Compared with metals and semiconductors, the electrical properties of conductive polymers have the following characteristics: by controlling the doping degree, the room temperature conductivity of conductive polymers can change in the range of insulator-semiconductor-metal state. At present, the highest room temperature conductivity can reach 105S/cm, which is comparable to copper, and its weight is only112 of copper. Conductive polymers can be stretched and oriented. The conductivity along the stretching direction increases with the increase of stretching degree, while the conductivity along the vertical stretching direction is basically unchanged, showing strong conductivity anisotropy; Although the room temperature conductivity of conductive polymers can reach metallic state, its conductivity-temperature dependence does not show metallic characteristics, but obeys semiconductor characteristics; The carriers of conductive polymers are not only different from the free electrons of metals, but also different from the electrons or holes of semiconductors, which are described by the concepts of soliton, polaron and bipolaron. Applications mainly include electromagnetic wave shielding, electronic components (diodes, transistors, field effect transistors, etc. ), microwave absorbing materials, stealth materials, etc. (1) reverse osmosis membrane
Reverse osmosis membranes mainly include asymmetric membranes, composite membranes and hollow fiber membranes. The micropores on the surface active layer of asymmetric membrane are very small (about 2nm), and the macroporous support layer is sponge-like structure. The composite membrane consists of ultra-thin film and porous support layer. Ultrathin film is very thin, only 0.4mm, which is beneficial to reduce flow resistance and improve water permeability; The diameter of hollow fiber reverse osmosis membrane is extremely small, and the ratio of wall thickness to diameter is relatively large, so it can withstand high external pressure without support.
The materials of reverse osmosis membrane mainly include cellulose acetate, polyamide, polybenzimidazole and sulfonated polyphenylene ether. Cellulose acetate membrane has high water permeability, high desalination rate, low price and wide application. Aromatic polyamide membrane has excellent mechanical strength, stable chemical properties and high pressure resistance, and can be used in the range of pH 4- 10. The polybenzimidazole reverse osmosis membrane has high temperature resistance and good water absorption, and is suitable for operation at higher temperature. The reverse osmosis device has been successfully applied to seawater desalination and reached the drinking quality. The principle of seawater desalination is to separate seawater from fresh water by using a semi-permeable membrane that only allows solvents to penetrate and does not allow solutes to penetrate. When RO (reverse osmosis) is used for seawater desalination, because of its high salt content, it is generally necessary to use two-stage RO desalination in addition to the special membrane with high desalination rate. However, the cost of seawater desalination is high, and it is mainly used in the Middle East oil-producing countries that are particularly short of water. For example, according to the statistics of 20 12, the largest desalination plant in the world is located in Saudi Arabia.
(2) Ultrafiltration membrane
Ultrafiltration membrane is a porous membrane with a pore size of 1-20nm, which can almost completely intercept and separate particles such as viruses and polymer colloids contained in the solution. The separation performance of ultrafiltration membrane is defined by the molecular weight of the substance it intercepts. Ultrafiltration membrane separation technology is mainly used to separate macromolecules and colloidal particles in solution. It is a membrane process in which solute molecules are separated from small molecular solvents, and macromolecular solutes larger than membrane pores in the solution are intercepted by membrane screening.
(3) microfiltration membrane
Microfiltration membrane refers to a porous separation membrane with a pore size range of 0.0 1- 10μm, which can completely separate and remove tiny particles such as bacteria, colloid and aerosol in fluid. The use of microfiltration membrane varies with the concentration of particles in the fluid. When the concentration is low, disposable filter membrane is often used; When the concentration is high, it is necessary to choose a membrane that can be reused.
(4) gas separation membrane
The polymer membrane commonly used in gas separation is asymmetric or composite membrane, and its surface layer is dense polymer layer, that is, non-porous polymer membrane. This membrane material needs to have excellent permeability.
(5) catalytic membrane
In the membrane reactor, the catalyst is fixed on the surface or in the membrane by using the carrier function of the membrane to prepare the catalytic membrane. Some membrane materials have catalytic activity. When reactions involve hydrogenation, dehydrogenation, oxidation and systems related to the formation of oxygen, metal membranes and solid electrolyte membranes are usually used, which have the ability to selectively permeate hydrogen and oxygen. The main characteristics of the effectiveness of membrane catalytic technology are productivity and selectivity. The productivity is determined by the separation rate of reactants and products passing through the membrane and on the surface of the membrane. Adsorptive polymer materials mainly refer to those polymer materials with selective affinity for certain ions or molecules. From the appearance, there are mainly micropores, macropores, popcorn and macroporous resin. The adsorption capacity of adsorption resin is not only affected by internal factors such as structure and morphology, but also closely related to the use environment: temperature factors and media around the resin.
