摘要:

Highly swollen ion-exchange resins result from the polymerization of diallylamine in the presence of 2 mol% of a bis-diallyl-amino compound as the cross-linking reagent. It is shown that post cross-linking with a dihalo compound is an acceptable method for decreasing the swelling propensity of the resins. The secondary amino groups are then converted to tertiary types, although there is some formation of quaternary ammonium groups which is detrimental in ion-exchange resins which are to be regenerated thermally. The aromatic compound α,α-dichloro-p-xylene is more suitable than the less rapidly reacting aliphatic compound Br(CH2)4Br and the even slower reacting reagent Cl(CH2)4Cl. However, satisfactory products are obtained with the use of Br(CH2)6Br. The additional cross-linking of the poly-diallylamine results in a lowering of the basicity level by one to two orders of magnitude, with the electron-withdrawing aromatic product exhibiting the greatest effect. Better pH buffering properties are usually obtained when the product is subsequently treated with hot alkali, which transforms any quaternary ammonium groups present to tertiary amino types.

ISSN:0022-233X    

DOI:10.1080/00222338208063253

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The compact conformation of poly(methacrylic acid) which is observed in the unneutralized polymer has been studied using the fluorescence probes 9-methyl anthracene and Rhodamine B. Steady-state and time-resolved fluorescence anisotropy measurements have been made. The results show that this conformation contains a number of binding sites which have molecular weights in the range 9,000–10,000 and which can rotate independently of the remainder of the chain.

ISSN:0022-233X    

DOI:10.1080/00222338208063254

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The analyses of resinous polyamides has been very limited; the sole available work would appear to be a cooperative IUPAC study where the overall results were generally poor, particularly considering the effort devoted to the study. The examinations reported employed chemical analyses of the samples as received and after hydrolysis, together with instrumental analyses using IR and NMR spectroscopy and gas and gel permeation chromatography. A successful procedure for the rapid analyses of these IUPAC polyamides has been developed in which cleavage is carried out using alkali fusion rather than the prolonged acidic hydrolysis procedures previously used. The various acidic and amine fragments produced have been identified after formation of methyl esters of the dicarboxylic acids and trifluoracetyl derivatives of the diamines using gas and gel permeation chromatography. The limitations of examination of the free diamines is described.

ISSN:0022-233X    

DOI:10.1080/00222338208063255

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The modification of polymer surfaces by gas plasma treatment is reviewed. The two regimes of major interest are radio-frequency at low pressure (about 1 torr) and corona discharge at atmospheric pressure. The reactions produced by plasmas at polymer surfaces are due to both radiation and chemically active species created by electron bombardment. The major changes produced are in wettability, molecular weight, chemical composition, and surface morphology. The mechanisms of plasma polymerization and the properties of polymers produced by this technique are described. Finally, a brief outline is given of the industrial applications of plasma techniques.

ISSN:0022-233X    

DOI:10.1080/00222338208063256

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The aging of a carboxylated nitrile rubber-epoxy structural film adhesive at 40° C over a period of 15 d has been examined. Properties of the uncured adhesive, the curing reaction, and properties of the cured adhesive have been studied by a number of instrumental techniques. It was found that significant changes occurred in the solubility, epoxy content, and the molecular weight distribution. The cure reaction was “Advanced” but not altered in general form, and the flow during cure was substantially reduced but the mechanical performance of the adhesive was only slightly affected. These results have been interpreted in terms of a carboxyl-epoxy reaction involving the nitrile rubber and epoxy resin.

ISSN:0022-233X    

DOI:10.1080/00222338208063257

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The predominant degradation reaction in the γ-irradiation of nine poly(olefin sulfone)s was found to be C-S bond scission with elimination of SO2and olefin. The extent of depolymerization, measured by the yields of the two comonomers, increased over five irradiation temperatures from 0 to 150° C and could be correlated with the ceiling temperature. Thus G (total volatile products) increased from 10 to 10,000 over this temperature range. Minor radiolysis products included the alkanes corresponding to (1) loss of the side chain group and (2) scavenging of the side chain radical by monomer olefin. There was a deficiency of olefin relative to SO2, except at high temperatures, and isomerization of the product olefin in some cases. These observations are attributed to reactions of radiation-induced polymeric cations.

ISSN:0022-233X    

DOI:10.1080/00222338208063258

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The weathering characteristics of grey and black PVC-covered conductors from several manufacturers were investigated after long-term exposure under both in-service and weather station conditions. Visual examination and physical testing revealed significant deterioration of light grey and dark grey conductor samples provided by one manufacturer. Accelerated weathering tests confirmed these results. Molecular weight distributions as determined by gel-permeation chromatography indicated that surface degradation by chain scission of the PVC resin had occurred in the deteriorated samples. The prime cause of this deterioration is believed to be the absence of suitable UV blocking properties, in these cases insufficient quantities of titanium dioxide.

ISSN:0022-233X    

DOI:10.1080/00222338208063259

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A styrene-butadiene-styrene thermoplastic elastomer was compounded with several different types and amounts of fillers and antidegradants. Molded sheets of the resulting compounds were exposed outdoors in Melbourne, Australia, for up to 12 months. The effects of filler loading on the stress/strain properties of the compounds both before and after weathering were evaluated. The compound which showed the best overall resistance to weathering contained about 2% of carbon black. The best white compound, which contained titanium dioxide (2% approx) and an ultraviolet stabilizer, was almost as resistant to weathering as the black compound.

ISSN:0022-233X    

DOI:10.1080/00222338208063260

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

A statistical experiment has been conducted to investigate the influence of silica fillers on the mobility of poly(vinyl chloride -co-vinyl acetate) molecules as reflected in glass transition temperatures. Measurement of glass transitions was made graphically from DSC curves. The data showed that the glass transition was affected by the presence of filler. The effect was dependent on the type and level of filler in the polymer. The filler was of either large or small particle size, or had had surface treatment to form trimethylsilyl groups. Significant interaction effects were found between filler types, filler level, and the level of polar vinyl acetate groups in the copolymer.

ISSN:0022-233X    

DOI:10.1080/00222338208063261

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The dynamic mechanical properties of some cross-linked and crystallizable polyurethanes based on polycaprolactone have been investigated with a Rheovibron Elastometer in the temperature range 150–370 K. Crystallizable samples have been studied in both quenched and annealed forms. Cold crystallization of the quenched forms occurs a few degrees above the glass temperature. Structural factors influencing both ease of crystallization and decrease in glass transition temperature are (a) decrease in cross-link density, (b) increase in MW of polycaprolactone segment, and (c) use of a flexible aliphatic diisocyanate as linking agent rather than aromatic types.

ISSN:0022-233X    

DOI:10.1080/00222338208063262

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor