Elrefaey Ibrahim, Mahgoub Hend, Vettorazzo Chiara, Marinšek Marjan, Meden Anton, Jamnik Andrej, Tomšič Matija, Strlič Matija
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, 1000 Ljubljana, Slovenia.
ARCHES Research Group, University of Antwerp, Blindestraat 9, 2000 Antwerp, Belgium.
Polymers (Basel). 2024 Aug 30;16(17):2481. doi: 10.3390/polym16172481.
In the 19th century, the weighting of silk with metal salts, such as tin, was a common practice to enhance certain properties of silk fabrics and compensate for the weight loss incurred during the degumming process. This technique induces both physical and chemical modifications to the fibres, contributing to their long-term degradation, which requires thorough investigation. This study aims to examine the structural changes in silk fibres caused by the accumulation of metal salts from the tin-weighting process, using mock-up samples prepared through successive loading with weighting agents using a traditional tin-phosphate treatment method. Unweighted and tin-weighted silk samples were compared using scanning electron (SEM) micrographs, which presented the dispersed nanoparticles on the fibres, while through energy-dispersive X-ray spectroscopy (EDS) elemental mapping, the presence and uniform distribution of the weighting agents were confirmed. Fourier-transform infrared spectroscopy (FTIR) analysis revealed structural changes in tin-weighted silk samples compared to untreated ones, including shifts in amide bands, altered water/hydroxyl and skeletal stretching regions, and increased skeletal band intensities suggesting modifications in hydrogen bonding, β-sheet content, and structural disorder without significantly impacting the overall crystallinity index. X-ray diffraction (XRD) analysis of both pristine and tin-weighted silk samples revealed significant alterations, predominantly in the amorphous regions of the silk upon weighting. These structural changes were further examined using small-angle X-ray scattering (SAXS) and small- and wide-angle X-ray scattering (SWAXS), which provided detailed insights into modifications occurring at the nanometre scale. The analyses suggested disruptions in β-sheet crystals and intermolecular packing, especially in the amorphous regions, with increasing amounts of tin-weighting. Contact angle analysis (CA) revealed that the tin-phosphate-weighting process significantly impacted silk surface properties, transforming it from moderately hydrophobic to highly hydrophilic. These changes indicate that the incorporation of tin-phosphate nanoparticles on and within silk fibres could restrict the flexibility of polymer chains, impacting the physical properties and potentially the degradation behaviour of silk textiles. By studying these structural changes, we aim to deepen our understanding of how tin-weighting impacts silk fibre structure, contributing valuable insights into the longevity, conservation, and preservation strategies of silk textiles in the context of cultural heritage.
在19世纪，用金属盐（如锡）对丝绸进行增重处理是一种常见的做法，目的是增强丝绸织物的某些性能，并弥补脱胶过程中造成的重量损失。这种技术会对纤维产生物理和化学改性，导致其长期降解，这需要进行深入研究。本研究旨在通过使用传统的磷酸锡处理方法，通过连续加载增重剂制备的模拟样品，研究锡增重过程中金属盐积累对丝绸纤维结构的影响。使用扫描电子显微镜（SEM）图像对未增重和锡增重的丝绸样品进行比较，SEM图像显示了纤维上分散的纳米颗粒，而通过能量色散X射线光谱（EDS）元素映射，确认了增重剂的存在和均匀分布。傅里叶变换红外光谱（FTIR）分析表明，与未处理的丝绸样品相比，锡增重的丝绸样品发生了结构变化，包括酰胺带的位移、水/羟基和骨架伸缩区域的改变，以及骨架带强度的增加，这表明氢键、β-折叠含量和结构无序发生了变化，但对整体结晶度指数没有显著影响。对原始丝绸样品和锡增重丝绸样品的X射线衍射（XRD）分析显示出显著变化，主要是在增重后丝绸的无定形区域。使用小角X射线散射（SAXS）以及小角和广角X射线散射（SWAXS）对这些结构变化进行了进一步研究，这提供了对纳米尺度上发生的改性的详细见解。分析表明，随着锡增重剂用量的增加，β-折叠晶体和分子间堆积受到破坏，尤其是在无定形区域。接触角分析（CA）表明，磷酸锡增重过程显著影响了丝绸的表面性能，使其从适度疏水转变为高度亲水。这些变化表明，在丝绸纤维表面和内部引入磷酸锡纳米颗粒可能会限制聚合物链的灵活性，影响丝绸纺织品的物理性能以及潜在的降解行为。通过研究这些结构变化，我们旨在加深对锡增重如何影响丝绸纤维结构的理解，为文化遗产背景下丝绸纺织品的寿命、保护和保存策略提供有价值的见解。
