The characteristics of polymer combustion andthe flame retardant mechanism classifying to vapor phase and solid phase are described and the recent trend of flame retardant technology by these two mechanisms are also introduced.

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Thermal stability of polyurethane (PU) have been improved by incorporating polyamide (PA) or poly-imide (PI). The PU-PI (PA) various reactant ratio were analyzed by means of TG-DTG. The heating rate were 10, 20 and 40°C /min, and temperature range was 25-800°C. Thermal decomposition behavior was studied by Ozawa's analysis method of TG-DTG curves. The quantitative relation between weight loss ratio and the reactant ratio was found. The thermal-resistance increased with the increase of the PA or PI content. The heat-resistance of PU as elastomer was significantly improved by incorporating of PA or PI of 10-20 wt % in PU. Life temperature designated as temperature at 10 wt % weight loss for 100 years was 110°C for PU-PA (80/20 wt%) and PU-PI (80/20 wt%).

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The degradation tests of typical biodegradable polymers were carried out in a personal garbage disposal machine. The degradation rate judged by a tensile strength was as follows, PLA>PCL=PBSA, where PLA is poly (L-lactic acid), PCL is Poly (ε-caprolactone) and PBSA is poly (butylenesuccinate adipate). The tensile strength of PLA fell down to zero in 10 days. For PCL and PBSA, however, the strength did not reach zero for over 40 days. The degradation rates were very slow compared with that of organic garbage in the disposal machine. The degradation rates of the biodegradable polymers were also affected by the composition of organic garbage. The degradation rate was highest in a mixture of animal and plant (50: 50) garbage. The garbage produced NH3, which enhanced the hydrolysis of the biodegradable polymers.

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By increasing the strength of concrete members, it is possible to prolong the life of buildings. However, CO₂ emission rate tends to increase because the increased strength may lead to increased cement consumption. In this report, followings are discussed. (1) Estimation for the prolongment of the life of concrete members, as protective concrete cover length and design strength of concrete changed. (2) The influence of these factors on the carbon dioxide emission rate in the life cycle.
The results showed as followings.
(1) From the viewpoint of prolonging the life of buildings, increasing the covering depth was more effective than increasing the design strength.
(2) If the design strength is increased, the life cycle CO₂ emission ratewill be reduced.
(3) On the premise that the buildings will be used for the long period of 100 years, the most effective measure for reducing life cycle CO₂ emission rate is to change the concrete materials from Ordinary Portland Cement to Blast-furnace Slag Cement or Fly-ash Cement, rather than to increase the design strength, if effective protective concrete cover length is secured.

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