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  • ●聚氨酯保温材料行业未来发展前景可 [05-12] ● The future development prospects of polyurethane thermal insulation material industry are promising
  • ●详解聚氨酯发泡机操作规程 [05-07] ● Detailed operation rules of polyurethane foaming machine
  • ●「聚氨酯产品」地铁防水工程复合防 [07-24] ● "Polyurethane Products"
  • ●温度控制是解决聚氨酯发泡机的空泡 [05-08] ● Temperature control is to solve the cavitation of polyurethane foaming machine
  • ●现代建筑工地为什么要用【聚氨酯发 [03-21] ● Why use modern polyurethane construction site
  • ●保温材料阻燃性能不合格成冷库安全 [05-05] Insufficient flame retardant performance of insulation materials to become safe in cold storage
  • ●如何在屋顶操作聚氨酯喷涂 [09-10] ● How to operate polyurethane spray on the roof
  • ●聚氨酯发泡机混合器中物料的流场分 [05-18] ● Flow field analysis of materials in mixer of polyurethane foaming machine
  • ●必看! [05-10] ● Must see! The relationship between waterproof coating thickness and waterproof life
  • ●怎么解决聚氨酯发泡机空泡现象 [05-08] ● How to solve the cavitation phenomenon of polyurethane foaming machine
  • ●异氰酸酯与聚脲弹性体性能的关系 [08-17] The relationship between isocyanate and polyurea elastomer performance
  • ●喷涂硬泡聚氨酯外墙防水保温施工流 [05-16] ● Waterproof thermal insulation construction flow for spraying rigid foam polyurethane exterior
  • ●使用聚氨酯喷涂机白料时要细致什么 [05-10] ● What to be careful when using polyurethane sprayer white material
  • ●购买防水涂料需要重点关注的性能指 [05-10] ● The performance indicators that need to focus on when buying waterproof coatings
  • ●哪些因素会影响聚氨酯发泡质量 [05-07] ● What factors will affect the quality of polyurethane foam
  • ●聚氨酯喷涂作业时“应该”和“不应 [10-29] ● "should" and "should not" when spraying polyurethane
  • ●影响聚氨酯喷涂施工出方率的几个因 [10-29] ● Several factors affecting the yield of polyurethane spraying construction
  • ●聚氨酯喷涂施工的常见问题及原因 [10-29] ● Common problems and reasons of polyurethane spraying construction
  • ●聚氨酯防腐应用以及储存 [10-21] ● Application and storage of polyurethane anticorrosion
  • ●聚氨酯防腐漆在出现剥落现象 [10-21] ● The polyurethane anticorrosive paint is peeling off
  • ●聚氨酯防腐的主要涂覆方法 [10-21] ● Main coating methods for polyurethane anticorrosion
  • ●聚氨酯防腐的涂装工艺 [10-21] ● Polyurethane anticorrosive coating process
  • ●如何提高聚氨酯防腐的性能 [10-21] ● How to improve the anticorrosive performance of polyurethane
  • ●聚氨酯防腐适用领域以及特点 [10-21] ● Application areas and characteristics of polyurethane anticorrosion
  • ●聚氨酯高压喷涂设备的主要优点 [10-19] ● Main advantages of high pressure polyurethane spray equipment
  • ●聚氨酯发泡机选购前的对比方法 [09-19] ● Comparison method before purchasing polyurethane foaming machine
  • ●聚氨酯发泡机特点和工作流程介绍 [09-19] ● Introduction of polyurethane foam machine characteristics and work flow
  • ●聚氨酯高压发泡机和低压发泡机的区 [08-08] ● The area of polyurethane high pressure foaming machine and low pressure foaming machine
  • ●「耐高温材料」聚氨酯硬泡的发展方 [07-25] ● Development method of "high temperature resistant material" polyurethane rigid foam
  • ●「ws15」喷涂型聚氨酯应用指南 [07-25] ● "ws15" Spraying Polyurethane Application Guide
  • Effects of different raw materials (structures) on the properties of polyurethane elastomers
    来源:http://motokone.com发布时间: 2018-05-11 15:17 Author: Polyurethane foam machine Source: http: //motokone.com Published: 2018-05-11 15:17
    Polyurethane elastomers have a wide variety of raw materials, complex group composition and arrangement in the macromolecular structure, and polyurethane elastomers are synthesized and processed in a variety of ways. The difference, which incurs a change in the properties of the polyurethane elastomer.

