What issues should be paid attention to when designing modified PP formula?

1. The choice of resin

(1) Selection of resin varieties

The resin should be selected with the closest performance to the modification purpose, in order to save the number of additives added.

(2) Selection of resin grades

Different grades of the same resin have great differences in performance, and the grade with the performance closest to the modified purpose should be selected. For example, heat-resistant modified PP can be selected within the range of PP grades with a heat distortion temperature of 100~140℃. We should choose PP grades that are heat-resistant to 120℃.

(3) Choice of resin fluidity

The viscosity of various plasticized materials in the formula should be close to ensure processing fluidity.

The same type of plastic also has different fluidity, mainly due to the different molecular weight and molecular chain distribution, so the same raw material is divided into different brands. Different processing methods require different fluidity, so the grades are divided into injection molding grade, extrusion grade, blow molding grade, calendering grade, and so on.

(4) Selectivity of resin to additives

The acidity and alkalinity of the auxiliary agent should be consistent with the acidity and alkalinity of the resin, otherwise, there will be a reaction between the two.

2. The choice of additives

(1) Choose additives according to the purpose to be achieved

Choose suitable additives according to the purpose to be achieved, and the additives added should be able to give full play to their expected effects and reach the specified indicators. The prescribed index is generally the national standard, international standard of the product, or the performance requirement put forward by the customer.

The specific selection range of additives is as follows:

Toughening-choose elastomers, thermoplastic elastomers, and rigid toughening materials;

Reinforcement-select glass fiber, carbon fiber, whisker, and organic fiber;

Flame retardant-bromine (common bromine and environmentally friendly bromine), phosphorus, nitrogen, nitrogen/phosphorus composite intumescent flame retardant, antimony trioxide, hydrated metal hydroxide;

Antistatic-all kinds of antistatic agents;

Conductivity-carbon (carbon black, graphite, carbon fiber, carbon nanotube), metal fiber and metal powder, metal oxide;

Magnetism-ferrite magnetic powder and rare earth magnetic powder includes three types of samarium cobalt (SmCo5 or Sm2Co17), neodymium iron boron (NdFeB), samarium iron nitrogen (SmFeN), and alnico powder;

Thermal conductivity-metal fibers and metal powders, metal oxides, nitrides, and carbides; carbon materials such as carbon black, carbon fibers, graphite, and carbon nanotubes; semiconductor materials such as silicon and boron;

Heat resistance-glass fiber, inorganic fillers, heat-resistant agents such as substituted maleimides and β crystal nucleating agents;

Transparent-nucleating agent, Millad 3988, a sorbitol series of α crystal nucleating agent, works best for PP;

Wear resistance-graphite, molybdenum disulfide, copper powder, etc.;

Insulation-calcined kaolin;

Barrier-mica, montmorillonite, quartz, etc.

(2) Additives are selective to resin

The nucleating agent has a good effect on copolymerized polypropylene; the heat-resistant modification of glass fiber has a good effect on crystalline plastics, but has a poor effect on amorphous plastics; carbon black is filled with conductive plastics and has a good effect on crystalline resins.

3. The form of additives

The additives of the same composition have different forms, which have a great influence on the modification effect.

(1) The shape of the additive

The reinforcing effect of fibrous additives is good. The degree of fiberization of the additives can be expressed by the aspect ratio. The larger the L/D, the better the reinforcement effect. This is why we add glass fiber through the vent hole. The molten state is better than the powder state to maintain the aspect ratio and reduce the probability of fiber breakage. The spherical additives have a good toughening effect and high brightness.

(2) Particle size of additives

The smaller the particle size, the more beneficial the tensile strength and impact strength of the filled PP modified plastic material.

Polyrocks-5002CF30A modified polypropylene is a polypropylene-filled and reinforced material with calcium carbonate as the filler. 5002CF30A modified polypropylene has the characteristics of excellent comprehensive performance, good processing fluidity, and not easy to warp and deform.