Thermo-Reversible Covalent Cross-Linked And Flame Retardant Polyvinyl Chloride

The polyvinyl chlorides (PVC)-based materials produced in different technological formulations have been already widely used in quite a lot of field because of low cost and excellent properties. However, adding too much additives into PVC resin greatly reduces the flame-resistant property of PVC material, therefore, how to maintain the mechanical property while improve the flame resistant performance of PVC products which containing a higher proportion of plasticizer is an important problem to be solved at present. Cross-linking is an effective method to improve the mechanical property of PVC, but the traditional crosslinking methods will result in a kind of unrecyclable thermosetting plastic.In this paper, sodium dicyclopentadiene formate (DCPD (COONa)2) was used as cross-linking agent, and thermally reversible covalent crosslinking PVC material was obtained. Research to improve the PVC flame resistant property has been carried on as follows:1. The fact that aluminum hydroxide (ATH) does not react with PVC was proved.2. Aluminum hydroxide (ATH) was chosen as a flame resistant addictive and add it into the reversible crosslinking PVC formulations, the oxygen index(LOI%) of the hard PVC samples increased by 42% while the soft one’s increased by 20% when adding 30phr ATH, it has almost no effect on the mechanical and thermal-reversible properties.3. Modify the surface of ATH, the modified ATH with active index 89% is obtained. The dispersion situation and tensile property was improved when filled with the modified ATH compared with ATH.4. ATH-Ammonium polyphosphate (APP) mixture was used as a flame resistant addictive, the LOI of soft PVC increased by 60% when adding 20phr ATH and 8phr APP.This thermo-reversible cross-linked and flame resistant PVC possess shape memory property. The effect of the thickness and radius of curvature of the samples, and the amount of ATH addition on the shape memory property were studied.The thermally reversible covalent crosslinking PVC pipe (φ300×10mm) was obtained by extrusion. The performance meets the national standard, and the impact property reachs 45.2KJ/m2.