Epoxy adhesive growth rate

Despite epoxy adhesives finding use in many fragmented markets, actual consumption in volume is surprisingly concentrated in a few specific end-use market segments. For example, automotive assembly applications account for nearly 50 percent of the total volume of epoxy adhesives consumed in the United States. The highest-value market areas include structural automotive, aircraft, and many specialty product assembly applications. These market areas are also expected to enjoy the highest growth rates. 

Although the overall annual growth rate for epoxy adhesive is in the 3 to 5 percent range, certain regional markets, such as China, are expected to have an annual growth rate... 

FIGURE 1.3 Epoxy adhesive regional growth rate.12 (Source DPNA International Inc.)... 

Just as their counterparts rejuvenated the aircraft industry decades ago, modem epoxy structural adhesives are providing automobile designers and manufacturers with innovative possibilities that could not have been considered only a short time ago. As a result, structural automotive adhesives will have an average annual growth rate of greater than 7 percent over the next 5 years.15 This growth rate is additive to any growth that will occur in the automotive industry itself. 

In 1995, U.S. consumption of radiation cured products was 77 million lb, valued at 450 million.1 Growth is forecast to average about 7 percent per year—a rate about twice that of conventional thermal cured products. Although radiation curable adhesives comprise a relatively small segment of the overall adhesive market (13 percent) and epoxy adhesives represent an even smaller component, epoxy systems are a fast-growing part of the market. 

Figure 8.42 shows one outcome of such studies. The addition of surface treated glass beads requires substantially higher stress to support the same growth rate of cracks compared with neat epoxy. Good adhesion and stress distribution are responsible for improvement. 

Fig, 3. Logarithmic crack growth rate per cycle, da/dN, versus logarithmic Gmax for aluminium-alloy substrates (grit-blasted and degreased (GBD) pretreatment) bonded using an epoxy-film adhesive. Circles are for tests conducted in a dry environment of 23°C and 55% relative humidity and dots for tests conducted in a wet environment of distilled water at 28 C. Different styles of the symbols represent replicate tests [10],... 

Figure 8.2 Crack growth rate, da/dN as a function of AGi for an epoxy adhesive bonding aluminium alloy substrates for different test frequencies [12]. O, 3 Hz A, 0.25 Hz 0,0.01 Hz.

Of particular interest is whether there is a lower limit to the applied stress below which no environmental attack is observed and this has been investigated in some detail using a fracture mechanics approach [36,45,136,137]. The TDCB geometry (see Table 7.1), consisting of aluminium alloy beams bonded with an epoxy adhesive, has been widely employed and the commonly used experimental technique has been to place this specimen under an applied load in the environment of interest and monitor the rate and locus of crack growth. The typical observation is that the cohesive in adhesive starter crack does not... 

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