scholarly journals The characterization of linear polyethylene SRM 1475. IX. Number average molecular weight of fractions by membrane osmometry

1972 ◽  
Vol 76A (2) ◽  
pp. 161 ◽  
Author(s):  
James E. Brown ◽  
Peter H. Verdier
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight ◽  
Linear Polyethylene

Synthesis and Characterization of Coumarin–Trioxane–Urea Copolymers

1996 ◽  
Vol 8 (2) ◽  
pp. 295-300 ◽  
Author(s):  
D I Brahmbhatt ◽  
B R Hirani
Keyword(s):  
Molecular Weight ◽  
Elemental Analysis ◽  
Average Molecular Weight ◽  
Synthesis And Characterization ◽  
Number Average Molecular Weight ◽  
Molar Ratios

4-methyl-7-hydroxycoumarin trioxane urea (MHCTU) copolymers were prepared by copolycondensation of 4-methyl-7 hydroxycoumarin (MHC), trioxane (T) and urea (U) in the presence of 2 M HCl/H2SO4 as a catalyst with different molar ratios of reacting monomers. The copolymers were characterized by elemental analysis, IR spectral and TGA studies. The number average molecular weight ( Mn) of all the produced copolymers was determined by non-aqueous titrimetry.

scholarly journals Synthesis and Characterization of Colored Polyureas

2004 ◽  
Vol 1 (1) ◽  
pp. 51-56 ◽  
Author(s):  
M. G. Patel ◽  
K. R. Desai ◽  
H. S. Patel
Keyword(s):  
Electrical Conductivity ◽  
Molecular Weight ◽  
Room Temperature ◽  
Average Molecular Weight ◽  
Conductometric Titration ◽  
Spectral Studies ◽  
Synthesis And Characterization ◽  
Disperse Dyes ◽  
Number Average Molecular Weight

Various disperse dyes based onm-phenylenediamine have been prepared. These dyes then polycondensation with 4,4'-Diphenyl methane diisocyanate. The resultant colored polyureas were characterized by N content, IR spectral studies, Number Average Molecular Weight (Mn) estimation by nonaqueous conductometric titration and thermogravimetry. All the polyureas were subjected to measure electrical conductivity at room temperature.

CHARACTERIZATION OF SOME IRAQI ASPHALTS I. NUMBER AVERAGE MOLECULAR WEIGHT INVESTIGATION OF DORA AND QAIYARAH ASPHALTS

1986 ◽  
Vol 4 (3) ◽  
pp. 249-260 ◽  
Author(s):  
Mustafa M. F. Al-Jarrah ◽  
Hussain H. Al-Soufi ◽  
Rita L. Apikian ◽  
H. I. Al-Saleem ◽  
S. S. Naoom
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Number Average Molecular Weight

Preparation and characterization of novel soluble polyarylates derived from 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene with various bisphenols

2017 ◽  
Vol 30 (10) ◽  
pp. 1203-1209
Author(s):  
Yu-Ting Zhou ◽  
Shou-Ri Sheng ◽  
Chuan-Chao Tang ◽  
Cheng Song ◽  
Zhen-Zhong Huang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Room Temperature ◽  
Phase Transfer ◽  
Average Molecular Weight ◽  
Interfacial Polycondensation ◽  
Number Average Molecular Weight ◽  
Glass Transition Temperatures ◽  
Flexible Films

A series of new polyarylates bearing cardo xanthene groups were synthesized by phase-transfer-catalyzed interfacial polycondensation of 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene with various bisphenols containing the isopropylidene, hexafluoroisopropylidene, 1-phenylethylidene, diphenylmethane, cyclohexane, and xanthene structures. High-molecular-weight polyarylates with number-average molecular weight and polydispersity index in the range of 30,100–35,300 and 1.82–2.17, respectively, exhibited high glass transition temperatures ranged from 226°C to 261°C, and their 10% weight loss temperatures were in the range of 421–452°C with char yields above 45% at 700°C in nitrogen. All the polyarylates were amorphous and readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent, and flexible films with tensile strengths of 85.6–108.3 MPa, elongations at break of 2–3%, and tensile moduli of 7–9 GPa.

