Six points that should be paid attention to when using plastic additives

1. Compatibility of plastic additives and polymers

In general, plastic additives should have good compatibility with polymers. If the compatibility is not good, the plastic additives are easy to precipitate. The precipitation of solid plastic additives is commonly known as "blooming"; the precipitation of liquid plastic additives is called "seepage" or "sweating". After the plastic additive is precipitated, it loses the effect of the plastic additive and affects the appearance of the plastic product. However, it should also be noted that for some plastic additives, it is not required to have good compatibility with polymers. For example, the compatibility of the lubricant should not be too large, otherwise it will act as a plasticizer and soften the polymer.

The compatibility of plastic additives with polymers mainly depends on their structural similarity. For example, more polar plasticizers are more compatible in polar PVC than less polar ones. As another example, the introduction of longer-chain alkyl groups into antioxidants and light stabilizers can improve their compatibility with polyolefins. As for inorganic fillers and inorganic pigments, they are not soluble in polymers, but are dispersed in polymers heterogeneously. For this type of plastic additives, they are required to have good dispersibility, and the smaller the fineness, the better.

2. Stability of plastic additives

Plastic additives must exist in plastic products stably for a long time. Therefore, attention should be paid to the interaction between plastic additives and polymers in terms of stability. The decomposition products of some polymers (such as polyvinyl chloride) are acidic and alkaline, which can decompose some plastic additives; there are also some plastic additives that can accelerate the degradation of polymers.

3. Durability of plastic additives

The loss of plastic additives is mainly through three ways: volatilization, extraction and migration. The volatility depends on the structure of plastic additives. For example, since the molecular weight of butyl phthalate is smaller than that of dioctyl phthalate, the former is much more volatile than the latter. The extractability of plastic additives is directly related to their solubility in different media, and appropriate plastic additives should be selected according to the environment in which the product is used. Mobility refers to the transfer of plastic additives from the product to adjacent items, and its possibility is related to the solubility of plastic additives in different polymers.

4. Adaptability of plastic additives to processing conditions

The requirements of processing conditions for plastic additives are mainly heat resistance, that is, plastic additives are required not to decompose, volatilize and sublime at the processing temperature. At the same time, attention should also be paid to the possible corrosive effect of plastic additives on processing equipment and molds. Different polymers have different processing conditions; the same polymer may require different plastic additives due to different processing methods. In short, the selected plastic additives should have applicability to the processing conditions.

5. The relationship between product use and selection of plastic additives

An important basis for selecting plastic additives is the end use of the product. Products with different uses have certain requirements on the appearance, odor, durability, pollution, electrical properties, thermal properties, weather resistance, and toxicity of the plastic additives used.

The toxicity of plastic additives has long attracted widespread attention, especially the health and safety of plastic products such as food and drug packaging materials, medical equipment, water pipes, and toys have attracted more and more attention. Various countries have strictly regulated the types and dosages of the plastic additives used in the above-mentioned plastic products.

6. Synergistic and antagonistic effects of plastic additives

Multiple plastic additives in the same polymer, if properly coordinated, will often synergize with each other and play a "synergistic effect". One of the main purposes of research on modified plastic formulations is to discover the synergy between plastic additives. Of course, simplifying components, reducing costs, etc. are also the purpose of formula research. Improper selection of formula may cause "resistance" between plastic additives, so it should be avoided as much as possible. The possible chemical changes and discoloration between different plastic additives should also be avoided.

Nanjing Haisi Extrusion supply twin screw extruder for plastic compounding and modification.

Any interest please feel free to contact us!