pvc profiles due to physical constraints, in the production process will occur when the PVC material crisp situation. One of the main reasons is due to unreasonable PVC formula and mixing process and type of material brittle situation. Rushan North to the new material to help you analyze the reasons for the brittle PVC profiles and how to avoid.
In the case of
Hot mixing order, temperature setting and curing time
PVC-U formula a lot of components, additives, the order of additives should help to improve the complementary effect of additives to overcome the role of phase grams of elimination, should be dispersed in the PVC resin additives such as polyethylene wax, fully into the PVC Resin inside. General hot mixing temperature of about 120 ℃, the temperature is too low when the material does not reach gelation and mixing evenly above the temperature part of the material may decompose volatile, and dry powder yellow.
Excessive amount of external lubricant
The low compatibility between the external lubricant and the resin can promote the sliding between the resin particles, thereby reducing the amount of frictional heat and delaying the melting process. This effect of the lubricant is greatest at the early stage of the process. If the amount of lubricant is not correct, it may cause flow marks, low yield, turbidity, poor impact, rough surface, adhesion, poor plasticity, causing profiles brittle
Too many or too few stabilizers
The effect of the stabilizer is to inhibit the degradation, or with the release of hydrogen chloride reaction and to prevent the discoloration of PVC processing. Excessive amount of stabilizer will delay the plasticizing time of the material so that the material is also less plastic when the export mold, the formula system between the molecules are not fully soluble. And when the dosage is too small will cause the degradation or decomposition of the relatively low molecular substances in the formulation system, and the damage to the intermolecular structure of each component is caused. So the amount of stabilizer too much or too little will result in reduced profile strength caused by the phenomenon of brittle profiles.
Too much packing
With the development of technology, now most of the use of ultra-fine light activated calcium carbonate, and even nano-calcium carbonate, which not only play a role in increasing rigidity and filling, but also has the role of modification, but its filling is not Infinitely, the proportion should be controlled. Now some manufacturers in order to reduce the cost of calcium carbonate added to 20-50 copies, which greatly reduces the physical and mechanical properties of profiles, resulting in the chapter mentioned in this section brittle phenomenon.
Hot mixing order, temperature setting and curing time
PVC-U formula a lot of components, additives, the order of additives should help to improve the complementary effect of additives to overcome the role of phase grams of elimination, should be dispersed in the PVC resin additives such as polyethylene wax, fully into the PVC Resin inside. General hot mixing temperature of about 120 ℃, the temperature is too low when the material does not reach the gelation and mixing evenly above the temperature part of the material may decompose volatile, and dry powder color will turn yellow.
The amount of impact modifier added
The impact modifier is a high molecular polymer capable of increasing the total energy of PVC cracking under stress. At present, the main varieties of the impact resistance modifier of the rigid polyvinyl chloride are CPE, abs and so on. They are blended with PVC, which can effectively improve the impact resistance, workability, weatherability and hardening of polyvinyl chloride in a certain range Improve the welding angle strength.
The experimental demonstration, ACR and CPE compared to the impact strength is about 30% higher. So in the formula as much as possible using PVC / ACR blending system, and with CPE modified and the amount of less than 8 parts of mass tend to cause the profile brittle.
In the case of
Hot mixing order, temperature setting and curing time
PVC-U formula a lot of components, additives, the order of additives should help to improve the complementary effect of additives to overcome the role of phase grams of elimination, should be dispersed in the PVC resin additives such as polyethylene wax, fully into the PVC Resin inside. General hot mixing temperature of about 120 ℃, the temperature is too low when the material does not reach gelation and mixing evenly above the temperature part of the material may decompose volatile, and dry powder yellow.
Excessive amount of external lubricant
The low compatibility between the external lubricant and the resin can promote the sliding between the resin particles, thereby reducing the amount of frictional heat and delaying the melting process. This effect of the lubricant is greatest at the early stage of the process. If the amount of lubricant is not correct, it may cause flow marks, low yield, turbidity, poor impact, rough surface, adhesion, poor plasticity, causing profiles brittle
Too many or too few stabilizers
The effect of the stabilizer is to inhibit the degradation, or with the release of hydrogen chloride reaction and to prevent the discoloration of PVC processing. Excessive amount of stabilizer will delay the plasticizing time of the material so that the material is also less plastic when the export mold, the formula system between the molecules are not fully soluble. And when the dosage is too small will cause the degradation or decomposition of the relatively low molecular substances in the formulation system, and the damage to the intermolecular structure of each component is caused. So the amount of stabilizer too much or too little will result in reduced profile strength caused by the phenomenon of brittle profiles.
Too much packing
With the development of technology, now most of the use of ultra-fine light activated calcium carbonate, and even nano-calcium carbonate, which not only play a role in increasing rigidity and filling, but also has the role of modification, but its filling is not Infinitely, the proportion should be controlled. Now some manufacturers in order to reduce the cost of calcium carbonate added to 20-50 copies, which greatly reduces the physical and mechanical properties of profiles, resulting in the chapter mentioned in this section brittle phenomenon.
Hot mixing order, temperature setting and curing time
PVC-U formula a lot of components, additives, the order of additives should help to improve the complementary effect of additives to overcome the role of phase grams of elimination, should be dispersed in the PVC resin additives such as polyethylene wax, fully into the PVC Resin inside. General hot mixing temperature of about 120 ℃, the temperature is too low when the material does not reach the gelation and mixing evenly above the temperature part of the material may decompose volatile, and dry powder color will turn yellow.
The amount of impact modifier added
The impact modifier is a high molecular polymer capable of increasing the total energy of PVC cracking under stress. At present, the main varieties of the impact resistance modifier of the rigid polyvinyl chloride are CPE, abs and so on. They are blended with PVC, which can effectively improve the impact resistance, workability, weatherability and hardening of polyvinyl chloride in a certain range Improve the welding angle strength.
The experimental demonstration, ACR and CPE compared to the impact strength is about 30% higher. So in the formula as much as possible using PVC / ACR blending system, and with CPE modified and the amount of less than 8 parts of mass tend to cause the profile brittle.
