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        1. Tuyere profile manufacturer
          Source:Tuyere profile manufacturer   Addtime:2008.04.29   Read:
          The brittleness of profiles is basically reflected in physical and mechanical properties of WIP. The main features are: collapse and cold impact. There are many reasons for poor physical and mechanical properties of profile products. It is mainly expressed as follows: first, the formulation and mixing process are unreasonable.

          1 fillers too much

          In view of the current market profile price low, and the price of raw materials rising pattern, profile manufacturers are reducing interest on the article, the regular profile manufacturers through the formula optimization combination, without reducing the quality of the premise, reduce the cost; some manufacturers also reduce the cost of the same time also reduced the quality of products. The most direct and effective way is to increase fillers because of the composition of the ingredients. The commonly used fillers in PVC-U plastic profiles are calcium carbonate. Most of the former formula system is filled with calcium, which aims to increase the rigidity and reduce the cost. However, due to the irregular shape of its own particles and the poor phase solubility of the PVC resin body, the number of added parts is very low, and the color and apparent effect of the profile will be affected by the increase of the number of parts. With the development of technology, most of the ultrafine light activated calcium carbonate, even nano calcium carbonate, not only plays a role in increasing rigidity and filling, but also has the effect of modification, but the proportion of its filling amount is not infinite and should be controlled. Now some manufacturers add calcium carbonate to 20-50 parts in order to reduce the interest, which greatly reduces the physical and mechanical properties of the profiles, resulting in the brittle phenomenon of the profiles described in this chapter.

          2 addition and quantity of anti impact modifier

          Impact modifier is a kind of high molecular polymer which can improve the total energy of PVC rupture under stress. At present, the main varieties of the hard PVC anti impact modifier are CPEACRMBSABSEVA and so on. The molecular structure of the CPEEVA ACR modifier has no double bonds in the molecular structure, and the weatherproof property is good. It is suitable to do outdoor building materials and blend with PVC. It can effectively improve the impact resistance, processability, weatherability and certain range of the hard PVC. The welding angle strength is improved within.

          The impact strength of PVC/CPE blends increases with the increase of CPE content, showing a S shape curve. When the amount of addition is below 8 mass, the impact strength of the system is very small, and the increase of the added amount is the largest in 8-15 mass, and then the increase tends to be slow. When the amount of CPE is below 8 mass, the network structure is not formed. When the amount of CPE is 8-15 mass, it is continuously dispersed in the blending system, forming a phase separation network structure, which makes the impact strength of the blends increase greatly. When the amount of CPE exceeds the 15 quantity, the continuous and uniform distribution can not be formed. In addition, some CPE formed gelatinous form, so that there would be no suitable dispersed CPE particles to absorb the impact energy on the two-phase interface, thus the impact strength increased slowly.

          In PVC/A CR blends, ACR can significantly improve the impact resistance of the blends. At the same time, the "nuclear shell" particles can be dispersed evenly in the PVC matrix, PVC continuous phase, ACR dispersion phase, dispersed in the PVC continuous phase and PVC interaction, play the role of processing aids, promote the plasticization and gelation of PVC, the plasticizing time is short, and has good processing performance.  The influence of forming temperature and plasticizing time on notched impact strength is small, and the bending modulus decreases. The general dosage is 5-7 mass fraction, and the hardened PVC products modified by ACR have excellent room temperature impact strength or low temperature impact strength.

          The experimental results show that the impact strength of ACR is about 30% higher than that of CPE. Therefore, it is possible to use PVC/A CR blends as much as possible in the formula, while CPE modified and less than 8 mass fraction tend to cause brittle profiles.

          3 or too few stabilizers

          The role of stabilizer is to inhibit degradation, or react with the released hydrogen chloride and prevent polyvinyl chloride from discoloring during processing. The stabilizers are also different according to the different kinds, but on the whole, excessive dosage will delay the plasticizing time of the material so that the material entrance mold is not plasticized, and the molecules in the formula system are not completely dissolved and the intermolecular structure is not strong. When the dosage is too low, the degradation or decomposition of relatively low molecular objects in the formula system (also can be said to be plasticized) will cause damage to the stability of the structure of each component. Therefore, the amount of stabilizer will also affect the impact strength of profiles. Too much or too little will cause the strength reduction of profiles to cause crispness of profiles.

          Excessive amount of 4 external lubricants

          The low solubility of the external lubricant and the resin can promote the sliding between the resin particles, thereby reducing the friction heat and postponing the melting process. The effect of the lubricant is the largest in the early processing process (before the external heating and internal friction heat made the resin completely melted and the resin lost the recognition characteristics in the melt body). The external lubricant is also divided into earlier lubrication, late lubrication and excessive lubrication in various conditions. If the lubricant is not properly used, it may cause flow marks, low output, turbidity, poor impact, rough appearance, adhesion and poor plasticization. Especially when the amount is too much, it will cause poor density and poor plasticization of profile, resulting in poor impact performance and brittle profile.

          5, the order of hot mix, temperature setting and curing time also have decisive factors on the performance of profiles.

          There are a lot of components in the PVC-U formula. The feeding order should be beneficial to play the role of each auxiliary, and to improve the dispersing speed and prevent the bad synergy effect. The addition order of the additives should be promoted.

          This article is divided into 1 pages


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