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1.
High molecular weight poly(ester-urethane) based on diphenyl methane-4,4′-diisocyanate (MDI), PU1, and also on toluene diisocyanate (TD1), PU2, have been metallated using sodium hydride in N,N-dimethylformamide, (DMF). Metallation was confirmed by coupling samples of metallated PU1 and PU2 with methyl iodide and the use of infra-red, and n.m.r. G.p.c. studies indicated that an increase in the percentage of metallation at about 0°C in DMF caused a decrease in the stability of the soluble metallated backbone polymer and was accompanied by degradation. An increase in temperature from 0° to 100°C of a 15% metallated polyurethane sample in DMF increased the extent of degradation. At 0°C, polymers with a degree of metallation of less than 50% were relatively stable. At about 0°C in DMF, acrylonitrile was successfully grafted by anionic polymerization following metallation of PU1 and the graft copolymers were readily separated by fractionation from small amounts of the homopolymer, polyacrylonitrile. The graft copolymers were characterized by micro-analysis, solubility measurements, infra-red spectroscopy and viscometry. The vinyl monomers styrene, methyl methacrylate and vinyl acetate, and the cyclic monomers ethylene oxide, propylene oxide, N-methyl-2-pyrrolidone and hexamethylcyclotrisiloxane, could not be grafted anionically to the metallated polyurethane based on MDI. 相似文献
2.
Two aromatic polysulfones, poly(oxy-1,4-phenylenesulfonyl-1,4-phenyleneoxy-1,4-phenyleneisopropylidene-1,4-phenylene) (I) and poly (oxy-1,4-phenylenesulfonyl-1,4-phenylene) (II), undergo crosslinking and chain scission at 30°C during γ-irradiation, the former being predominant in vacuum and the latter in air. Both processes occurred more readily in I, which contains isopropylidene linkages. Gel measurements gave G(crosslink) = 0.051, G(scission) = 0.012 for this polymer at 30°C in vacuum. Increased irradiation temperatures resulted in higher crosslinking and gas yields, especially above the glass transition temperature. The tensile strength, flexural strength, and modulus of I were unaffected by γ-irradiation up to about 50 Mrad in air, but the strength decreased markedly at higher doses. The elongation at break decreased progressively with dose. For both polymers, G(gas) = 0.04 at 30°C with the main products being SO2, H2, CO2, CH4, and H2O. 相似文献
3.
Summary
An efficient method for the synthesis of PPV based polymers, poly ( 2,5-dimethyl-1,4-phenylene vinylene) (DMe-PPV) and poly
(2,5-dimethoxy-1,4-phenylene vinylene) (DOMe-PPV) were developed using 2,5-dimethyl-1,4-bis ( chloromethyl ) benzene and 2,5-dimethoxy
1,4-bis ( chloromethyl ) benzene via vapor phase pyrolysis and followed by vapor deposition polymerization. The structure
of polymer films were confirmed by FT-IR, solid state NMR and elemental analysis. Thermal gravimetry analysis reveals that
the precursor polymer films form a conjugated polymer after thermal conversion at 250°C. The optical and electrical properties
of the polymer films were investigated by UV-Vis absorption and photoluminescence spectroscopies. Electroluminescent devices
were fabricated using these polymers.
Received: 18 May 2000/Revised version: 21 July 2000/Accepted: 28 July 2000 相似文献
4.
Heat capacities were measured for three aromatic polysulphones: poly(1,4-phenylene sulphonyl), PAS; poly(oxy-1,4-phenylene-sulphonyl-1,4-phenylene), PPES; and poly[oxy-1,4-phenylene-sulphonyl-1,4-phenylene-oxy-1,4-phenylene-(1-methylidene)-1,4-phenylene], PBISP; from 150 to 620 K using differential scanning calorimetry. These new data, along with the prior ATHAS (Laboratory for Advanced Thermal Analysis, University of Tennessee) recommended experimental heat capacities for three aliphatic polysulphones: poly(1-propene sulphone), P1PS (20–300 K); poly(1-butene sulphone), P1BS (100–300 K); poly(1-hexene sulphone), P1HS (20–300 K), were fitted to an approximate frequency spectrum below their respective glass transition temperatures. The ATHAS computation scheme was used to compute the heat capacities that arise from these vibrations from 0.1 to 1000 K. The 1-temperature changed from 685 K for P1PS to 587 K for P1HS while for PPES and PBISP much higher values (799.5 K and 777.8 K) than the other phenylene polymers analysed at ATHAS, were obtained. Using these data and the smoothed experimental liquid heat capacities, the glass transition temperatures for PAS, PPES and PBISP were obtained at 492.6, 497.4 and 458.2 K. The corresponding values for ΔCp were 18.1, 37.7 and 126.6 J K−1 mol−1, respectively. 相似文献
5.
