The thermal degradation of flexible PVC treated with various metal chelates containing Cr,Al,Fe,Co,Ni,Cu,or Zn combined with two compounds,AI(OH)_3 and Mg(OH)_2,was studied by thermal analysis.Limiting Oxygen Index (LOI),Smoke Density Rating (SDR),and mechanical properties were investigated.The structure of the char formed after combustion of the PVC compounds was observed through scanning electron microscopy (SEM).The high LOI and char yield of flexible PVC treated with flame retardants showed that there was a good synergistic effect between AI(OH)_3,Mg(OH)_2,and metal chelates.
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