Indian Institute of Technology Roorkee, Roorkee, India.
Department of Paper Technology, Indian Institute of Technology Roorkee, Saharanpur Campus, India.
Sci Rep. 2023 Apr 20;13(1):6426. doi: 10.1038/s41598-022-23898-z.
Paper and packaging materials a lignocellulose-based natural biodegradable polymer that spontaneously releases acetic acid, aldehydes, alcohol, and ester-based volatile organic compounds (VOCs) upon ageing and these VOCs start degrading the paper products and decline their mechanical strength properties. The reactivity of the paper of unbleached wheat straw pulp towards acetic acid and hexanal, which has been proven to have more degrading effects on paper than other VOCs, was considered in this work. The papers were exposed to these volatile compounds for 90 days in an air-tight vessel under ambient environmental conditions. The results showed that hexanal was more destructive than acetic acid with regards to cellulose degradation and depletion in the mechanical strength properties. The paper properties like, tensile, tear and burst index, viscosity, pH and carbonyl group content was measured. The growth of the carbonyl group, evidence of the ageing effects in the paper, detected more in the paper exposed to acetic acid. However, the strength of paper properties declined more with hexanal. FE-SEM analysis of the sample showed the development of pores and damage of cellulose fibre upon ageing. Similarly, the damaging effects of VOCs on cellulose, hemicelluloses and lignin were confirmed by significantly reduced peak detection through FT-IR \analysis. The high crystallinity index of the paper products due to exposure to VOCs was detected by XRD analysis, which confirmed the degradation of the low molecular weight cellulose molecule. Thus, the results are strongly recommended that VOCs that generates due to natural or artificial ageing could be the leading cause of paper degradation.
纸张和包装材料是一种基于木质纤维素的天然可生物降解聚合物，会在老化时自发释放出乙酸、醛、醇和酯类挥发性有机化合物（VOCs），这些 VOCs 会开始降解纸制品并降低其机械强度性能。本工作中考虑了未漂麦草浆纸对乙酸和己醛的反应性，这两种 VOC 已被证明对纸的降解作用比其他 VOC 更强。将这些挥发性化合物在密封容器中于环境条件下放置 90 天，使纸张暴露于这些挥发性化合物中。结果表明，与乙酸相比，己醛对纤维素的降解和机械强度性能的损耗更具破坏性。测量了纸张的拉伸、撕裂和耐破指数、粘度、pH 值和羰基含量等性能。在暴露于乙酸的纸张中检测到更多的羰基增长，这是纸张老化效应的证据。然而，纸张性能的强度下降更多是由于己醛。FE-SEM 分析表明，在老化过程中，纤维素纤维出现了孔和损伤。同样，FT-IR 分析也证实了 VOC 对纤维素、半纤维素和木质素的破坏作用，因为通过分析明显减少了峰值的检测。通过 XRD 分析检测到纸制品由于暴露于 VOC 而具有较高的结晶度指数，这证实了低分子量纤维素分子的降解。因此，强烈建议生成于自然或人工老化的 VOC 可能是纸张降解的主要原因。
