-4 B S T RA C T 'I'etrahydrofuran and propylene oxide were copolymerized in the presence of the catalyst boron fluoride ethyl ether, and various co-catalysts, such as 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol. Ethylene chloride was used as a solvent and a s an internal reference for analytical purposes. Reactions were carried out a t 0 OC and a t atmospheric pressure. Monomer concentrations were determined by vapor phase chromatography, and copolymer ~nolecular structure analyses were carried out by physical and chemical methods including infrared spectroscopy, vapor pressure osmometry, hydroxyl end-group analysis, and chemical reduction of unsaturated linlcages.The ho~l~opolymerizatio~~ of tetrahydrofuran did not take place, whereas that of propylene oxide proceeded a t a rapid rate. In the copolymerization of tetrahydrofuran with propylene oxide, the rate of disappearance of tetrahydrofuran was found to be independent of its concentration, but varied d~rectly with the concentration of propylene oxide. Under similar conditions, the rate of disappearance of propylene oxide was found to be ( a ) proportio~lal to the square of its concentration, and (b) inversely proportional to the concentration of tetrahydrofuran.Reactivity ratios varied between 1.3 and 1.8 for propylene oxide and between 0.1 and 0.6 for tetrahydrofuran. Molecular weights obtained by vapor pressure osmometry ranged between 460 and 740, and those obtained by hydroxyl end-group analysis ranged between 520 and 1 660. Infrared spectra confirmed the presence of hydroxyl groups and ether linkages in the copolylners preparecl. liesults 011 terminal unsaturation were negative. RESUMJ?La copolymCrisation du tCtrahydrofural1 et de l'oxyde de propylbne fut effectuee en pr6sence clu catalyseur 1'CthCrate du fluorure de bore, et de cocatalyseurs tels le 1,2-propanediol, le 1,3-propanediol e t le 1,4butanediol. Le chlorure d1Cthylblle servait de solvant e t d'6talon interne pour fins d'analyse. Les concelltrations de monombres furent suivies, en fonction du temps, par la chromatographie en phase vapeur. L'analyse des copolymPres a port6 surtout sur l'btude de la structure au moyen de techniques physiques e t chimiques telles que la spectroscopie infrarouge, 110smom6trie B tension de vapeur, l'analyse chimique des groupements hydroxyles ter~ninaux e t la rCduction chimique des liaisons doubles.L'homopolymCrisation du tetrahydrofuran n'a pu @tre effectube, tandis qu'avec l'oxyde de propylhne seul, dans les conditions de rCaction adoptees, la rCaction s'est poursuivie B grande vitesse. Dans la copolymCrisation du tCtrahydrofuran avec l'oxyde de propylbne, la vitesse de disparition du tetrahydrofuran 6tait indCpendante de sa col~centratioll e t variait directement avec la concentration d'oxyde de propylbne. Dans les m@mes conditions, la vitesse de disparition de l'oxyde cle propylbne Ctait ( a ) proportionnelle au carre de sa concentratio11 e t (b) lnversement proportionnelle B la concentration du tbtrahydrofuran.Les rapports de rCactivit6 de l'oxyde d...

SynopeisThe cationic copolymerization of tetrahydrofuran and propylene oxide was studied in a batch system. Boron fluoride ethyl ether and 1,2-propa~ediol were used as catalyst-cocatalyst system. Number-average molecular weights M , of various copolymers were determined by vapor-pressure osmometry (VPO) and hydroxyl endgroup analysis (OH).The VPO and OH molecular weights differed considerably. To explain the differences, several copolymers were analyzed by gel permeation chromatography (GPC). The chromatograms obtained showed for each copolymer analyzed two peaks, one located in the high molecular weight region, the other in the low molecular weight region. An attempt is made to correlate the results and to show the usefulness of GPC in the characterization of THF-PO copolymers.

synopsisPolyethylene glycols and polypropylene glycols were irradiated with gamma-rays from Electron spin resonance spectra of the free radicals produced It was found that the rupture in the polymer chain takes place a t * C CThe radicals identified were +CHS in polyethylene glycols and a 6OCo source at 77°K. Thermal decay of these radicals followed asecond-order law, A complete

The cationic copolymerization of tetrahydrofuran with propylene oxide was carried out in the presence of boron fluoride etherate, 1,2‐propanediol, and ethylene chloride, used as catalyst–cocatalyst–solvent system. Reactions were carried out in the −40 to +20°C. temperature range, at atmospheric pressure. The influence of various other parameters on the composition and structure of the copolyetherdiols obtained has been studied. Kinetic data, including energies of activation (E) and frequency factors (A) for the comonomer (THF and PO) consumptions and data on the molecular weights and the per cent yields of the copolyetherdiols obtained are reported.

The suggested simplification for first-order decompositions was tested by repetition of the 114 °C rate curve of A-phenyl-vV'-tosyloxydi-imide TV-oxide (cupferron tosylate), reported by Dorko et al. ( 2), and the 271 °C rate constant for "cyclotetramethylenetetranitramine" (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, HMX), reported by Robertson (5). EXPERIMENTAL Decompositions were run in a Perkin-Elmer Model DSC-IB differential scanning calorimeter. Samples were sealed in aluminum cells, Perkin-Elmer Part Number 219-0062, which were perforated with a single hole approximately 0.15 mm in diameter. Both the differential and average temperature calibrations of the DSC-IB were carefully checked before the runs.The sample of cupferron tosylate was prepared and purified by M. D. Coburn of this Laboratory. The HMX sample was crystallized from a filtered acetone solution of 99.9+ % pure HMX, provided by the United Kingdom Atomic Weapons Research Establishment, Aldermaston. RESULTS AND DISCUSSIONA plot of In deflection vs. time for what Dorko et al. called the "decay" portion of the 114 °C rate curve of cupferron tosylate is shown in Figure 1. The linearity of the plot shows that the decomposition is first order. The least-squares slope (5) A.