Research On Several High Residual Poly(Cyclotriphosphazene Amide)s At High Temperature

Polyphosphazene and its derivatives are a class of novel macromoleculescontaining alternate phosphorus-nitrogen single and double bonds with two changingorganic side groups to be prepared new organic-inorganic hybird materials with awide range of chemical and physical properties, like excellent heat resistance, wearresistance, flame retardant and radicalization resistance performances in many areas.The synthetic process of hexachlorocyclotriphosphazene （HCCP） was improved,firtly. Four high-temperature residual poly（cyclotriphosphazene amide）s weresynthesized to study the mechanism of thermal decomposition and high residualduring high temperature progress. And a series of different phosphazene ringcontents of poly（cyclotriphosphazene-ether amide）s were synthesized to investigatedthe influence of the proportion of phosphazene ring on the characteristics of thermaldecomposition and high-temperature residual. Polycyclotriphosphazene-sulfonemicrospheres were synthesized to evaluate the friction and wear properties of itsmodificated epoxy resin solid lubrication coating, and discussed the wearmechanism.In order to overcome the disadvantage of low yield at direct synthesis andcompound catalyst method, use acid agent method to synthetized HCCP throughPCl₅and NH₄Cl. The reaction time shortened2/3and achieved the yield of82.3%,the sublimation temperature of coarse product was120oC and the purity was99.2%.The influencing factors of reaction such as reaction time, temperature, bind acidagent etc were researched to obtain the best synthesis condition. Used chlorobenzeneas solvent, pyridine as the bind acid agent, nPCl₅:nNH₄Cl:npyridine=1:（1.25-1.3）:（3.0-3.5）, the reaction temperature was130-135oC, thereaction time was2h. Through nucleophilic replace, anotherhexaphenoxycyclotriphosphazene were synthesized. Using FTIR, NMR, XRD, DSCand TGA analyse the structure, purity and thermal performance of the two cyclotriphosphazene derivatives.Four phosphazene-diamines with active end amino groups were synthesized intwo steps from phenol, PPD, ODA, DDS and EDA via nucleophilic substitution andcatalytic reduction with HCCP. Four poly（cyclotriphosphazene amide）s weresynthesized from these diamines by direct polycondensation reaction withterephthaloyl chloride and pyridine in N-methyl pyrrolidinone, respectively. Theinitial decomposition temperature of the4poly（cyclotriphosphazene amide）sbetween198to259°C, the maximum thermal degradation rate between350to400°C, and the solid residual rate at600°C between36.9%to62.6%, respectively. XRDanalysis showed that the poly（cyclotriphosphazene amide）s belong to the amorphousstructure at room temperature. Thermo-gravimetric analysis showed that theintroduction of cyclotriphosphazene structure destroy the conjugation effect betweenbenzene ring and amide groups and the regularity of the main chain, inhibit theformation of hydrogen bond between molecular chain segments and lower initialdecomposition temperature of polyamide, but retard thermal decomposition rate oflate. FTIR, SEM and elemental analysis of high temperature solid residues analysisshowed that lots of phosphorus and P-O-P and P=O bonds in the residues whichprove that phosphazene rings openedand crosslinked at600°C, acid substances weregenerated to promote the aromatic ring carbonization and gel state transition, carpetlayered solid residues covered on polymer surface, impeded the heat transfer andinternal smaller molecules spillover, slowed decomposition late rate and improvedthe rate of solid residues.Using one reactive double end amino TPAPCP, PPD and TPC as reactivemonomers to synthetic a series of containing different proportion of phosphazenering poly（cyclotriphosphazene-ether amide）s via low temperature polycondensationreaction. Crystalline properties of the polymers decreased with the proportion ofphosphazene ring increases. The structure gradually transformed into amorphousfrom crystalline structure, the initial decomposition temperatures were graduallyreduced from467.9°C to198.6°C. But the high-temperature solid residue rate wassignificantly increased at first and then decreased. The introduction of the proportion of phosphazene ring structure is generated acid materials to effectively promote thebenzene ring carbonization and gel state carbide material in the process of thermaldecomposition, and improve the high temperature solid retention rate of the polymer.But with the increase of proportion of phosphazene ring, the acid amount increasedand benzene ring carbonization dehydration seriously, enhanced the consumptionand expansion of blanket carbon layer, which led to lower the high temperature solidretention rate. The hydrophobic properties increased with the introduction of thephosphazene ring structures and the super-hydrophobic was changed fromhydrophilic.One step to synthesize PZs with HCCP and BPS via precipitation polymerization.The initial decomposition temperature of the PZs is457.5°C, solid residual rate is63.09%at600°C, an average particle diameter of493nm and amorphous structureat room temperature. The frictional coefficient of the epoxy/PZs composite coatingreduced from0.61of pure EP to a minimum0.38and the volumetric wear ratereached a minimum13.2×10^-11mm³with3wt.%PZs filling. The SEM morphologyof grinding crack showed that pure epoxy coating reflected a typical adhesive wear.PZs microspheres have an effect of solid lubrication, reduce the friction heat andpromote the proliferation of it. Meanwhile, improve the heat-resisting performanceand reduce the adhesion effect with friction pair, which led to decrease the frictioncoefficientand and reduce the wear rate. In addition, nitrogen and phosphoruselements abundanted in the PZs which rich in in polymer transfer membrane topromote friction chemistry and facilitate solid lubrication function.