Synthesis and characterization of new liquid, branched and random poly(methylhydrosiloxanes)

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Zofia Michalska ◽  
Witold Fortuniak
Keyword(s):  
Vacuum Distillation ◽  
Size Exclusion ◽  
Synthesis And Characterization ◽  
Low Molecular Weight ◽  
Structural Units ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Random Structures ◽  
Ft Ir

AbstractTwelve new liquid branched poly(methylhydrosiloxanes) of random structures (b-r-PMHS), containing triple branching units MeSiO1.5 (T), both Me2SiO (D) and MeHSiO (DH) chain building units (or only mers MeHSiO), and terminal groups Me3SiO0.5, have been prepared by hydrolytic polycondensation method of appropriate organic chlorosilanes in diethyl ether medium at temperatures < 0 °C. Two b-r-PMHS containing structural units: M, D, DH, T and TH have been obtained as well. Volatile low molecular weight oligosiloxanes were removed by vacuum distillation at 125-150 °C. Yields of b-r-PMHS ranged from 57 to 84 wt. %. All polymeric products were characterized by FT-IR, 1H- and 29Si-NMR, and elemental analysis. Their dynamic viscosities were determined in the Brookfield HBDV+IIcP cone-plate viscometer. The molecular weights of b-r-PMHS and polydispersities of MW were analyzed by size exclusion chromatography (SEC).

Behavior of xylans from the Eucalyptus species. Part 2. Characterization of 4-O-methylglucuronoxylans isolated from black liquors of kraft pulping of Eucalyptus grandis and E. urophylla

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 123-128
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres ◽  
...  
Keyword(s):  
Average Molecular Weight ◽  
Eucalyptus Grandis ◽  
Kraft Pulping ◽  
Raw Material ◽  
Size Exclusion ◽  
Eucalyptus Species ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Black Liquors

Abstract 4-O-methylglucuronoxylans isolated from Eucalyptus grandis and Eucalyptus urophylla kraft black liquors (KBLs) were chemically characterized by Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), and nuclear magnetic resonance (NMR) spectroscopy. Doses of alkali charge, expressed as active alkali (AA), were 16, 17, and 18% while the sulfidity was kept at 25%. Kappa numbers of 19.1, 17.5, and 16.1 for E. grandis and 20.4, 16.8, and 15.4 for E. urophylla were obtained. At higher alkali charges, the recovery of xylans from the KBLs was lower and the degree of substitution of xylans with uronic acids decreased. The average molecular weight (Mw) of the recovered xylans was greater under conditions of mild pulping, i.e., in the case of pulps with higher kappa numbers. Mw of xylans ranged from 16.1 to 19.1 kDa for E. grandis and from 15.4 to 20.4 kDa for E. urophylla. The xylans from KBL may be useful as pulp modifying agents or as a raw material for advanced applications.

Synthesis and characterization of new, liquid, branched poly(methylvinylborosiloxanes)

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Witold Fortuniak
Keyword(s):  
Functional Groups ◽  
Atomic Spectroscopy ◽  
Size Exclusion ◽  
Random Structure ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Siloxane Oligomers ◽  
Exclusion Chromatography ◽  
Ether Solution

Abstract New liquid branched poly(methylvinylborosiloxanes) (br-PMVBS) of random structure were synthesized in three steps. By reacting boric acid with an excess of dimethyldichlorosilane (Me2SiCl2) in dry ether a “borosiloxane precursor”: tris(chlorodimethylsilyl) borate B(OSiMe2Cl)3 was prepared. In the second step of synthesis ether solution of B(OSiMe2Cl)3 was added to a mixture of appropriate organic chlorosilanes (Me2SiCl2, MeViSiCl2, MeSiCl3, and Me3SiCl) and all reagents were reacted with stoichiometric amounts of water, in the presence of pyridine (as an acceptor of HCl), in dry ether, at low temperature (usually at -10 to 0 C). In order to fully react (“to block”) trace silanol groups, reactions of intermediate PMVBS with additional batches of Me3SiCl were carried out in the third step, C5H5N·HCl was filtered off and washed with a dry ether. The solvent was distilled off from filtrates and low molecular weight siloxane oligomers were removed by a vacuum distillation at 130-150 C. Chemical structures of br-PMVBS were confirmed by elemental analysis and spectroscopic methods (FTIR, emission atomic spectroscopy ICP-AES, and NMR: 1H, 29Si and 11B). On the basis of analysis of their 29Si-NMR spectra the microstructure of polysiloxane chains was proposed. The prepared br-PMVBS had in their structures: triple branching borosiloxane units: BO1.5 and in some cases methylsiloxane moiety CH3SiO1.5 (T). They contained linkages: Si-O-Si, Si-O-B, vinyl(methyl)siloxane functional groups (CH2=CH)MeSiO (Dvi), dimethylsiloxane mers (CH3)2SiO (D), and non-reactive trimethylsiloxy terminal groups (CH3)3SiO0.5 (M), but they did not have: hydroxyl functional groups: Si-OH and B-OH, and sensitive to water B-O-B linkages. Molecular weights of br-PMVBS (Mn = 1500-3300 g/mol; Mw = 3800-7400 g/mol) and their polydispersity (Mw/Mn = 2.0-2.5) were determined by a size exclusion chromatography (SEC).

