How to choose auxiliaries for plastic modification? 6 considerations

Plastic modification formula seems simple, but hidden, which requires us to be careful in the selection of additives, then how to obtain higher performance, low cost, easy to process formula? Today, we will introduce you to the selection of additives from the following six aspects.

First, choose additives according to the purpose

(1)Improve processing performance: lubricants, release agents, stabilizers, processing AIDS, thixotropic agents, plasticizers, PVC stabilizers.

(2)Improve mechanical properties: plasticizer, reinforcing filler, toughening agent, impact modifier.

(3)Improved optical properties: pigments, dyes, nucleating agents, fluorescent whitening agents.

(4)Improve aging performance: antioxidant, PVC stabilizer, UV absorbent, fungicide, anti-mold agent.

(5)Improve surface properties: antistatic agent, slippery agent, wear agent, anti-adhesion agent, anti-fogging agent.

(6)Cost reduction: thinner, filler.

(7)Improve other properties: blowing agent, accelerant, chemical crosslinking agent, coupling agent, etc.

Second, the additive is selective to the resin

(1)Red phosphorus flame retardants are effective on PA, PBT and PET. Nitrogen-based flame retardants are effective on oxygen-containing substances, such as PA, PBT, PET, etc.

(2)Glass fiber heat resistant modification has good effect on crystalline plastics, but poor effect on amorphous plastics.

(3)Carbon black filled conductive plastics, in the crystalline resin effect is good;

(4)Nucleating agent has good effect on copolymer polypropylene.

Third, the compatibility of additives and resins

The compatibility of the auxiliary agent and the resin is better, so as to ensure that the auxiliary agent and the resin are dispersed according to the expected structure, to ensure the completion of the design index, to ensure that the effect is sustained in the service life, and to resist extraction, migration and precipitation. In addition to a few additives such as surfactants, good compatibility with the resin is the key to play its efficacy and increase the amount of addition. Therefore, it is necessary to find ways to improve or improve its compatibility, such as using compatibilizers or coupling agents for surface activation treatment.

Fourth,Shape selection of auxiliaries

The fiber auxiliaries have good reinforcement effect. The degree of fibrosis of the auxiliary can be expressed by the length-diameter ratio, and the larger the length-diameter ratio, the better the enhancement effect, which is why we add glass fiber from the exhaust hole.

Molten state is better than powdered state to maintain length-diameter ratio and reduce the probability of fiber breakage.
Spherical auxiliaries have good toughening effect and high brightness. Barium sulfate is a typical spherical auxiliary agent, so the filling of high-gloss PP is barium sulfate, and the small amplitude rigid toughening can also be barium sulfate.

FifthStrength selection of auxiliaries

Effect of additive particle size on mechanical properties: The smaller the particle size, the more beneficial to the tensile strength and impact strength of the filling material.

Effect of additive particle size on flame retardant performance: The smaller the particle size of the flame retardant, the better the flame retardant effect. For example, the smaller the particle size of hydrated metal oxide and antimony trioxide, the less the amount of addition to achieve the same flame retardant effect.

Effect of additive particle size on color matching: The smaller the particle size of the colorant, the higher the coloring power, the stronger the hiding power and the more uniform the color. However, the particle size of the colorant is not the smaller the better, there is a limit value, and the limit value is different for different properties. The limit particle size of azo colorants is 0.1μm, and that of phthalocyanine colorants is 0.05μm. For the hiding power, the limiting particle size of the colorant is about 0.05μm.

Effect of additive particle size on conductivity: Taking carbon black as an example, the smaller the particle size, the easier it is to form a network conductive path, and the amount of carbon black added to achieve the same conductive effect is reduced. However, like the colorant, the particle size also has a limit value, too small particle size is easy to gather and difficult to disperse, but the effect is not good.

SixthThe amount of additives added

The appropriate amount of additives can not only improve the performance of the resin, but also control the cost. For different additives add amount requirements are different:

(1) Flame retardants, tougheners, magnetic powder, barrier agents, etc., although the more the better the performance Angle, but also to check the cost;

(2) conductive additives, generally form a circuit path;

(3) Antistatic agent, the surface can form a charge discharge layer;

(4) The coupling agent can form a surface coating.

YIHOO POLYMER is a global supplier of additives for the modification of plastics and coatings, including UV absorbers, antioxidants, light stabilizers and flame retardants, which have been widely used by customers in Europe, the United States and Asia Pacific. 

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Post time: Jan-12-2024