions, e.g. certain labelling materials such as heat sensitive and self-adhesive labels when in contact with plastic materials. Both the plastic and the adhesives may contain plasticisers or migratory constituents. Most cellulosics use phthalate, sebacate, phosphate-type plasticisers (e.g. methyl phthalate (DMP) may be used in cellulose acetate). Plasticisers may also be found in poly vinyl chloride/acetate copolymers, polyvinyl acetate and polyvinyl alcohol formulations, polymethyl methacrylate, nylon and certain thermosetting resins. 

Solvents in inks may also permeate into the products and occasionally product ingredients may change the permanency of the ink if they pass through the plastic. Similarly, labels adhesives may also contain migratory constituents. (Special checks are essential on pressure and heat sensitive adhesives.)... 

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