免费看无码自慰一区二区,女同另类国产精品视频,天堂草原电视剧在线观看免费,日韩成人片免费永久在线观看网站,欧美国产精品一区久久,欧美一区二区性爱视频,一本无码aⅴ久久久国产,亚洲丁香五月婷婷

Engineering plastics is a general term of plastics with outstanding performance in all aspects. It can replace many traditional raw materials such as copper, steel, wood and so on as a new type of plastics.

Although China has mastered many production principles of engineering plastics, there is a large gap with foreign advanced technologies in terms of technical control, production equipment and development strength, so there will be some differences, even in quality, mainly as follows:

1. Quality gap: the quality of domestic engineering plastics is relatively poor, and there is no sense of quality of imported plastics;

2. Purity gap: purity has always been the weakness of domestic engineering plastics;

3. Production technology gap: due to the lack of technological breakthrough in China, the production technology is relatively backward and the uniformity of product quality is poor;

Of course, domestic engineering plastics are also catching up. I believe that in the near future, after facing up to our shortcomings, China' s engineering plastics will have considerable progress and great development.

Source: Jiangmen engineering plastics http://www.wcyxs8888.com/