Formation of long-lived radicals in addition reactions to perfluoro-4-methyl-2-pentene

Conclusions The photolysis of liquid solutions of CF₃I and (CF₃)₂CFI in perfluoro-4-methyl-2-pentene at 240 run gives longlived radicals, which were identified as radical-adducts formed by the addition of CF₃ and (CF₃)₂CF radicals to the double bond of the perfluorolefin.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 184–185, January, 1989.     

Formation of long-lived radicals in radiolysis of oxygen-containing organofluorine compounds

Conclusions In the radiolysis of organofluorine compounds containing a phenoxyl substituent, we have observed the formation of radicals, long-lived in the liquid, in the course of gamma irradiation at 77 K. From an analysis of the EPR spectra of the long-lived radicals, it has been shown that the radiolysis forms two types of long-lived radicals: cyclodienyl and alkoxyl. The lifetimes of these radicals depend on the structure of the compound from which they are obtained by radiolysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1255–1260, June, 1988.The authors wish to express their appreciation to L. M. Buchachenko for assistance in this work.     

ESR spectra of spin-adducts of hydroxyalkyl radicals with perfluoro-4-methyl-2-pentene

A study was carried out on the ESR spectra of the spin-adducts of hydroxyalkyl radicals with perfluoro-4-methyl-2-pentene (I) formed upon the photolysis of alcoholic solutions of this perfluoroolefin. The stable conformational positions of the substituents in the spin-adducts depend on the structure of the hydroxyalkyl radicals. The spin-adducts are annihilated as a consequence of hydrogen atom abstraction as indicated in a preparative experiment.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 730–732, March, 1991.     

EPR study of radiolysis of perfluoro(isobutyl-p-methylcyclohexane)

Conclusions Radiation of perfluoro(isobutyl-p-methylcyclohexane) results in the formation of at least three types of perfluorocarbon radicals that have long lives in the liquid. The extremely low probability of their recombination in the liquid at room temperature may be due to steric shielding of the unpaired electron. The lifetime of the LRs that are formed depends on the radiation dose and temperature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1260–1263, June, 1988.The authors wish to express their appreciation to K. N. Makarov for assistance in this work.     

Crystal structure of isotactic poly(4-methyl-1-pentene)

The crystal structure of isotactic poly(4-methyl-1-pentene) was determined by x-ray analysis. The unit cell is tetragonal, P4 b2, with α = 18.70 Å and c (fiber axis) = 13.68 Å; it contains four molecular chains each consisting of seven monomeric units in the fiber period. The molecular conformation is essentially a (7/2) helix, but deviates slightly from the uniform (7/2) helix. The unusual low density is discussed from the structural point of view.     

Gas sorption-induced dilation of poly(4-methyl-1-pentene)

Sorption and volume dilation isotherms of semicrystalline poly(4-methyl-1-pentene) (PMP) were measured using CO₂ and C₃H₈ as penetrants, which have sieving diameters of 3.3 and 4.3 Å, respectively. On the other hand, the PMP crystal has a void width of approximately 4 Å as estimated by X-ray diffraction, so it was anticipated that CO₂ would be able to sorb into the PMP crystal while C₃H₈ would not. The data show that C₃H₈ has a constant partial molar volume of approximately 87 cc/mol, just above the value reported in other rubbery polymers, and are consistent with the hypothesis that the C₃H₈ molecules are too large to sorb into the PMP crystals. The partial molar volume of CO₂ was found to be 39 cc/mol for CO₂ weight fractions of up to 0.03. Since the typical partial molar volume of CO₂ in rubbery materials is 46 cc/mol, the lower values in this study were attributed to CO₂ sorption into crystalline regions of the polymer, which provided no dilation. Application of a two-phase model using the assumption of Henry's law sorption showed that apparently all C₃H₈ sorption was occurring in the amorphous region but approximately 16% of CO₂ sorption occurred in the crystalline regions. © 1996 John Wiley & Sons, Inc.     

Formation of perfluoro-1,1,3-trimethylindane in the reaction of trimethylsilylpentafluorobenzene with perfluoro-4-methyl-2-pentene

Conclusions The reaction of pentafluorophenyltrimethylsilane with perfluoro-2-methyl-2-pentene in the presence of cesium fluoride gives perfluoro-1,1,3-trimethylindane in addition to the product of the pentafluorophenylation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 477–479, February, 1989.     

Small-angle X-ray scattering of isotactic poly(4-methyl-1-pentene)

Although the crystalline phase of poly(4-methyl-1-pentene) (P4MP) is less dense than the amorphous phase, the density difference is very small at room temperature. This makes it difficult to study the fine structure of P4MP by small-angle x-ray scattering (SAXS). It has therefore not been clear whether a so-called superlattice, or long-spacing structure, is formed in P4MP as in other synthetic polymers. However, it is found that raising the temperature increases the density difference sufficiently to make SAXS study feasible, and the existence of the long-spacing structure of P4MP is indicated. Annealing studies reveal two characteristic temperatures of 170 and 200°C: above 170°C the long-spacing structure is formed with an abrupt increase of crystallinity, and at 200°C the structure is further developed.     

