Bonding agents bond strengths

ABS plastic, a polymer consisting of polybutadiene spheroids is dispersed in a continuous phase of poly(styrene—acrylonitrile). The chromic acid attacks the polybutadiene at a much higher rate than the continuous phase. This gives an excellent microroughened surface with superior metal-to-plastic bond strength. A typical recommended formulation consists of 20 vol % sulfuric acid, 420 g/L chromic acid, and 0.1—1.0% of a fluorocarbon wetting agent. The plastic is treated with this formulation for 6—10 min at 60—65°C. 

Terpene phenolic resins can also be added to solvent-borne CR adhesives to increase open tack time and to provide a softer glue line than /-butyl phenolic resins. To provide adequate hot bond strength, these resins are used in combination with a polyisocyanate curing agent. 

The most common use of curing agents is with carboxylic latices. Isocyanates and melamines can be used but zinc oxide is the most common curing agent. Zinc oxide cross-links carboxylated latices and improves bond strength by ionomer formation [78]. Carboxylated polychloroprene reacts slowly with zinc oxide in dispersed form, causing a gradual increase in adhesive gel content. This can lead to restricted adhesive shelf life. Resin acid sites compete with the polymer acid sites for Zn(II). The more resin acid sites, the more stable the adhesive. 

Prati, C., Nucci, C. Montanari, G. (1989). Effects of acid and cleansing agents on shear bond strength and marginal microleakage of glass-ionomer cements. Dental Materials, 5, 260-5. 

Table 8.14 Effect of Coupling Agents on Tensile Bond Strength of an Acrylic Resin on Teeth...

Bonding strengths of experimental agents were evaluated on laminated copper foil after samples were subjected to plasma treatment or after being heated to 380°C. Testing results are provided in Table 2. 

This paper discusses some recent developments in the understanding of the various factors controlling the efficacy of coupling agents, and also emphasizes the importance of considering corrosion processes in addition to bond strengths. 

The following advantages come to mind. The increased interfacial bond strength often observed when an aminosilane coupling agent is used may be explained by the in situ formation of an interpenetrating network. This would... 

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