THE NUMBER-AVERAGE AND WEIGHT-AVERAGE MOLECULAR WEIGHT OF SOME NONIONIC SURFACE-ACTIVE AGENTS

1962 ◽  
Vol 40 (5) ◽  
pp. 957-962 ◽  
Author(s):  
A. F. Sirianni ◽  
J. M. G. Cowie ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Benzene Solution ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Surface Active Agents ◽  
Pressure Lowering ◽  
Surface Active ◽  
Active Substances

Further evidence for the existence of large differences between the weight- and number-average molecular weight for nonionic surface-active substances in nonaqueous solvents has been found when the property is assessed by light-scattering and vapor-pressure-lowering measurements. Equilibrium ultracentrifuge measurements support the results obtained by vapor-pressure-lowering determinations. Sorbitan and glycerol monostearates have been examined in benzene solution.

scholarly journals Synthesis of Highcis-1,4-BR with Neodymium for the Manufacture of Tires

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Maria Leonor Méndez-Hernández ◽  
José Luis Rivera-Armenta ◽  
Ulises Páramo-García ◽  
Sergio Corona Galvan ◽  
Ricardo García-Alamilla ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Rheological Properties ◽  
Average Molecular Weight ◽  
Catalyst System ◽  
Polydispersity Index ◽  
Fatigue Properties ◽  
Number Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Permanent Set ◽  
Reinforcing Filler

The salt of neodymium has been widely used in industrial polymerization of 1,3-butadiene. We used the ternary catalytic system neodymium versatate/diethylaluminum chloride/triisobutylaluminum (NdV3/DEAC/TIBA) with 0.5 mM NdV3/100 g Bd, NdV3 : DEAC = 1 : 9 mol : mol, and TIBA = 25, 50, 100, and 200 mM. The number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity index (PDI) were analyzed by GPC; the rheological properties were analyzed by DMA. The formulations were prepared with carbon black (IRB6) as reinforcing filler and the mechanical properties were compared to behavior of the different elastomeric compounds. The elastomeric compounds were characterized by their rheological properties, tensile strength, abrasion resistance, tear strength, permanent set, resilience, and fatigue properties. The highcis-1,4 polybutadiene (highcis-1,4-BR) was obtained with a percentage ofcis-1,4 ≥97%. The weight-average molecular weight (Mw) was from 150 × 103to 900 × 103 g/mol and polydispersity index (PDI) was from 3.1 to 5.1. This work is based on evaluation of the effect of the catalyst system on the final properties of the synthesized polybutadiene.

scholarly journals Fabrication of Magnetic Catalyst Fe3O4-SiO2-V3 and Its Application on Lignin Extraction from Corncob in Deep Eutectic Solvent

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1545
Author(s):  
Maonan Yuan ◽  
Zhen Wang ◽  
Yu Liu ◽  
Guihua Yang
Keyword(s):  
Molecular Weight ◽  
Choline Chloride ◽  
Average Molecular Weight ◽  
Deep Eutectic Solvent ◽  
Reaction System ◽  
2D Nmr ◽  
Number Average Molecular Weight ◽  
Batch Experiments ◽  
Weight Average Molecular Weight ◽  
Lignin Extraction

Fe3O4-SiO2-V3 was prepared by deposited H6PMo9V3O40 on Fe3O4-SiO2 and employed as a catalyst to extract lignin from corncob in deep eutectic solvent (choline chloride/lactic acid = 1/10). Batch experiments were conducted in an autoclave under the conditions of 500 kPa, 90–130 °C and 15 h, while the dosage of the catalyst was set as a variable. Results indicated that the catalyst could effectively improve the qualities of the lignin, while the characteristics of the lignin showed prominent changes with the participation of the catalyst: the extraction rate increased from 71.65% to 98.13%, the purity was improved from 85.62% to 97.09%, and both the number average molecular weight and the weight average molecular weight also decreased significantly. Besides, the molecular distribution of the lignin achieved from the CC-LA-Fe-Si-V3 reaction system was found to be more highly concentrated (Polydispersity index = 1.746). Results from 2D NMR HSQC analysis indicated that lignin fractions achieved from the CC-LA-Fe-Si-V3 system showed distinct destruction involving C2-H2 in guaiacyl units (G), C5-H5 in guaiacyl units (G), and the Cγ-Hγ in γ-hydroxylated β-O-4′ substructures, but little changes in the Cγ-Hγ in phenylcoumaran substructures.

