Various PVA/nanoclay hydrogel nanocomposites with different weight fractions of nanoclay (0, 0.25, 0.5, 0.75 and 1) were prepared, characterized and their performances were investigated. The structures of the synthesized hydrogel nanocomposites and the samples loaded with a potassium phosphate fertilizer were proved by FTIR spectroscopy method. The interactions between the hydrogels and nanoclay and also the effect of fertilizer loading capacity on the nanocomposites were investigated using TGA method. TGA showed that the loading of the fertilizer decreased the hydrogel weight loss which was affected by the nanoclay weight percent. In addition, the effects of glutaraldehyde as crosslinking agent and incorporation of the nanoclay and fertilizer on the glass transition temperature of the prepared hydrogels were studied using DSC method. The Tg of the hydrogels increased by adding the nanoclay and decreased with the loading of the fertilizer. The SEM images showed that the microstructure and morphology of the hydrogel changed in the presence of the nanoclay and fertilizer. The increase of the nanoclay decreased the porosity of the hydrogel and made it denser. Furthermore, the EDX spectroscopy images of the samples proved the uniform dispersion of the fertilizer and nanoclay in the prepared hybrid hydrogels. The swelling of the hydrogels decreased with increasing of the nanoclay weight percent. The results showed that the swelling under load was the highest for the hydrogel nanocomposite with 0.5 wt% of the nanoclay. The increase of the nanoclay led to increasing of the physical networking that caused more desirable controlled release of the fertilizer.

中文翻译：

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PVA /纳米粘土水凝胶纳米复合材料的制备及其对磷钾肥释放行为的微观结构影响

制备了具有不同重量分数的纳米粘土（0、0.25、0.5、0.75和1）的各种PVA /纳米粘土水凝胶纳米复合材料，并对其性能进行了研究。通过FTIR光谱法证实了合成的水凝胶纳米复合材料的结构和负载磷钾肥的样品。利用TGA方法研究了水凝胶与纳米粘土之间的相互作用以及肥料负载量对纳米复合材料的影响。TGA表明，肥料的加入减少了水凝胶的重量损失，水凝胶的重量损失受到纳米粘土重量百分比的影响。此外，使用DSC方法研究了戊二醛作为交联剂以及纳米粘土和肥料的掺入对制备的水凝胶的玻璃化转变温度的影响。水凝胶的Tg通过添加纳米粘土而增加，并且随着肥料的负载而降低。SEM图像表明，在存在纳米粘土和肥料的情况下，水凝胶的微观结构和形态发生了变化。纳米粘土的增加降低了水凝胶的孔隙率并使其更致密。此外，样品的EDX光谱图像证明了肥料和纳米粘土在制备的混合水凝胶中的均匀分散。水凝胶的溶胀随着纳米粘土重量百分比的增加而降低。结果表明，具有0.5wt％的纳米粘土的水凝胶纳米复合材料在负载下的溶胀最高。纳米粘土的增加导致物理网络的增加，这导致了更理想的肥料控释。