ZnO/MgO, ZnO/CaO, and ZnO/CaO/ MgO can form solid solutions. The solid solution for we as flame retardant (SSFR) was obtained by annealing at 1023 K for 4.5 h in a muffle furnace. Flexible poly (vinyl chloride) (PVC) filled with SSFR and Sb 2 O 3 was investigated by differential thermal analysis thermogravimetry. Limiting oxygen index (LOI), mechanical properties, and electrical properties were studied. The surface of the char formed after combusting of the PVC compounds was observed through scanning electron microscopy and the effect of the surface area to the LOI was also studied. The data suggested that a small amount of SSFR and Sb 2 O 3 have good synergy and can greatly increase the LOI and the char yield, and that the thermal degradation temperature and the activation energy decreased. It can be concluded that the mechanism of SSFR is a condensed-phase mechanism. Moreover, one can conclude that the surface area can enhance the LOI. All the results showed that SSFR is effective and safe as a flame retardant in flexible PVC.

The thermal degradation in air of hemp fabric treated with various compounds containing nitrogen, phosphorus, halogens, and boron, in combinations of two compounds, has been studied by differential thermal analysis and thermogravimetry from ambient temperature to 600 C. The kinetic parameters were obtained using the equation of Broido. The values of activation energies for the oxidative decomposition of samples were found to be in the range 52-102 KJmol 1. Hemp fabric treated with flame retardants showed a high limiting oxygen index and char yield which indicated that the flame retardance of treated hemp was improved. Effect of the different elements on degradation behaviors has been proposed.

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The thermal degradation in air of flexible PVC treated with various metal chelates containing Fe, Co, Ni, Cu, or Zn combined with two compounds Al(OH) 3 and Mg(OH) 2 , have been studied by differential thermal analysis and thermogravimetry from ambient temperature to 1023 K. The kinetic parameters were obtained using the equation of Kissinger. Flexible PVC treated with flame-retardants showed a high limiting oxygen index, char yield and a low smoke density rating, maximum smoke density, which indicated that the flame retardance of the treated PVC was improved.