Plastic modified formula classification

(1) Adding small molecules of inorganic or organic matter

A modification method in which a small molecule inorganic or organic substance is added to a polymer (resin) to obtain a desired property by physical or chemical action. This method is the earliest modification method, which has obvious modification effect, simple process and low cost, so it is widely used.

This modification method is divided into cost reduction (addition of various inexpensive inorganic and organic fillers), improvement of strength (addition of various reinforcing fibers), improvement of toughness (addition of elastomers and ultrafine fillers, etc.) and improvement according to the purpose of modification. Flame retardant (addition of metal oxides, metal hydroxides, inorganic phosphorus, organic halides, organic phosphides, silicones, nitrides, etc.), improved life (addition of various antioxidants, light stabilizers, etc.), improvement Processability (adding plasticizer, heat stabilizer, lubricant and processing aid, etc.), increasing wear resistance (adding graphite, MoS2, SiO2, etc.), improving crystal structure (adding nucleating agent, specifically organic carboxylic acid) , sorbitol, etc.), improve antistatic and electrical conductivity (add antistatic agent and conductive agent), improve degradability (starch filling, degradation additives, etc.), improve radiation resistance and so on.

Commonly used additives in this method are: inorganic additives (fillers, reinforcing agents, flame retardants, colorants and nucleating agents, etc.), organic additives (plasticizers, organotin stabilizers, antioxidants and organic flame retardants). , degradation additives, etc.).

(2) Adding high molecular substances

This method also becomes a blend modification, the main method of which is to incorporate one or more other resins (including plastics and rubber) into one resin to achieve the original resin properties. Since the blended modified composite system is a high molecular substance, its compatibility is better than that of adding a small molecule, and the modification does not have much influence on other properties of the original resin. Our common polymer alloys are the products modified by this method. Blending and modification is the most effective way to develop new polymer materials, and it is also the main way to achieve high performance and refinement of existing plastic varieties.

2. Morphological and structural modification

This method is mainly modified for the resin form and structure of the plastic itself. The usual method is to change the crystal form, crosslink, copolymerization, grafting, etc. of the plastic.

(1) Morphological control modification

The morphology control of plastics controls the different aggregation patterns of plastic products to achieve our desired performance. This method is controlled by the adjustment of the processing conditions under the action of non-external force, and is generally called self-modification, among which self-reinforcement is most commonly used. Plastic shape control can improve many properties of plastics, such as mechanics, thermal, optical and other aspects, and some aspects of the modification effect is very obvious. For example, the crystallization quality is controlled by a nucleation technique, and the biaxial stretching technique is used to obtain a high orientation.

(2) cross-linking modification

Crosslinking should be familiar, generally linear structure cross-linking into a network structure or a three-dimensional structure. Initiating cross-linking requires external conditions, usually different forms of energy (such as light, heat, radiation, etc.). The macromolecular chain generates reactive radicals or functional groups due to external action, thereby forming new chemical bonds between the macromolecular chains, so that the linear structural polymers form polymers of different degrees of network structure. For example, cross-linking modification of polypropylene can improve its mechanical properties.

(3) Copolymerization and graft modification

This method mainly adds other molecular segments or functional groups to the original molecular chain. Copolymerization refers to the polymerization of two or more monomers, which can expand the polymer properties and is an important way to improve the properties and uses of the polymer. For example, the copolymerization of polystyrene and acrylonitrile improves the weakness of polystyrene brittleness; the copolymerization of polyvinyl chloride and vinyl acetate improves the plasticity of polyvinyl chloride. Grafting has chain transfer grafting, chemical grafting, and radiation grafting. Its modification has many applications in rigid bodies and elastomers. For example, styrene-butadiene graft copolymer improves the impact properties of PS.

3, composite modification

The composite modification of plastic is a method of forming a multilayer film, a sheet or the like by combining two or more layers of a film, a sheet or the like by a method such as an adhesive or hot melt. The composite modification of plastic is actually the extreme of layered blending in the plastic blending modification method, and can also be regarded as a special plastic blending modification.

4, surface modification

Plastic surface modification refers to a type of modification method that changes the surface properties of plastic products by physical or chemical methods. There are two differences between plastic surface modification and other modification: one is that the modification is limited to the surface of the product, and its internal performance does not change; the second is that its modification is applied to the plastic product after one molding process, belonging to two Secondary processing modification.

The purpose of plastic surface modification can be divided into two main categories: one is direct application modification, and the other is indirect application modification.

(1) Direct application of plastic surface modification Direct application modification refers to some modification that can be directly applied, specifically surface gloss, surface hardness, surface abrasion resistance and friction, surface anti-aging, surface flame retardant, Surface conduction and surface barrier. The modification of plastic surface in this respect has been rapidly developed and applied in recent years. For example, in the aspect of plastic barrier modification, surface barrier modification plays an important role.

(2) Indirect application of plastic surface modification Indirect application modification refers to some modification of the basic application for direct application, such as improving the surface tension of plastics for improving the adhesion, printability and stratification of plastics. Modification. For example, in the case of plastic plating, the surface hardness of the untreated plastics can only meet the requirements of abs; especially for polyolefin plastics, the coating fastness is very low, and surface modification must be carried out to improve the bonding with the coating. Degree can only be electroplated.