Cellulose thermal stability

See CALORIMETRY, CELLULOSE, THERMAL STABILITY OF REACTION MIXTURES AND... 

TGA is a thermal method that measures the weight loss as a function of temperature or time. Polypropylene decomposes at a lower temperature than polyethylene because of the substitution of a methyl group. Some works showed an increase of the degradation temperature of composites with the addition of carbon nanotubes and other synthetic fibers [52]. PE with natural fiber composites show two steps degradation processes because of cellulose, Thermal stability of PE/cellulosic fiber composites decreases with increase in fiber loading, showing two degradation processes. However,... 

A composition containing polyanionic cellulose and a synthetic polymer of sulfonate has been tested for reducing the fluid loss and for the thermal stabilization of a water-based drilling fluid for extended periods at deep well drilling temperatures [812]. 

Thomas, D.C. "Thermal Stability of Starch and Carboxymethyl Cellulose Polymers Used in Drilling Fluids," SPE Paper 8463, 1979 SPE Annual Technical Conference and Exhibition Las Vegas, September 23-26. 

Formation of polymeric peroxycarboxylic acids of variously grafted celluloses, such as 228 and 229, where the thick line represents the main cellulose strand, and assessment of their thermal stability by following their decomposition at various temperatures is based on iodometric determination of the peracids . 

By analogy with the works which dealt with cellulose micro crystal-reinforced nanocomposite materials, microcrystals of starch [95] or chitin [96, 97] were used as a reinforcing phase in a polymer matrix. Poly(styrene-co-butyl acrylate) [95,96], poly(e-caprolactone) [96], and natural rubber [97] were reinforced, and again the formation of aggregates or clustering of the fillers within the matrices was considered to account for the improvement in the mechanical properties and thermal stability of the respective composites processed from suspensions in water or suitable organic solvents. 

Immobilized cellulase and amylase are able to hydrolyze cellulose and starch. However, the immobilized enzymes possess only about 1-6% of the activity of the soluble forms. In addition, immobilization clearly enhanced the thermal stability of amylase. Immobilized amylase retained more than half of its activity, even after incubation at 125°C. By comparison, soluble amylase was almost completely inactivated under these conditions. Furthermore, kinetics modeling indicates that the susceptibility to product inhibition is dependent on the amylase source. Finally, immobilization can reduce the susceptibility to product inhibition fQ was less for each of the immobilized forms, compared with their soluble counterparts. 

The present Section is mainly concerned with differences of stability between the two classes of derivatives and any variations within each class. Their stability toward hydrolytic agents has frequently been examined, and, for the thiocarbonates, the thermal stability has also received attention. These studies have, in general, been neither exhaustive nor quantitative, and comparative data are directly available for certain cellulose derivatives only. The progressive replacement of the oxygen atoms in a neutral carbonic ester by sulfur appears to lead to a decrease in the sensitivity to alkali and an increase in the sensitivity toward acids, water, and heat. As expected, the acid esters are less stable than their neutral analogs toward the last-named agents. 

Very little information is available concerning the thermal stability of the metallic salts of the acid carbonates and thiocarbonates. Calcium glyc-eritol dicarbonate [C3H60H(C0s )2Ca ], although very unstable in solution, could be stored at room temperature in an anhydrous state for a short period of time. On being strongly heated it charred, with the evolution of acrolein. A hydrated 0-(sodium thiocarbonyl) derivative of cellulose became insoluble in alkali within 24 hours at room temperature, due to decomposition. On the other hand, many metal xanthates, particularly the insoluble copper salts, which are readily obtained in a pure, anhydrous state, appear to be reasonably stable at about 20°. This very limited evi-... 

This process gives rise to products possessing the properties of both polymer components. Cellulose, in particular, may retain its valuable features such as high hydrophilic-ity, low electrifiability and considerable thermal stability and acquire new properties inherent to synthetic polymers. 

Cellulose acetate is used in films, cigarette filters, and moldings. It is made by reacting cellulose with acetic anhydride. U.S. 5,608,050 (to Eastman) describes an acetylation process that improves the thermal stability of the polymer. U.S. 5,962,677 (to Daicel) describes a process for improving the processing properties of the polymer. Estimate the cost of production of the polymer by each route. 

Pyrolysis of cellulose acetate has been applied for analytical purposes of the fibers [44], structural elucidation [45], study of thermal stability [46], etc. The main pyrolysis product of cellulose acetate is acetic acid. Several compounds typical in cellulose pyrolysis such as 5-hydroxymethyl-2-furancarboxaldehyde can be seen as its ester with acetic acid. Also, some compounds tentatively identified as dihydroxydioxanes and dihydroxydioxolanes in cellulose pyrolysate are found as acetic acid esters in the pyrolysate of cellulose acetate. Depending on the degree of substitution (D.S.), for D.S < 3, free -OH groups are still present in cellulose. This allows the formation of compounds typical for cellulose pyrolysate in addition to the compounds resulting from... 

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