Several kinds of commercially available polymers of the type poly(oxy-1,4-phenylenecarbonyl-1,4-phenylene) were sulfonated by reaction with mixtures of sulfuric acid and oleum. The ether/carbonyl group ratio of the polymer chain varied from 0.67 to 2.0. With decreasing amounts of ether links in the polymer backbone the sulfonation is hindered and the reaction conditions have to be stronger. To yield the same degree of sulfonation, the sulfuric trioxide concentration of the reaction mixture has to be increased. The achievable degree of substitution is limited, in general, to one sulfonate group per substitutable unit (oxy-phenylene-oxy- or oxy-phenylene-carbonyl unit). In dependence on the polymer structure, polymers with contents of sulfonate groups between 1.2 and 2.0 meq·g–1 polymer are well soluble in dimethylformamide or N-methylpyrrolidone and it is possible to produce membranes with permselectivities >96% and electrical resistances < 2 Ω cm–2. The sulfonated polymers were characterized by viscosimetry, sedimentation analysis and 13C NMR spectroscopy. 相似文献
6.
Summary Using optical and electron microscopy it is evidenced that the introduction of graft copolymer poly(2,6-dimethyl-1,4-phenylene
oxide) on poly (n-butylmethacrylate) improves substantially the degree of dispersion in the incompatible polymer blend polystyrene/poly
(n-butylmethacrylate). The action of the copolymer is attributed-besides the mutual dissolution of the PBMA sequences — to
the compatiblity between the PPO-grafts and the PS component of the blend. This is supported by the Tg data which show that
the Tg of the PS in the blend is influenced by the present graft copolymer. The observed decrease of the Tg is explained by
the concomitant admittance in the PS phase of the PBMA backbone together with the PPO grafts. 相似文献
7.
Summary The chemical modification of poly(2,6-dimethyl- 1,4-phenylene oxide) (PPO) has been carried out by incorporating amide groups on PPO backbone by electrophilic substitution reaction with isocyanates. The modified polymers obtained have been characterized by IR and IH-NMR spectroscopy, nitrogen analysis, solubility tests and X-ray diffraction studies.NCL Communication No. 4455 相似文献
8.
A new variation in the bismaleimide (BMI) resin family, maleimide-terminated poly(oxy-1,4-phenylene sulfonyl-1,4-phenylene) oligomers, has been synthesized. The preparation of oligomers (n = 1–12) is described in this study. The structure of these oligomers is characterized by FT-IR and NMR spectroscopy. These oligomers are light yellow to light gray powders that can be melted or dissolved in solvents. Their terminating group bismaleimide has relatively high reactivity. Therefore, these BMI resins can be cured at 250°C to form a crosslinked product. Since the backbone chain is poly(arylene ether sulfone), the cured polymers have high Tg's, which increased from 220°C to higher than 340°C as the number of repeating units n of the corresponding oligomers decreases. 相似文献
9.
Blend membranes were prepared by casting chloroform solutions of mixtures of styrene-N-phenylmaleimide copolymer containing ca. 10 mol % imide units with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), and their phase behavior was evaluated. At a content of 20% PPO, the membranes were homogeneous; those having 40 or more % PPO exhibited phase separation. Membranes made of the parent polymers and their blends were tested in the pervaporation of aqueous ethanol solutions; permeabilities to oxygen, nitrogen, and carbon dioxide were also determined. The pervaporation characteristics and gas transport properties are discussed considering the interactions of polymer chains and the phase structure of the membranes. © 1995 John Wiley & Sons, Inc. 相似文献
10.