Comparison of exopolysaccharides from mucoid and nonmucoid strains of Clavibacter michiganensis subspecies sepedonicus

1993 ◽  
Vol 39 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Paul J. Henningson ◽  
Neil C. Gudmestad
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
Neutral Sugar ◽  
Clavibacter Michiganensis ◽  
Serological Reaction ◽  
Molecular Weights ◽  
Exclusion Chromatography

The exopolysaccharides produced by six strains of Clavibacter michiganensis ssp. sepedonicus were isolated and purified by liquid chromatography. Neutral sugar composition and molecular weights were determined for each polysaccharide fraction, using gas chromatography and high-performance size-exclusion chromatography. The serological reaction of each fraction was tested using enzyme-linked immunosorbent assay. Exopolysaccharide from nonmucoid strains contained only low molecular weight polysaccharides (1.5 × 103 to 1.1 × 104). Exopolysaccharide from mucoid and intermediate strains could be separated into low (4.0 × 103 to 1.1 × 104) molecular weight and high (5.0 × 105 to 1.6 × 106) molecular weight fractions. High molecular weight polysaccharides were composed almost exclusively of galactose, glucose, and fucose. The ratios of these sugars were highly variable among strains. Low molecular weight polysaccharides were primarily composed of galactose with significant and varying amounts of glucose, rhamnose, mannose, and ribose. All polysaccharide fractions except one, produced by a nonmucoid strain, reacted in the immunoassay test.Key words: exopolysaccharide, polysaccharide, Clavibacter, michiganensis, sepedonicus.

Synthesis and Characterization of Aliphatic Ammonium Ionenes: Aqueous Size Exclusion Chromatography for Absolute Molecular Weight Characterization

2008 ◽  
Vol 41 (13) ◽  
pp. 4635-4641 ◽  
Author(s):  
John M. Layman ◽  
Erika M. Borgerding ◽  
Sharlene R. Williams ◽  
William H. Heath ◽  
Timothy E. Long
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Synthesis And Characterization ◽  
Exclusion Chromatography

Characterization of polyamides 6, 11, and 12. Determination of molecular weight by size exclusion chromatography (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2009-2025 ◽  
Author(s):  
E. C. Robert ◽  
Rudolf Bruessau ◽  
J.-E. Dubois ◽  
Bernard Jacques ◽  
Nico Meijerink ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Working Party ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Relative Standard ◽  
Exclusion Chromatography ◽  
Iupac Commission ◽  
Commercial Polymers

This report presents the results from IUPAC Working Party IV.2.2 of the global trial within the framework of IUPAC Commission IV.2, “Characterization of Commercial Polymers”. The results were compared on the basis of molecular weight obtained by size exclusion chromatography (SEC)using different techniques practiced in participating laboratories, the majority of which were materials suppliers. The practical methodologies used different solvents for the polymers, in particular, benzyl alcohol, 1,1,1,3,3,3 hexafluoropropan-2-ol and tetrahydrofuran; the latter solvent was used after chemical modification of the polyamides, in general with trifluoroacetic anhydride. Eight laboratories participated in the trial. The repeatability for molecular weight in each laboratory was good, whatever technique was used, the relative standard deviation averaged over all laboratories being around 3%. The deviations in distribution of molecular weights with different experimental methodologies were broader, but were reasonably good despite the diversity of methods. The differences in the distribution correspond to a confidence interval of about 30% in molecular weight.

