Determination of crosslinking

For low extents of photodegradation the total number of chain scissions (S) (per molecule) [Pg.475]

The quantum yield of chain scission f can be determined from equation 10.73. [Pg.475]

The soluble fraction (s) of a polymer, with an initial random molecular mass distribution (Pw)o/(F )o, undergoing simultaneous main chain scission and crosslinking, is related to the intensity of radiation absorbed (/J by the equation [336, 431, 1769] [Pg.475]

Po = fraction of broken units in the main chain per unit incident energy Qo = fraction of crosslinked units per unit incident energy (one crosslink involves two crosslinking units) [Pg.475]

The intensity of radiation absorbed required for gel formation (/g), in the absence of simultaneous chain scission, is given by [Pg.475]

Karade Y, Pihan SA, Brunger WH, Dietzel A, Berger R, Graf K (2009) Determination of crosslink density in ion-irradiated polystyrene surfaces from rippling. Langmuir 25 3108-3114... [Pg.97]

Solid-state 13C MAS NMR has been applied for quantitative determination of crosslink density in accelerated sulfur-vulcanised NR [27]. The concepts used to calculate the crosslink density by 13C NMR are the same as the one mentioned above, but different resonances were used for the quantitative treatment based on the different assignments... [Pg.329]

The non-conjugated BNI double bond is less reactive. However, the polymerization mechanism has not up to now been definitely established although a radical process is postulated for the propagation. Recent approaches towards the structure determinations of crosslinked networks and, by the way, towards the best knowledge of polymerization mechanisms, were undertaken in order to obtain BMI and BNI polymers presenting improved properties. In this section particular attention will be paid to this point. [Pg.151]

A more critical test of the gravimetric method for determination of crosslink density (1/7.) would be a comparison of results obtained on the basis of Eq. 16 for poly(Sty-co-DVB) samples made via free-radical polymerization in various... [Pg.28]

Schreiber, H., Holden, H., Barna, G., Rapid Determination of Crosslink... [Pg.124]

The determination of crosslink densities, covalent, and physical, at various temperatures by the stress relaxation method could help to elucidate to what degree and at what conversion level the fringed micelle crystallites would cause and affect the deviation from the straight line dependence. [Pg.66]

Determination of Crosslink Density in Covalently CrossUnked SMPs. 104... [Pg.98]

Determination of crosslinking Equation 10.83 can be presented in another expression ... [Pg.475]

The key point of this section is thus that while crosslink density and ionic content control the sorption capacity, they cannot be easily estimated without direct experimental measurement. The determination of crosslink density and ionic content of polymeric networks has been carefully studied in the literature the former by scientists interested in elastomers, and the latter by those working with ion exchange resins. Here we will briefly discuss these topics as they apply to water absorbent polymers, especially methods for the inexpensive, routine measurement of these properties for irregular, particulate hydrogels. [Pg.111]

Recent Advances in the Determination of Crosslinking and Scission in Irradiated Polymers... [Pg.5]

Analytical Chemistry 71, No.2, 15th Jan.1999, p.468-75 IDENTIFICATION AND DETERMINATION OF CROSSLINKERS IN CROSSLINKED POLYVINYLPYRROLIDONE(PVP) BY PYROLYSIS-GAS CHROMATOGRAPHY(GC)/ MASS SPECTROMETRY(MS)... [Pg.101]

Mark, J. E. (1982). Experimental determinations of crosslink densities. Rubber Chem. Technol. 55, 762. [Pg.954]

Nomenclature for branch caihon resonances Determination of crosslinking in polyethylene Determination of thermal oxidation in polyethylene Determination of stcreoregulariiy of polymers... [Pg.498]

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