Blending modification of polyethylene and chlorinated polyethylene

日期:2021/4/1 8:38:34 / 阅读: / 来源:本站

Blending modification of polyethylene and chlorinated polyethylene

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     PE itself is flammable. Generally, inorganic substances such as aluminum hydroxide and organic low molecular weight such as chlorinated paraffin are added to PE products to make them flame retardant. However, this method is easy to cause the degradation of material properties, which can not meet the use requirements. CPE is a kind of polymer modified by montmorillonite, which can be blended with PE to achieve the purpose of flame retardant. There are many kinds of CPE, including CPE elastomer, high degree of chlorination E and low degree of chlorination PE. Different chlorine content leads to different properties, especially flame retardancy. In order to investigate the properties of CPE / E blends with different chlorine content, CPE with different oxygen content was prepared by the same HDPE and chlorination method. With the increase of chlorine content in CPE, the tensile strength and elongation at break of the blends increased, and then decreased after a certain chlorine content. CPE with low hydrogen content has the structure of E and CPE in the molecular chain, and has good compatibility with PE. With the increase of chlorination degree, due to the introduction of polar group chlorine, the drop parameter of CPE increases, the compatibility with PE becomes poor, and the properties of the blends decrease. When the oxygen content of CPE is about 20%, the blends show better properties. However, if CPE with 20% chlorine content is blended with PE, a large amount of CPE should be added in order to achieve the purpose of flame retardancy, resulting in the increase of material cost. Therefore, CPE with chlorine content of 30% is suitable. With the addition of CPE, the elongation at break and tensile strength decrease monotonously except for a minimum value with the increase of CPE content. With the increase of CPE content, the processability of the blends becomes better. When the content of CPE is about 20 phr, the blends show better comprehensive properties. Hollow board production line www.handern.com
     The compatibility of PE and CPE is related to the structure of CPE. Different preparation methods of CPE lead to different distribution of chlorine atoms in the molecular chain of PE. Although the chlorine content is the same, the structure of CPE changes, so the compatibility with PE is different. CPE with the same chlorine content was prepared by one-step chlorination at lower temperature and two-step chlorination at lower temperature and then at higher temperature. CPE prepared by two-step chlorination was blended with PE. When CPE prepared by two-step chlorination was blended with PE, only a small amount of CPE was added to improve the adhesion between PE and ink The blending effect of CPE by one-step chlorination is better than that by one-step chlorination. The melting point of PE is about 110 ℃. When chlorinated at low temperature, chlorine can only enter into the amorphous part of the chain. At high temperature, the residual crystal in the chloride is destroyed, and chlorine atoms are added to the molecular chain in the crystal region. When CPE is used as flame retardant for PE, the effect of flame retardant modification is more remarkable when adding TiO2 at the same time. CPE can also improve the environmental stress cracking resistance (ESCR) of HDPE. ESCR is the ability of a material to resist cracking and failure in the presence of certain media and below its ultimate strength. HDPE is very sensitive to environmental stress cracking. In practical application, the actual life of HDPE products is greatly shortened. The ESCR performance of pure HDPE is very poor. When 5% CPE is added, the environmental stress cracking resistance of HDPE can be greatly improved.Hollow board production line www.handern.com

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