Each plastic prior to processing, if the polymer once selected, and then to consider is the choice of what kind of aid, as well as its usage. Plastic additives whether the election was correct, a direct impact on processing, product performance and service life. The selection of additives, generally need to consider four main issues.

1. The compatibility of the additives with the polymer

Compatibility is additive with the polymer means can uniformly mix well together, no precipitated phase separation properties. Aid necessary long-term stability in the presence of the article, so as to play its due role, we should try to use good compatibility with the polymer additives. However, only a specific range of compatibility between the various additives and given polymer, beyond this range, the aid will be precipitated.

2. aid for processing conditions adaptability

For example, the polymer is processed at high temperatures For a long time, whether in the selection of aid must consider the possibility to adapt to this processing conditions. Such as polypropylene processing temperature is relatively high, it should be used not decomposed at this temperature, non-volatile or less volatile stabilizer; selection does not decompose at high temperatures do not fade colorant. The same polymer, due to the different processing methods used, additives required are not the same.

3. To help maximize synergies Jing

A plastic often used a variety of additives, these auxiliaries in a system, often to interact with each other, if fit properly, have a synergistic effect when used, is called "synergy." UV absorbers such as 2-hydroxy-4-octyloxy benzophenone when mixed with antioxidant decyl phenyl phosphite ester, has significant synergies. Conversely, if the optional improperly, resulting in reduced efficiency effect when used, called. When the antagonism. "Amine antioxidants such as carbon black and polyethylene and used, the resulting antagonism to each other to weaken the original stabilizing effect.

4. The article uses constraints on aid

Plastic additives choices often restricted use products, such as plastic products always in contact with people, especially those of food and packaging materials, such as blood transfusion, more closely related to human health, it is necessary to use non-toxic survey Jing: for the regular in contact with water or oil products. Must be selected easily extracted oil or water additives.