New methods for acylation of pure and sawdust‐extracted cellulose by fatty acid derivatives—Thermal and mechanical analyses of cellulose‐based plastic films

Abstract

This work deals with the synthesis of cellulosic plastic films obtained in homogeneous conditions by microwave-induced acylation of commercial or chestnut tree sawdust cellulose by fatty acids. The acylation reaction was studied according to N,N-dimethyl-4-aminopyridine (DMAP) amount, DMAP simultaneously playing the role of catalyst and proton trapping base. This study clearly showed that DMAP does not influence degrees of substitution (DS), massic, and molar yields. Plastic films synthesized in the absence of DMAP showed a decrease in mechanical behavior. Organic (tributylamine) or inorganic bases (CaCO 3 , Na 2 CO 3 ) were then added to replace DMAP basic activity, and no changes were observed. Concerning thermal and mechanical properties of plastics obtained with various bases, glass transition temperatures (T g ) and degradation temperature (T d ) were found constant whatever the base, and the best mechanical properties were obtained for films synthesized in the presence of CaCO 3 . The same remarks were made concerning the valorization of chestnut tree sawdust cellulose. Microbial biodegradation of plastic films with DS ϭ 2.2 led to a loss of their mechanical behaviors.

Synthesis of Cellulose Fatty Esters as Plastics—Influence of the Degree of Substitution and the Fatty Chain Length on Mechanical Properties

“…1 H NMR spectroscopy was performed using a Bruker DRX-300 Spectrometer (operating at 300 MHz) on solutions in CDCl 3 to determine the degree of substitution (DS) by an integration method described elsewhere. [8] The degree of substitution is defined as the number of fatty chains attached per anhydroglucose unit (maximum value of 3).…”

“…Additionally, the appearance of a new peak at 3010 cm À1 (CH anti-symmetric stretching) was observed which is characteristic of the unsaturated function (H-C=C) of the oleic chain. 1 H NMR spectroscopy was used to determine the degree of substitution [8] for each of the cellulose esters prepared and to elucidate the presence of the fatty chains on the cellulose backbone ( Table 2). The …”

“…Similar approaches were used with cellulose in LiCl/DMAc and fatty acyl chlorides under microwave irradiation in the presence of the basic catalyst N,N-dimethyl-4-aminopyridine (DMAP). [8,13] These reactions led to cellulose esters with a high DS value and a reduced synthesis time.…”

“…These plant biopolymer products could be construed as resulting from green chemistry and can potentially replace the plastics obtained from petrochemistry. In addition, cellulose fatty esters can be converted into plastics [8] that have interesting mechanical characteristics. [9] There are different ways to acylate cellulose with fatty substituents.…”

Thermal Properties and Thermal Degradation of Cellulose Tri-Stearate (CTs)

“…However, acylation of cellulose with acyl chlorides in DMA/LiCl by microwave irradiation gave esters with a DS approaching 3 in times as short as 3 min [9,10]. Microwave-induced acylation of cellulose by fatty acids or acyl chlorides was a rapid method to prepare LCCEs [9][10][11]. One of the potential disadvantages of the acylation of cellulose with acyl chlorides was the degradation of cellulose or cellulose esters for the existence of HCl produced in the reaction [3].…”