The development of polymer blending theory and modification technology
DATE：2021/3/8 8:54:48 / READ： / SOURCE：This station
The development of polymer blending theory and modification technology
Production line of air permeability film(1) The development of toughening theory
In the 1950s-1970s, microcracks theory, multiple silver grain theory, shear yield theory and silver grain shear yield theory appeared in polymer field. The basic idea of these theories is that the production of silver grain consumes a lot of energy, while the existence of rubber particles and shear bands hinders and stops the development of silver grain, which makes the toughness of materials increase. In 1980s, Yee AF proposed cavitation theory, souheng Wu proposed percolation theory and several models to quantitatively describe the toughening process of polyamide 66 (PA66) by elastomer, and proposed the concept of matrix thickness and particle spacing, which has become an important theory in the world. In addition, kuranchi of Japan also proposed the theory of non elastic toughening in 1984, and proposed a new concept of toughening plastic with organic rigid particles for the first time, and explained the reason for the improvement of the toughness of blends by using the concept of cold pull. In 1991, Chinese scholar lidongming and others discovered the toughening effect of inorganic particles on plastics, and put forward the toughening mechanism of inorganic particles. Production line of air permeability film www.handern.com
(2) The development of compatibility theory of polymer blending
The theory of compatibility of polymer blends has been developed on the basis of statistical thermodynamics. Hildebrand first proposed the concept of solubility parameters, and obtained solubility parameters of various polymers through the research of many scientists. These parameters are one of the criteria used to predict the compatibility of polymers. Later, some people put forward the theory of interface layer of blends based on the study of compatibility of blends. The theory holds that there are two kinds of polymer coexisting zones in the two polymer blends, which are the interface layers of two phases. The thickness of the interface layer reflects the compatibility to some extent. Production line of air permeability film www.handern.com
(3) Blending modification technology and its development
With the development of automobile, electronics, communication and other related industries, the application of modified plastics has been increasing, its application fields are expanding, and the market demand is increasing, which promotes the development of plastic modification technology, mainly in the following aspects.
1. The compatibility technology of polymer alloy has developed different compatibility alloy systems, and realized the practicability of the blend polymer alloy. The appearance of various copolymers and grafted polymers effectively solved the compatibility problem among different polymers in the blend system, and promoted the development of CO mixed gold.
The application of liquid crystal modification technology the appearance and special properties of liquid crystal polymer have added new content to the theory and practice of the polymer modification. Liquid crystal polymers have excellent physical, chemical and mechanical properties, such as high strength, high modulus of elasticity, high temperature of thermal deformation, minimal linear expansion coefficient and excellent flame retardant. The high strength modified PA can be produced by blending the high performance liquid crystal polymer with polyamide (PA). This technology is called "in situ composite" technology. It is easy to orient in the melt blending extrusion flow of liquid crystal polymer and PA, forming micro fiber dispersed in PA matrix, thus enhancing the effect. This technology has changed the traditional filling and strengthening method. Production line of air permeability film www.handern.com
The application of IPN technology, such as adding ethylene containing siloxane and catalyst in the resin such as PA, was used in the process of blending and extrusion of two polymers. Siloxane was crosslinked under the action of catalyst, and the co crystalline network was formed in PA, and the structure of entangled with siloxane was formed. This semi interpenetrating network structure reduces the water absorption of PA, and has excellent dimensional stability and sliding property.
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