The scope of the present article is to study the effect of surface functionalization of SiO₂ nanoparticles on the dynamic mechanical, thermal and fire properties of wheat straw flour (WSF) reinforced low-density polyethylene (LDPE) composites. Firstly, the SiO₂ nanoparticles were modified by 3-aminopropyl-trimethoxysilane (APTMS), and then the WSF/LDPE composites containing different percentages of modified nano-SiO₂ were prepared via a melt compounding using an internal mixer followed by injection molding. Changes in the chemical structure of treated SiO₂ were tracked by Fourier transform infrared (FTIR). The appearance of N–H bond at 695 cm⁻¹ and aliphatic C–H bonds at 2841 cm⁻¹ and 2947 cm⁻¹ were indications of successful grafting of APTMS on the SiO₂ nanoparticles. Finally, the viscoelastic behavior, thermal stability and fire retardancy of the nanocomposites were evaluated by means of DMTA, TGA, DSC and CCT techniques. Results indicated that the dynamic modulus of the composites was greatly improved through the addition of functionalized SiO₂ nanoparticles. In general, the specimens filled with 3 phr modified nano-SiO₂ showed the highest values of storage and loss modulus compared with the other ones. Moreover, the tan δ peak signifying the glass transition temperature of nanocomposites shifted to higher temperature. The TGA results demonstrated that the introduction of APTMS grafted SiO₂ nanoparticles can distinctly enhance thermal stability of the composites by increasing the thermo-oxidation decomposition temperature and char residues. The maximum activation energy value represents a higher thermal stability of the nanocomposites was obtained with modified nano-SiO₂ at 5 phr content. In addition, the DSC data revealed that both the melting temperature and the degree of crystallinity of the specimens tended to substantially increase in presence of modified nano-SiO₂. The surface functionalization of SiO₂ particles produced remarkable evolution in the fire performance as indicated by reductions in the heat release rate, burning rate and mass loss rate. Furthermore, promoting the time to ignition and limiting oxygen index of the specimens equally to accommodate the addition of treated SiO₂ nanoparticles.

中文翻译：

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SiO 2纳米粒子的表面功能化对麦草/ LDPE复合材料动态力学，热学和燃烧性能的影响

本文的范围是研究SiO ₂纳米颗粒的表面功能化对小麦草粉（WSF）增强的低密度聚乙烯（LDPE）复合材料的动态力学，热学和燃烧性能的影响。首先，通过3-氨基丙基-三甲氧基硅烷（APTMS）对SiO ₂纳米颗粒进行改性，然后使用内部混合器通过熔体配混然后注射成型制备包含不同百分比的改性纳米SiO ₂的WSF / LDPE复合材料。通过傅立叶变换红外光谱（FTIR）跟踪处理过的SiO ₂的化学结构变化。在695 cm ^-1处出现N–H键，在2841 cm ^-1处出现脂肪族C–H键和2947 cm ^-1是成功将APTMS接枝到SiO ₂纳米颗粒上的迹象。最后，通过DMTA，TGA，DSC和CCT技术评估了纳米复合材料的粘弹性，热稳定性和阻燃性。结果表明，通过添加功能化的SiO ₂纳米粒子，可以大大提高复合材料的动态模量。通常，与其他样品相比，填充有3 phr改性纳米SiO ₂的样品显示出最高的储能值和损耗模量。此外，表示纳米复合材料的玻璃化转变温度的tanδ峰转移到更高的温度。TGA结果表明APTMS接枝SiO ₂的引入纳米颗粒可以通过提高热氧化分解温度和残炭来显着提高复合材料的热稳定性。最大活化能值表示用5 phr含量的改性纳米SiO ₂获得的纳米复合材料具有较高的热稳定性。另外，DSC数据表明，在存在改性的纳米SiO _2的情况下，样品的熔融温度和结晶度均趋于大幅增加。SiO ₂的表面官能化颗粒的放热速率，燃烧速率和质量损失速率降低表明，其防火性能显着提高。此外，延长点火时间并同样限制样品的氧指数，以适应处理过的SiO ₂纳米粒子的添加。