Characterization of lignin residues derived from the alkaline hydrolysis of glycol lignin

1990 ◽  
Vol 68 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Ronald W. Thring ◽  
Esteban Chornet ◽  
Jean Bouchard ◽  
Pierre F. Vidal ◽  
Ralph P. Overend
Keyword(s):  
Alkaline Hydrolysis ◽  
Size Exclusion ◽  
Absorption Intensity ◽  
Molecular Weights ◽  
Carbon Carbon Bonds ◽  
Lower Oxygen ◽  
Exclusion Chromatography ◽  
Hydrolysis Of ◽  
C Nmr

Lignin residues from the alkaline hydrolysis of solvolytic lignin have been characterized by elemental analysis, size exclusion chromatography, Fourier transform infrared spectroscopy, 13C NMR, and for methoxyl content. All lignin residues were found to have higher carbon and lower oxygen contents than the original glycol lignin. Methoxyl contents decreased with increasing severity of treatment. All treated lignins have lower molecular weights than the original, which is indicative of the extensive depolymerization of glycol lignin by alkaline hydrolysis. The appearance of new bands in the 3050–2800 cm−1 and 900–800 cm−1 regions in the infrared spectra along with increasing absorption intensity under more severe conditions demonstrates that, despite the tendency to depolymerization, new carbon–carbon bonds are formed due to repolymerization reactions. 13C NMR revealed that extensive cleavage of the side chains and β-O-4 interunit linkages had occurred during alkaline hydrolysis and that the new bonds formed due to condensation reactions at higher severities are of the methine, methylene, methyl and carboxyl types. Keywords: residual lignins, alkaline hydrolysis, characterization.

scholarly journals Synthesis and characterization of amphiphilic graft copolymers of poly(1,3 dioxolane) macromonomers with styrene and methyl methacrylate

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Hayet Bendaikha ◽  
Gérald Clisson ◽  
Abdelouahad Khoukh ◽  
Jeanne François ◽  
Seghier Ould Kada
Keyword(s):  
Methyl Methacrylate ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Molecular Weights ◽  
Molar Ratios ◽  
H Nmr ◽  
Amphiphilic Graft Copolymers ◽  
Exclusion Chromatography ◽  
Cationic Ring Opening Polymerization

AbstractMethacrylate-terminated Poly(1,3 dioxolane) (PDXL) macromonomers were synthesized by cationic ring-opening polymerization in the presence of 2- hydroxypropyl methacrylate (2-HPMA) as transfer agent. Molecular weights, polydispersity index and functionality of the PDXL macromonomers were evaluated by size exclusion chromatography (SEC) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Copolymerizations of PDXL macromonomers, of different molecular weights, with styrene (St) and methyl methacrylate (MMA) were carried out using various feed molar ratios. The resulting polymers confirmed the grafting of PDXL with PS and PMMA by SEC and 1H-NMR Monomer reactivity ratios between the macromonomers and the comonomers were estimated from the copolymerization results. Macromonomer reactivity depends on the comonomer considered. Glass transition temperatures of the copolymers were found to decrease with an increase in the amount of PDXL in the copolymers. The values of Tg depend on the composition and the size of the PDXL grafts.

Molecular Weight Characterization of Food Grade Polyethylenes and Extractables by Size Exclusion Chromatography

1981 ◽  
Vol 64 (4) ◽  
pp. 1008-1013
Author(s):  
Roger C Snyder ◽  
Charles V Breder
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
High Density ◽  
Size Exclusion ◽  
Low Density ◽  
Food Grade ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Band Spreading

Abstract Size exclusion chromatography (SEC) was used to characterize the molecular weight distribution (MWD) of 6 low density and 6 high density food grade polyethylene resins. The hexane and xylene extractable fractions of these 12 resins were also analyzed by SEC. An IBM 370/168 computer with an APL program was used to analyze the chromatograms and correct for chromatographic band spreading and skewing. Calculated weight average molecular weights (Mw) for the resins ranged from 40 000 to 200 000 and number average molecular weights (Mn) ranged from 6000 to 60 000. Median values of Mw and Mn were 1800 and 950, respectively, for hexane extractables from the low density resins, and were 310 and 290, respectively, for hexane extractables from the high density resins. Corresponding Mw and Mn values for xylene extractables were consistently larger than those for hexane extractables.

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