Radiation-Induced Copolymerization of Tetrafluoroethylene and Propylene. 2. Copolymerization in Solution

Copolymerization of tetrafluoroethylene and propylene in chlorofluorohydrocarbon solvents was carried out below room temperature with γ-rays from a ⁶⁰Co source. A remarkable rate-accerelating effect was observed in these solution systems, although the activation energies and the compositions of copolymers were almost the same as those in bulk system. The most effective solvent was found to be trichlorotrifluoroethane. Kinetic results of the copolymerization in trichlorotrifluoroethane solution system revealed the role of solvent to be complicated, with the possibility of affecting almost all reaction steps of the polymerization.     

The Radiation-Induced Polymerization and Copolymerization of Butadiene in Emulsion

Abstract

The polymerization of butadiene in emulsion initiated by ^{6 0}Co gamma radiation has been studied in some detail. Similar studies with styrene and styrene-butadiene comonomer mixtures were also conducted. The rates of polymerization were found to be much lower than anticipated from the reported k_p values for butadiene and for the comonomer mixtures. Styrene, on the other hand, polymerizes at normal rates. A number of possible explanations for this behavior is discussed.     

Radiation-Induced Copolymerization of Chlorotrifluoroethylene with Olefins

The copolymerizations of chlorotrifluoroethylene with propylene and isobutylene were carried out at 0 ～ ?78°C by γ-ray irradiation. It was found that alternating copolymers are obtained over a wide range of monomer composition for both systems. The alternating copolymer of chlorotrifluoroethylene with isobutylene was found to be highly crystalline, but the copolymer of chlorotrifluoroethylene with propylene was found to be amorphous. The copolymerizations were considered to proceed via a radical mechanism, but in the case of the isobutylene-chlorotrifluoroethylene system a cationic polymerization also takes place simultaneously at ?78°C.     

Radiation-Induced Copolymerization of Trioxane with 1,3-Dioxolane

Copolymerization of 1,3-dioxolane (DOX) with trioxane in the solid state was studied by radiation. The effects of radiation dose, DOX concentration, postpolymerization temperature and duration on the copolymer yield, and DOX incorporation were investigated and compared with published data.     

Radiation-Induced Copolymerization of Trioxane with Styrene Oxide

Copolymerization of trioxane (TOX) and styrene oxide (STO) induced by gamma radiation was studied under varying operating conditions to see the effects of radiation dose, STO concentration, postpolymerization temperature, and duration on the polymer yield. Charging 5% STO with TOX STO conversion was 65% but yield was only 23% compared with 62% for the homopolymer. Molecular weight, melting point, density, and thermal stability of the copolymer samples were determined.     

Radiation-Induced Copolymerization of Thiophene with Maleic Anhydride

Radiation-induced copolymerization of thiophene with maleic anhydride has been studied. On the copolymerization in chloroform solution, the effects of dose rate, polymerization temperature, and, monomer composition and concentration on the yield and molecular weight of the copolymer were determined. The copolymerization proceeds via a radical mechanism with bimolecular termination of propagating polymer radicals, and the apparent activation energy is 5.3 kcal/mole. By NMR spectroscopy of copolymer, it was also found that these monomers copolymerize alternately to give a copolymer having structure I. In this copolymerization, the higher initial rates were obtained at an equimolar composition of monomers and by using solvents containing chlorine, such as CC1₄, CHC1₃, and C₆H₅C1.     

The Radiation-Induced Copolymerization of Methyl Methacrylate with Di- and Trimethacrylates

The rates and gel formation of the radiation-induced co-polymerization of a number of dimethacrylates and trimethylol propane trimethacrylate with methyl methacrylate has been studied in detail. The rates were found to be linked to the nature and amount of gel formed rather than to differences in the reactivities of the monomers.     

