Curing techniques

In lacquers, (1) is the only stage in the drying process. Fast air movement is even more important than heat for drying there. In 100% polymerisable coatings, only in stage (2) 

Due to technical advances and increasing pressure to reduce VOC, use of UV curable water-based coatings are experiencing rapid growth in the market place especially for wood parts finishing. 

Recent developments in the dispersion technology such as the technique of surfactant selection, the optimisation of various parameters in the dispersion process and the enhancement to dispersion stability have made it possible to disperse a variety of curable oligomers such as acrylated EP, acrylated PU, acrylated polyester resins in water. Films based on the dispersions can have faster UV cure speed, better surface hardness and better flexibility compared with films based on undispersed resin systems [102]. UV curing offers many advantages including 100% solids with no solvents present in formulation and polymerisation is instantaneous leading to a large MW polymer [103]. 

In consideration of the intrinsic characteristics of the laser emission, these powerful light sources present many advantages which make them very attractive for curing applications. After absorbing a laser photon, the photoinitiator will split into radicals which will act on the monomer double bond, initiating in a fraction of millisecond the polymerisation that will develop in three-dimensions [105]. 

Determining when the coating film is completely cured is very important. The standard methods are generally well accepted, but the data obtained are not always reproducible. A new method called evaporation rate analysis (ERA) is the most objective and reproducible [107]. 

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CeUulose phosphate esters are also produced by treatment with sodium hexametaphosphate [14550-21-1] by the pad-dry-cure technique. These treated fabrics have high retention of breakiag and tearing strength (61). The reaction products contain more than 1.6% phosphoms and are iasoluble ia cupriethylenediamine [15243-01 -3] iadicating that some ceUulose cross-linking occurs. However, siace durable-press (DP) levels and wrinkle recovery values are low, it seems reasonable that only limited cross-linking takes place. 

Phosphonomethylated Ethers. A phosphoms-containing ether of ceUulose can be prepared by the reaction of cotton ceUulose with chioromethylphosphonic acid [2565-58-4] ia the presence of sodium hydroxide [1310-73-2] by the pad-dry-cure technique (62). Phosphoms contents of between 0.2 and 4.0% are obtained. This finish is durable but has high ion-exchange properties and is flame resistant only as the ammonium salt. DurabUity on medium weight fabrics is obtained with chi oromethylph osph onic diamide. This finish has never penetrated the flame retardant market (63). 

Dialkylphosphonopropionamides. CeUulosic derivatives that closely resemble those based on the dialkylphosphonopropionamides have been prepared (71). The fabric was treated with AJ-hydrox raethylhaloacetamides (chloro, bromo, or iodo) in DME solution by a pad-dry-cure technique with a 2inc nitrate [10196-18-6] catalyst. It was then allowed to react in solution with trimethyl phosphite [121 -45-9] at about 140—150°C the reaction rates decreased in the order iodo > bromo > chloro. With phosphoms contents above 1.5%, good flame resistance, durable to laundering, was obtained without noticeable loss in fabric strength. 

A typical method of preparation of 5- and 7-ply plywood panels is by pressing at room temperature and the simultaneous use of a one-step exothermic heat gluing/ monomer curing technique. Prior to monomer impregnation, all veneer samples were conditioned at room temperature. The assembly was compressed to 1.03 MPa (150 psi) between steel plates in a hydraulic press, and the steel plates fastened with a pair of bolts and nuts at both ends. 

Hose which has been vulcanised by covering it with an extruded lead sheath which acts as a mould. The lead is stripped off after cure. Now superseded by modem continuous curing techniques. 

Luniewski, R. S., and Ely, J. H., in Proceedings of Regional Technical Conference "Irradiation and Other Curing Techniques in the Wire Industry," Newton, MA, March 20-21 (1975). 

Figure 7 shows the representative bright field HRTEM images of nanocomposites of NR and unmodified montmorillonite (NR/NA) prepared by different processing and curing techniques. It is apparent that the methodology followed to prepare the nanocomposites by latex blending facilitates the formation of exfoliated clay structure, even with unmodified nanoclays. It has been reported in the literature that hydration of montmorillonite clay leads to extensive delamination and breakdown of silicate layers [94, 95]. It has also been shown that NA disperses fully into the individual layers in its dilute aqueous dispersion (clay concentration <10%)... 

The properties of a syntactic material can be varied quite significantly by changing the filler type, the binder-filler ratio, and the manufacturing and curing techniques. Syntactic plastics are heavier than conventional foams, with apparent densities of 200-800 kg/m3. 

Lommel (1967) says of shamanism as a possible cure technique ... 

The data at this time is only qualitative but efforts are being made to develop the torsional pen-dulum-UV-curIng techniques and to quantify relationships between relative rigidity, damping, gel-point, vitrification, and irradiation intensity or exposure time for clear as well as pigmented photocurable coatings. ... 

Dual Cure Photopolymerization The dual cure technique is a two-step process involving two different types of chemistry [ 1 i]. It usually consists in combining a UV irradiation and a thermal drying process and usually appears as a two-pack material, typically based on a polyisocyanate and an acrylate (10.87). The acrylate is... 

Primo et al. (55) studied the effects of formaldehyde and iodate on the properties of flours related to breadmaking (Table IX). Their data indicated that chemical treatments might be used in lieu of the curing techniques. Since formaldehyde is known to cause cross-links (9, 56), the results might indicate some effects caused by cross-linking. No attempts to characterize cross-links in the flour were reported. 

A good deal of flexible urethane foam is now being made by the cold-cure technique. This involves more reactive polyols and isocyanates in special foaming formulations which would cure in a reasonable time to their maximum physical properties without the need for additional heat over and above that supplied by the exothermic reaction of the foaming process. 

Small spots of the adhesive (typically 5-10 mm in diameter) are placed on the substrates using application and curing techniques comparable to those expected in service or specified by the manufacturer. 

Doakhan et al. [28] have studied the feasibility of using sericin/ Ti02 nanocomposite as antimicrobial finishing agent to impart antimicrobial functionality to cotton fabric, using the pad-dry-cure technique in the presence and absence of polycarboxylic acid as a cross-linker, e.g., BTCA, CA. The obtained results showed that... 

Sodium alginate (SA]/3-(trimethoxysilyl) propyl-octadecyl-dimethylammonium chloride (TSA) complex nanoparticles were used for antimicrobial finishing of cotton fabrics by pad-diy-cure technique... 

J.W.V. van Dijken, A 6-year clinical evaluation Class I poly-acid modified resin com-posite/resin composite laminate and resin composite restorations cured with a two-step curing technique. Dent Mater. 19 (2003) 423-428. 

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