Analysis on Improving the Heat Resistance of Polyurethane Adhesive

The increase of the aromatic ring density in the Pu segment increases the rigidity of the segment and increases the intermolecular force, so that the thermal decomposition temperature of the polymer increases. Oxazolidinone can be synthesized from isocyanate groups with epoxy groups, the thermal decomposition temperature of 300 ℃ or more. The isocyanurate ring is an isocyanate trimerization product, and there is no unstable hydrogen atom and amide structure on the heterocycle, which makes it have good thermal stability. The polyimide is formed by the condensation polymerization of an acid anhydride and a diamine, which decomposes in air at a temperature of 400 to 450C, a decomposition temperature in N is 2400 to 500C, and an imide ring is introduced into a polyurethane material In the hard segment, the C = O content increases, increasing the hydrogen bonding between -NH and C = O and weakening the interaction between the hard segment -NH and the soft segment -O-, so that the interaction between the hard segments is enhanced, The hydrogen bond between the soft segment and the hard segment is deteriorated, and the degree of phase separation is increased, thereby improving the heat resistance of the polyurethane. Lu Liang, who through the bulk polymerization, synthesis of a new type of naphthalene-containing biphenyl structure of the PU plastic, the normal temperature shear strength of not less than 20MPa, with a high T (170 ~ 200 ℃), in a nitrogen atmosphere 250 ℃ without weight loss, g10% heat loss temperature of 300 ℃, and has a strong acid, hydrolysis resistance. The adhesive is suitable for use in high temperature environments. Solemnity and others through the introduction of high heat resistance and hydrolysis resistance of the structural unit to improve the molecular softening point, a reasonable control of intermediate indicators and other means to improve the resistance of PU plastic heat and humidity stability. The adhesive can be resistant to high temperature cooking at 135 ℃. With its production of composite bags PET / Al / CPP built by 135 ℃ cooking 40min, the bag is still intact. Petrova studied the borane-containing PU glue and found that only 20% of the total mass loss was heated to 600 ° C, while the loss of PU glue without borane was 80%. Russian scientists use kaplan to modify the polyurethane, made for steel, titanium, brass and steel bonded BK-20 adhesive, the use of temperature 500 ~ 800 ℃, up to 800 ~ 1000 ℃. Add filler PU glue to add the appropriate filler can reduce the shrinkage stress and thermal stress, thereby enhancing its heat resistance. Due to the interaction of organic and inorganic parts in the polyurethane to form a unique interfacial effect and synergistic effect, this material has higher thermal and oxygen stability. The interaction between the organic phase and the inorganic phase can be divided into two categories: the first type is organic and inorganic phase through the weak bond such as hydrogen bond, van der Waals force and electrostatic interaction, the other is the organic phase and The inorganic phase is bonded by covalent bonding. Commonly used fillers (such as glass fiber, mica, etc.), powders (such as cellulose, silica, aluminum oxide, etc.), sheet materials (such as talc), bulk materials (such as barite) and nanoparticles Or functional nanoparticles. SebastianClauβ and so on in the one-component PU glue by adding 30% of the volume of chalk, glued joint heat stability was significantly improved. B.S.Kim, respectively, with hydrophobic and hydrophilic groups modified two kinds of nano-silica enhanced UV curing polyurethane emulsion, found that with the increase in nano-silica, the degradation rate of polyurethane, especially hardened degradation of the temperature increase. Lee et al. Studied waterborne polyurethane / clay nanocomposites, and found that the higher the heat resistance of the system was. In the preparation and use of polyurethane adhesives should be fully understand the relationship between its structure and performance, according to the purpose and requirements of the rational design. At present, the development of new heat-resistant polyurethane adhesive, research and development of new synthetic technology, new additives and the corresponding mechanism of research has become the focus of polyurethane research.

High - molecular materials intelligent manufacturing and energy - saving technology Summit Forum

