Non-solvent System Research Articles

Turbidimetric determinations of theta compositions

AbstractThe turbidimetric titration method of determining theta conditions developed by Elias and modified by Cornet and van Ballegooijen has been extended and generalized for different types of polymer–solvent–nonsolvent systems. The modified procedures for the determination of theta compositions have been verified with the following systems: polystyrene–cyclohexane–n‐hexane, polystyrene–cyclohexane–n‐butanol, and polystyrene–toluene–nonsolvent.

Elution fractionation of crystalline polypropylene

AbstractA number of commercial and experimental samples of crystalline polypropylene were fractionated by sand column solvent gradient elution techniques. Two different solvent—nonsolvent systems were studied under several sets of experimental conditions. Deposition of polymer upon the sand from a thermodynamically poor solvent was found to be necessary to achieve selective fractionation according to molecular weights. Both selective and nonselective fractionation results are illustrated with the latter occurring whenever the polymer is deposited upon the substrate from a thermodynamically good solvent. Molecular weight distributions for ten samples are given as obtained from elution fractionation using o‐dichlorobenzene—diethylene glycol monomethyl ether as solvent—nonsolvent system at 168°C. These molecular weight distributions could be adequately described by the logarithmic‐normal probability distribution function found by Wesslau and others to be applicable for linear polyethylene and by Davis and Tobias for polypropylene. Many of the distributions observed in this work were found to be narrower than those previously reported in the literature.

Synthesis of styrene–methyl methacrylate nonrandom copolymers in emulsion systems with cobalt‐60 gamma radiation

AbstractGraft copolymers have been prepared by the irradiation of polymer latices swollen with monomer. The latices used were prepared by radiation polymerization of emulsions to avoid the presence of initiator molecules in the second stage. Latices of polystyrene swollen with methyl methacrylate and polymethyl methacrylate swollen with styrene have been used. Polymerizations were followed dilatometrically and the dependence of polymerization rate on monomer concentration and radiation intensity obtained for both systems studied. Separation of copolymer from homopolymers has been attempted by thermal gradient elution chromatography; the method proved satisfactory when the solvent—nonsolvent system benzene—petroleum ether was used, but failed to give separations when benzene—methanol was used. This failure is thought to be due to cosolution phenomena.

The Fractionation of Starch

Publisher Summary This chapter discusses the fractionation of starch. Precise knowledge of the quantitative relationships existing between the chain length of amylose and the amount of foreign molecular species adsorbed and desorbed as functions of temperature and concentration parameters, clarify many of the details of complex formation. Prerequisite to the studies of this kind is the availability of an adequate method of subfractionation for amylose. More-quantitative knowledge concerning the fractional precipitation is gathered; hence, the additional investigation of solvent–nonsolvent systems that show graded disparity as solvents for starch polymers seems indicated. The use of the Phase Rule and its enlightening descriptive representations cannot be overestimated as a tool for starch chemistry as a whole, and certainly, it is indispensable for research into the fractionation of starch.

Polyester and Epoxy Based Non-Solvent Coatings for Corrosion Control

Abstract Discusses non-solvent coatings based on polyester and epoxy resins that give thicker film thicknesses in one application than do conventional solvent type coatings. Briefly describes special spraying equipment required for these non-solvent systems. Suggested application procedure is given. Comparison data are given on shrinkage rates of non-solvent and solvent type epoxies. Cost comparisons are made also between the two systems, showing the cost advantages derived from the thick, one-coat applications obtainable with the non-solvent coatings. Photographic examples are given of applications using the non-solvent coatings. Tabular data are included on chemical resistance of non-solvent and solvent types of epoxy coatings after a six-month continuous immersion test on sandblasted steel coupons. 5.4.5