摘要:

Reactivity ratios for the copolymerization of styrene (r1) meta-divinylben-zene (r2–m) and with para-divinylbenzene (r2–p) have been redetermined under different reaction conditions and with different radioactivity assay techniques. The copolymers were prepared at two conversion levels [0.55 to 3.7% and 2.7 to 7.5% and at 80° (rather than 100°)] with benzoyl peroxide (in place of τ-butylhydroperoxide) initiator. The ionization chamber-vibrating reed electrometer radioactivity assay technique developed for other copolymerization studies was used in place of the direct counting technique previously used for the styrene/divinylbenzene systems. The new values arer1= 0.605/r2-m= 0.88:r1= 0.77/r2-p= 2.08 at 0.55 to 3.7% conversion andr1= 1.27;r2–m= 1.08 at 2.7 to 7.5% conversion. These are not in close agreement with previous values partly because of the difference in conditions of copolymerization (temperature, per cent conversion, initiator) and in the improved analytical precision. Also the high-DVB-content (80%) para copolymer data are not assumed to be invalid and are not omitted (as they were before) from selection of ther2–pvalues.

ISSN:0022-233X    

DOI:10.1080/10601326708053986

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The sorption of polymers on glass surfaces, and the effects produced thereby on measurements of intrinsic viscosity, hitherto studied in capillary viscometers, is here analyzed by the sensitive viscodensitometric technique, based on the principle of the moving-sphere viscometer. By working with several spheres ofequalsize, the errors in viscometry due to sorption can be practically eliminated. The use of two spheres differing in radius by a factor of 10 allows the direct weighing of the polymer sorbed per unit geometric surface. In this way the sorption isotherm of an alkali-bone gelatin on Pyrex glass from 0.17MKCl solution was found to rise to a plateau of 3 mg/m2at a gelatin concentration of 0.1 g/dl. The plateau extends from this lower limit to 0.5 g/dl. The partial specific volume of gelatin, directly obtained in the viscodensitometer along with the viscosity, was found to be 0.702 cc/g in water and 0.725 cc/g in 0.95MKCl.

ISSN:0022-233X    

DOI:10.1080/10601326708053987

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The fractionation technique described in this paper was used to characterize the melting-point, monomer, and blocking distributions for polymers and copolymers. It is different from the molecular-weight fractionation technique in that the fractions are obtained by using a single solvent to extract the solid polymer below its melting point at stepwise-increasing temperatures. The reproducibility of this technique is excellent, and the technique is sufficient to distinguish pellet-to-pellet variation in a commercially available polypropylene. It was used to show the influence of preparation variables on the melting-point distributions of polyethylene and polypropylene and on the monomer and blocking distribution of copolymers, and to distinguish copolymers from blends.

ISSN:0022-233X    

DOI:10.1080/10601326708053988

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601326708053989

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601326708053990

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601326708053991

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601326708053992

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0022-233X    

DOI:10.1080/10601326708053975

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor