Novel cellulose derivatives. IV. Preparation and thermal analysis of waxy esters of cellulose

✍ Scribed by James E. Sealey; Gamini Samaranayake; Jason G. Todd; Wolfgang G. Glasser

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 657 KB
• Volume: 34
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19960715)34:9<1613::aid-polb10>3.0.co;2-a

✦ Synopsis

Cellulose esters with linear aliphatic acyl substituents ranging in size from CI2 (lauric acid) to C,, (eicosanoic acid) were prepared in homogeneous solution (DMAc/LiCl) using a novel synthetic method based on the use of a mixedp-toluenesulfonic/carboxylic acid anhydride. The resulting waxy cellulose esters had a high degree of substitution (DS), between 2.8 and 2.9, and showed little degradation. Thermal analysis of these cellulose derivatives by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) revealed a series of transitions that represented motion by both ester substituents and cellulosic main chain. Broad crystallization and melting transitions attributed to side-chain crystallinity were observed in the range between -19 and +55"C; these side-chain T , and T, transition temperatures increased by 10°C per carbon atom of the ester substituent. The Tg of these derivatives increased linearly with increasing substituent size from 94°C for Clz (cellulose laurate) to 134OC for Cz0 (cellulose eicosanoate). Evidence of "mainchain" crystallization was not observed for these samples, except in the case of peracetylated C,, and C,, esters, which had T,,, values of 96OC and 107"C, respectively.