Investigations on the pyrolysis and potential flame retardancy imparted by solvent-free and semi-dry phosphorylation of different starches using sodium orthophosphates were conducted. The samples – low-substituted starch phosphates (SP) with degrees of substitution DS_P < 0.5 - were subjected to differential scanning calorimetry, thermogravimetry coupled with evolved gas analysis and pyrolysis – gas chromatography – mass spectrometry. The data obtained as well as features of charring residues examined using microscopic and spectroscopic methods were related to structural aspects of SP – analysed by means of various spectroscopic techniques - and compared with those of native starches. It was found that charring and polyphosphate formation and the thermal resistance of the solid SP residues increased significantly if the DS_P was at least 0.1. Accordingly, the exothermal decomposition, the temperature-induced loss of mass and the decomposition rates of SP decreased distinctly compared to native starch. The activation temperatures of SP and the formation of low-molecular pyrolysis products including aliphatic, cyclic, and aromatic aldehydes and ketones as well as anhydrosugars decreased markedly, even at DS_P < 0.1. The results confirm the potential flame-retardancy of SP achieved by flame-inhibiting effects, despite low phosphorylation degrees, in both the gas and condensed phases.

中文翻译：

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低取代淀粉磷酸盐的热解和潜在阻燃性研究


研究了使用正磷酸钠对不同淀粉进行无溶剂和半干磷酸化所赋予的热解和潜在的阻燃性。样品 - 取代度为 DS_P < 0.5 的低取代淀粉磷酸盐 （SP） - 进行差示扫描量热法、热重分析结合逸出气体分析和热解 - 气相色谱 - 质谱法。使用显微和光谱方法检查的数据以及炭化残留物的特征与 SP 的结构方面有关——通过各种光谱技术进行分析——并与天然淀粉的结构进行比较。结果发现，如果 DS_P 至少为 0.1，则炭化和多磷酸盐的形成以及固体 SP 残基的热阻显着增加。因此，与天然淀粉相比，SP 的放热分解、温度诱导的质量损失和 SP 的分解速率明显降低。SP 的活化温度和低分子热解产物（包括脂肪族、环状和芳香族醛和酮以及无糖）的形成显着降低，即使在 DS_P < 0.1 时也是如此。结果证实了 SP 在气相和冷凝相中通过阻燃作用实现的潜在阻燃性，尽管磷酸化程度较低。