Degree of -acetylation

Degree of acetylation is often expressed as percent combined acetic acid. 

The product at this stage is referred to as secondary cellulose acetate. Different degrees of acetylation are required for different end-products and these are indicated in Table 22.3. 

It makes the polymer less polar—the polarity depending on the degree of acetylation. 

The greater the molecular weight the higher is the flow temperature and the heat distortion temperature. Variations in molecular weight, in the normal range, however, have less effect than do variations in the degree of acetylation and in the plasticiser used. 

Figure 22.4. Effect of degree of acetylation on (a) hardness, (b) water absorption, (c) impact strength and (d) flow temperature. (31% plasticiser content) (Hercules Powder Co. literature)...

In the linear konjac mannan, the degree of acetylation profoundly affects the solubility and flow properties of this hydrocolloid. The acetyl substitution prevents self-association of the mannan chains, but following deacetylation chain interactions become more energetically favorable [230]. 

A novel fiber-reactive chitosan derivative was synthesized in two steps from a chitosan of low molecular weight and low degree of acetylation. First, a water-soluble chitosan derivative, N-[(2-hydroxy-3-trimethylammonium)-... 

Table 4. Sugar composition (mol%) and degree of acetylation (DA) and methylation (DM) of the pectic substrates.

Figure 2. Degree of methylation (DM) and degree of acetylation (DAc) of the total pectin of fresh and canned carrots...

Degree of methylation (DM%) and degree of acetylation (DAc%) of the pectin fractions of carrots canned by conventional and by a new process in the presence of CaCk Fraction Fresh Conv. Conv.+ New +... 

Interactions studies between some divalents metal ions and pectins from citms and sugar-beet revealed that the chemical structure of the latter, namely the presence of acetyl functions, induces differences of binding process whereas the scale of selectivity was not affected. Some further studies could be carried out on the correlation between the binding mode and the degree of acetylation. Lastly, pectins showed a clear scale of selectivity towards heavy metals with high capacities of binding which make them suitable to be used in waste-waters depollution. 

Mark returned to research after the modernization program was organized and operating smoothly. Limited to cellulose chemistry by the necessity of commercial feasibility, he studied cellulose acetate and the effect of the degree of acetylation on product solubility. At the same time he worked closely on the development of suitable analytical methods to measure molecular weight distribution and the degree of functionality. 

Cellulose and Acetylated Cellulose These adsorbents are commercially available in various forms e.g., particle size, degree of acetylation, with or without binders like starch or Plaster of Paris. 

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