Silver striation of PPR water pipes

Silver grain phenomenon refers to the phenomenon that the polymer under the action of tensile stress, in some weak places of the material stress concentration and local plastic deformation, and even in the material surface or internal perpendicular to the stress direction of the appearance of the length of 100μm, width of about 10μm, thickness of about 1μm micro groove or "crack" phenomenon.

When cutting the PPR water pipe, the blade cuts the water pipe in the longitudinal direction, and at the same time, a tensile stress is generated in the transverse direction. This force causes the silver grain phenomenon in the incision of the PPR material, which is also the plastic deformation. Due to the different refractive index of PPR material from that of normal PPR material, the silver grain will appear silver-white luster under light irradiation. One of the characteristics of the site of the silver streaking phenomenon is its reversibility. It can disappear spontaneously above the glass transition temperature of the material, which is called "self-healing". Therefore, for the pipe incision that produces silver grain, blow it with a heat gun for a while, and the silver grain will disappear naturally.