| In this paper, benzoxazine/naphthoxazine precursor was synthesized from aniline,phenol,2-naphthol and formaldehyde under solvent and solvent-free conditions. And thispaper also discusses the effects of the order of material addition, the reaction temperatureand the reaction time and stirring rate on synthesis of a naphthoxazine(benzoxazine)precursor, studies the new methods of reversed-phase suspensionsolidification and directional solidification on polar solid surface of benzoxazine andnaphthoxazine in methysilicone oil, the effects of curing medium property, solidificationtemperature and heating rate on the nature of curing product is investigated. At the sametime, we tested the absorption of UV of curing product with Nicolet Evolution 300 (USAThermoelectric Group) UV spectrometer, the shape, appearance and the surfacecomposition of reversed-phase suspension curing product with SIRION scanning electronmicroscope (Philips), the thermal stability of curing product with NETZSCH TG 209thermal analyzer respectively. The "clean" surface of spherical resin is obtained by thereversed-phase suspension solidification of naphthoxazine, then the resin is sulphonate bysulphuric acid to generate resin acid catalyst and the catalytic activity of the resin acid isevaluated by the esterification reaction of glacial acetic acid and ethanol. Lastesterification rate is measured by using HATACHI163 Gas Chromatograph.The results show: (1)The order of material addition is, formaldehyde and aniline, thenphenol,2-naphthol with the stirring rate(30-40r/s) when benzoxazine/naphthoxazineprecursor was synthesized under solvent condition. (2) The best curing medium ismethysilicone oil when spherical resin is obtained by the reversed-phase suspensionsolidification reaction of benzoxazine/naphthoxazine.(3) Curing product has strongerability of absorption of UV than general curing product. The range of absorptionwavelength is 250-450 nm and absorbance is from 5 to 6.(4) The thermal stability ofpolymers is highest at 180℃in the range of curing temperature at general curing conditionand, the thermal stability of polymers increases as the temperature increases under 180℃.Above 180℃the thermal stability of polymer reduces as curing temperature increases. Indirectional solidification condition, the thermal stability of polymer reduces with thecuring temperature increased; At general curing condition , the temperature of heatweight loss 5% is at 290℃., whereas the thermal stability of curing product is highest at1500C directional solidification in the range of curing temperature and the temperature ofheat weight loss5% is at 340℃; Spherical polynaphthoxazine has obviously heatweight loss till at 300℃, heat weight loss less than 40% at 600℃. But under generalcuring at 200℃, polynaphthoxazine starts showing obviously heat weight loss at 200 ℃, heat weight loss greater than 60% at 600℃. (5) The conversion rate of glacial aceticacid is 78.7%. at sulfonation reaction temperature 45℃, reaction time 2h and catalystdosage of spherical naphthoxazine 4.8% (on glacial acetic acid mass).The new methods of reversed-phase suspension solidification and directionalsolidification of benzoxazine/naphthoxazine precursor are explored, meanwhile the newnature of benzoxazine at this new type of curing conditions is investigated, and theapplication areas of benzoxazine and naphthoxazine resin will be enlarged.
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