Mechanisms of degradation of cotton and effects of mercerization-stretching upon the course of these mechanisms,part VII. Characterization of microstructural differences between scoured cotton and slack mercerized-stretched cottons

Conditions were established to introduce almost equal and reproduciple amounts of diethylaminoethyl (DEAE) substituents into the molecular structure of scoured cotton (substrate I), slack mercerized cotton (substrate II), slack mercerized-stretched (94%, substrate III), and slack mercerized-stretched (103%, substrate IV) cotton. Similarities between the original structures of these substrates before and after the chemical modification were assessed by X-ray analysis. Comparison between the DEAE cottons and the corresponding unmodified cottons upon acid hydrolysis with respect to moisture regain, loss in weight and degree of polymerization was also made. Chemical analysis was used to study the compositions and structures of the hydrolyzates (i.e., hydrocelluloses and solublized fractions) resulting from hydrolysis of the modified cottons with 2.5 N HCl under reflux for different lengths of time. Studies of rates of hydrolysis of the cellulose, rates of removal of substituted glucoses and rates of removal of individual types of substituted glucose units were considered as means to provide information regarding: (a) distribution of DEAE substitutents throughout the structure of cellulose, (b) nature of accessible regions where the DEAE substituents are developed, and (c) selective availability of the hydroxyl groups at C-2, C-3 and C-6 of the D-glucopyranosyl units in the cellulose elementary fibril.     

High ionic conduction in tetragonal solid solution of the system La2O3-MgF2

LaOF-type tetragonal solid solution was found in the system La₂O₃–MgF₂. This phase showed higher anionic conduction than the previously reported cubic solid solution in the system La₂O₃–CaF₂. Electrolysis by Tubandt's method showed that fluoride ion conduction was dominant in this solid solution. The fluoride ions were considered to be easily substituted by oxide ions through cathode reaction in the oxygen atmosphere.     

Upper critical solution temperature lubricants for CPVC

Chlorinated polyvinyl chloride (CPVC) is often used in injection molding for products that demand high heat resistance. However, proper control of its flow properties is difficult. To improve flow behavior some internal lubricants are usually used, but they reduce heat resistance of the products. Upper critical solution temperature (UCST) lubricants were found to enhance its flow properties, and also high heat resistance was retained. They act as internal lubricants during processing, improving flow and phase separation during cooling. Therefore they are present essentially as inert filler and thus have little effect on heat distortion temperature.     

TRANSIENT ANALYSIS OF CRYSTALLIZATION: EFFECT OF THE SIZE DEPENDENT GROWTH RATE

The dynamics of the crystal size distribution in a continuous mixed suspension, mixed product removal crystallizer is modeled stochastically. The model is fairly general in that it involves a size-dependent growth rate function: this size-dependent growth rate as a possible cause of deviation on the behavior of the crystallizer from that of an idealized or simplified counterpart has been investigated based upon the model.     

Stochastic modeling of segregation in a motionless mixer

The mixing of particles with different characteristics is generally accompanied by segregation which prevents the particles from attaining the randomly mixed state. A discrete steady-state Markov chain model was employed to model the axial segregation of solid particles in a motionless mixer. Three systems containing particles of different sizes and/or densities were studied. One step transition probabilities of the model were experimentally determined. The model can predict the concentration profiles, the degrees of mixedness, and the equilibrium states of these particle systems blended by passing the particles through a motionless mixer. Experimental results are in good agreement with those predicted from the model.     

Optimal synthesis of process systems Necessary condition for optimal system and its use in synthesis of systems

The necessary condition for the optimal process system structure which includes both the optimal interconnection and optimal design of processing units is derived in terms of the structural parameters. The structural parameters are essentially splitting factors of process streams connecting processing units. The necessary condition requires the structural parameters and the design vectors to satisfy the weak maximum condition of the Hamiltonian type scalar functions. On the basis of the condition, a search method, evolutionary search for optimal structure (ESOS), for attaining the optimal structure starting from a simple structure is developed and its convergence is proved. An example of synthesizing a reactor-separator system illustrates its use.     

Multivariate statistical analysis of solids mixing

The applicability of multivariate statistics to the analysis of mixing processes and mixtures of multicomponent solid particles in a drum mixer has been successfully demonstrated. The applications include (1) test of sampling techniques, (2) test of the completely random state, (3) test of the completely segregated state, and (4) definition of a mixing index for a multicomponent mixture.