Departamento de Ingeniería Química, Química Física y Química Orgánica, Campus de El Carmen, Universidad de Huelva, Campus de Excelencia Internacional Agroalimentario, ceiA3, 21071 Huelva, Spain.
Carbohydr Polym. 2013 Oct 15;98(1):152-60. doi: 10.1016/j.carbpol.2013.04.104. Epub 2013 Jun 6.
The -NCO-functionalization of methyl cellulose with HMDI and its application to chemically gel the castor oil is explored in this work by analyzing the influence of functionalization degree on the rheological and thermogravimetric behavior of resulting chemical oleogels. With this aim, different methyl cellulose chemical modifications were achieved by limiting the proportion of HMDI and, subsequently, oleogels were obtained by dispersing these polymers in castor oil and promoting the reaction between those biopolymers and the hydroxyl groups located in the ricinoleic fatty acid chain. -NCO-functionalized methyl cellulose-based oleogels were characterized from themogravimetric and rheological points of view. Suitable thermal resistance and rheological characteristics were found in order to propose these oleogels as promising bio-based alternatives to traditional lubricating greases based on non-renewable resources. In general, -NCO-functionalized methyl cellulose thermally decomposed in three main steps whereas resulting oleogels thermal decomposition takes place in one main single stage which comprises the thermal degradation of both the polymer and the castor oil. Temperature range for thermal degradation is broadened when using highly -NCO-functionalized methyl cellulose. A cross-linked viscoelastic gel was obtained with methyl cellulose functionalized in a relatively low degree (around 6% -NCO molar content). The rheological properties of highly functionalized methyl cellulose-based oleogels evolve during several months of aging, but mainly during the first week, due to the progress of the reaction between -NCO functional groups and castor oil -OH groups. SAOS functions analyzed and oleogel relative elasticity increase with the functionalization degree. Oleogel linear viscoelastic response is also extremely dependent on NCO-functionalized methyl cellulose concentration.
本文探讨了通过分析功能化程度对所得化学油凝胶流变和热重行为的影响，用 HMDI 对甲基纤维素进行-NCO 功能化，并将其应用于蓖麻油的化学凝胶化。为此，通过限制 HMDI 的比例实现了不同的甲基纤维素化学修饰，随后通过将这些聚合物分散在蓖麻油中并促进这些生物聚合物与存在于巴豆油的羟基之间的反应来获得油凝胶。从热重和流变学的角度对-NCO 功能化的甲基纤维素基油凝胶进行了表征。为了提出这些油凝胶作为有前途的基于生物的传统基于不可再生资源的润滑脂的替代品，找到了合适的耐热性和流变特性。一般来说，-NCO 功能化的甲基纤维素在三个主要步骤中热分解，而所得的油凝胶的热分解发生在一个主要的单一阶段，其中包括聚合物和蓖麻油的热降解。当使用高度-NCO 功能化的甲基纤维素时，热降解温度范围变宽。用相对低程度（约 6％-NCO 摩尔含量）功能化的甲基纤维素获得了交联的粘弹性凝胶。高度功能化的甲基纤维素基油凝胶的流变性质在几个月的老化过程中发生变化，但主要在第一周内，这是由于-NCO 官能团和蓖麻油-OH 基团之间的反应进展。分析了 SAOS 函数，并且随着功能化程度的增加，油凝胶的相对弹性增加。油凝胶的线性粘弹性响应也非常依赖于-NCO 功能化的甲基纤维素浓度。
