Poly(propylene) samples were reprocessed in multiple cycles by a single-screw extruder. The heat degraded samples reprocessed were characterized by dynamic viscoelasticity and stress-strain measurement. The decrease (Mw/Mw0) in molecular weight of poly(propylene) with reprocessing was expressed by the product (f(n, T)·g(t, T)) of a function of cycles number (n) of extrusion consisting of virgin and degraded samples and a function of time (t) required in extrusion at a given temperature (T). Especially, at a temperature below 190°C, Mw/Mw0 was expressed only by f(n, T). In blend system Mw/Mw0 was expressed by similar relationship, suggesting that the synergy effect of blend on the heat degradation was absent. Young’s modulus (E) and yield stress (σy) obtained from stress-strain curves did not change regardless of the virgin, heat degraded and blend samples.
For the purpose of recycling unused wood resources, such as thinned timber and discarded lumber, experiments were conducted on carbonized wood-ceramic composites made from cedar (Cryptomeria japonica D. Don) for their ability to serve as a microhabitat in bioremedial applications. The composites were inoculated with hard-to-degrade organochloric compound-degrading bacteria and were used to degrade two hard-to-degrade organochloric agricultural chemicals, 6-chloro-N2, N4-diethyl-1, 3, 5-triazine-2, 4-diamine (CAT, or commonly known as “simazine”) and pentachloronitrobenzene (PCNB, or commonly known as “quintozene”). Results of the CAT degradation experiments confirmed that almost all of the CAT-degrading bacteria were successfully inoculated on the composites and that the composites served as an excellent microhabitat for the bacteria. The rate of decline in CAT concentration began to increase after two weeks of refluxing, achieving nearly 100% of CAT degradation with steady production of chlorine ions as a by-product. Similarly, the PCNB degradation experiments showed that the composites served as an ideal and efficient microhabitat for nearly 100% of the inoculated PCNB-degrading bacteria. The rate of decline in PCNB concentration began to increase after two weeks of refluxing, achieving roughly 80% of PCNB degradation with steady production of chlorine ions as a by-product. In view of the high CAT and PCNB adsorption by the carbonized wood-ceramic composites used in the experiments, the results seem to indicate that the CAT and PCNB (which were the sole sources of carbon and nitrogen for the degrading bacteria) adsorbed primarily into the mesopores of the composites were degraded by the degrading bacteria aggregating mostly within the macropores of the composites. Therefore, the results showed efficient adsorption and degradation of agricultural chemicals by the bacteria in the meso- and macropores of the carbonized wood-ceramic composites.
As one of effective usages of the wastes in an aluminum regeneration process, the syntheses of hydrotalcite (HT), which is a functional inorganic material having layered structure of complex hydroxide, were carried out by using aluminum dross and MgCl2 waste solution as raw materials. Various physical properties such as crystal structure, surface texture and anion exchange properties were measured for the obtained products. The removal of chromic acid ion was investigated with various products. CO32- type HT can be obtained from the aluminum dross and MgCl2 waste solution by a co-precipitation method. A slight amount of Ca, Na, Si, Fe etc. remains in the product as impurity components. The anion exchange order of HT is as follows; CO32- > SO42- > F- > Cl- > NO3- ≥ I-. It is possible to remove chromic acid ion from an aqueous solution with various products by an anion exchange reaction. The Mg/Al complex oxide, which is obtained by calcination of the CO32- type HT at 773 K, is superior to the original HT for the removal of chromic acid ion.