Standard enthalpies of formation of perfluoro(2-methyl-3-oxa)hexanoic and perfluoro(2,5-dimethyl-3,6-dioxa)nonanoic acids

The energies of combustion of perfluoro(2-methyl-3-oxa)hexanoic and perfluoro(2,5-dimethyl-3,6-dioxa)nonanoic acids are for the first time measured in a calorimeter with a rotating platinized bomb and used to calculate the standard enthalpies of formation of these compounds in the liquid state. Based on the enthalpies of formation, the contribution from the [-CF₂OCF(CF₃)-] group to the enthalpies of formation of perfluoro acids is calculated.     

Kinetics of epoxidation of 2-methyl-2-pentene

The kinetics of epoxidation of 2-methyl-2-pentene with cumene hydroperoxide catalyzed by MoO₂ (acac)₂ has been studied in the temperature range of 35–65°C. The observed kinetic behavior is consistent with the formation of a hydroperoxide-catalyst complex and a simple competitive inhibition step, involving the formation of an inactive epoxide-catalyst complex. The reaction parameters have been calculated.     

聚4-甲基-1-戊烯膜的制备与应用研究进展

聚4-甲基-1-戊烯是一种具有低密度、高透气性等优良性质的膜材料,具有广泛的应用前景.本文从制备方法和具体应用两个方面综述了近年来国内外PMP膜的研究进展,重点介绍了热致相分离法、熔融拉伸法、溶剂挥发法及静电纺丝法、非溶剂致相分离法、热致相分离-熔融拉伸耦合法等其它方法进行PMP膜制备的原理及影响因素,并对PMP膜在体...     

Equibiaxial deformation of poly(4-methyl-1-pentene) by a forging process

Poly(4-methyl-1-pentene) (PMP) has been uniaxially compressed by a forging (equibiaxial) process. The rheology of the process has been examined for this semicrystalline polyolefin, melting point about 235°C. The yield energy, area under the compressive stress-strain curve up to the yield point, as a function of temperature was found to consist of two linear components of different slope. These two linear relations arise from the glassy and crystalline phases of PMP. The intercept temperature (T_i) at zero yield energy for the glassy phase has been evaluated. The attainable maximum compression ratio without sample rupture (CR_max) increased steadily on increasing forging temperature above T_i, and below T_m. In this range, the crystalline relaxation temperature (T_c), evaluated from an Arrhenius plot of yield stress was 160°C. Above T_c, a CR_max of 240 was reached. This value is five times higher than that attained for isotactic polypropylene (i-PP). However, the draw efficiency evaluated by elastic recovery in the plane direction of PMP (0.76) is lower than for i-PP (0.97). Differential scanning calorimetry analyses showed that the melting peak became a complex doublet on increasing compression ratio ( > 100). The drawing and stress-strain behavior of PMP are compared with i-PP. © 1994 John Wiley & Sons, Inc.     

FTIR and FT Raman spectra and analysis of poly(4-methyl-1-pentene)

Poly(4-methyl-1-pentene) is the most widely used polymer in industry and medical products. Fourier transform infrared and Raman Spectra of poly(4-methyl-1-pentene) have been recorded in the range of 4000-400 and 4000-100 cm(-1), respectively. In the present investigation a detailed assignments of the observed fundamental bands of poly(4-methyl-1-pentene) has been analyzed in terms of peak positions and relative intensities. With the hope of providing more and effective information on the fundamental vibrations, a normal coordinate analysis has also been performed on poly(4-methyl-1-pentene) by assuming Cs symmetry. The simple general valence force field (SGVFF) method has been employed in normal coordinate analysis and the potential energy distribution (PED) has been calculated for each fundamental vibration. The PED contribution corresponding to each of the observed frequencies shows the reliability and accuracy of spectral analysis. The validity of the SGVFF method as a practical tool for complete analysis of vibrational spectra, for poly(4-methyl-1-pentene) is confirmed in the present work.     

On thermal properties of poly(4-methyl-1-pentene) membranes cast from solution

Thermoanalytical investigations of poly(4-methyl-1-pentene) membranes of two substantially different types (opaque and transparent), cast from solution, have been carried out using the derivatograph (Q-1500 D). On the basis of simultaneous DTA, TG and DTG measurements, enthalpy changes, weight losses and rates of weight losses have been determined, respectively. DSC has been done using the Perkin-Elmer 7-Series Thermal Analysis System. The results obtained have been used to get some structural information like decompositions and glass as well as crystallization properties of the membrane material.     

Reaction of perfluoro-2-methyl-2-pentene with thiourea

The reaction of perfluoro-2-methyl-2-pentene with thiourea in aprotic bipolar solvents gives 4,4-bis(trifluoro-methyl-5-(tetrafluoroethylidene)-2-aminodihydrothiazole, the structure of which was confirmed by ¹⁹F and ¹³C NMR and x-ray structural analyses. The mechanism of the reaction is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 253–256, February, 1993.