Research and application of polyurethane foam
Abstract: With the continuous advancement of science and technology, polyurethane foam has received more and more attention. Because of its excellent performance, it is widely used in various industries. This paper mainly discusses the development and application of polyurethane foam, and introduces how researchers can optimize and improve its performance in various aspects through modification of polyurethane foam, so as to broaden its application range.
Key words: polyurethane, foam, application, modification
1. Overview of Styrofoam
Foamed plastics, also known as porous plastics, are prepared from traditional thermoplastic and thermosetting resins through various foaming techniques. A large number of gas micropores are filled in traditional solid plastics. Its structure is like a sponge and belongs to the polymer category. Material. Because foam plastics have excellent properties, such as low density, low mass, good noise absorption effect, and excellent thermal insulation performance, etc., they have received more and more attention in recent years. The preparation and molding process of foamed plastics is simple, with many varieties and excellent performance, and has become an indispensable product in the modern plastics industry.
2. Overview of Polyurethane Foam
Polyurethane (PU), the full name of polyurethane, is a polymer produced by the reaction of polyisocyanates and polyols. It was invented by German scientist Bayer in the 1940s. Polyurethane materials have different molecular structures, such as linear structures and body structures, so they have different properties, and their structures and properties can be adjusted by adjusting the number of functional groups in the raw materials. Polyurethane products can be divided into foam and non-foam. Polyurethane foam is the most important variety of polyurethane products and an important branch of foam, known as the "fifth largest plastic". Polyurethane foam is prepared by the reaction of black material and white material, wherein the black material is polyisocyanate, and the white material contains polyol, surfactant, catalyst, foaming agent and so on. According to different formulations, changing the amount of one of the raw materials and adjusting the number of functional groups of raw materials can prepare polyurethane foams with different structures and properties. Due to the unique characteristics of polyurethane, there are many kinds of foams prepared from polyurethane materials . Varieties, with different properties, can meet the needs of different fields.
3. Applications of Polyurethane Foam
Polyurethane foam ranks fifth in the global functional plastics consumption, and is one of the most widely used polymer materials. The thermal conductivity of polyurethane foam is very low, and the thermal insulation effect is better. Compared with other thermal insulation materials, to achieve the same thermal insulation effect, polyurethane foam requires the smallest thickness, so it can be used as an excellent thermal insulation material. According to different formulations, materials with different structures and properties can be prepared, and polyurethane foam can be divided into: flexible polyurethane foam, semi-rigid polyurethane foam and rigid polyurethane foam.
The structure of soft polyurethane foam is open-cell, with a large specific surface area, good elasticity, air permeability, thermal insulation, and relatively low density. It is mainly used in seat cushions, packaging and sound insulation materials.
The hardness and comprehensive properties of semi-rigid polyurethane foam are between soft polyurethane foam and rigid polyurethane foam. Insulated fish boxes and other aspects are widely used.
Rigid polyurethane foam mostly has a closed-cell structure, and its rigidity and load-bearing capacity are better than ordinary foam plastics. At the same time, it also has the characteristics of heat insulation, waterproof and moisture-proof. It has been widely used in the insulation layer of oil and gas pipelines.
4. Modification and Application of Polyurethane Foam
With the continuous advancement of science and technology, researchers have carried out a lot of research work on the modification of polyurethane foam to improve and optimize the performance of polyurethane foam. At the same time, some properties that polyurethane foam itself does not have can be added to expand its application range.
Due to the excellent characteristics of flexible polyurethane foam, such as open-cell structure, large specific surface area, corrosion resistance, and strong adsorption capacity, and high strength, the internal void structure is relatively rich. It can be used as a carrier of sewage treatment after being treated by a positive method. Dong Panpan and other researchers used nano-attapulgite and sponge iron composite hydrophilic polyurethane foam as a carrier to conduct a high-efficiency contact oxidation treatment test on rural domestic sewage. The experimental results showed that various pollutants in sewage were relatively High removal rate, the water quality after treatment reaches the first grade A standard of GB18918-2002. It can be explained that the modified polyurethane foam has a special spatial structure, which enhances the hydrophilicity and adsorption capacity of the polyurethane foam, and plays a key role in the sewage treatment process.
Researchers such as Liang Shuen have studied the antistatic properties of semi-rigid polyurethane foams, and modified semi-rigid polyurethane foams with conductive carbon black and quaternary ammonium salts as antistatic agents to prepare antistatic type The semi-rigid polyurethane foam has expanded the application range of semi-rigid polyurethane foam.
Compared with other foams, rigid polyurethane foam has excellent mechanical strength, but in some special application environments that require high-strength plastic materials, the mechanical strength of rigid polyurethane foam itself cannot meet the requirements. It needs to be modified to enhance its mechanical properties. When the researchers add lignin, glass fiber, jute fiber and other substances to the polymerization system, the compressive strength and impact resistance of the rigid polyurethane foam composite materials prepared will be improved. The mechanical properties have been significantly improved, indicating that the addition of different fillers or polymer materials in the polymerization process of rigid polyurethane foam can be modified to prepare composite materials with better performance, which can meet the needs of different fields. needs and expand the scope of application.
Compared with other foams, polyurethane foam has the characteristics of low density, light weight, good air permeability, high strength, good heat insulation, aging resistance and corrosion resistance. At the same time, by chemically modifying the polyurethane foam, various properties of the polyurethane foam can be further improved and optimized, and its application range is greatly expanded.