Simona Percec 《应用聚合物科学杂志》1988,36(2):415-427
The chemical modification of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) has been performed under phase transfer catalyzed (PTC) conditions. Four types of reactions: Williamson etherification, cyanide displacement, esterification, and heterocyclic group transfer have been identified as positive reactions involving the nucleophilic displacement on PPO. In reaction with alcohols, under PTC conditions, functional yields as high as 100% were obtained while for the esterification reaction functional yields of 92% were reached. Low conversions were found in reactions with cyanides and heterocylic compounds. Possible interactions of the reactive sites leading to additional crosslinking are being suggested. Minor changes in thermal stability of substituted PPO compared with the parent polymer were recorded. The modification of their permeation properties to gases was attributed to changes in polymer chain mobility and packing as well as to changes in polymer side chain polarity. 相似文献
11.
Infra-red measurements of the dichroic ratio of atactic polystyrene and poly(2,6-dimethyl 1,4-phenylene oxide) absorption bands provide a valuable method for the determination of orientation as well as relaxation of chains of both polymers during stretching of their compatible blends. Influence of strain rate, temperature of stretching, and molecular weight of the polymers on orientation of both polymer chains in blends containing up to 35% PPO has been studied. Orientation relaxation for both polymers has been analysed using Lodge's constitutive equation. Master curves have been obtained for PPO and PS in the blends at a reference temperature T0 = Tg + 10°C. Results are interpreted in terms of an hindrance of relaxation of PS chains induced by interaction with a highly-oriented PPO network which slowly relaxes. 相似文献
12.
Blending of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO resin) with a triblock butadiene–styrene–butadiene copolymer (Kraton 101) monotonically increases the softening temperature of the latter as measured by TOA. The TOA transition temperatures of the styrene/PPO resin phases closely approximate those of polystyrene/PPO resin blends having the same styrene/aromatic ether unit compositions. Uniform mixtures of the styrene blocks with the poly(2,6-dimethyl-1,4-phenylene oxide) molecules is inferred. 相似文献
13.
Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) multi-bonded carbon nanotube (CNT) (CNT-PPO) was prepared using brominated PPO under the condition of atom transfer radical polymerization. The structure and properties of CNT-PPO were characterized with FTIR, Raman spectroscopy and thermal analyzer. The PPO layer in a thickness of about 4.5 nm was observed covering on the side wall of CNT with a high-resolution TEM. The PPO modification warrants the good dispersion of CNTs in PPO in the formation of PPO/CNT nanocomposites, which demonstrated enhanced mechanical properties and increases in electrical conductivity. The developed approach of CNT modification with engineering plastics can be applied to other polymers and preparation of functional polymer/CNT nanocomposites. 相似文献
14.
Polyoxyphenylenes were obtained from phenol, 2-methylphenol, 2,5-dimethyl-phenol in oxidative polycondensations using dimethylpyridineCuCl complexes as catalysts. Samples of polymers from polycondensations were not completely linear as found by i.r. analysis. The m.s. and c.c.—m.s. analysis of degradation products of poly(2-methylphenylene oxide) (PMPO) and poly(2,5-dimethylphenylene oxide) (P2, 5DMPO) have shown that both polymers undergo Fries-type rearrangement prior to statistical scission of benzyl bonds. Ether linkages of poly(1,4-phenylene oxide) (PPO) decompose without rearrangement though cyclization to benzofurane systems has been observed. 相似文献
15.
Blends of poly(p-fluorostyrene) (PpFS), poly(o-fluorostyrene) (PoFS), poly(styrene-co-p-fluorostyrene) (SP46), poly(styrene-co-o-fluorostyrene) (SO49), with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and with polystyrene (PS), have been prepared by compression molding of coprecipitated polymers. Compatibility of these systems has been studied by differential scanning calorimetry. Detection of one or two glass transition regions was used to classify the blends as compatible or incompatible. Homopolymers of pFS and oFS were found to be incompatible with PPO and PS. The SP46 copolymer and SO49 copolymer were compatible with PPO in all proportions. 相似文献
16.
G. A. Polotskaya S. A. Agranova N. V. Gazdina Yu. P. Kuznetsov V. V. Nesterov 《应用聚合物科学杂志》1996,62(13):2215-2218
The gas permeability of O2 and N2 for homogeneous and composite membranes prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) samples with different molecular weight parameters was investigated. Temperature dependencies of gas permeability coefficients and permselectivity were determined for homogeneous membranes. It was established that gas permeability coefficients of homogeneous membranes depend on molecular weight of the polymers used. The gas permeability of composite membranes with a PPO selective layer was investigated as a function of PPO intrinsic viscosity [η] and its casting solution concentration (c). It was shown that under the condition [η]·c = const it is possible to obtain composite membranes with the same transport properties by using polymers with different molecular weight parameters. © 1996 John Wiley & Sons, Inc. 相似文献
17.