Biodegradable Polymer Composites for Temporary Replacement of Trabecular Bone: The Effect of Polymer Molecular Weight on Composite Strength and Modulus

1993 ◽  
Vol 331 ◽  
Author(s):  
Michael J. Yaszemski ◽  
Antonios G. Mikos ◽  
Richard G. Payne ◽  
Wilson C. Hayes
Keyword(s):  
Molecular Weight ◽  
Composite Material ◽  
Trabecular Bone ◽  
Average Molecular Weight ◽  
Particulate Composite ◽  
Reaction Scheme ◽  
The Body ◽  
Number Average Molecular Weight ◽  
Polymer Molecular Weight ◽  
Weight Average Molecular Weight

AbstractOur laboratory has been developing a particulate composite material as a temporary replacement for trabecular bone. The material is degradable in physiologic fluids, and uses starting materials that the body can metabolize and excrete. This study investigates the influence of the molecular weight of one component, a linear polyester, on the mechanical strength of the composite material. The compressive strength and modulus increase from “low” to “medium” molecular weight, but do not increase further from “medium” to “high” molecular weight. Low, medium, and high are relative to the highest molecular weight attainable with the current reaction scheme, which is a number average molecular weight (Mn) of 2,038 and a weight average molecular weight (Mw) of 11,916.

scholarly journals A Preliminary Study on the Synthesis of poly(vinylbenzyl chloride) with Different Solvents

2021 ◽  
Vol 50 (6) ◽  
pp. 1767-1773
Author(s):  
Manjusha Elizabeth Mathew ◽  
Ishak Ahmad ◽  
Sabu Thomas ◽  
Muhammad Kassim ◽  
Rusli Daik
Keyword(s):  
Molecular Weight ◽  
Thermogravimetric Analysis ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Spectroscopic Techniques ◽  
Number Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Gel Permeation ◽  
Differential Thermogravimetric Analysis ◽  
Preliminary Study

Polyvinyl benzyl chloride (PVBC) was synthesized by free radical polymerization of 4-vinylbenzyl chloride using benzoyl peroxide initiator at 60 °C. PVBC was synthesised in different solvents such as toluene, xylene, 1,4-dioxane, and tetrahydrofuran. The polymers were structurally characterized by 1H NMR and FTIR spectroscopic techniques. The thermal property of the polymer was investigated by thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTA).The number average molecular weight, weight average molecular weight and polydispersity index of PVBC synthesised in different solvents were determined and compared by gel permeation chromatography technique.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

Chemistry and Properties of Imide Oligomers from Phenylethynyl-Containing Diamines

2000 ◽  
Vol 12 (1) ◽  
pp. 213-223 ◽  
Author(s):  
J G Smith ◽  
J W Connell
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Research Effort ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Similar Composition ◽  
Imide Oligomers ◽  
Calculated Number

As an extension of work on pendent phenylethynyl-containing imide oligomers, three new diamines containing pendent phenylethynyl groups were prepared and characterized. These diamines were used to prepare pendent and pendent and terminal phenylethynyl imide oligomers via the amide acid route in N-methyl-2-pyrrolidinone at a calculated number average molecular weight of 5000 g mol−1. The pendent phenylethynyl groups were randomly distributed along the oligomer backbone and provided a means of controlling the distance between reactive sites. The imide oligomers were characterized and thermally cured, and the cured polymers evaluated as thin films and compared with materials of similar composition prepared from 3,5-diamino-4′-phenylethynylbenzophenone. This work was performed as part of a continuing research effort to develop structural resins for potential aeronautical applications.

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