Abstract
We investigated the occurrence of solvent cracking in unplasticized poly vinyl chloride pipes by preparing test materials based on the conventional method. As a results, it was confirmed that voids were occured on the inner surface of the pipe at holding time of 2 weeks under the conditions of room temperature (298 K), adhesive application amount 1.0 g and, U-band tightening torque 4 N/m. These voids were occurred linearly in the circumferential direction at the part in contact with the U-band and linearly in the axial direction at the part not in contact with the support materials. Tetrahidrofuran (THF) and 2-butane, and cyclohexanone were detected as a result of analysis of the void generation part on the inner surface of the pipe and the residual gas in the pipe. At these results, it is considered that the stress generated by the tightening of the U-band and the environmental agents THF, 2-butane, and cyclohexanone affected the void generation. Furthermore, the results of the stress analysis simulation of the U-band fixed portion showed that the tensile stress was in the part on contact with U-band and compressive stress was in the part not on contact with the support material. It was considered that the difference in these stresses and the regularity of the molecular arrangement during pipes manufacturing influence the direction of void generation. Such voids were considered to progress into cracks.
