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SYNOPSISTwo reaction routes for the preparation of aromatic poly-1,3,4-oxadiazoles and poly-1,2,4-triazoles are studied and their influence on the physical properties, i.e., inherent viscosity, glass transition, degradation temperature, and film integrity of the final products are discussed. Aromatic poly-1,3,4-oxadiazoles are prepared by means of a polycondensation reaction of terephthaloyl chloride and isophthalic dihydrazide yielding a precursor polymer, poly (p,m-phenylene ) hydrazide, which is converted into the corresponding poly-1,3,4-0~-adiazole by means of a cyclodehydration reaction. Poly-1,3,4-oxadiazoles are also prepared by means of a polycondensation reaction between terephthalic and isophthalic acid and hydrazine yielding poly-1,3,4-oxadiazoles with higher inherent viscosities. Flexible poly-1,3,4-oxadiazole films are obtained only if the inherent viscosities of the polymers used are higher than 2.7 dL/g. The thermal stability is found to i n c r e a s with increasing content of p-phenylene groups in the polymer backbone. Aromatic poly-1,2,4-triazoles are prepared using polyhydrazides with alternating para-and meta-phenylene groups and poly-1,3,4-oxadiazoles with a random incorporation of para-and rneta-phenylene groups in the main chain as precursor polymers. The glass transition temperatures are found to increase with increasing content of p -phenylene groups in the main chain of these polymers. Cold crystallization is observed only for the alternating polymer. 0 1994 John Wiley & Sons, Inc. Keywords: poly-1,3,4-oxadiazoles polyhydrazide poly-l,2,4-triazoles cold crystallization I NTRO DU CTI ON Aromatic poly-1,3,4-oxadiazoles and poly-1,2,4-triazoles are chemically resistant and thermally stable polymers soluble only in strong acids and stable up to 45OOC.l We have studied these polymers as new membrane material^,^'^ with the aim to develop membranes that can be applied under severe operating conditions, such as elevated temperatures and acidic or basic environments. Such membranes also should be highly resistant towards organic solvents. A number of reaction routes are known for the preparation of these poly-l,3,4-oxadiazoles and poly-1,2,4-triazoles.~ We decided to study the preparation of aromatic poly-1,3,4-oxadiazoles by means of a solid state cy- To whom correspondence should be addressed.clodehydration reaction of an aromatic polyhydra~i d e ,~'~ the latter being used as a tractable precursor polymer. Since poly-1,3,4-oxadiazoles with inferior mechanical properties were obtained,' a second reaction route was also studied. This route directly yields aromatic poly-1,3,4-oxadiazoles from hydrazine sulphate, and terephthalic and isophthalic acid as m o n o m e r~.~ Aromatic poly-1,2,4-triazoles were prepared by a reaction of an aromatic polyhydrazide' and poly-1,3,4-oxadiazoles9 with aniline in polyphosphoric acid.The synthesis routes are represented in Figure 1. Polyhydrazides with alternating para-and metaphenylene groups in the main chain were prepared using terephthaloyl chloride and iso...

In-line hydro-treatment of bio-oil vapor from fast pyrolysis of lignocellulosic biomass (hydro-pyrolysis of biomass) is studied as a method of upgrading the liquefied bio-oil for a possible precursor to green fuels. The nobel metal (Pt) and non-noble metal catalysts (Mo 2 C and WC) were compared at 500 °C and atmospheric pressure which are same as the reaction conditions for fast pyrolysis of biomass. Results indicated that under the pyrolysis conditions, the major components, such as acids and carbonyls, of the fast pyrolysis bio-oil can be completely and partially hydrogenated to form hydrocarbons, an ideal fossil fuel blend, in the hydro-treated bio-oil. The carbide catalysts perform equally well as the Pt catalyst regarding to the aliphatic and aromatic hydrocarbon formation (ca. 60%), showing the feasibility of using the cheap non-noble catalysts for hydro-pyrolysis of biomass.