Release time: 2020-02-08 18:59:09
When the polyurethane thermal insulation pipe expands due to heat, it will definitely change and move, and it is also possible to produce a displacement phenomenon, and the thermal insulation structure layer and the outer casing are generally an integral structure. The external fixing means that the working steel pipe and the external protection pipe must be fixed together. It is necessary to set two large reinforced concrete piers at each end of the pipeline and the compensator. of. The external fixation requires reinforced concrete support pier, so the construction occupies a large area, requires a lot of investment, and the construction period is sometimes long, so it is better to pay attention before. According to the different outer protective tube you want to use, it can be divided into plastic sleeve steel structure, FRP sleeve steel structure and steel sleeve steel structure. It has been proved through practice that the plastic sleeve steel structure is no longer suitable for the development trend of directly buried steam pipelines.
A variety of cell adhesion factors such as collagen, fibronectin, and albumin are added to the polyurethane surface to make the material surface more biological and closer to the physiological conditions of cell growth, thereby improving the adhesion and growth of endothelial cells on the surface of the polyurethane material. In recent years, the immobilization of RGD tripeptide sequences on the surface of polyurethane materials has become an important way to improve the adhesion and growth of endothelial cells, which has been confirmed in related studies of various biological materials.
Polytetrahydrofuran glycol (PTHF) or polyoxytetramethylene glycol (PIG, PTMEG, PTMG, PTMO) is produced by ring-opening polymerization of tetrahydrofuran in the presence of a cationic catalyst.
Due to its special structure, medical polyurethane has the advantages of large structural design freedom, excellent physical and mechanical properties, and good biocompatibility. Therefore, it is widely used in medical materials. However, the biocompatibility of polyurethane can not fully meet the clinical medical requirements, and solving such problems is the focus of future research.
So far, although the application proportion of polyurethane coatings in China's entire coatings field is only about 4%, the engineering application of water-based polyurethane coatings has maintained a growth rate of nearly 10% in recent years. In general, no additional dispersant or emulsifier is needed for water-based polyurethane coatings. The molecular size and molecular structure can be adjusted as appropriate.
Water-based PU has lower application cost, pollution-free, easy to handle, and better adhesion effect than organic solvent-based PU, and has a good development prospect in the adhesive and coating industry. PU ionic polymers have good adhesion to both natural and synthetic rubber surfaces and can be used in the manufacture of footwear. Water-based PU is mainly used for furniture paint, electrophoretic paint, electrodeposition coating, architectural coating, paper treatment coating, glass fiber coating, etc. In addition, water-based coating has some special applications, such as the intermediate coating film of safety glass, to make It is an unbreakable safety glass, which is widely used in automobiles, airplanes, ships or aerospace instruments. Water-based dispersions are mainly used as metal coatings, such as cationic electrodeposition coatings are widely used in automotive primers to improve the anti-corrosion performance of car bodies.
Construction steps of polyurethane exterior wall insulation: 1. Base treatment. First, do the foundation treatment to make the roof (wall surface) basically flat and free of floating ash and oil pollution. 2. Spray rigid polyurethane foam. Rigid polyurethane foam is sprayed on the base surface by special equipment to instantly form a dense layer of foam material. According to the thickness of the insulation layer, a construction work surface can be sprayed several times. The construction work surface of the day must be sprayed continuously on that day. After spraying for 24 hours, a local planer can be used for local trimming. Function characteristics: excellent water resistance, excellent thermal insulation. 3. Apply the surface glue in batches. Apply surface glue on the surface of the polyurethane foam in batches. During the construction, the surface must be smooth and maintain a certain humidity. Function and characteristics: Ensure the strength of the outer decoration layer. 4. Add grid cloth. While the glue is still dry, cover the surface of the glass fiber mesh cloth with a batch knife and press the mesh cloth into the glue. Function and characteristics: After the glue is solidified, the force of the mesh cloths on each other can play an anti-cracking effect and effectively prevent water leakage.