Thermal, thermooxidative and photooxidative degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide). Review

Abstract

Thermal, thermooxidative and photooxidative degradations of polyphenylene oxide are reviewed. Emphasis is given to analytical data of volatile products formed during the thermal degradation. Changes of the solid substrate, such as the methyl group oxidation, crosslinking and chain scission, are of particular importance during the thermooxidative and photooxidative degradation. Thermischer, thermooqdativer und photooxydativer Abbau von Poly(2,6-dimethyl-l,C-phenylemxid). FortschrittsberiehtEs wird eine Ubersicht uber den thermischen, thermooxydativen und photooxydativen Abbau von Polyphenylenoxid gegeben. Darin wird insbesondere auf die Analyse der beim thermischen Abbau entstehenden fluchtigen Produkte eingegangen. Weiterhin werden die Anderungen des festen Substrats beim thermooxydativen und photooxydativen Abbau, wie die Oxydation der Methylgruppen, die Bildung von Vernetzungen und die Kettenspaltung, diskutiert. $60moozucdaumeabnaa deempyzym noau-2,6-d~.~emu-l,P-&enunenozcuda. O630p npmenn oco6oe BHHMaHHe ynenseTcrr a~a~n m y neTymx ~POAYKTOB, 0 6 p a~y m~~x c~ B npoqecce TepMH9eCKOft OKHcnnTenbHoB AecTpyKqnH, xax Hanpmep , OKHcneme MeTHJIOBhIX rpynn , CmiBaHne H pacwenneme qenea . aaeTcJ3 0630p no TepMHWCKOi, TePMOOHHCJIHTeJIbHOt H (POTOOHHCJIHTeJIbHOfi AeCTPYKqHH nOJIH(PeHHJIeHOKCHp3, p3CTpyKqHH. KpOMe TOrO, paCCMaTpHBaloTCR H3MeHeHMH IlOJIHMepa B pe3yJIbTaTe TePMOOKHCJIHTeJIbHOa H (POTO- TepNuueczax mepMoorcucaumeaanafi u

Precocene II is no Anti-Juvenile Hormone in the Honey Bee, Apis mellifera

“…However, this hormonal disturbance was not observed in the honey bee, a holometabolous insect. The observation that precocene had no effect on the developm ent of Graphosoma italicum, which is resistant to a large num ber of anti feeding com pounds due to its adaptation for feeding on aromatic seeds of Umbelliferous plants [8 ], also supports that antifeeding effect is the prim ary mode of action of precocene. In the present study, the de creased weight-gains of the treated honey bee larvae are also indicative of antifeeding action of precoce ne.…”

“…We did not observe any change in the duration of larval and pupal pe riods in precocene treated larvae as com pared to the controls. W ith only few exceptions, all the compounds which showed antifeeding effects on larvae also de layed or suppressed the m aturation o f the oocytes in the ovaries o f the adult females [8 ]. Certain antifeedants can produce developmental changes which suggest disturbance o f the endocrine integrity.…”

“…A specific anti-juvenile hormone should suppress or prevent the action of exogenous JH [8 ], or the simultaneous application of both to an insect should result in its normal development. However, according to Bowers [13] mixed application of pre cocene and JH will only show JH effects.…”

“…However, Slama [8 ] concluded that prothetelies in precocene treated seed-feeding hem ipterans were due to its antifeeding action as prothetelic specimens always appeared among the larvae with most inhibit ed growth, close to lethality. Kelly and Fuchs [9] also proposed that precocene does not act as an antigonadotropic agent in adult Aedes aegypti, but in duces a general toxic state in the treated animals.…”

Injection molding of engineering plastics

“…15-In the presence of oxygen at temperatures above 250°C poly(pheny1ene ether) undergoes a rapid oxidation reaction with the formation of gel and colored byproducts. 16 The poly(pheny1ene ether) employed in our study had a number average molecular weight of 20,000, weight average molecular weight of 48,000, and an intrinsic viscosity of 0.46 dL/g in chloroform at 25°C. Its glass transition temperature was measured as 205°C.…”