Polypropylene is the lightest general plastic, because of its comprehensive performance, low production costs, widely used in home appliances, packaging, chemicals and automotive and other fields, the output living in the first two plastics; polypropylene shortcomings of low temperature impact performance Poor, easy to aging, and antistatic, weatherability and poor dyeing, so the material industry and industry are very concerned about the modification of polypropylene.
Xiao Bian on the polypropylene several common modification method for a brief introduction, hoping to communicate with peers, mutual benefit.
First, polypropylene / inorganic nanocomposites
Rigidity and toughness are two important indicators of plastic performance. How to make plastic at the same time have good rigidity and toughness is the goal that people have been pursuing. Inorganic nano-example modification is one of the ways to solve this contradiction.
Compared with the large particle size filler modified polymer, inorganic nano-particles filled modified polymer has more excellent mechanical properties.In order to make inorganic nano-particles as evenly dispersed in the polymer matrix, the need for inorganic nanoparticles Surface modification, surface modification of inorganic nanoparticles can improve the bonding strength of the interface layer with the matrix resin, and give full play to the enhanced toughening effect of rigid inorganic particles on the polymer.
At the same time, it is found that the morphology of nano-calcium carbonate is different, and the mechanical properties of the composites are also different. The nano-calcium carbonate can improve the impact properties of composite materials, and fiber-like nano-calcium carbonate can significantly improve the tensile properties of materials, nano-calcium carbonate can make PP fine crystal refinement.
Second, polypropylene microporous foam material
Polypropylene material for microcellular foam modification, its strength will not be reduced, the reason is very interesting, because the material contains less than the original defects or micro-cracks are much smaller pore size, because the existence of this pore size, Passivation of the original cracks in the plastic tip, and will not reduce the strength of plastic.
Microporous foam material has high toughness, long fatigue life, high specific strength, high thermal stability and low dielectric constant, and there are other characteristics such as light weight, heat insulation, shock absorption, sound insulation and low price.Therefore, In the automotive, aerospace and other various means of transport and other fields of porous foam polypropylene has been strong development.
Third, the nucleating agent modified polypropylene material
PP is a kind of incomplete crystallization of the general plastic, its crystallization speed is slow, easy to form a larger spherical crystal, resulting in poor gloss and transparency of the product, the appearance of the lack of beauty products, limiting its transparent packaging Daily necessities and other fields of application.
The use of nucleating agents to modify polypropylene is a simple and effective method for the preparation of polypropylene materials with high transparency and excellent mechanical properties and is therefore widely used in the modification of polypropylene.
PP transparent nucleating agent is currently common talc, silica, mica, aryl phosphate, etc., in general, the amount of not more than 0.8% effect is better, the specific application should be based on specific analysis of the scene.
Fourth, long glass fiber reinforced polypropylene material
Long glass fiber reinforced polypropylene composite material is one of the fastest growing plastic varieties in the market for thermoplastics. Especially in automotive plastics, in order to be able to better play the role of fiber, the fiber length in plastic is greater than Lc, the critical length, Lc value and the type of plastic has a direct relationship.If the fiber length is less than Lc, its enhancement effect and the general powder filler is not very different.For example, glass fiber reinforced PP, the critical length of glass fiber 3.1mm, and in another chemically modified PP, Lc may fall below 0.9mm. For ordinary short-wave fiber reinforced plastic, the fiber length in the product is generally only 0.2 ~ 0.6mm, limiting the performance of finished products In the long glass fiber reinforced plastic parts, the residual length of glass fiber can reach more than 3mm, greatly improving the physical and mechanical properties of products.
Due to the long fiber length in long glass fiber reinforced thermoplastics, the impact strength is about four times higher than that of conventional fiber reinforcements. The specific strength (17.2%) is higher than that of aluminum (9.8%), In addition, the processing of this material is good mobility, product appearance bright, no collapse and other defects, the product shrinkage of the molding is also small.