| Aluminum diethylphosphinate as a novel class of phosphorous based flame retardants,which was exploited by Clariant company in Germany, has been applied as organic materials for high value-added such as flame-retarded polyamide(PA) and polybutylene terephthalate(PBT). Clariant company applied for a large number of patents about core technology of Al Pi.In this paper, a proprietary intellectual property rights of prepared technology of Al Pi was exploited. The preparation methods and mechanism of flame retardant epoxy resins was studied in this thesis. The main research is as following:(1) Al Pi was synthesized after the following steps:(1) diethyl phosphinic acid was synthesized by free radical reaction of hypophosphorous acid and ethene using azobisisobutyronitrile as evocator after the reaction of sodium hypophosphite and concentrated sulfuric acid in organic solvent;(2) Al Pi was synthesized after the reaction of diethyl phosphinic acid and aluminum sulfate in aqueous solution. The chemical shift ofethylphosphinic acid and diethylphosphinic acid, which was confirmed by31 P NMR, was32.0~36.6 ppm(d, J=502 Hz, D2O) and 56.1 ppm(s, D2O) respectively, The chemical structure of Al Pi was confimed by FT-IR, Solid-State31 P NMR. The T1%(define as the temperature at 1% weight loss) of Al Pi was 329 °C, The T5%(define as the temperature at 5%weight loss) of Al Pi was 418 °C.(2) M-phenylenediamine as curing agent, Al Pi, melamine polyphosphoate(MPP), melamine cyanuate(MCA) and ammonium polyphosphoate(APP) as flame retardant were blended with epoxy resins to prepared a series of flame-retardant EP, respectively. The flame retardance of these materials were evaluated by limiting oxygen index(LOI) and vertical burning(UL-94).The results could be summarized as follows: the same effect of UL-94 V-0 was achieved with the additional volume of 7 wt%,14 wt% and 15 wt% respectively, when using Al Pi, MPP and APP to prepare flame-retardant EP materials; The effect of UL-94 V-1 with the additional volume of 30 wt% was achieved, when using MCA to prepare flame-retardant EP materials;In contrast, best performance of flame retardant was Al Pi.(3) M-phenylenediamine as curing agent, Al Pi/MPP, Al Pi/MCA and Al Pi/APP as composite flame retardant were blended with epoxy resins to prepared a series of flame-retardant EP,respectively. The flame retardancy of these materials were evaluated by limiting oxygen index(LOI) and vertical burning(UL-94). The results show: the best performance of flame retardant was Al Pi/MPP. The same effect of UL-94 V-0 was achieved with the additional volume of 6 wt% and 7 wt%, respectively, when Al Pi and MPP mass ratio was determined as2 : 1 or 1 : 2 to prepare flame-retardant EP materials, respectively, the LOI reached to 31.5%and 26.0%, respectively. On the basis of mass ratio was 2 : 1 of Al Pi and MPP to prepare flame-retardant EP materials, a small amount of aluminium oxide was added in this system,the results show: the same effect of UL-94 V-0 was achieved with the additional volume of 5wt%, when Al Pi, MPP and Al2O3 mass ratio was determined as 18 : 9 : 1, the LOI reached to29%.(4) The flame retardant mechanism were preliminarily deduced via Cone calorimeter(Cone),TG, TG-IR, XPS analysis and FT-IR of carbon analysis among those sample groups(EP/7%Al Pi; EP/7%MPP; EP/4.7%Al Pi/2.3%MPP; EP/2.3%Al Pi/4.7%MPP; EP/4.5% Al Pi/2.25%MPP/0.25% Al2O3). The results could be summarized as follow: the sample of EP/7% Al Pi showed more gaseous phase mechanism than condensed phase; the sample of EP/7% MPP showed condensed phase mechanism without gas phase; the sample of EP/4.7% Al Pi/2.3%MPP showed more gaseous phase mechanism than condensed phase; the sample of EP/2.3%Al Pi/4.7% MPP showed more condensed phase mechanism than gaseous phase; the sample of EP/4.5% Al Pi/2.25% MPP/0.25% Al2O3 showed more condensed phase mechanism than gaseous phase. |
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