Thermosetting polymer, definition

Synonyms Formaldehyde, phenol polymer Formaldehyde, polymer with paraformaldehyde and phenol Paraformaldehyde, formaldehyde, phenol polymer Paraformaldehyde, phenol polymer Phenol-formaldehyde copolymer Phenol, formaldehyde polymer Phenol, polymer with formaldehyde Phenol, polymer with paraformaldehyde Classification Thermosetting polymer Definition Reaction prod, of phenol with aq. 37-50% formaldehyde with basic catalyst chief class of phenolic resin Formula (CeHeO (CH20)x)x Properties Gray to bik., hard, infusible solid when cured resist, to moisture, soivs., heat to 200 C dimensionally stable good elec, resist. noncombustible... 

Thermoset polymers assume a permanent shape or set once cured. Once set, they cannot be reshaped. They are formed by a large amoimt of cross-linking of linear prepolymers (a small amount of cross-linking will produce elastomers) or by direct formation of networks by the reaction of two monomers. The latter is the more prominent of the two methods. It is a stepwise or condensation method that has been defined as "the reaction of two monomers to produce a third plus a by-product, usually water or alcohol." Because in some cases a by-product is not produced, this definition is no longer exactly correct. The reaction is now referred to as a "stepwise" polymerization. When the reaction results in a by-product, it is called a "condensation reaction." Table 3.1 lists the principal thermoset polymers. 

Synonyms Eormaldehyde copolymer with urea Eormaldehyde/urea condensate Eormaldehyde/urea copolymer Eormaldehyde/urea polymer Eormaldehyde/urea precondensate Eormaldehyde/urea prepolymer Eormaldehyde/urea resin Formalin/urea copolymer Methylolurea resin Paraformaldehyde/urea polymer Paraformaldehyde/urea resin Polynoxylin Polyoxymethylene urea (INCI) UF Ure ormaldehyde adduct Urea/formaldehyde condensate Urea/formaldehyde copolymer Urea/formaldehyde oligomer Urea/formaldehyde polymer Urea/ formaldehyde precondensate Urea/formaldehyde prepolymer Urea, polymer with formaldehyde Classification Amino resin thermosetting resin Definition Thermosetting resin formed from condensation reaction of formaldehyde with urea formu/a (CH,N20 CH2O),... 

Synonyms Condensation prods., epoxy Epoxides, polymers, epoxy resins Epoxy compds. Ethers, cyclic, epoxides, polymers Plastics, epoxy Polyethers, epoxy resins Classification Polymer Definition A thermosetting resin based on the reactivity of the epoxide group Toxicology LD50 (oral, rat) 2200 mg/kg strong skin irritant in uncured state poison by inhalation moderately toxic by ingestion little or no toxicity in cured state Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of Cr... 

Polyolefins in fact lend themselves to this straightforward recycling procedure. Other thermoplastics like polyamides and polyesters need more careful handling because of their sensitivity to moisture absorption and molecular degradation. Thermosets are, by definition, not recyclable in the true sense however by comminuting and recompounding with fresh monomers, most thermoset polymers can in effect be recycled without significant loss of performance. 

Syntactic foams are obtained by mixing hollow micro- or macro-balloons, generally made of glass but sometimes of polymer, directly with a liquid resin, generally a thermoset. Some extend this definition to all composites with a foamed core. 

Chapter 22 didn t give you a very satisfying definition of resins. But its useful here to talk about two classes of polymers called resins thermosets and engineering thermoplastics. 

Thermal stability as measured by these ramped TGA experiments of the sort previously described are not the definitive test of a polymer s utility at elevated temperature. Rather, for a polymer to be useful at elevated temperatures, it must exhibit some significant retention of useful mechanical properties over a predetermined lifetime at the maximum temperature that will be encountered in its final end use application. While many of the bisbenzocyclobutene polymers have been reported in the literature, only a few have been studied in detail with regards to their thermal and mechanical performance at both room and elevated temperatures. Tables 7-10 show some of the preliminary mechanical data as well as some other physical properties of molded samples of polymers derived from amide monomer 32, ester monomer 40, diketone monomer 14 and polysiloxane monomer 13. The use of the term polyamide, ester etc. with these materials is not meant to imply that they are to be regarded as merely modified linear thermoplastics. Rather, these polymers are for the most part highly crosslinked thermosets. 

The definition of chemorheology (in this text) is the study of the deformation properties of reactive polymer systems. Figure 4.1 shows a schematic representation of the structural development during thermoset cure. 

Very little is known about the structure of the cured polyester resin. The products definitely belong in the thermoset class. There is some correlation between maximum physical properties a nd a molar ratio of 1 1 between double bonds in the alkyd and monomer. However, this is not critical and simple cross-linking does not tell the full story. The styrene monomer can be present in twice the molar amount needed, and yet complete copolymerization takes place without apparent formation of styrene polymer. 

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