摘要:

The effects of various polar modifiers, their concentration, and the polymerization temperature on the microstructure of poly-butadiene obtained during anionic polymerization using lithium α-methyl naphthalene as the bifunctional initiator were studied. 1,2-1,4-1,2-Stereotriblock polybutadiene was synthesized by polymerization in cyclohexane to a certain conversion and polymerization was completed in the presence of diethylene glycol dimethyl ether. The microstructure of the stereotriblock copolymer was characterized by IR and1H-NMR. GPC showed that the stereo-block polybutadiene has a narrow MWD. Two Tg's of the copolymer with higher molecular weight exist, as shown by dynamic mechanical test. The stereotriblock copolymer was hydrogenated using cobalt 2-ethyl hexanoate and triisobutyl aluminum as the catalyst. The hydrogenated product was shown to be a (butene-1-ethylene-butene-1) triblock copolymer which consists of more than 30% crystallinity and exhibits the behavior of a thermoplastic elastomer. The relationship between stress-strain properties arid the contents of the blocks was also studied.

ISSN:0022-233X    

DOI:10.1080/00222338508063338

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The homopolymerization of a series of alkyl vinyl sulfoxides (CH2˭CHSOR; R = CH3(MVSO), C2H5(EVSO), t-C4H9(BVSO)) and their copolymerization with vinyl acetate (VAc) with 2,2′-azobisisobutyronitrile (AIBN) as initiator at 60°C was attempted. MVSO was found to homopolymerize radically, but EVSO and BVSO were not. Poly-MVSO is soluble in chloroform, methanol, DMSO, and water, but insoluble in acetone and benzene. MVSO and EVSO were found to copolymerize with VAc, but BVSO was not. The copolymerization parameters obtained for both systems were as follows; r1(MVSO) = 2.23, r2(VAc) = 0.09, and r1(EVSO) = 3.40, r2(VAc) = 0.11, respectively. MVSO/vinyl alcohol (VA) copolymers were obtained through the saponification of MVSO/VAc copolymers by sodium hydroxide in methanol. The solubility of MVSO/VAc and of MVSO/VA copolymers toward various solvents was examined, and it was observed that the sulfoxide comonomer has a tendency to give amphiphilicit to poly(vinyl acetate) and poly(vinyl alcohol). The 24 mol% MVSO containing VAc copolymer is soluble in both benzene and water.

ISSN:0022-233X    

DOI:10.1080/00222338508063339

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The Michael addition reaction of a series of alkyl vinyl sulfoxides (CH2˭CH-SO-R; R = CH3(MVSO), C2H5(EVSO), t-C4H9(BVSO)) with poly(vinyl alcohol) (PVA) was carried out after investigating the model reaction with isopropyl alcohol. The addition reaction was found to proceed in the presence of sodium hydroxide as catalyst. This sulfinylation of PVA proceeded more easily with MVSO and EVSO than with BVSO, and a polymer containing up to 60 mol% sulfoxide unit was obtained with MVSO and EVSO. The solution viscosity as well as the solubility behavior of the modified PVA' having various types and contents of sulfoxide group were also examined.

ISSN:0022-233X    

DOI:10.1080/00222338508063340

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The syntheses and characterizations of poly[oxy(2-methyl-1,3-phenylene) oxyisophthaloyl-b-oxy (2-methyl-1,3-phenylene)oxy-terephthaloyl] and the corresponding homopolymers are described. The synthesis involves the coupling of dihydroxy-terminated homo-polymers with terephthaloyl chloride. The resulting block copoly-ester was characterized by infrared spectroscopy, proton and carbon- 13 nuclear magnetic resonance spectroscopy, solution viscosity, differential scanning calorimetry, and thermogravimetric analysis.

ISSN:0022-233X    

DOI:10.1080/00222338508063341

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Terephthalate unsaturated copolyesters with ethylene glycol and 2-butene-1,4-diol, with ethylene glycol and 2-butyne-1,4-diol, with ethylene glycol and diethylene glycol, and with 2-butyne-1,4-diol were synthesized by trans-esterification reactions. Proton nuclear magnetic resonance spectroscopy was used to elucidate the structures of the copolyesters. The intrinsic viscosities of the copolyesters were measured in o-chlorophenol at 30°C. The number-average molecular weights of these copolyesters were determined by using a vapor pressure osmometer. The thermal behaviors of the copolyesters were studied by differential thermal analysis and are discussed in terms of structural differences.