Radiation-Induced Copolymerization of Fluorine-Containing Monomers

Radiation-induced copolymerizations of various monomers, including perfluoro-olefines with CF₂ O and of α-olefines with monochlorotrifluoro-ethylene, have been studied. It was found that CF₂O can be copolymerized randomly via radical process, with most of monomers examined and that alternating copolymers can be obtained from the copolymerization of a-olefines with monochlorotrifluoroethylene. The structural study of these copolymers was carried out by infrared, X-ray diffraction and NMR measurements. The structure of isobutylene-monochlorotrifluoroethylene copolymer was determined precisely through proton and fluorine resonances.     

Characterization of Macrocycles Formed from Cationic Copolymerization of Tetrahydrofuran with Propylene Oxide by GPC and GC/MS

Abstract

The copolymers obtained from a THF/PO-BF₃O(C₂H₅)₅-glycerin-ethylene chloride cationic copolymerization system were analyzed by GPC. The chromatograms show two groups of peaks, one located in the high molecular weight (MW) region and the other in the low MW region. In order to examine the low MW region in detail, the oligomers were separated from the copolymer by distillation under high vacuum, and further identified by GC/MS, NMR. It was found that these were an expected series of cyclic oligomers, i.e., PO:THF crown ethers: 1:2, 3:1, 2:2, 1:3, 3:2, 2:3, 1:4, 4:2, 3:3, 2:4, 4:3. Through the study of the elution behavior of these crown ethers in toluene with GPC, a linear relationship of the elution time against the logarithm of their MW's was obtained. Under the same GPC conditions, the relationship between the elution time and MW of n-alkanes was also determined. It was found that the hydrodynamic volume of the crown ethers is less than that of the n-alkanes with same MW, and they can be treated as homologous series as in the case of n-alkanes on the study of GPC elution behavior ignoring the influence of PO:THF composition ratios in crown ether rings.     

Radiation-Induced Cryogenic Copolymerization of Some Monomers with Sulfur Dioxide

A comparative study was performed on the radiation postpolymerization of a number of dienes and -olefins with sulfur dioxide occurring both on heating of the samples radiolyzed at 77 K and spontaneously by mutual dissolution. The cryopolymerization of sulfur dioxide with butadiene was studied in most detail. It was found that, unlike the case of the isoprene–SO₂system, a polycrystalline phase with the eutectic that corresponded to the equimolar composition was formed on rapidly freezing over the entire range of initial ratios between the butadiene and SO₂comonomers. It was suggested that the 1 : 1 donor–acceptor complex takes part in the postpolymerization process, and the monomers enter the resulting copolymer in a near-equimolar ratio. The copolymer obtained was found to behave as a crosslinked system. It is likely that a three-dimensional network resulted from the opening of C=C bonds in butadiene.     

Anionic Copolymerization of Elemental Sulfur with Propylene Sulfide. Equilibrium Sulfur Concentration

In the anionic copolymerization of elemental sulfur (S₈) with propylene sulfide (P) below the floor temperature of elemental sulfur homopolymerization (T_f = 159°C), there is a certain concentration of elemental sulfur left when copolymerization is completed ([S₈]_eq). The dependence of [S₈]_eq on the feed ratio [P]₀/[S₈]₀ and temperature was determined by using laser Raman spectroscopy, and this enabled us to distinguish between the S-S bonds in elemental sulfur and in the linear polysulfide. [S₈]_eq was found to decrease with increasing temperature and with an increasing [P₀]/[S₈]₀ ratio. The experimental dependence of the average enthalpy and entropy of polymerization (δ[Hbar]_[Xbar], and δ [Sbar]_[Xbar]) on [Xbar], as described by the equilibrium …-CH₂CH(CH₃)S_X ^? + S₈ = …-CH₂CH(CH₃)S_X+8 ^?, has shown that at [Xbar] ?; 9 the experimental δ[Hbar]_[Xbar] and δ [Sbar]_[Xbar] approach values determined earlier for the free radical homopolymerization of elemental sulfur …-S_n ^? + S₈ ≤ …-S^? _n+8&; The corresponding values are 3.1 kcal/mol and 4.76 cal/mol · degree.     

