Influence of main indexes of chlorinated polyethylene (CPE) on modification of rigid PVC products(8)

Effect of CPE with different tensile strength and elongation at break on PVC modification:

Tensile property is also the key performance index of CPE materials, and the tensile property of materials is characterized by tensile strength and elongation at break. The tensile properties of CPE are closely related to the raw material HDPE, chlorine content, chlorine atom distribution, melting enthalpy (residual crystallinity) and Shore hardness. Elongation at break is also a measure of the toughness of CPE indicators, HDPE selection, chlorine content, chlorine atom distribution, melting enthalpy (residual crystallinity) and the level of elongation at break has a great relationship, different application field requirements are also different. Because the elongation at break is closely related to Shore hardness, the current industry standard HG/T2704-2010 only Shore hardness does not require the elongation at break.

According to experience and application verification, the elongation at break of the PVC impact modified CPE135A reaches 650%, that is, it has a comprehensive balance of technological and mechanical properties. Under normal circumstances, for rigid PVC modification, the elongation at break of CPE135A can basically meet the requirements of toughening when it reaches more than 650%; Considering the strength of the product, it is not considered that the higher the elongation at break, the better, because CPE is too soft or the elongation at break is too high will inevitably affect the strength of the product, the product strength reflected in the application of PVC profiles and pipes is tensile strength, bending elastic modulus and welding strength, adding too much CPE, tensile strength and welding strength will usually be reduced. So you need to find a balance between strength and toughness.

According to experience and application verification, the elongation at break of the PVC impact modified CPE135A reaches 650%, that is, it has a comprehensive balance of technological and mechanical properties. Under normal circumstances, for rigid PVC modification, the elongation at break of CPE135A can basically meet the requirements of toughening when it reaches more than 650%; Considering the strength of the product, it is not considered that the higher the elongation at break, the better, because CPE is too soft or the elongation at break is too high will inevitably affect the strength of the product, the product strength reflected in the application of PVC profiles and pipes is tensile strength, bending elastic modulus and welding strength, adding too much CPE, tensile strength and welding strength will usually be reduced. So you need to find a balance between strength and toughness.

However, for PVC products that require better low-temperature toughness, such as power pipes used in cold areas, better low-temperature toughness is needed. According to the comparative test of CPE with high elongation (> 800%) and low elongation (800-600%), it was found that the elongation at break of CPE had little effect on the plasticization speed of CPE modified PVC composite, and the plasticization speed of CPE with high elongation was slightly faster.

CPE with high elongation is superior to CPE with low elongation in low temperature toughness of PVC profiles and power pipes. The tensile impact strength of CPE with high elongation is also slightly higher. The low temperature performance of CPE with high elongation is better than that of CPE with low elongation, which has advantages in the low temperature bending performance of power pipe.