ISSN:0022-233X    

DOI:10.1080/00222338508063342

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Blending of acrylic terpolymer (AT) with vinyl acetate-vinyl chloride (VAc-VC) copolymer, polyvinyl alcohol (PVA) polymer, and polyvinyl acetate (PVAc) polymer, respectively, resulted in sealant compositions with improved properties and enhanced outdoor weathering resistance. The morphology of these blends was studied by SEM, energy-dispersive x-ray analysis (EDXA), and DSC. The blends are heterogeneous and consist of a continuous phase which is either pure or mixed AT and a particulate phase having the morphology of the added component. The particulate phase of AT and AT-(VAc-VC) copolymer blends contains mixed AT, whereas that of AT-PVA and AT-PVAc does not. The AT-based blends have generally improved mechanical properties (e.g., ultimate tensile strength, adhesive strength). The improvement in mechanical properties is particularly strong in mixtures of AT with (VAc-VC) copolymer, probably because the added component has greater specific interaction capabilities with AT than the polymers incorporated in the other blends. Whereas the unblended AT has very low outdoor durability, the AT-based blends display enhanced resistance to weathering, as evidenced by substantially higher ultimate tensile strength of weathered specimens than those of the controls (unweathered).

ISSN:0022-233X    

DOI:10.1080/00222338508063343

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

For a four-parameter reaction-mass transport model of melt polycondensation, the constants of polycondensation, thermolysis, and diffusion were determined by means of experiments in thin-layer polycondensation. Based on these constants, the convectional mass transport and efficient melt thickness in polycondensation systems under conditions of compelled mixing can be estimated. However, for stirred polycondensation systems a reaction-mass transfer model proves more suitable. The constants of polycondensation and thermolysis obtained by the diffusion model can be transferred to the reaction-mass transfer model. Thus, only the mass transfer coefficient has to be determined.

ISSN:0022-233X    

DOI:10.1080/00222338508063344

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Butadiyne was thermally polymerized from the vapor phase onto substrate polyethylene, poly(vinylidene fluoride), polytetrafluoro-ethylene, and fluorinated ethylene propylene films at 20°C. The reaction is characterized as an initial absorption of monomer into the film followed by polymerization in the condensed state. A postpolymerization thermal reaction of the polybutadiyne pendant ethynyl groups was conducted over a 120 to 470°C temperature range with a subsequent surface electrical resistivity decrease to 7 × 1011ohm/square. The reaction of the pendant acetylenic groups was monitored by DSC and IR spectroscopy and found to be more complex than an intramolecular conversion of an acetylenic polyene to a polyacene structure.

ISSN:0022-233X    

DOI:10.1080/00222338508063345

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Three new bis-triazolinediones, 3,3′-dimethyl-4,4′-bis-[3,5-dioxo-1,2,4-triazoline-4-yl]biphenyl, t-1,4-bis-[3,5-dioxo-1,2,4-triazoline-4-yl]methyl cyclohexane, and 4,4′-bis-[3,5-dioxo-1,2,4-triazoline-4-yl] phenyl ether, were synthesized from their corresponding bis-amines or bis-isocyanates. The compounds were identified by their quantitative ene reaction with 2,3-dimethyl-2-butene. The high degree of reactivity of the triazoline moiety makes solvent selection for reaction media rather difficult. This fact prompted a study of rates of reaction with a variety of polar and nonpolar solvents, including halogenated aliphatics, aromatics, tetrahydrofuran (THF), and N,N-dimethylformamide (DMF). The compounds exhibited reasonable stability in the halogenated solvents, as well as in the aliphatic and aromatic hydrocarbons, but they underwent reaction with THF and DMF. The structure of the reaction product of N-phenyl-1,2,4-triazoline-3,5-dione in DMF solution was determined, and a mechanism for product formation was proposed. Two of the bis- triazolinediones were polymerized via a base-catalyzed condensation mechanism which eliminates N2from the triazolinedione ring.

ISSN:0022-233X    

DOI:10.1080/00222338508063346

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A new heat-resistant polymer has been synthesized from N-(4-carboxy phenyl) trimellitimide and benzidine. The polymer was characterized by nitrogen analysis, IR spectroscopy, density, viscosity, and x-ray measurements. The polymer was found to be insoluble in all polar organic solvents and only soluble in formic acid and concentrated H2SO4. The solubility parameter value has been determined. Thermal studies show that the polymer is thermostable up to 300°C. The electrical properties have also been measured.

ISSN:0022-233X    

DOI:10.1080/00222338508063347

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor