国产 Av 仑乱内谢|奇米影视亚洲春色|一级A一级a爱片免费免免3,爱草免费视频,a毛片视频免费观看影院,欧美最猛性xxxxx短视频

First of all, if you have experimental equipment, you can do the heat deformation temperature or Vicat softening point temperature to test its heat resistance, Izod impact test its impact resistance, as well as flexural modulus and elongation, tensile strength, and fire rating, etc. .

If it is used daily without any testing tools, it can be roughly identified based on the appearance of Liansu pvc pipes.

1. Regular pipe diameter and uniform thickness.

2. The color should not be yellowish, which may decompose or age during the processing of the material.

3. If the amount is large, you can take a small part to bend or beat hard to see if it has toughness.