Studies On Preparation And Properties Of Ceramifying And Fireproof PVC Sheets

Ceramifying PVC sheet is a new type of fireproof material. Compared with the traditional PVC sheets which generate powdered chars under flame, the ceramifying PVC sheets can not only maintain excellent properties at room temperature, but also quickly form self-supporting porous ceramic structure under flame, thus behaving outstanding fireproof performance. In this paper, the ceramifying fireproof PVC sheets were prepared by adding compound ceramifying fillers. The effects of ceramifying fillers, toughening modifier and filler surface treatment on the properties of PVC sheets were discussed in detail, and the ceramifying mechanism was also investigated. The investigation consists of the following three parts.(1) Two kinds of glass frits (low melting glass frit and high melting glass frit) with different element content, particle size and volatile were employed as the ceramifying filler. According to the test results of ceramifying effect and mechanical properties of the sheets, when the loading amount of the filler was 100 phr with the proportion of low melting glass frit and high melting glass frit reaching 40:60, the sheets acquired optimum properties. The sheets had no crack and small deformation after burning for 20 minutes, the impact strength was 11.97KJ/m2, the tensile strength was 19.21MPa, the flexural strength was 42.56MPa, the shore D hardness was 79.1, the volume resistivity was 2.78×1013?·cm, the thermal conductivity was 0.2305Wm-1K-1, the oxygen index was 77.2%. The results of TG analysis, FTIR spectra, XRD and surface topography analysis showed that ceramic solid phase reaction had occurred between the two kinds of glass frits, which generated new acrystalline materials and formed hard and porous ceramic layer.(2) As the content of toughening modifier CPE and SRC increased, the impact strength of the PVC sheets increased gradually, the tensile strength and flexural strength increased at first and then decreased. When the loading amount of CPE exeeded 10 phr, the impact strength curves of the sheets approached to be flat, and the tensile strength and flexural strength came down. The same trend arose when the loading amount of SRC was 15 phr. The mechanical properties and processability of SRC modified was better than CPE modified. The SEM pictures showed that both extrudates modified by CPE and SRC showed ductile fracture, whereas SRC significantly enhanced the compatibility of the glass frit and PVC resin.(3) The FTIR spectra showed that the silane coupling agent had a significant compatibility-promoting effect on the glass frit with PVC. With the increase of the content of silane coupling agent, the impact strength of the sheet increased at first and then decreased, the tensile strength and flexural strength increased gradually. When the loading amount of coupling agent was 1 phr, the impact strength was maximum by dry modification. With the further more addition of coupling agent, then the increasing of tensile strength and flexural strength tended to slow down. For wet modification, the same trend arose when the optimum loading amount of coupling agent was 1.5 phr. The DSC curves and SEM pictures showed that silane coupling agent could significantly enhance the compatibility of the glass frit and PVC resin, and the effect of the wet modification was better than the dry modification.