Thermal analysis of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) and poly 1,3‐phenylene‐1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene

Abstract

S U M M A R Y :Poly( 1,3,4-oxadiazole-2,5-diyl-l,4-phenylene) (I) and poly(l,3-phenylene-l,3,4-oxadiazole-2,5-diyl-1,4-phenylene) (11) and its nitroderivative have been prepared by condensation polymerization using fuming H2S04 and different quantities of terephthalic acid (TA), isophthalic acid (IA), nitrophthalic acid (NA), and hydrazine sulphate (HS) respectively. Homopolymers of TA and HS, and copolymers of TA, IA, HS, and TA, NA, and HS of different intrinsic viscosities were prepared by varying the reaction conditions. The polymer structures were investigated by visible range spectra, UV spectra, IR spectra and elemental analysis. The existence of poly( 1,3,4-oxadiazolediyl-pheny1ene)-and poiy(hydrazoterephthaloy1)structures was revealed by these studies. These polymers were thermally stable and most of them did not show any loss in weight below 360°C. The maximum weight loss was in the temperature range of 460-480°C. The activation energy E and the frequency factor A for the thermal degradation were evaluated. Linear relationships between E and the intrinsic viscosity and between the "integral procedural decomposition temperature" and the intrinsic viscosity were observed. The polymers I showed a higher stability than the copolymers I1 of similar molecular weights. Z U S A M M E N F A S S U N G :Durch Polykondensation von Terephthalsaure (TA), Isophthalsaure (IA) und Nitrophthalsaure (NA) mit Hydrazinsulfat (HS) in Gegenwart von rauchender Schwefelsaure, wurden Poly( 1,3,4-oxadiazol-2,5-diyl-1,4-phenylen) (I) und Poly( 1,3-phenylen-l,3,4-oxadiazol-2,5-diyl-l,4-phenylen) (11) und dessen Nitroderivat erhalten. Homopolymere von TA und HS, sowie Copolymere vom Typ TA/IA-HS und TA/NA-HS mit verschiedenen STAU-DINGER Indices wurden unter verschiedenen Reaktionsbedingungen erhalten. Die Produkte wurden spektroskopisch (sichtbares Licht, UV, IR) und durch Elementaranalyse untersucht, wobei Poly(oxadiazoldiylpheny1en)-und Poly(hydrazoterephthaloy1)-Strukturen nachgewiesen werden konnten. Die Polymeren waren thermisch stabil. Die meisten zeigten unterhalb von 360°C keine Gewichtsabnahme. Erst bei 460-480°C wiesen die Thermogramme Maxima des Gewichtsverlustes auf. Aus solchen Messungen wurden die Aktivierungsenergien E und die Frequenzfaktoren A der thermischen Zersetzung ermittelt. Zwischen dem STAUDINGER Index einerseits und E oder auch der ,,integral procedural decomposition temperature" andererseits, wurden lineare Abhangigkeiten festgestellt. Es zeigte sich, daR die Polymeren vom Typ I stabiler waren, als die Copolymeren vom Typ I1 von ahnlichem Molekulargewicht.

Poly‐p‐phenylene terephthamide modified poly(1,3,4‐oxadiazole) fibers with superior ultraviolet resistance

“…Poly-p-phenylene-(1,3,4-oxadiazole) (POD) is a rigid-rod polymer containing benzene and oxadiazole rings alternately in its backbone, which endows its exceptional heat resistance. [1][2][3] The additional advantages, including excellent fiber-and film-forming capability, outstanding chemical resistance, and good mechanical properties at elevated temperatures, make POD a promising candidate for protective garments, heat-resistant filter materials, and electric-insulated materials. 4 Besides, similar to polyvinyl carbazole, POD exhibits high photoconductivity owing to its long-range π-conjugated macromolecular structure.…”

Ultraviolet resistance modification of poly(1,3,4‐oxadiazole) fibers by dihydroxyterephthalic acid

“…POD fiber is one of the best thermal resistant fibers with excellent chemical resistance, hydrolytic stability, and good mechanical properties at elevated temperatures. [1][2][3][4][5] Thus, POD fiber is widely used as advanced material in many fields, such as fire protective products, heat resistant filter materials, electric-insulated materials, and other industrial fabrics. [6][7][8][9] However, the photostability of POD fiber is very poor, and its mechanical properties would dramatically deteriorate after exposure to ultraviolet, which largely limits the application of POD fiber.…”

“…Aromatic poly(1,3,4‐oxadiazole) (POD) is a rigid‐rod polymer containing benzene and oxadiazole rings alternately in its backbone, which endows it many unique mechanical, thermal, and photoelectrical properties. POD fiber is one of the best thermal resistant fibers with excellent chemical resistance, hydrolytic stability, and good mechanical properties at elevated temperatures 1–5 . Thus, POD fiber is widely used as advanced material in many fields, such as fire protective products, heat resistant filter materials, electric‐insulated materials, and other industrial fabrics 6–9 .…”

Sulfonated polyoxadiazole synthesis and processing into ion‐conducting films

“…38 Copolymers of 1,3,4-oxadiazole can be synthesized by a one-pot method using polycondensation of aromatic dicarboxylic acid with hydrazine sulfate in fuming sulfuric acid. [39][40][41][42][43][44] This allows sulfo-containing monomers to be used for embedding them directly into the chain, bypassing the polymer sulfonation stage. The 1,3,4-oxadiazole copolymers containing DE fragments are characterized by a high glass transition temperature, strength and rigidity, 45 whereas copolymers with S,S-dioxodibenzothiophene fragments have high strength and good thermo-and fire-resistance.…”

“…Copolymers of 1,3,4‐oxadiazole can be synthesized by a one‐pot method using polycondensation of aromatic dicarboxylic acid with hydrazine sulfate in fuming sulfuric acid 39–44 . This allows sulfo‐containing monomers to be used for embedding them directly into the chain, bypassing the polymer sulfonation stage.…”