Papers by Keyword: Crystalline Form

Abstract: Ammonium polyphosphate (APP) produced by non-P2O5 process and traditional P2O5 process were used in the intumescent flame retardant (IFR) polypropylene (PP) composite (IFR-PP). The composite was tested by limited oxygen index (LOI) and UL-94. TGA and SEM were used to study the decomposition processes. Results showed that when the ratio of APP-II/ pentaerythritol/melamine is 3/1/1, the LOI value is 33.1, and all composite could reach UL-94 V0 rating. The results showed that APP by non-P2O5 process had similar IFR properties as APP of traditional P2O5 process

Abstract: Ammonium polyphosphate form V (APP-V) is prepared by melting phosphoric acid and melamine in ammonia atmosphere. The effect of dehydration temperature is studied by detailed investigation of the XRD patterns during the synthesis process. Results show that temperature higher than 3000C is suitable for preparation of APP-V. However, some impure other crystals are still coexisted in the synthesized product. The results are informative for controllable preparation of APP in industrial production

Abstract: A non-P2O5 process to prepare ammonium polyphosphate is studied in this paper, the effect of raw materials is investigated. The XRD spectra of synthesized product are studied in detail. Results show that when the ratio of Mono-ammonium hydrogen phosphate to urea is 0.8:1, ammonium polyphosphate form V is the mostly occurrence. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonium polyphosphate (APP) is a long chain polyphosphate salt, it has six crystalline forms. In preparation of APP, temperature is significant to controllably obtain a certain crystalline forms. In this paper, the effect of temperature is investigated during the preparation process of APP. Some intermediates are detected, the XRD spectra of these intermediates are discussed. The results show that temperature at 2800C is suitable for preparation of form II. With temperature increasing, water insolubility increases. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonia atmosphere is significant to controllably obtain a certain crystalline forms. In this paper, the effect of ammoniating rate is investigated. Some intermediates are detected during the preparation process of APP, the XRD spectra of these intermediates are discussed. The results show that low ammoniating rate is suitable for preparation of APP form II. With ammoniating rate increasing, most of the crystals transform to APP V in the intermediate and water insolubility of the product increases. The results are informative for controllable preparation of APP in industrial production.

Abstract: Detection of intermediates is the general way to investigate a reaction mechanism, because the intermediates connect the reactants and the products, the intermediates can reflect some internal relationships between the reactants and the products. By studying the the structures of intermediates, the reaction process and reaction mechanism can thus be understood. Ammonium polyphosphate (APP) is an effective material as halogen-free flame retardants, it has six crystalline forms.In preparation of APP, the factor of temperature raising rate is investigated, some intermediates are detected, the XRD spectra of these intermediates are discussed. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonium polyphosphate have six crystalline forms, of them, form I and form II have industrial uses, their flame retardant properties have been studied extensively. Form V is seldom studied, its flame retardant is not fully known. In this paper, the flame retardant effects of ammonium polyphosphate with crystalline form II (APP-II) and crystalline form V (APP-V) in polypropylene were tested. Results show that the flame retardant effect of APP-V is better than APP-II, and has better mechanical strength that APP-II, meaning it should has a good market perspective in field of halogen-free flame retardation.

Abstract: Ammonium polyphosphate (APP) is usually synthesized by heating diammonium hydrogen phosphate and phosphorus pentaoxide at ammonia atmosphere, in which phosphorus pentaoxide is used as condensing agent. In this paper, a new process is pointed out in which APP is synthesized by heating diammonium hydrogen phosphate and melamine to a certain temperature at ammonia atmosphere, melamine is used as the sole condensing agent, the XRD patterns of synthesized product are investigated and discussed in detail. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonium polyphosphate (APP) has six crystalline forms, in which form II is commercially applied as flame retardant in engineering plastics such as PP and ABS, form V is extensively studied recently. In preparation of APP, the reaction atmosphere is significant to controllably obtain a certain crystalline forms. In this paper, the effect of wet ammonia is investigated. The results show that low concentration of wet ammonia is suitable for preparation of form II, while dry ammonia is suitable for preparation of form V. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonium polyphosphate (APP) with crystalline form II is usually synthesized in temperature 280-3100C, APP with crystalline form V is usually synthesized in temperature 340-3500C. By process of diammonium hydrogen phosphate, the effect of temperature on crystalline forms of APP was studied and discussed in detail. The results were informative for controllable preparation of APP in industrial production.