1. Demolding ability
The quality of demolding is an important performance of mixed rubber in molding processing. If the demolding is poor, it is easy to cause waste, reduce labor efficiency, pollute the mold, and increase costs. The reasons for mixing adhesive molds or suction molds include: firstly, the hydroxyl groups in the adhesive material react chemically with the hydroxyl groups on the metal surface of the mold at high temperatures; The second issue is that there are many low molecular weight compounds and reaction groups in the rubber material, and the internal crosslinking is not sufficient. In addition to adding internal release agents and other coordination agents, measures to improve demolding performance also need to pay attention to controlling the amount of hydroxyl silicone oil added, reducing the content of hydroxyl and oligomers in the raw rubber, and strengthening vacuum mixing, appropriately extending the mixing time.

2. Yellowing degeneration
When making transparent or semi transparent products, blended rubber sometimes experiences yellowing, especially after secondary vulcanization, where yellowing becomes more pronounced. The reasons for yellowing: Firstly, white carbon black may contain impurities and undergo oxidation at high temperatures, resulting in yellowing; The second is the oxidation of residual trimethylamine in raw rubber into chromogenic genes; Thirdly, the decomposition of peroxides may also produce yellow substances. In order to overcome yellowing, it is important to choose white carbon black that is not prone to yellowing, add anti yellowing agents such as hydrogen containing silicone oil to the blend formula, and finally choose anti yellowing vulcanizing agents to have an anti yellowing effect.

3. Storage stability
As a commodity, the storage stability of mixed rubber is very important. If it exceeds the deadline, structural phenomena will occur, leading to poor processing performance. The main reason for the formation of structure is due to the hydroxyl groups on the surface of white carbon black in the adhesive. Therefore, studying the performance, quality, and dosage of structural control agents is an important aspect of improving the storage life of mixed rubber; Strengthening the mixing process, extending the vacuum mixing time, and improving the return mixing effect are all the main measures to improve storage stability.

4. Bubble problem
Extrusion is an important processing technology for mixed rubber, but if not handled properly, bubbles are easily generated during the extrusion process. Main reasons: Firstly, precipitation method white carbon black is used as a reinforcing filler, which has a high water content (5% -8%) and is difficult to remove during production. Moreover, it is easy to absorb water after being made into a mixed rubber; The second is that the rubber material brings in humid air during the return refining process; The third issue is that the air brought in by the rubber material during the extrusion process is not discharged in a timely manner. To solve the problem of extruded rubber bubbles (especially in winter), various measures need to be taken, such as using some special structural control agents to better react with the hydroxyl groups in white carbon black; At the same time, strengthen the mixing process, try to extract moisture and low molecular weight substances from the rubber material, appropriately increase the plasticity value of the rubber material, so that it can better discharge bubbles during processing.

Regarding silicone rubber, please refer to the details:
https://www.htvsilicone.com/product-high-temperature-resistance-silicone-rubber(250-)-.html