Cellulose Esters, Organic

Abstract

Cellulose is one of nature's most abundant structural materials, providing the primary framework of most plants. For industrial purposes cellulose is derived from two primary sources, cotton linters and wood pulp. Cellulose esters are commonly derived from natural cellulose by reaction with organic acids, anhydrides, or acid chlorides. Cellulose esters of almost any organic acid can be prepared, but because of practical limitations esters of acids containing more than four carbon atoms have not achieved commercial significance. Cellulose acetate is the most important organic ester because of its broad application in fibers and plastics; it is prepared in multi‐ton quantities with degrees of substitution (DS) ranging from that of hydrolyzed, water‐soluble monoacetates to those of fully substituted triacetate. Although cellulose acetate remains the most widely used organic ester of cellulose, its usefulness is restricted by its moisture sensitivity, limited compatibility with other synthetic resins, and relatively higher processing temperature. Cellulose esters of higher aliphatic acids, C 3 and C 4 , circumvent these shortcomings with varying degrees of success. Mixed cellulose esters containing acetate and either the propionate or butyrate moieties are produced commercially in large quantities by Eastman Chemical Co. in the United States. The properties, manufacturing methods, uses, economics, and safety of organic esters of cellulose are discussed.

Ionic liquid mediated technology for synthesis of cellulose acetates using different co-solvents

“…It was only in one case (SCA5) that the resulting cellulose acetate was insoluble in CH 2 Cl 2 or CHCl 3 due to partial substitution. These observations are partly consistent with literature data (Edgar, 2004). According to the previous investigations; cellulose acetates with DS <2.7 are supposedly insoluble in CH 2 Cl 2 or CHCl 3 .…”

Cellulose Acetate for Thermoplastic Foam Extrusion

“…For these tests, an externally plasticized CA compound with 20 wt.-% of glycerol triacetate (GTA) was produced because of a good balance between melt processing, melt flow, melt extensibility, and melt strength. The compound were prepared by means of a co-rotating twinscrew extruder (TSA EMP [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] with an L/D of 40/1. The screw speed was set at 250 rpm and the throughput was fixed at 10 kg h -1 .…”

“…At first, cellulose is activated and fully acetylated to cellulose triacetate (CTA). In a second step, a specific amount of water is added to CTA and the induced partial hydrolysis leads to partially substituted cellulose acetate [28,29]. Cellulose acetates with a degree of substitution (DS) between 2.0 to 2.7 are usually used for thermoplastics [29].…”

“…Cellulose acetates with a degree of substitution (DS) between 2.0 to 2.7 are usually used for thermoplastics [29]. The specific gravity of CA is about 1.30 g cm -3 and the refractive index is 1.48 [28]. In Figure 1, the general structure of cellulose acetate is shown.…”

Extrusion foaming of thermoplastic cellulose acetate sheets with HFO‐1234ze and co‐blowing agents

“…The production of thermoplastic CA includes esterification of the raw cellulose material, followed by partial alkaline hydrolysis of the primary cellulose triacetate. Thermoplastic CA has a degree of substitution of 2.4–2.5 . External plasticizers have to be added to lower the processing temperature below the decomposition temperature .…”