    Polyurethane elastomer is used in a solid state, and its mechanical strength under various external forces is an important indicator of its performance. Generally speaking, polyurethane elastomers, like other polymers, have properties and molecular weights, intermolecular forces, toughness of the segments, crystallization tendency, branching and crosslinking, and the position, polarity and volume of the substituents. Other factors have a close relationship. However, polyurethane elastomers are different from hydrocarbon-based (PP, PE, etc.) polymers. Their molecular structure is composed of soft segments (oligomeric polyols) and hard segments (polyisocyanates, chain extensions). Cross-linking agents, etc.) block, the electrostatic force between its macromolecules, especially between the hard segments is very strong, and often a large number of hydrogen bonds are generated, this intense electrostatic force, in addition to direct In addition to affecting the mechanical properties, it can also promote the collection of hard segments, produce micro phase separation, and improve the mechanical properties and temperature properties of elastomers.
    1.Relationship between mechanical properties and structure
    The mechanical properties of polyurethane elastomers depend on the crystallization tendency of polyurethane elastomers, especially the crystallization tendency of soft segments. However, polyurethane elastomers are used in a highly elastic state and do not want to exhibit crystallization. Therefore, formulation and Process design, find a balance between elasticity and strength, so that the prepared polyurethane elastomer does not crystallize at the application temperature, has good elasticity, and can crystallize rapidly when highly stretched, and the ablation temperature of this crystal is at room temperature Up and down, when the external force is released, the crystals melt rapidly. This reversible crystalline structure is very beneficial to improve the mechanical strength of the polyurethane elastomer.
    Whether a polyurethane elastomer has reversible crystallization depends mainly on the polarity, molecular weight, intermolecular forces, and structural regularity of the soft segment. The molecular polarity and intermolecular force of polyester are greater than those of polyether, so the mechanical strength of polyester polyurethane elastomer is greater than that of polyether polyurethane elastomer; the side groups in the soft segment will reduce the crystallinity, which will reduce the product's Mechanical behavior. The structure of polyurethane hard segments also has a direct and indirect impact on the mechanical properties of polyurethane elastomers. Generally, aromatic diisocyanates (such as MDI, TDI) are larger than ester diisocyanates (such as HDI); diisocyanates with symmetrical structure ( Such as MDI) can give polyurethane elastomers higher hardness, tensile strength and tear strength; the effect of chain extension crosslinker structure on the mechanical properties of elastomers is similar to that of diisocyanates.
    2.Relationship between heat resistance and structure
    The thermal stability of a polymer can be weighed against the softening temperature and the thermal synthesis temperature. Under normal conditions, the thermal synthesis temperature of the polyurethane elastomer is lower than the softening temperature. Generally speaking, the heat resistance of polyester polyurethane elastomer is better than that of polyether polyurethane elastomer. For aromatic diisocyanate, the heat resistance is PPDI> NDI> MDI> TDI.
    3. Relationship between low temperature performance and structure
    The low temperature elasticity of polymers is usually weighed by the glass transition temperature and the cold resistance coefficient (or brittleness temperature). Under normal conditions, the low-temperature compliance of polyether polyurethane elastomer is better than that of polyester.
    4.Relationship between water resistance and structure
    The effect of water on polyurethane elastomers: the plasticizing effect (water absorption) of water and the degradation effect of water. When the relative humidity is 100%: the water absorption of polyester polyurethane elastomer is about 1.1%, and the performance drop is about 10%; the water absorption of polyether polyurethane elastomer is about 1.4%, and the performance drop is about 20%; However, the hydrolysis stability of polyether polyurethane elastomer is greater than that of polyester polyurethane elastomer.
    5, the relationship between oil resistance and chemical resistance and structure
    Polyurethane elastomers are very resistant to grease and non-polar solvents. Ordinary polyester polyurethane elastomers have better resistance to grease than polyether polyurethane elastomers; the higher the hardness of polyurethane elastomers, the better their grease resistance; the chemical resistance of polycaprolactone polyurethane elastomers (Such as sulfuric acid, nitric acid, etc.) performance is better than other types of polyurethane.
    The overall alkali resistance of polyurethane elasticity and the resistance to strong polar solvents (such as cyclohexanone, Tianna water, etc.) are not good. 6, NDI, PPDI high-performance polyurethane elastomer
    NDI polyurethane elastomer with high tear strength, good abrasion resistance, good heat resistance (heat resistance up to 100 ~ 120 ℃), low shrinkage and permanent deformation, good resilience, excellent oil and solvent resistance, extremely Good dynamic mechanical properties and excellent cutting resistance, etc .; In the temperature range of 20 ~ 80 ℃ and high dynamic load conditions, it has lower damping value, lower internal heat, and is more durable than TDI and MDI systems durable.
    PPDI polyurethane elastomer has excellent physical and mechanical properties, resilience, abrasion resistance, fatigue resistance, heat resistance and damp heat resistance, solvent resistance, etc. are much better than MDI / 1.4-BD system and TDI / MOCA system. The mechanical properties are better than NDI elastomers.