Poly(styrene) samples were reprocessed in multiple cycles by a single-screw extruder. The reprocessed heat degraded samples were characterized by dynamic viscoelasticity and stress-strain measurement. The decrease in molecular weight (Mη) for poly(styrene) with reprocessing was expressed by the product of the function of cycles number (n) of extrusion and the function of time (t) required in extrusion at a given temperature (T) in low t region. This decrease was not so large as that for poly(propylene), but larger than that for low density poly(ethylene). In poly(styrene), the scission of polymer chain is caused by heat degradation mainly at the highest molecular weight component. Young's modulus (E) obtained from stress-strain curves did not change for both the virgin, and heat degraded samples.
Japanese modern houses become highly airtight and thermally insulated, because of saving energy. As a result, problems related to humidity of indoor air have been increased, for example, excessive dew formation etc. To solve these problems, we have developed a new humidity controlling material using porous soil "allophane". It was found that the moisture adsorption property of this material was higher than that of wood in laboratory test. Effects of this material in the living space were examined by measuring humidity and the amount of dew condensation before and after applying this material in practical houses. It was cleared that this building material could decrease humidity change and the amount of dew condensation in the living space.