A light‐scattering photometer for the angular range 6–170°

Meyerhoff, G.; Moritz, U.; Darskus, R. L.

doi:10.1002/pol.1968.110060311

J. Polym. Sci. B Polym. Lett.

1968

DOI: 10.1002/pol.1968.110060311

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A light‐scattering photometer for the angular range 6–170°

G. Meyerhoff

U. Moritz

R. L. Darskus

Abstract: A light‐scattering phtometer for measurements on solutions in the angular range 6–170° is described. Its use is illustrated by the determination of the average molecular weights Mw and Mn, as well as the gyration radii 〈r2〉z1/2 and 〈r2〉n1/2, on a polystryene fraction.

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1974

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Cited by 16 publications

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Measurement of molecular weight of poly(vinyl chloride)

Rudin

Benschop‐Hendrychova

1971

J of Applied Polymer Sci

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synopsisMolecular weights of six bulk-process and five suspension-process PVC samples have been measured as part of a study aimed at developing a technique for gel permeationchromatographic analysis of this polymer in tetrahydrofuran at room temperature. Osmometric a,, values measured in cyclohexanone appear to be valid; the results are insensitive to thermal history or ultrasonic irradiation of the solution. Corresponding measurements in tetrahydrofuran changed with measurement temperature and indicated the presence of stable supermolecular PVC aggregates in this solvent. Such aggregates can be dispersed by ultrasonic treatment of the solution for brief periods. Simultaneous degradation of PVC molecules appears to be prevented by addition of small concentrations of nonionic surfactant to the tetrahydrofuran solutions. Treated solutions are suitable for GPC analyses a t ambient temperatures. The results of osmometry, light scattering, and GPC agreed well.

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Measurement of molecular weight of poly(vinyl chloride)

Rudin

Benschop‐Hendrychova

1971

J of Applied Polymer Sci

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Streulichtmessungen im nahen Ultrarot

Burmeister

Meyerhoff

1974

Ber Bunsenges Phys Chem

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Die elastische Lichtstreuung ist eine der wichtigsten Bestimmungsmethoden für die Lösungsstruktur insbesondere von Makromolekülen. Sie wurde bisher ausschließlich im Bereich sichtbarer Wellenlängen angewandt. Eine Erweiterung des Wellenlängenbereiches bis in das nahe Ultrarot führt bei, Messungen der Winkelabhängigkeit ‐zu kleineren Streuparametern μ = (4π/λ) sin δ/2 und damit zu einer genaueren Charakterisierung größerer Moleküle durch Molekulargewicht und Trägheitsradius.Die Absorption vieler organischer Lösungsmittel und die geringe Streuintensität beschränken die Auswahl der Wellenlängen. Ein bei 1086 nm mit einem Helium‐Neon‐Laser betriebenes Streulichtphotometer wird beschrieben, ebenso ein Differentialrefraktometer. Bei 1086 nm werden die Brechungsinkrernente von Polystyrol‐Toluol und Cellulosenitrat‐Aceton und die Rayleigh‐Verhältnisse von Toluol und Benzol bestimmt. Anhand von Messungen an synthetischen und biologischen Molekülen, deren Molekulargewichte bis zu 40 Millionen und deren Knäueldurchmesser über 104 Å erreichen, werden die Vorteile und Grenzen der Meßtechnik im nahen Ultrarot aufgezeigt.

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Über die verzweigung von polydodecylmethacrylat

Moritz

Meyerhoff

1970

Makromol. Chem.

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Es ist fraglich, ob das beobachtete AusmaB der Verzweigung durch die meistens angenommene obertragungsreaktion zwischen einer wachsenden Kette und einem inaktiven Polymeren znstande kommt. Ein Einbau von inaktiven Polymeren uber eine endstandige Doppelbindung, die z. B. beim Disproportionierungsabbruch gebildet wurde, erscheint mindestens ebenso wahrscheinlich. SUMMARY:The solution behaviour and the degree of branching of fractions of polydodecylmethacrylate radically polymerized at low and high conversion were determined. The molecular weights covering a range from 1.5.105-8.106 and the coil dimensions were measured by light scattering, viscometry, sedimentation in the ultracentrifuge, osmometry and gel chromatography. U. MORITZ und G. MEYERHOFFThe light scattering measurements were done in a special apparatus with a broader angular range than available with commercial photometers. This allowed a quite precise observation of the zero angle slope and hence of the radius of gyration. The squared radius of gyration for the linear fractions in the @-solvent n-amylalcohol a t 29.5'C proved to be exactly proportional to the molecular weight. Also the intrinsic viscosity in this solvent exhibited with[q] = 2.85.10-2.M0.50 the expected exponent in the molecular weight relation.These and analogous relations for good solvents were used to estimate the degree of branching, which results from the diminished radius of gyration and intrinsic viscosity of branched samples as compared with the linear samples of the same molecular weight. The methods of ZIMM-STOCKMAYER, STOCKMAYER-FIXMAN, and ZIMM-KILB were applied, resulting in an average of one branching point for every 3000-4000 monomer units within a polymer molecule.It is open to question whether this degree of branching may as usually be accounted for a transfer process of the growing chain to an inactive polymer. Polymer molecules with double bonded endgroups may be acquired by a growing chain thus producing a branched molecule. This type of branching via unsaturated terminal units which result e.g. from disproportionation seems at least just as probable.

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A light‐scattering photometer for the angular range 6–170°

Abstract: A light‐scattering phtometer for measurements on solutions in the angular range 6–170° is described. Its use is illustrated by the determination of the average molecular weights Mw and Mn, as well as the gyration radii 〈r2〉z1/2 and 〈r2〉n1/2, on a polystryene fraction.

Cited by 16 publications

References 5 publications

Measurement of molecular weight of poly(vinyl chloride)

Measurement of molecular weight of poly(vinyl chloride)

Streulichtmessungen im nahen Ultrarot

Über die verzweigung von polydodecylmethacrylat

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