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Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10−5 for styrene polymerization and 0.4 × 10−5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10−5. Reactivity ratios measured in emulsion were r1 (styrene) = 0.44, r2 = 0.46. Those in bulk polymerizations were r1 = 0.45, r2 = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.

Estimation of molecular weights from GPC data is complicated when the polymer sample consists of a mixture of homopolymers or of statistical copolymers with nonuniform compositions. This is because sizes of solvated polymer coils depend on solvent interaction with both the homo-and hetero-units of the copolymers and because the extent of solvation of different homopolymers can differ. The overall degree of solvation may change effectively with composition and use of a single “average” set of Mark-Houwink constants in calibration procedures will then produce false molecular weight data from the GPC data. A new molecular weight average, M x, is defined to overcome this problem. This average can be determined from the GPC chromatogram and intrinsic viscosity of the sample in the GPC solvent. Mark-Houwink coefficients are not needed. M x lies between M w and M z.

A method is introduced for the estimation of Mark-Houwink constants of block and statistical copolymers. The homopolymer Mark-Houwink constants and copolymer composition are required. Use of estimated Mark-Houwink constants in GPC analyses gives results which agree well with those calculated with experimentally determined constants. Comparisons between this method and those of Runyon and coworkers (11) and Chang (12) are made for block copolymers. Chang's method was also extended to statistical copolymers, and where it compared closely with the one introduced here. The use of copolymer Mark-Houwink constants as a qualitative measure of polymer compatibilities in different solvents is also discussed.

Poly(ethylene terephthalate) and polypropylene are considered, to be incompatible by the usual criteria for polymer blends. Sheath/core filaments of these polymers could not be oriented because of poor adhesion of the base polymers. Melt blends of the two polymers with 30 and 50 weight percent polypropylene produced useful, oriented monofilaments. Tensile and dynamic mechanical properties of these filaments indicate that the structures consist of interlocked microfibrillar domains of the polyester and polyolefim. The glass transition region of poly(ethylene terephthalate) is not affected by admixture with polypropylene. A fine mutual dispersion of the two polymers was possible because the melt viscosities of the ingredients were reasonably well matched under the conditions of mixing. The melt viscosity and elasticity of blends were lower than those of either component as expected if the two polymers are immiscible. Monofilament extrusion and melt flow measurements were made with a one-half inch single screw extruder.

A fast and specific method has been developed for the determination of hydroxyl content in prepolymers that contain hydroxymethylene functional groups. This method involves reaction of the sample with either trifluoroacetic anhydride or hexafluoroacetone to separate the terminal oxymethylene signals in the 1H NMR spectrum from those of the repeating unit and integration against an internal trinitrobenzene standard. This procedure generally requires less than 50 mg of polymer and has been employed in the analysis of prepolymers with number average molecular weights ranging up to 10000. The analysis has been tested using several different prepolymers. Precision of analysis was determined to be within 2.7 percent using a Varian XL-200 spectrometer.

The work described in this report, consisted of two separate tasks which will be discussed in turn: (1) synthesis of energetic monomers and polymers, and (2) synthesis of polycyclic and adamantoid nitramines. Both tasks were continuations of previous work, and pre-1983 results. The principal objectives of the work are the synthesis of energetic (nitro) polymers with improved energy and physical properties, specifically polyformals derived from nitro substituted diols, and the synthesis of nitramines with high crystal density and energy-density greater than HMX.

Investigation of the synthesis of polyformals from fluoro- and nitrodiols was continued at a low level. The synthesis of 3,5,5,11,11,13- hexanitro-3,13-diaza-7,9 dioxapentadecane-1,15,-diol polyformal, a high energy nitro polymer for use in cast-curable binders, was completed. A new fluoropolyformal was prepared from 3M fluoropolyether diol L-9939. One pound of 2,4,4,5,5,6,6-heptafluoro-2-trifluoromethyl-3-oxaheptane-1,7-diol polyformal was prepared for evaluation in pyrotechnic formulations. A series of copolyformals was prepared from nitrodiols and fluorodiols with the objective to obtain energetic prepolymers with low T sub G useful as cast-curable binder and as energetic soft blocks for thermoplastic-elastomeric (TPE) block copolymers. Several of the new polymers appear to meet this goal, based on qualitative observation of their properties. A copolymer of 2,2,3,3,4,4,5,5- octafluorohexane-1,6-diol and 3-nitrazapentane-1,5-diol may be useful as a replacement for hexafluoropentanediol polyformal (FPF-1) in cast-curable binder applications. A second copolymer in bis (hydroxyethyl)orthocarborane, with octafluorohexanediol, was prepared. The synthesis of a series of acid chloride- terminated polyesters from fluoro- and nitrodiols and 4,4-dinitropimeloyl chloride and malonyl chloride, respectively, and their reaction with monomeric and polymeric diols to form (AB)N block copolymer was investigated.