Adhesive dry’ strength

Waterborne contact adhesives contain an elastomer in latex form, usually an acryflc or neoprene-based latex, and a heat-reactive, cross-linkable phenohc resin in the form of an aqueous dispersion. The phenoHc resin improves metal adhesion, green strength, and peel strength at elevated temperature. A typical formulation contains three parts latex and one part phenohc dispersion (dry weight bases). Although metal oxides may be added, reaction of the oxide with the phenohc resin does not occur readily. 

Cationic oat starch was used to improve the dry strength of paper handsheets and found to be comparable to wheat starch in functionality.14 Oat starch might possibly be a replacement for rice starch in pharmaceutical applications.19 Oat flour has been used in adhesive preparations.19... 

FIG. 30 Lap shear strength at break between two identical AAc graft-polymerized PTFE films as a function of adhesion (drying) time and plasma pretreatment time. The dashed line indicates the lap shear force at which the PTFE substrate started to yield. (From Ref. 93.)... 

Figure V demonstrates the effect of adhesive dry coating weight on 180° peel strength and rolling ball tack with OH/NCO ratios of 1.7 and 1.3 for Hycar 2103 and Hycar 2106, respectively. Static shear tests run both at room temperature and 70°C show no creep for both systems throughout the thickness range tested.

An emulsion polymer-isocyanate adhesive, a crosslinked polyvinyl acetate adhesive, a resorcinol-formaldehyde adhesive, a phenol-resorcinol-formalde-hyde adhesive, and an acid-catalyzed phenolic-formaldehyde adhesive developed bonds of high shear strength and wood failure at all levels of acetylation in the dry condition. A neoprene contact bond adhesive and a moisture-curing polyurethane hot-melt adhesive performed as well on acetylated wood as untreated wood in tests of dry strength. Only a cold-setting resorcinol-formal-... 

Figure 2 also points out another important point. Despite the very high shear strength achieved with methylenedianiline in the dry state, this system is actually the least durable of the four compositions examined. Dry strength adhesion is not a good measure of water durability. 

The sulphate attack is more severe as the concrete is subjected to cyclic wetting and drying. Therefore the laboratory expansion measurements do not reflect completely the field conditions. Mehta [251], basing on the observations of various concrete structures, foimd that the decrease of adhesion and strength, as well as the... 

Properties Soften, pt. 120-160 C Uses Gloss/adhesion promoter and hardener in alkyd resins, nitrocellulose lacquers, varnishes, printing inks, emulsion floor polishes dry-strength additive in paper binder in varnishes, stoving lacquers, printing inks Manuf./Distiib. Chemcentral Chemical http //www.thechemco.com, Monomer-Polymer Dajac Labs... 

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