Characterization of Chemical Composition along the Molar Mass Distribution in Polyolefin Copolymers by GPC Using a Modern Filter-Based IR Detector

2013 ◽  
Vol 330 (1) ◽  
pp. 63-80 ◽  
Author(s):  
A. Ortín ◽  
J. Montesinos ◽  
E. López ◽  
P. del Hierro ◽  
B. Monrabal ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Ir Detector

Composition and molar mass characterisation of bacterial extracellular polymeric substances by using chemical, spectroscopic and fractionation techniques

2011 ◽  
Vol 8 (2) ◽  
pp. 155 ◽  
Author(s):  
Enrica Alasonati ◽  
Vera I. Slaveykova
Keyword(s):  
Chemical Composition ◽  
Mass Distribution ◽  
Sinorhizobium Meliloti ◽  
Extracellular Polymeric Substances ◽  
Molar Mass ◽  
Waste Water Treatment ◽  
Molar Mass Distribution ◽  
Spectroscopic Techniques ◽  
High Molar Mass ◽  
Vis Spectroscopy

Environmental contextExtracellular polymeric substances (EPS) released by microorganisms are an important component of organic matter in the environment. EPS play an essential role in cell adhesion to surfaces, biofilm and floc formation, soil aggregation and stability and in the activated sludge of waste water treatment plants. EPS are complex mixtures containing components of different chemical nature and molecular size, which make their characterisation difficult. The present work explores the link between chemical composition and molar-mass distribution of the EPS released by the bacterium Sinorhizobium meliloti by using a combination of chemical, spectroscopic and fractionation techniques. AbstractThe chemical composition and molar-mass distribution of extracellular polymeric substances (EPS) produced by the bacterium Sinorhizobium meliloti have been characterised by combining asymmetrical flow field-flow fractionation (AFlFFF), chemical and spectroscopic techniques. The relationship between the EPS composition and molar-mass distribution has been studied by comparing the characteristics of EPS excreted by the wild type S. meliloti and by a mutant deficient in the production of high-molar-mass EPS, as well as by the analysis of total protein content in the collected AFlFFF fractions. Total organic carbon, protein and polysaccharide contents of the EPS were also determined. Obtained results demonstrate the existence of two major populations with weight-average molar masses of 1.40 × 105 and 4.57 × 105 g mol–1 respectively. The lower molar-mass population contained predominantly protein-like substances, detectable by UV-VIS spectroscopy, whereas the higher molar-mass population was rich in exopolysaccharides and exoproteins. These findings are in general agreement with the size distributions and chemical heterogeneity observed by nanoparticle tracking analysis, and the characterisation of the composition of all the EPS by different analytical techniques.

Controlled synthesis and characterization of poly[methyl(3,3,3-trifluoropropyl)siloxane] with selective end groups

RSC Advances ◽  
2014 ◽  
Vol 4 (99) ◽  
pp. 56279-56287 ◽  
Author(s):  
Hua-Feng Fei ◽  
Wenchun Xie ◽  
Qian Wang ◽  
Xiyin Gao ◽  
Tao Hu ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Synthesis And Characterization ◽  
Controlled Synthesis ◽  
Controlled Polymerization ◽  
End Groups ◽  
Polymerization Method

Controlled polymerization method to synthesize poly[methyl(3,3,3-trifluoropropyl)siloxane] with narrow molar mass distribution, broad “termination window”, selective end groups and quantitative transformation.

scholarly journals On-line SEC-MR-NMR hyphenation: optimization of sensitivity and selectivity on a 62 MHz benchtop NMR spectrometer

2019 ◽  
Vol 10 (18) ◽  
pp. 2230-2246 ◽  
Author(s):  
Carlo Botha ◽  
Johannes Höpfner ◽  
Britta Mayerhöfer ◽  
Manfred Wilhelm
Keyword(s):  
Chemical Composition ◽  
Mass Distribution ◽  
Molar Mass ◽  
Analytical Techniques ◽  
Polymeric Materials ◽  
Molar Mass Distribution ◽  
Complex Formulation ◽  
Sensitivity And Selectivity ◽  
On Line ◽  
Synthetic Routes

The development of sophisticated synthetic routes for polymeric materials and more complex formulation used in current polymers require more advanced analytical techniques. A direct correlation between molar mass distribution and chemical composition is provided.

Degradation of unstabilised polypropylene and a propene- 1-pentene copolymer

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Stefan de Goede ◽  
Robert Brüll ◽  
Harald Pasch ◽  
Niall Marshall
Keyword(s):  
Chemical Composition ◽  
Mass Distribution ◽  
Molar Mass ◽  
Degradation Process ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
Low Molecular Weight ◽  
Composition Distribution ◽  
Chemical Composition Distribution ◽  
Exclusion Chromatography

Abstract The degradation of polypropylene (PP) and a propene-1-pentene copolymer (P2) have been monitored with regard to chemical composition, molar mass distribution and chemical composition distribution. The increase in the carbonyl index can be monitored by IR and a decrease in molar mass can be observed from size-exclusion chromatography (SEC). CRYSTAF shows that the chemical heterogeneity of the samples broadens with continuing degradation. SEC-FTIR reveals that the degraded species are mainly found in the low-molecular-weight end of the molar mass distribution. Spatial heterogeneity of the degradation process has been proven by the analysis of abrased layers. It was found that the P2 copolymer degrades at a higher rate compared to PP.

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.

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