Hot curing

The resulting bisepoxy compounds are cross-linked cold with polyamines, if necessary with added accelerators. A hot cure can either be accomphshed with amines or anhydrides (eg, phthaUc acid anhydride). If suitable initiators are present, EP systems can also be cross-linked by radiation. 

Hardener Parrs used per 100 pts resin Pot life (500 g batch) Typical cure schedule Skin irritant Max HOT cured resin rcj Features Applications... 

The hot curing process normally uses polyether diol precursors with molecular weights of 3,000 to 5,000 g/mole. We can control the stiffness of the foam by adjusting the average number of isocyanate groups on the chain extender molecules. The higher the functionality of the isocyanate molecules, the more crosslinked, and hence stiffer, will be the product. 

Hotcuring Jo carry out the crosslinking at higher temperatures (hot curing), 0.1 g of dibenzoyl peroxide is dissolved in 10 g of the polyester solution prepared in a) and heated to 80 °C.The polymerization sets in after a few minutes (gelation) and is essentially complete after 15 min. 

After curing lhe sample obtained by cold or hot curing is not yet fully polymerized and to obtain optimum rigidity, an after-curing treatment is necessary. If it is performed at room temperature it takes 2-3 weeks, at 30-40 °C a few days are sufficient and at 70-80 °C some hours are adequate. 

Industrially the curing (vulcanization) of diene homopolymers and copolymers with elementary sulfur is carried out in a heated press at 100-140 °C (hot curing) this cannot be done in a normal laboratory on account of the expensive apparatus required. However, the principle of curing can be illustrated by crosslinking a butadiene-styrene copolymer (SBR 1500) with disulfur dichloride (SjCy at room temperature (cold curing) ... 

Most epoxy syntactic foams are vacuum molded at 70-120 °C, and vibrating stirrers are used to degas the mixture40 . Recent formulations can be processed without external heating (cured for 30 days at 20 °C) and yet yield syntactic foams with properties comparable to those of hot-cured foamsthe shrinkage is less than 1 % for both. 

Soviet scientists have developed a cold-cure EDS material87). Note that the epoxy binders used are in fact generally hot-cure oligomers (from the point of view of the functional groups used and the completion of cure). It turned out that the forced elastic limit and the compression elastic modulus of the matrix are the same for both hot and cold cures. The good mechanical properties of a cold cured syntactic foam seem to be due to strong intermolecular bonds. 

The mechanical characteristics of the epoxy and polyester cold-cured syntactic molded foams do not differ much from the hot-cured materials (Table 12)1),... 

Hot cure Casting process for the production of high-performance elastomers in which the elastomer is mixed, dispensed, and cured at elevated... 

MDI MEK MOCA (MBOCA) Therefore, a two-part mold would have two master patterns. An abbreviation for diphenylmethane-4,4 -diisocyanate. Methyl Ethyl Ketone Trade name for methylene bischloroaniline, which is a widely used curing agent for hot cure polyurethane elastomers. There are... 

Heat resistant IPN systems were obtained by simultaneous radical polymerization of divinylbenzene with benzoyl peroxide as an initiator and Zn acetate as cyclotri-merization catalyst [122], Hot-curing composition contains BPA/DC, BMI, epoxide resin, Zn acetate and divinylbenzene [123]. Crosslinked compositions consisting of BPA/DC and BPA bis(vinylbenzyl) ether show Tg values above 240 °C [124]. 

Adhesives. Two single part, rubber toughened hot cured structural epoxy adhesives were used throughout the current research. Both adhesives were provided by Dow Automotive,... 

TECHNIQUE HOT-CURE COLD-CURE GRAFT PHD POLYOL SPECIALTY... 

Cold glue or hot curing adhesive as a reference to the processing temperature. 

To protect neighboring areas of the adherend surface from being wetted by the adhesive, these areas can be covered by adhesive tapes. However, in the case of hot curing up to approximately 110 °C, temperature-resistant adhesive tapes are required. 

The fixing of adherends is also possible in a simple way with adhesive tapes that, in case of hot curing, have to be heat resistant. 

Check time and temperature control in the case of hot-curing adhesives... 

Heat or hot-curing reactive adhesives, due to the limited thermal resistance of the plastic materials. 

This rule refers to circular bonded joints, for example, tubular bonded joints or shaft-hub joints, with heat or hot-curing reactive adhesives, if different metal materials are to be bonded, Figure 11.5. 

In connection with this special interest present phenolic Mannich bases (PMBs) due to two types of reactive groups, such as phenolic hydroxyl and amine, connected with intermolecular hydrogen bonds. Depending on their amino groups, PMBs can be used as hardeners for cold and hot curing. 

So the best stress-strain properties of hot-cured epoxy nanostructured coatings are achieved with use of 2-dimethylaminomethylphenols. 

As modifiers, low molecular weight rubbers with carboxyl terminal reactive groups are more effective. As hardeners, we recommend phenolic Mannich bases, such as dimethylaminomethyl phenols for hot curing and ethylene di aminomethyl phenols for cold curing. 

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