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In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer . [1] Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst .
HDPE is known for its high strength-to-density ratio. [4] The density of HDPE ranges from 930 to 970 kg/m 3. [5] Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. [6]
Condensites are similar thermoset materials having much the same properties, characteristics, and uses. [77] Crystalate is an early plastic. [78] Faturan is a phenolic resin, also similar to Bakelite, that turns red over time, regardless of its original color. [79] Galalith is an early plastic derived from milk products. [80]
Thermosetting plastics are polymer materials which are liquid or malleable at low temperatures, but which change irreversibly to become hard at high temperatures.
For example, molding at a high temperature improves the gloss and heat resistance of the product whereas the highest impact resistance and strength are obtained by molding at low temperature. Fibers (usually glass fibers) and additives can be mixed in the resin pellets to make the final product strong and raise the maximum operating temperature ...
Thermosets, or thermosetting polymers, can melt and take shape only once: after they have solidified, they stay solid and retain their shape permanently. [16] If reheated, thermosets decompose rather than melt. Examples of thermosets include epoxy resin, polyimide, and Bakelite. The vulcanization of rubber is an example of this process.
Urea-formaldehyde (UF), also known as urea-methanal, so named for its common synthesis pathway and overall structure, [1] is a nontransparent thermosetting resin or polymer. It is produced from urea and formaldehyde. These resins are used in adhesives, plywood, particle board, medium-density fibreboard (MDF), and molded objects.
An acrylic resin is a thermoplastic or thermosetting plastic substance typically derived from acrylic acid, methacrylic acid and acrylate monomers such as butyl acrylate and methacrylate monomers such as methyl methacrylate. Thermoplastic acrylics designate a group of acrylic resins typically containing both a high molecular weight and a high ...