(1) water-absorbent polymer
The research of super absorbent resin began in 1960s. The earliest super absorbent resin developed in the world is the hydrolysis product of starch-acrylonitrile graft copolymerization, that is, acrylonitrile is grafted onto starch and then hydrolyzed.
Usually, the water absorption capacity of cellulose super absorbent resin is lower than that of starch resin, but its fast water absorption is one of its characteristics, which can not be replaced by starch resin in some special cases.
Structural characteristics of super absorbent resin: strong hydrophilic groups, such as hydroxyl and carboxyl, can form hydrogen bonds with water molecules; The resin has a cross-linked structure; The polymer has high ion concentration; Polymers have higher molecular weight (2) Oil-absorbing polymers
High oil absorption resin is a new functional polymer material. For different kinds of oil, it can absorb several times its own weight, nearly a hundred times more. It has large oil absorption capacity, fast oil absorption speed and strong oil retention capacity, and is widely used in industrial waste liquid treatment and environmental protection. In addition, it can also be used as rubber modifier, oil mist filter material, base material of spices and pesticides, paper additive and so on.
Structural characteristics of high oil absorption resin: three-dimensional cross-linked network structure is formed between polymers, and there is a certain micropore structure in the material. Due to the solvation of lipophilic segments and oil molecules, the high oil absorption resin swells. Based on the existence of crosslinking, the resin is insoluble in oil. It can be seen that the degree of crosslinking and lipophilic groups are closely related to the properties of high oil absorption resin.
(3) Other polymeric adsorbents
Polyacrylamide product introduction: Polyacrylamide (PAM) is a water-soluble polymer, which is insoluble in most organic solvents and has good flocculation property, which can reduce the friction resistance between liquids. According to ionic characteristics, PAM can be divided into four types: nonionic, anionic, cationic and amphoteric. Product Description of Anionic Polyacrylamide (APAM): The appearance of anionic polyacrylamide (APAM) is white powder, and its molecular weight is between 6 million and 25 million. Good water solubility, soluble in water in any proportion, insoluble in organic solvents. The effective PH value ranges from 7 to 14. It has the characteristics of polymer electrolyte in neutral alkaline medium, is sensitive to salt electrolyte, and can cross-link with high-valent metal ions to form insoluble gel.
Industrial wastewater treatment: For suspended particles, high-concentration wastewater, positively charged particles with neutral or alkaline PH value of water, wastewater from iron and steel plants, electroplating plants, metallurgical wastewater and coal washing wastewater, the effect is the best. Drinking water treatment: the water source of many domestic waterworks comes from rivers, with high sediment and mineral content, which is relatively turbid. Although it was filtered by precipitation, it still failed to meet the requirements. Flocculants need to be added, and the dosage is 1/50 of inorganic flocculants, but the effect is several times that of inorganic flocculants. For rivers with serious organic pollution, inorganic flocculant and cationic polyacrylamide can be used together to achieve better results. Starch particles are flocculated and precipitated by anionic polyacrylamide, and then pressed into cakes by filter press, which can be used as feed. Alcohol in an alcohol factory can also be dehydrated by anionic polyacrylamide and recovered by pressure filtration. Used for settling river mud. Dry strength agent for papermaking.
Used as paper additives and auxiliaries. Before papermaking, adding a small amount of PAM-LB-3 anionic polyacrylamide into the pulp storage tank at the pump mouth can improve the retention rate of fillers and fine fibers in the online water by 20-30%. 20-30 kilograms of pulp can be saved per ton.
For example, a large amount of wastewater is generated in the process of coal washing, which directly pollutes the environment. It is also valuable to recover mucus from water after precipitation, but it is time-consuming and laborious to rely on natural precipitation, and the water is not clear.
In addition, the application of anionic polyacrylamide in perfume industry is becoming more and more common. Anionic polyacrylamide products are characterized by good solubility, high viscosity, strong toughness, flammability, no (little) smoke when burning, tasteless and non-toxic; The product performance is stable, which avoids the uneven bonding quality between other plant rubber powder and ordinary starch due to different production places and time, and the need to repeatedly debug the formula in the production of perfume industry to avoid the unstable product quality; Fragrant products have smooth appearance, good molding and are not easy to break; Especially its cold water gelatinization characteristics, without boiling, the materials can be directly mixed evenly, and the materials added with water can be produced by stirring, and the materials added with water will not harden and cannot be used for a long time, which effectively saves energy and is convenient for production and operation.
