Liquid-Liquid Phase Separation in Multicomponent Polymer Systems: Influence of Molar-Mass Distribution on Shadow Curve and Phase-Volume Ratio

1993 ◽  
Vol 58 (10) ◽  
pp. 2305-2320 ◽  
Author(s):  
Ron Koningsveld ◽  
Karel Šolc
Keyword(s):  
Liquid Phase ◽  
Cloud Point ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Simple Relationship ◽  
Phase Volume ◽  
Constant Weight ◽  
Point Curve ◽  
Cloud Point Curve

The effect of the molar-mass distribution (MMD), in particular the effect of a few higher molar-mass averages, on liquid-liquid phase behaviour is studied with the aid of data based on the Flory-Huggis-Staverman model. The critical concentration and the critical slopes of the cloud-point curve and the shadow curve appear to be quite sensitive to mz and mz+1, and, theoretically, they could serve as a unique data source for estimating these averages. In practice, however, experimental difficulties and errors encountered, especially with the shadow-curve slope determination, are probably too great for these data to be of any use. Next, the entire cloud-point and shadow-curves, and phase-volume ratios are examined with respect to the possible use to supply information on the MMD. At constant weight- and number-average molar mass, the cloud-point curve does not appear to be overly sensitive to Mz-average in the studied range. As to the other curves, no simple relationship evolves either, higher averages and details of the MMD both determining shape and location of shadow and phase-volume curves. An alternative procedure is suggested which consists of fitting a set of delta functions to a series of data points.

QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

1989 ◽  
Vol 54 (7) ◽  
pp. 1821-1829
Author(s):  
Bedřich Porsch ◽  
Simon King ◽  
Lars-Olof Sundelöf
Keyword(s):  
Diffusion Coefficient ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Diffusion Data ◽  
Mass Distributions ◽  
Classical Diffusion ◽  
Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

Evaluation of post-consumer cellulosic textile waste for chemical recycling based on cellulose degree of polymerization and molar mass distribution

2019 ◽  
Vol 89 (23-24) ◽  
pp. 5067-5075 ◽  
Author(s):  
Helena Wedin ◽  
Marta Lopes ◽  
Herbert Sixta ◽  
Michael Hummel
Keyword(s):  
End Of Life ◽  
Intrinsic Viscosity ◽  
Mass Distribution ◽  
Service Sector ◽  
Molar Mass ◽  
Degree Of Polymerization ◽  
Molar Mass Distribution ◽  
Chemical Recycling ◽  
Cellulose Content ◽  
Cellulosic Textiles

The aim of this study is to improve the understanding of which end-of-life cellulosic textiles can be used for chemical recycling according to their composition, wear life and laundering—domestic versus service sector. For that purpose, end-of-life textiles were generated through laboratorial laundering of virgin fabrics under domestic and industrial conditions, and the cellulose content and its intrinsic viscosity and molar mass distribution were measured in all samples after two, 10, 20, and 50 laundering cycles. Results presented herein also address the knowledge gap concerning polymer properties of end-of-life man-made cellulosic fabrics—viscose and Lyocell. The results show that post-consumer textiles from the home consumer sector, using domestic laundering, can be assumed to have a similar, or only slightly lower, degree of polymerization than the virgin textiles (−15%). Post-consumer textiles from the service sector, using industrial laundering, can be assumed to have a substantially lower degree of polymerization. An approximate decrease of up to 80% of the original degree of polymerization can be expected when they are worn out. A higher relative decrease for cotton than man-made cellulosic textiles is expected. Furthermore, in these laboratorial laundering trials, no evidence evolved that the cellulose content in blended polyester fabrics would be significantly affected by domestic or industrial laundering. With respect to molar mass distribution, domestic post-consumer cotton waste seems to be the most suitable feedstock for chemical textile recycling using Lyocell-type processes, although a pre-treatment step might be required to remove contaminants and lower the intrinsic viscosity to 400–500 ml/g.

Synthesis and liquid crystalline properties of azobenzene-containing poly(vinyl ether)s with narrow molar mass distribution

1995 ◽  
Vol 196 (10) ◽  
pp. 3187-3196 ◽  
Author(s):  
Emo Chiellini ◽  
Giancarlo Galli ◽  
Maria Chiara Bignozzi ◽  
Sante A. Angeloni ◽  
Marco Fagnani ◽  
...  
Keyword(s):  
Vinyl Ether ◽  
Mass Distribution ◽  
Liquid Crystalline ◽  
Molar Mass ◽  
Molar Mass Distribution

scholarly journals Polyethylene loss of ductility during oxidation: Effect of initial molar mass distribution

2018 ◽  
Vol 149 ◽  
pp. 78-84 ◽  
Author(s):  
Armando F. Reano ◽  
Alain Guinault ◽  
Emmanuel Richaud ◽  
Bruno Fayolle
Keyword(s):  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Oxidation Effect
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