C. K. Sham C. H. Lau D. J. Williams F. E. Karasz W. J. Macknight 《Polymer International》1988,20(2):149-155
Upper critical solution temperature (u.c.s.t.) phase behaviour was found in blends of the homopolymer poly(oxy-1,4-phenyleneoxy-1,4-phenylenesulphonyl-1,4-phenylene) (PEES) with the copolymer poly(oxy-l,4-phenyleneoxy-l,4-phenylenecarbonyl-l,4-phenylene-co-oxy-l,4-phenyleneoxy-1,4-phenylenesul-phonyl-1,4-phenylene) (COPEEKS) for copolymer compositions ranging from 43 mol% to 56 mol% of ether ether ketone (EEK) repeat units. Blend compositions studied ranged from 25wt% to 75wt% of PEES. The consolute temperature was found to occur at a PEES/COPEEKS blend composition of about 50/50 wt% and to increase with the EEK repeat unit content of the copolymer. This miscibility behaviour was interpreted, using a mean-field theoretical approach, in terms of a single positive segmental interaction parameter which ranged from 0.054 to 0.032. 相似文献
18.
Dihydroxyl telechelic poly(2,6-dimethyl-1,4-phenylene oxide)s (1) with regiocontrolled end-group structures have been synthesized by oxidative polymerization of 2,6-dimethylphenol with various aromatic diols in the presence of CuBr/dibutylamine catalysts. The novel one- or two-armed telechelic derivatives based on aromatic diols as core and 1 as arms were subsequently epoxidized with epichlorohydrin and a series of new epoxidized poly(2,6-dimethyl-1,4-phenylene oxide)s (2) were accessible with number average molecular weight ranged from 3500 to 14,000. The end-group structures and regioselectivity of polymers were controlled by the CuBr/dibutylamine catalysts under different reaction conditions, and the structures and properties were studied by nuclear magnetic resonance spectroscopy, gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. Upon heating in the presence of oxygen, the one-armed dihydroxyl telechelic polymer was converted via intermolecular coupling and redistribution reaction to the two-armed derivative with significant increase in its molecular weight and elimination of diol monomer. Treatment of dihydroxyl telechelic derivatives with epichlorohydrin and NaOH afforded the epoxide-terminated telechelic derivatives in 77-94% yields. 相似文献
19.
Transition temperatures by thermo-optical analysis (TOA) and by DSC were measured on films of polystyrene (PS), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO resin) and nine homogeneous blends of these polymers. The TOA procedure consists of automatically monitoring light transmission through birefringent scratches in a film during heating at constant rate in a microscope hot stage between crossed (90°) plane polarizers. The TTOA transition temperature, defined as the temperature of birefringence disappearance in the scratches, increased monotonically from 113°C for pure PS to 222°C for pure PPO resin at a 10°/min heating rate. The Tg (DSC) similarly ranged from 99°C to 212°C at a 20°/min heating rate. The TOA technique as described should be a useful addition to thermomechanical studies of transparent polymers and polymer blends. 相似文献
20.
In this work the statistical mechanical equation of state was developed for volumetric properties of crystal ine and amorphous polymer blends. The Ihm–Song–Mason equations of state (ISMEOS) based on temperature and density at melting point (Tm andρm) as scaling constants were developed for crystalline polymers such as poly(propylene glycol)+poly(ethylene glycol)-200 (PPG+PEG-200), poly(ethylene glycol) methyl ether-300 (PEGME-350)+PEG-200 and PEGME-350+PEG-600. Furthermore, for amorphous polymer blends con-taining poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)+polystyrene (PS) and PS+poly(vinylmethylether) (PVME), the density and surface tension at glass transition (ρg andγg) were used for estimation of second Virial coefficient. The calculation of second Virial coefficients (B2), effective van der Waals co-volume (b) and correction factor (α) was required for judgment about applicability of this model. The obtained results by ISMEOS for crys-talline and amorphous polymer blends were in good agreement with the experimental data with absolute aver-age deviations of 0.84%and 1.04%, respectively. 相似文献