Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Curing reaction

A large number of polymeric compounds have been investigated, but most modem propellants utilize prepolymers that ate hydroxy-functional polybutadienes (HTPB), carboxy-functional polybutadienes (CTPB), or a family of polyethylene oxides (PEGs) to form urethanes. Typical cure reactions... [Pg.38]

Chemical Stabilization Processes. This method is more versatile and thus has been used successfully for more materials than the physical stabilization process. Chemical stabilization is more adaptable for condensation polymers than for vinyl polymers because of the fast yet controUable curing reactions and the absence of atmospheric inhibition. [Pg.405]

Aromatic diacyl peroxides such as dibenzoyl peroxide (BPO) [94-36-0] may be used with promoters to lower the usehil decomposition temperatures of the peroxides, although usually with some sacrifice to radical generation efficiency. The most widely used promoter is dimethylaniline (DMA). The BPO—DMA combination is used for hardening (curing) of unsaturated polyester resin compositions, eg, body putty in auto repair kits. Here, the aromatic amine promoter attacks the BPO to initially form W-benzoyloxydimethylanilinium benzoate (ion pair) which subsequentiy decomposes at room temperature to form a benzoate ion, a dimethylaniline radical cation, and a benzoyloxy radical that, in turn, initiates the curing reaction (33) ... [Pg.223]

The maximum recommended film thickness is 25 p.m. At greater thicknesses, volatiles from the curing reaction, mainly water and some formaldehyde and phenol, can cause defects. These coatings have excellent electrical insulation properties, ie, up to 20 V/p.m, because of low moisture absorption and low conductance. The coatings are hard with low flexibiUty, depending on curing conditions and film thickness. [Pg.303]

Miscellaneous Curing Reactions. Other functional groups can react with the thiol terminal groups of the polysulfides to cross-link the polymer chains and build molecular weight. For example, aldehydes can form thioacetals and water. Organic and inorganic acids or esters can form thioesters. Active dienes such as diacrylates can add to the thiols (3). Examples of these have been mentioned in the Hterature, but none have achieved... [Pg.456]

An important aspect of this is the splitting of the polymer chain with thiol (eq. 5) or mercaptide ion (thiol + base catalyst). In fact, sodium sulfide or organic monothiols, eg, mercaptoethanol or decyhnercaptan, are utilized to lower the molecular weight of polysulftdes or to limit the extent of curing reactions. [Pg.457]

Certain polymeric stmctures can also be blended with other coreactive polymers or multifunctional reactive oligomers that affect curing reactions when exposed to ir radiation. These coreactive polymers and cross-linking oligomers undergo condensation or addition reactions, which cause the formation of network stmctures (Table 9) (4,5,47). [Pg.430]

Powder coatings are formulated from the reaction product of trimethylolpropane and IPDI, blocked with caprolactam, and polyester polyols. The saturated polyester polyols are based on aromatic acid diols, neopentyl glycol, and trimellitic anhydride for further branching. To avoid the release of caprolactam in the curing reaction, systems based on IPDI dimer diols are used. [Pg.350]

Bismaleimides are best defined as low molecular weight, at least diftinctional monomers or prepolymers, or mixtures thereof, that carry maleimide terminations (Eig. 3). Such maleimide end groups can undergo homopolymerization and a wide range of copolymerizations to form a highly cross-linked network. These cure reactions can be effected by the appHcation of heat and, if required, ia the presence of a suitable catalyst. The first patent for cross-linked resias obtained through the homopolymerization or copolymerization of BMI was granted to Rhc ne Poulenc, Erance, ia 1968 (13). Shordy after, a series of patents was issued on poly(amino bismaleimides) (14), which are synthesized from bismaleimide and aromatic diamines. [Pg.23]

Other ingredients may be added to prevent sticking to moulds (lubricants), to promote the curing reaction (accelerators), to improve the flow properties (plasticisers) and to colour the product (pigments). [Pg.645]

The Si—X linkages react with water to form a Si—O—Si linkage with the liberation of HX. Typical catalysts include diaryl alkyl tin acylates. Such a curing reaction may be brought about by atmospheric humidity and such rubbers are... [Pg.835]

The detailed structure of ebonite is not known but it is believed that the same structures occur in the rigid material as have been suggested for vulcanised rubber. There will, however, be far more S-containing structures per unit volume and the ratios of the various structures may differ. The curing reaction is highly exothermic. [Pg.860]

Scheme 12. Schematic structure of vinyl-eb-PDMS chains (dashed line) crosslinked with polymeric TMS-eb-PHMS through the hydrosilylation cure reaction. For illustration purpose the PDMS chains in this scheme are shorter and less abundant relative to PHMS than in real system. Scheme 12. Schematic structure of vinyl-eb-PDMS chains (dashed line) crosslinked with polymeric TMS-eb-PHMS through the hydrosilylation cure reaction. For illustration purpose the PDMS chains in this scheme are shorter and less abundant relative to PHMS than in real system.
The selection of the cure system in these applications is directed by constraints such as location of the adhesive in terms of confined space, speed and depth of cure, etc. The volumes of silicones typically applied are relatively small. In general, the uncured adhesive needs to be dispensed in a well-defined and limited area, and needs to stay in place without flowing during cure. No by-products of the cure reaction are acceptable as they may contaminate other sensitive areas of the devices. These constraints often direct the choice to the platinum-catalyzed hydrosilylation cure system that is relatively expensive. [Pg.703]

