Relationship Between Bond Strength and Crystallinity of High Polymers-Polyethylene, Polyethyleneterephthalate, and Nylon

The effect of crystallinity of polyethylene on the peel strength of aluminum plate-polyethylene-aluminum foil laminate was investigated. The 180° peel strength increased by rapid cooling with water, ice water, or liquid nitrogen after bonding with hot-melt polyethylene compared with slow cooling with air at room temperature. It was concluded that the increase of peel strength by rapid cooling was due to the decrease of modulus by the microcrystallization of polyethylene.

The tensile bond strength of steel-polyethyleneterephthalate (PET)-steel composite was investigated. The tensile bond strength increased about 10 times by rapid cooling of the composite bonded with hot-melt PET compared with slow cooling. On annealing the rapidly cooled composite over 100°C, the tensile bond strength decreased rapidly. It was concluded that the tensile bond strength decreases with the development of PET spherulite. Also in the case of Nylon 12, the tensile bond strength increased about 2 times by rapid cooling compared with slow cooling. In the case of Nylon 12, however, the tensile bond strengths of the both rapidly and slowly cooled specimens increased by annealing at high temperature.