The development of materials experienced structural materials → functional materials → intelligent materials → the process of fuzzy materials. Intelligent means that the role and function of the material can be consciously adjusted, modified and repaired as the external conditions change. As early as the 1970s, Tanaka Feng found a smart polymer phenomenon, that is, when the cooling polyacrylamide gel, the gel gradually become turbid from the transparent, the final was opaque, when heated, it turned transparent. In the 1980s, there were smart polymer materials used to make polymer sensors, separation membranes, and artificial organs. In the 1990s, intelligent polymer materials entered a high-speed development stage. After entering the 21st century, intelligent polymer materials are to the direction of intelligent polymer blurred material development. As the polymer material and has the function of sensing, processing and implementation of the body has a very similar chemical structure, more suitable for the manufacture of intelligent materials and the composition of the system, to the biological function of the approximation, so its research and development of particular concern.Intelligent polymer materials can be perceived changes in the external environment and stimulate the expansion and contraction of the corresponding self-regulation. It is widely used in sensors, actuators, displays, optical communications, drug carriers, size selective separators, biocatalysis, biotechnology, intelligent catalysts, smart fabrics, smart dimming materials, smart adhesives and artificial muscles field.Intelligent polymer materials research and development has made some progress, some have been commercialized. But on the whole, it is still facing some problems in the road to the practical, such as stability, processing technology still needs to be improved; polymer synthesis method of improvement, structural modification and molecular design to become high-performance intelligent polymer Material first to solve the problem. At the molecular level, the study of the behavior of light, electricity and magnetism, revealing the relationship between molecular structure and photoelectromagnetic properties will lead to the emergence of new generation of intelligent polymer materials, so that the optoelectronics industry, information science and technology, major changes and breakthroughs The At present, people in the intelligent polymer materials of various modification methods, molecular wires, molecular circuits and molecular devices will lead to the idea of electronic technology revolution.

Hot polyurethane foam insulation board low thermal conductivity

Polyurethane insulation board (chemical name: PU) 1, rigid polyurethane thermal conductivity is low, good thermal performance. When the rigid polyurethane density of 35 ~ 40kg / m3, the thermal conductivity of only 0.018 ~ 0.023w / (m.k), equivalent to about half of the extruded board (EPS), is the thermal insulation of all the best thermal conductivity of. 2, rigid polyurethane with moisture, water resistance. Rigid polyurethane closed porosity of 95% or more, are hydrophobic materials, will not increase the thermal conductivity due to moisture absorption, the wall will not seepage. 3, rigid polyurethane fire, flame retardant, high temperature. Polyurethane after the addition of flame retardant, is a flame retardant self-extinguishing material, its softening point can reach 250 degrees Celsius above, only in the higher temperature will be decomposed: In addition, the polyurethane in the combustion of its foam The surface of the formation of carbonized layer, this layer of carbonization layer to help isolate the following foam, can effectively prevent the spread of fire. Moreover, the polyurethane does not produce harmful gases at high temperatures. 4, because the polyurethane sheet has excellent insulation properties, to achieve the same insulation requirements, can reduce the thickness of the building outside the envelope, thereby increasing the indoor use area. 5, anti-deformation ability, easy to crack, finishes stable and safe. 6, polyurethane material porosity structure is stable, basically closed-cell structure, not only excellent insulation properties, and anti-freeze-thaw, sound absorption is also good. The average life expectancy of the polyurethane foam insulation structure can reach more than 30 years under the condition of normal use and maintenance. Can be done under normal conditions of use in the life of the structure, in the dry, wet or electrochemical corrosion, and because of insects, fungi or algae growth or damage due to rodents and other external factors, will not be destroyed. 7, comprehensive cost-effective. Although the price of rigid polyurethane foam is higher than that of other traditional insulation materials, the increased cost will be offset by a significant reduction in heating and cooling costs.Product range: Length range: (0.5 m -4 m); Width range: (0.5 m -1.2 m); Thickness range: (20 mm -200 mm) Size: (40-60 kg / m3) Cutting precision, thickness error of 0.5mm, thus ensuring the smoothness of the finished product surface. Foam fine, cell evenly. Light weight, can reduce the weight of manufactured goods, lower than the traditional 30-60%. Compressive strength, can withstand the great pressure in the process of manufacturing finished products. To facilitate the quality of the inspection, as in the cutting process to remove the surrounding skin, the quality of the plate at a glance, to ensure that the finished product insulation effect.

Polyurethane foam can be used as an analytical material

Polyurethane foam can be used in chromatographic separation of the column, a column of permeability, easy to install the simple, can match the solvent, the higher the capacity of the column and so on. According to the electron micrograph, the polyurethane foam is a polymer composed of 1-10um spherical particles, which determines the excellent mass transfer rate and high capacity of the polyurethane foam, whether it is used for rapid chromatographic separation or Preparation of chromatography, have the potential for superiority.Another application of polyurethane foams in analysis is the use of materials for pH meters, such as elastomeric joint springs on pH meters, package air valves for sealed cavities and components such as watertight gaskets and anti-splash baffles The