Bond Test Procedures

The different bond test methods yield results that do not always correlate closely in terms of bond strength or mode of failure [22]. Some of these contrasts in results reflect substantial differences in the manner in which the rubber to metal bond is stressed. This is likely to be more meaningful for some actual applications of bonded parts and less for others, depending on how the bond is stressed in such applications, e.g., shearing, tension or peeling. 

The test specimen geometry impacts the ability to discriminate between the bond strength of different formulation and adhesive systems. Of the methods used. Method A seems to be the least discriminating and the other tests should probably be used preferentially, depending on what kind of application is being evaluated. Method F appears to have the most consistent ability to discriminate differences in response [22]. 

Bonding rubber to metal is a complex and multifaceted combination of metallurgy, surface science, adhesion science, rubber chemistry, and process engineering, with a multitude of interactions. In all aspects of bonding, scrupulous cleanliness, adherence to process controls and meticulous attention to detail are essential if good adhesion is to be attained on a consistent production basis. 

Buchan, Rubber to Metal Bonding, Palmerton, New York, 1959. 

Jazenski and L. G. Manino, inventors Lord Corporation, assignee US Patent 4,119,587,1978. 

---

In comparing the various test procedures, there is always a good agreement found for hydrophobic retention and selectivity as well as for shape selectivity. However, the characterization of silanophilic interaction is still a matter of discussion. In part, the differences are due to the selection of the basic analyte. Therefore, the outcome of every test is different. It has been shown, that the peak asymmetry—used for detection of silanophilic interactions—does not correlate to the pA" value of the basic test solute [64]. A closer look at these data leads to the assumption, that the differences are related to the structure of the basic solute, irrespective of whether a primary, secondary, or a tertiary amine is used. The presence of NH bonds seems to be more important in stationary-phase differentiation than the basicity expressed by the pA value. For comparable test procedures for silanophilic interactions further studies seem to be required. 

Environmental Tests. It is desirable to know the rate at which an adhesive bond will lose strength due to environmental factors in service. Strength values determined by short-term tests do not give an adequate indication of an adhesive s performance during continuous environmental exposure. Laboratory-controlled aging tests seldom last longer than a few thousand hours. To predict the permanence of an adhesive over a 20-year product life requires accelerated test procedures and extrapolation of data. Such extrapolations are extremely risky because the causes of adhesive bond deterioration are complex (see Sec. 15.2.2). Unfortunately no universal method has yet been established to estimate bond life accurately from short-term aging data. 

Since no mechanical, or interfacial bonding, occurs between the resin and thermoplastic tubing, the cured specimen can be removed from the tubing and attached to the arms of the instrument. The characterization of the mechanical properties of the cured rod can be obtained from the usual testing procedure. The purpose of this paper is to show how this modification can be used to obtain curing data and mechanical information on thermoset resins. 

Comprehensive coverage of all aspects of adhesive technology for - microelectronic devices and packaging, Ifom theory to bonding to test procedures. 

---