Polymer fiber mixture

Malhotra JP, Deshmukh SR, Singh RP (1987) Turbulent drag reduction by polymer-fiber mixtures J Appl Polym Sci 33 2467... 

Reddy GV, Singh RP (1985) Drag reduction effectiveness and shear stability of polymer-polymer and polymer-fiber mixtures in redrculatory turbulent flow of water Rheol Acta 24 296... 

Combinatorial approach to unsymmetrically tiered macromolecules [214] is a brand new area of research which would allow dendrimerization of materials (e. g., glass, classical polymers, fibers) and thus enable fine tuning of macromole-cular properties. For example, treatment of an amine terminated dendrimer with a mixture of complementary, isocyanate-based monomers [215, 216] affords a heterogeneous surfaced dendrimer. Selective transformation of the surface nitrile moieties via metal-catalyzed reduction to obtain a new polyamine dendrimer allows further combinatorial-based elaboration as illustrated in Fig. 42. 

Finally the synthesis of inorganic-polymer composite membranes should be mentioned. Several attempts have been made to combine the high permeability of inorganic membranes with the good selectivity of polymer membranes. Furneaux and Davidson (1987) coated a anodized alumina with polymer films. The permeability increased by a factor of 100, as compared to that in the polymer fiber, but the selectivities were low (H2/O2 = 4). Ansorge (1985) made a supported polymer film and coated this film with a thin silica layer. Surprisingly, the silica layer was found to be selective for the separation mixture He-CH4 with a separation factor of 5 towards CH4. The function of the polymer film is only to increase the permeability. No further data are given. 

The properties of polymers may be improved by the presence of appropriately selected additives. With the exception of some cast plastics, such as polymethyl methacrylate (PMMA), and some fibers, such as unpigmented cotton, most commercial polymers are mixtures of the polymer with one or more additives. 

The survey covered a period of 3 years of potential exposure, but exposure levels were not reported. No adverse dermal effects were observed on the arms or legs of subjects after a 6-day application of polymer fibers containing commercial octabromobiphenyl mixture under an occlusive covering no additional information was reported (Waritz et al. 1977). 

Several approaches have been developed to prepare GRIN polymer fibers in our laboratories, e.g., initiator diffusion technique (70), interfacial-gel copolymerization (77), and extrusion technique (12,13). Our previous study successfully used a closed extrusion process to prepare GRIN polymer fibers (72,75). This new process has also overcomed several drawbacks in conventional extrusion processes, e.g., poor reproducibility and low production rate. The refractive index profiles of the GRIN polymer fibers prepared by the new process are affected by the following two factors (1) the formulation of the reactant mixtures, e.g., different types of monomer combination and variation of host polymers and (2)... 

Table I. The formulations of the reactant mixtures I-III and the An values of the resulting polymer fibers I-III from the extrusion process...

The closed extrusion process is a liquid (core mixture)-liquid (shell mixture) diffusion control process. The key parameters for controlling the refractive index distribution in this process are the compositions of the reactant mixtures, pump speed, the temperature and the length of the diffusion zone. In our previous study, we have shown that the refractive index distribution of the GRIN polymer fibers was significantly affected by the monomer composition of the reactant mixtures and the temperature of the diffusion zone (13). The refractive index difference between the... 

Mixtures of a polymer and a gas are generally classified as polymer foams, those with a plasticizer as plasticized plastics and those with intimately mixed second polymers as blends or polymer blends. Mixtures of polymers with particulates are called filled plastics such particulates may be rock flour, carbon black, salts, sawdust, etc., as well as polymeric or nonpolymeric materials. Mixtures of polymers with fiberlike materials are called fiber-... 

Dimethyl sulfoxide is used as a reaction solvent in the polymerization of acrylonitrile with a vinyl monomer (e.g., styrene) [2,3]. Reaction of diisocyanates and polyols or polyamines dissolved in DMSO yield solutions of the polyurethanes [4]. Mixtures of DMSO and water are used as a spinning solvent for polymer fibers. Polyaryl ether polymers are formed from DMSO... 

The melting-crystallization cycle of an oriented network that is conducted under equilibrium conditions results in a reversible contractile system when the force is held fixed. Alternatively, large changes in the tension are observed when the length is held constant. These two complementary observations are inherent properties of all types of macromolecular systems. The above analysis has been limited to apure one-component homopolymer of uniform cross-section. However, it can be extended, in a straightforward manner to include inhomogeneous fibers, copolymers, and polymer-diluent mixtures.(4)... 

Wood fibers are not random mixtures of cellulosic polymers and lignin but rather these polymers are arranged in a definite morphological pattern with respect to each other. The major parts of wood fiber are the middle lamella, which is amorphous in nature and consists chiefly of lignin and the fiber wall consisting mainly of cellulosic polymers. Fibers can be produced from wood so that the fiber surface is either primarily exposed lignin or primarily cellulosic in nature by a process called thermomechanical pulping. 

These types of microheterogeneity are inherent in all polymer systems, filled with particulate and fibrous fillers, in two-phase and multi-phase polymer systems (mixtures of polymers with discrete and continuous distribution of components), as well as in polymer glues, coatings, fiber-reinforced plastics, i.e., in all polymer composites. However, in polymers with mineral reinforcement, microheterogeneity appears as a result of interfacial phenomena only in the... 

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