As one of the first semi-synthetic plastics produced industrially, cellulose acetate (CA)-based artefacts represent valued items in museum collections and archives which, however, present stability issues. High temperature and relative humidity conditions have long been known to promote changes in CA properties, for instance, due to the deacetylation of CA polymer chains and the loss of plasticiser from the polymer matrix. However, there is a need for improved methods for the quantification of plasticiser loss and CA deacetylation. In this context, this contribution presents a new approach for enabling the investigation of plasticiser loss and deacetylation degradation processes in historic plasticised CA-based artefacts which is based on high-resolution proton nuclear magnetic resonance spectroscopy (¹H NMR). The proposed methods allow for simple and fast quantification of diethyl phthalate contents and average degree of substitution (DS), while requiring no need for extractive separation between the plasticiser and the CA polymer matrix prior to analysis. Both methods are demonstrated by their application towards a series of reference samples, historic artefacts and artificially aged plasticised CA materials. Our analysis indicates that plasticiser content and DS can be accurately quantified by using high-resolution ¹H NMR and both methods have been compared to analyses performed using infrared spectroscopy.

作为工业上生产的第一批半合成塑料之一，基于醋酸纤维素（CA）的人工制品代表了博物馆收藏和档案馆中的重要物品，但是，这些物品都存在稳定性问题。长期以来已知高温和相对湿度条件会促进CA性能的变化，例如，由于CA聚合物链脱乙酰化以及聚合物基质中增塑剂的损失。然而，需要用于量化增塑剂损失和CA脱乙酰基的改进方法。在此背景下，这项贡献提出了一种新方法，可用于研究基于高分辨率质子核磁共振波谱的历史可塑CA基人工制品中的增塑剂损失和脱乙酰化降解过程（¹1 H NMR）。所提出的方法可以简单，快速地定量邻苯二甲酸二乙酯含量和平均取代度（DS），而无需在分析之前在增塑剂和CA聚合物基质之间进行萃取分离。这两种方法均适用于一系列参考样品，历史文物和人工时效增塑的CA材料。我们的分析表明，通过使用高分辨率¹ H NMR可以准确定量增塑剂含量和DS，并且已将这两种方法与使用红外光谱法进行的分析进行了比较。