Piccolo Anna, Tomasin Patrizia, Zoleo Alfonso, Miorin Enrico, Nodari Luca
Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padua, Italy.
Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council (ICMATE-CNR), C.so Stati Uniti 4, 35127 Padua, Italy.
Polymers (Basel). 2025 Jun 13;17(12):1648. doi: 10.3390/polym17121648.
The role of humidity on the ageing of celluloid is investigated by performing accelerated ageing tests on mock-up samples. At 70 °C, three levels of relative humidity (RH) are selected: 30%, 50%, and 70%. Samples are monitored for the macro- and micro- changes occurring through ageing to relate the visible modifications to the molecular ones. Infrared and Raman spectroscopy, microscopy, mass and contact angle measurements, profilometry, and colourimetry are combined for this purpose. While the ageing test at 30% RH results in a slight embrittlement of the samples and small spectral changes, the one at 50% RH induces significant modifications at the molecular level and the formation of cracks, while the one at 70% RH causes a fast deformation of the samples and the development of bubbles. Although quite diverse, such results prove to be related to the same chemical processes: denitration, chain scission, and oxidation. These occur more promptly or extensively based on humidity level, resulting in different outcomes. Beyond morphology and brittleness, macroscopic effects also involve mass loss, surface roughening, and yellowing. A possible correlation between the macro and micro modifications is present, highlighting the influence humidity has on the degradation process of celluloid.
通过对模型样品进行加速老化试验，研究了湿度对赛璐珞老化的影响。在70°C下，选择了三个相对湿度（RH）水平：30%、50%和70%。对样品进行监测，以观察老化过程中发生的宏观和微观变化，从而将可见的变化与分子层面的变化联系起来。为此，结合了红外和拉曼光谱、显微镜、质量和接触角测量、轮廓测定法和比色法。在30%RH的老化试验中，样品会出现轻微脆化和微小的光谱变化，而在50%RH的试验中，会在分子水平上引起显著变化并形成裂纹，在70%RH的试验中，则会导致样品快速变形并产生气泡。尽管结果差异很大，但这些结果都与相同的化学过程有关：脱硝、断链和氧化。这些过程会根据湿度水平更迅速或更广泛地发生，从而导致不同的结果。除了形态和脆性外，宏观影响还包括质量损失、表面粗糙度增加和变黄。宏观和微观变化之间存在可能的相关性，突出了湿度对赛璐珞降解过程的影响。
