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The temperature is the main factor determining the shortening rate of polyurethane screen elastomer
- 2018-05-21-

The choice of shortening rate is one of the main factors that determines whether the mold planning is successful. Especially for large-scale (parts above 1 o00 m / n) polyurethane elastomer products, due to the large shortening rate (usually at 1.5%), therefore, analyze the reasons for the shortening of polyurethane elastomers, and discuss the shortening rate and skill conditions The qualitative relationship is of great significance to the planning of casting polyurethane elastomer molds. This article has gone through a lot of technical experiments and compared the effects of skill conditions, structural elements and environmental conditions on the shortening rate.
The rules for shortening the rate of polyurethane elastomer in polyurethane screens are:
1) It increases with the increase of the mold temperature;
2) Zigzag changes with the extension of the ripening moment;
3) It decreases as the ambient temperature increases;
4) Unstableness occurs as the ambient humidity increases;
5) Different mold structures have different degrees of resistance to shortening, with the smallest length and the largest width;
6) Before a certain length, the shortening rate increases with the increase of the length of the activity path. After exceeding a certain length, the shortening rate decreases with the increase of the length of the activity.
It can be seen that the skill conditions have a certain effect on the shortening rate, and the effect of temperature is the most obvious; the structure of the product itself has a greater impact on the shortening rate. The polyurethane elastic system in the polyurethane screen is mainly the active path. The same is formed; the environmental factors are the later influencing factors, and their changes are the main factors that cause the reduction rate to be unstable.