Application effect: The fragrant blank (fragrant product) made of this product has flat appearance, no fracture and mildew, strong bending resistance, good color, no fading after drying, sufficient ignition time, good flammability, and no "breaking" or extinguishing of the iron toothed disc, which is beneficial to improving the volatilization rate of effective components of mosquito-repellent incense and reducing the loss of finished products during drying. At the same time, it can greatly reduce the labor intensity of workers and improve work efficiency. In addition, the product has no pollution to the environment and meets the requirements of environmental protection.
Economic benefit: the use of this product can reduce raw material cost by 5- 12% and save energy consumption by 20-30%. Product features of cationic polyacrylamide (CPAM): The appearance of cationic polyacrylamide (CPAM) is white powder, and its ionic degree is between 20% and 55%. Good water solubility, soluble in water in any proportion, insoluble in organic solvents. It has the characteristics of polymer electrolyte and is suitable for treating wastewater with negative charge and rich organic matter. It is suitable for treating wastewater with high organic colloid content in printing and dyeing, papermaking, food, construction, metallurgy, mineral processing, coal powder, oil field, aquatic product processing, fermentation and other industries, especially for dewatering industrial sludge such as municipal sewage, municipal sludge and paper sludge.
Application: Used for sludge dewatering. According to the nature of sludge, the corresponding model of this product can be selected, which can effectively dehydrate the sludge before it enters the filter press. During dehydration, the floc is large, does not stick to the filter cloth, does not disperse during pressure filtration, has thick mud cake, has high dehydration efficiency, and the water content of the mud cake is below 80%. Used to treat domestic sewage and organic wastewater, this product is positively charged in mixed or alkaline media, and it is very effective for flocculation and precipitation of sewage with negatively charged suspended particles in sewage. For example, food alcohol production, paper making, urban sewage treatment plants, beer, monosodium glutamate plants, sugar making, wastewater with high organic content, feed wastewater, textile printing and dyeing wastewater, etc. The effect of using cationic polyacrylamide is several times or dozens of times higher than that of using anionic, nonionic polyacrylamide or inorganic salts, because such wastewater is generally negatively charged. The flocculant is used to treat tap water with river water as its source, which has the advantages of less dosage, good effect and low cost, especially when it is used in combination with inorganic flocculant, and will become an efficient flocculant for tap water plants in the Yangtze River and Yellow River basins. Reinforcing agents and other additives for papermaking. Improve the retention rate of fillers, pigments, etc. And the strength of the paper. It is used as an additive for oilfield economy, such as clay anti-swelling agent and thickener for oilfield acidification. The size is used as textile size, with stable performance, less sizing, low fabric breakage rate and smooth cloth surface. Packaging and storage
This product is non-toxic, pay attention to moisture and rain, and avoid sun exposure. Storage period: 2 years, 25 kg paper bag (lined with plastic kraft paper bag).
Production technology of acrylamide monomer
Acrylamide monomer is produced by taking acrylonitrile as raw material and hydration under the action of catalyst. The refined acrylamide monomer is obtained after flash refining, which is the raw material for producing polyacrylamide.
Acrylonitrile+(water catalyst/water) → synthesis → crude acrylamide → flash evaporation → refining → refined acrylamide.
According to the development history of catalysts, monomer technology has experienced three generations:
The first generation is sulfuric acid catalytic hydration technology, which has low acrylonitrile conversion rate, low acrylamide product yield and few by-products, which brings great burden to oil refining. In addition, due to the strong corrosiveness of sulfuric acid catalyst, the equipment cost is high, which increases the production cost.
The second generation of binary or ternary skeleton copper catalytic production technology, the disadvantage of this technology is that copper ions which affect polymerization are introduced into the final product, thus increasing the cost of post-treatment refining; The third generation microbial nitrile hydratase catalytic production technology has the characteristics of mild reaction conditions, high selectivity, high yield and high activity. The acrylonitrile conversion rate can reach 100%, and the reaction is complete without by-products and magazines.
The product acrylamide does not contain copper ions, so there is no need for ion exchange to remove copper ions produced in the production process, which simplifies the technological process. In addition, gas chromatography analysis shows that acrylamide products contain almost no free acrylonitrile and have high purity, which is especially suitable for preparing ultra-high relative molecular weight polyacrylamide and non-toxic polyacrylamide needed by food industry.