Curing bonding processes

Paraffin wax additives are effective in overcoming surface inhibition by forming a monomolecular wax layer at the curing surface. Although effective in excluding oxygen, this waxy layer must be removed for subsequent lamination or bonding processes (see Waxes). 

When a diamine curative is used, urea bonds are formed. These bonds also play an important part in the hydrogen bonding process. The unbonded urea has an absorption band at approximately 1690 cm1 and the bonded urea at 1682 cm-1. The time sequence spectra (Figure 2.37) show the formation of the bonded urea bands over the first hours of curing. 

Confirm the effectiveness of a bonding process, such as surface cleaning or curing. 

Crabtree, D. J. Ion graphing as an in-process cure monitoring procedure for composite and adhesively bonded structures, p. 636, Proc. 22nd SAMPE Symp., 1977... 

Figure 1 shows the cure cycle for the co-cured lap joints and table 1 shows the material properties of the carbon fiber-epoxy composite (USN 150) produced by SK Chemicals (Suwon, Korea). After the curing and bonding processes, the co-cured joint should be finished using various abrasive sandpapers to obtain a better joint strength by eliminating sharp edges. A... 

A fuse manufacturer replaced a 30 min epoxy used in a heat cure process to assemble stainless steel inserts into phenolic holders. By utilizing an aerobic adhesive bonding process, the assembly was complete in 30 s at room temperature. The resulting increase in productivity more than offset the higher adhesive cost. A cyanoacrylate bonding process was even faster, but did not resist aging in a moist atmospheric environment or pass a drop test for impact resistance. 

The assembly of composite structural elements into a complete integrated structure will often involve bonding processes. These may be co-bonds or secondary bonds. In co-bonds, a cured composite is assembled with a film adhesive to an uncured laminate layup. The assembly is cured in an oven or autoclave. Secondary bonds are bonds between two cured laminates. The adhesive may be film or paste, and the cure may be in an oven or at room temperature. Composite repair following a damage event usually involves a co-bond by scarfing out the damage area, laying... 

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