苯乙烯与N-对位取代苯基马来酰亚胺的乳液共聚

合成了苯乙烯(St)与 N-对位取代基马来酰亚胺的3种二元共聚物乳液.在苯乙烯与N-对位取代苯基马来酰亚胺(N-p-RPhMI)的最大共聚比内,通过种子滴加乳液聚合制得高稳定性、高固含量(40%)、低粘度的共聚物乳液.研究了 N-p-RPhMI 苯环对位上取代基团对共聚物乳液的性能以及共聚物热性能影响.结果表明:N-p-RPhMI 的加入提高了乳液的产率,并且随着取代基团极性的增强,乳液产率提高,乳胶粒的平均粒径增大,乳液的表观粘度降低;共聚物的热分解温度随着取代基团极性的增加而提高,但取代基极性对共聚物的玻璃化转变温度(Tg)的影响明显.同时,St/N-对甲氧基马来酰亚胺(N-p-MOPhMI)体系中助溶剂的加入对共聚物乳液性能影响很大,使共聚物的热起始分解温度升高,但对共聚物的 Tg 基本无影响.     

苯乙烯-甲基丙烯酸羟乙酯无皂乳液聚合过程

苯乙烯-甲基丙烯酸羟乙酯无皂乳液聚合过程;成核机理     

Radiation-Induced Copolymerization of Acrylonitrile with Methyl Acrylate: Synthesis and Characterization

Radiation-induced copolymerization of acrylonitrile with methyl acrylate was carried out in aqueous medium at room temperature. Different compositions of the copolymer were prepared and characterized by IR, ¹H-NMR, thermal, and dielectric studies. NMR spectroscopy was used to determine the composition and stereochemistry of the copolymer. Glass transition temperature values (T_g ) were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss.     

Cationic Copolymerization of Propylene Oxide with Tetrahydrofuran. XI. Calculation of Individual Rate Constants

Rate constants (k₁ k₁₁, k₁₂, k₂₂, k₂₁ and k_t) for various steps involved in the copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) have been calculated from reaction rate data obtained with the following catalyst system: (a) triphenyl-methyl cations ((C₆H₅)₃C⁺) associated with hexafluorophosphate (PF₆ ^?), hexafluoroarsenate (AsF₆ ^?) and hexafluoroantimonate (SbF₆ ^?) gegenions; (b) antimony pentachloride (SbCl₅); and, (c) boron trifluoride etherate, BF₃:(C₂H₅)₂O. The latter two systems were studied in the presence of cocatalysts. The effects of several parameters (the cocatalyst concentration and bulk size, the nature of the solvent, and the reaction temperature) on the rate constants are highlighted. The role of entropy in the initiation, propagation and termination steps is discussed in terms of solvation and desolvation processes. Based on termination activation energy considerations, the order of stability for the gegenions used in the copolymerization of PO with THF was found to be: AsF₆ ^? > SbF₆ ^? > HOBF₃ ^?PF₆ ^? > SbCl₆ ^?     

Semicontinuous Emulsion Polymerization of Vinyl Acetate. Part II. Copolymerization with Dibutyl Maleate

The semicontinuous emulsion copolymerization of vinyl acetate: dibutyl maleate (60:40, vol/vol) was carried out at different co-emulsifier distributions between initial reactor charge and continuously introduced monomer. The overall conversion, the co-polymer particle size, and the properties of films obtained from emulsions were determined experimentally. Polyvinyl alcohol and cetyl alcohol ethoxylated with ethylene oxide (20 moll were used as protective colloid and coemulsifier, respectively. Experimental investigations have shown that the unreacted monomer concentration and the copolymer particle size oscillate with time. These oscillations are related to a tendency for limited particle flocculation.