Catalysts serve a dual purpose in one-component moisture-curing urethanes. The first purpose is to accelerate the prepolymer synthesis. The second purpose is to catalyze the curing reaction of the adhesive with moisture. The most common catalysts used to promote both prepolymer formation (NCO/OH) and later the adhesive curing reaction (NCO/H2O) are dibutyltin dilaurate and DMDEE ((tertiary amine. A stabilizer such as 2,5-pentanedione is sometimes added when tin is used, but this specific stabilizer has fallen from favor in recent years, due to toxicity concerns. DMDEE is commonly used in many one-component moisture-curing urethanes. DMDEE is one of the few tertiary amines with a low alkalinity and a low vapor pressure. The latter... [Pg.782]

An example of the synthesis and curing reactions of a specific ketimine is shown below ... [Pg.800]

The cure reaction of structural acrylic adhesives can be started by any of a great number of redox reactions. One commonly used redox couple is the reaction of benzoyl peroxide (BPO) with tertiary aromatic amines. Pure BPO is hazardous when dry [39]. It is susceptible to explosion from shock, friction or heat, and has an autoignition temperature of 79°C. Water is a very effective stabilizer for BPO, and so the initiator is often available as a paste or a moist solid [40], The... [Pg.832]

Kinetics and mechanism of curing reactions using ylides as a new curing agent. [Pg.380]

The organofunctional group (R) in the coupling agent causes the reaction with the polymer. This could be a copolymerization and/or the formation of an interpenetrating network. This curing reaction of a silane-treated substrate enhances the wetting by the resin (Table 9). [Pg.798]

Curing reactions of epoxy resins with formaldehyde resins 0... [Pg.678]


See other pages where Curing reaction is mentioned: [Pg.1718]    [Pg.379]    [Pg.176]    [Pg.49]    [Pg.162]    [Pg.20]    [Pg.301]    [Pg.144]    [Pg.404]    [Pg.443]    [Pg.324]    [Pg.328]    [Pg.425]    [Pg.431]    [Pg.432]    [Pg.433]    [Pg.96]    [Pg.58]    [Pg.85]    [Pg.322]    [Pg.7]    [Pg.41]    [Pg.493]    [Pg.544]    [Pg.364]    [Pg.367]    [Pg.367]    [Pg.368]    [Pg.244]    [Pg.691]    [Pg.610]   
See also in sourсe #XX -- [ Pg.257 , Pg.259 ]

See also in sourсe #XX -- [ Pg.5 , Pg.11 ]




SEARCH



Additives cure reaction products

Adhesives chemistry, cure reactions

Amine-epoxy curing reactions

Amine-epoxy curing reactions formulation

Amine-epoxy curing reactions mechanism

Anhydride-cured epoxy reaction

Anhydride-cured epoxy reaction mechanism, catalysts

Cure Reaction Mechanism

Cure chemistry reaction

Cure exotherm reaction conversion

Cure reaction expression

Cure reaction factors, evaluation

Cure reaction kinetics

Cure reactions

Cure reactions diffusion control

Curing reaction calorimetry

Curing reaction epoxy, differential scanning

Curing reaction setting adhesives

Curing reaction studies

Curing reaction, initiation

Curing reaction/agent

Cyanate ester resins curing reaction

DSC Studies of the Cure Reactions

Differential scanning calorimetry epoxy curing reaction

Effect of plasticizers on polymerization and curing reactions

Electron beam curing radical reactions

Epoxy curing reaction, differential

Epoxy reaction mechanism phenolic cured, catalysts

Epoxy resin cure reaction

Epoxy resin curing reactions

Epoxy resins curing reactions summary

Exothermic curing reactions

Expression of the Cure Reaction

Free radical reactions curing mechanisms

Heating or Cooling Stages without Cure Reaction

Ionic curing, reaction mechanism

Isothermal curing reactions

Kinetics curing reaction

Kinetics of the Cure Reaction

Kinetics of the Overall Cure Reaction

Model curing reaction

Novolacs curing reactions

Parameter epoxy curing reactions

Peroxide curing process cross-linking reactions

Phenolic cured epoxy reaction

Poly cure reactions

Polymerization reaction cure exotherm

Polymerization reaction free radical curing mechanisms

Polyurethane curing reaction

Rates and Chemistry of Cure Reactions

Reaction cured glass

Reaction injection molding mold curing

Reaction kinetics apparent curing activation

Reaction parameters, epoxy curing reactions

Reactions during formation of PAM from 3BS-cured pastes

Resoles curing reactions

Scaling Relationships for Curing Reactions of Epoxy Polymers

TGDDM-DDS Cure Reactions

Thermoset cure chemical reactions

© 2024 chempedia.info