Viscosity reduction hydrogenation

Action of acids on cellulose ethers. Cellulose ethers, like cellulose, are hydrolyzable by acids. Methods for viscosity reduction of the ethers have been proposed which involve treatment of the ether with sulfuric acid31 or with gaseous hydrogen chloride.32... 

The hydrogen bonds are reiativeiy weak and get disrupted as soon as iight shear forces are appiied, with a consequent viscosity reduction. The three-dimensionai siiica chain structure reforms upon removai of shear force and thus produces thixotropic consistency in the system (Figure 5.8). The effect is more pronounced in systems without or with iow hydrogen bonding capability (such as hydrocarbons) than in a system capabie of hydrogen bond formation (such as water, an aicohoi or an amine). 

The viscosity of water also changes with temperature. It decreases with an increase in temperature because of the reduction in the number of hydrogen bonds binding the molecules together. The viscosity of water has an influence on the movement of solutes in water and on the sedimentation rate of suspended solids. 

The process centers on a fixed-bed downflow reactor that allows catalyst replacement without causing any interruption in the operation of the unit (Figure 9-28). Feedstock is introduced to the process via a filter (backwash, automatic) after which hydrogen and recycle gas are added to the feedstock stream which is then heated to reactor temperature by means of feed-effluent heat exchangers whereupon the feed stream passes down through the reactor in trickle flow. Sulfur removal is excellent (Table 9-18), and substantial reductions in the vanadium content and asphaltenes content are also noted. In addition, a marked increase occurs in the API gravity, and the viscosity is reduced considerably. 

Polypropylene (PP), on the other hand, undergoes predominantly chain scission under all processing conditions [7, 8, 9, 10, 11] with associated reduction in the molar mass and melt viscosity (see Scheme 3). The propagation reaction (Scheme 1, reaction 3) in PP is particularly facilitated by intramolecular hydrogen abstraction leading to the formation of adjacent hydroperoxides along the polymer chain that are less stable than isolated hydroperoxides and lead to an increased rate of initiation. 

The advantages of these products are low skin irritation potential and low viscosity. Physical properties and reactivity suffer somewhat due to the reduction of active amine hydrogens of DETA to four in the case of the monoadduct of ethylene oxide and three when the bisadduct is formed. 

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