Synthesis and characterization of poly(coumarin-urethane)s

1994 ◽  
Vol 6 (3) ◽  
pp. 257-262
Author(s):  
D I Brahmbbatt ◽  
L Jayabalan ◽  
Harshad D Patel
Keyword(s):  
Molecular Weight ◽  
Elemental Analysis ◽  
Vapour Pressure ◽  
Condensation Reaction ◽  
Average Molecular Weight ◽  
Spectral Studies ◽  
Synthesis And Characterization ◽  
Molecular Weight Determination ◽  
Number Average Molecular Weight

Poly(coumarin-urethane)s (PCUs) were prepared by the condensation reaction of 3,3'-dihydroxy-6,6'-methylcnebiscoumarin (DHMBC) with various diisocyanates. All the poly(coumarin-urethane)s were characterized by elemental analysis, IR spectral studies, number average molecular weight determination (by vapour pressure osmometry), viscosity studies and thermogravimetry.

scholarly journals Synthesis of co-poly(eugenol sulfonate)-DVB from eugenol as a major component of Syzygium aromaticum oils

2004 ◽  
Vol 2 (2) ◽  
pp. 53-57 ◽  
Author(s):  
DESI SUCI HANDAYANI ◽  
TRIANA KUSUMANINGSIH ◽  
MARIA YULI
Keyword(s):  
Molecular Weight ◽  
Melting Point ◽  
Average Molecular Weight ◽  
Nitrogen Atmosphere ◽  
Capillary Viscometer ◽  
Syzygium Aromaticum ◽  
Number Average Molecular Weight ◽  
Solid Matter ◽  
Concentrated Sulfuric Acid

Cationic co-polymerization between eugenol and divinylbenzene (DVB) (2%, 4%, 6%, 8%, 10% and 12%) with BF3O(C2H5)2 as a catalyst at room temperature without media under nitrogen atmosphere has been investigated. Co-poly (eugenol sulfonate)-DVB has been synthesized by sulfonation of co-poly(eugenol-DVB). In the sulfonation, concentrated sulfuric acid was used as the reagent and Ag2SO4 as a catalyst. Structure and characterization of co-poly (eugenol-DVB) and Co-poly(eugenol sulfonate)-DVB were analyzed by Infra Red (IR), Differential Thermal Analysis) DTA and UV-Vis. Measurement of the number-average molecular weight (Mn) of copolymer was used Ostwald capillary viscometer. The yields of co-polymerization of eugenol-DVB were solid matter and the highest result was found on a copolymer of 10% of DVB. Its melting point was 69.33oC. The increasing of mole of DVB increase the number-average molecular weight (Mn) of co-poly (eugenol sulfonate)-DVB. A copolymer of 12% of DVB gave the highest molecular weight, Mn = 2984 g/mole. Synthesized of co-poly (eugenol sulfonate)- DVB were solid matter too and the highest result was found on a copolymer of 12% of DVB. Its melting point was 95.5oC.

Some inequalities for moments and coefficients of variation for a large class of probability functions

1979 ◽  
Vol 16 (3) ◽  
pp. 665-670 ◽  
Author(s):  
Burt V. Bronk
Keyword(s):  
Large Class ◽  
Average Molecular Weight ◽  
Empirical Measure ◽  
Number Average Molecular Weight ◽  
Positive Real ◽  
Coefficients Of Variation ◽  
Probability Densities ◽  
Rigorous Bounds ◽  
Illustrative Application

Some inequalities for moments and coefficients of variation of probability densities over the positive real line are obtained by means of simple geometrical relationships. As an illustrative application rigorous bounds are obtained for the ratio of weight average to number average molecular weight for a large class of distributions of macromolecules, giving a more precise characterization of this empirical measure of heterogeneity.

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.

Study on the Preparation and Characterization of Carboxyl Terminated Poly(L-Lactic Acid) (PLLA) Prepolymers

2017 ◽  
Vol 872 ◽  
pp. 165-170
Author(s):  
Shi Chao Lu ◽  
Yang Chuan Ke ◽  
Qian Zhou ◽  
Zhao Rui Meng ◽  
Guo Liang Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Average Molecular Weight ◽  
Polymerization Temperature ◽  
Capping Agent ◽  
Molar Amount ◽  
Optimum Reaction ◽  
Catalyst Content ◽  
End Capping

The carboxyl terminated poly (L-lactic acid) (PLLA) prepolymers were prepared via polycondensation of L-lactic acid and 1,6-adipic acid (end capping agent) under the catalyst of stannous octoate. The effects of synthetic condition, such as reaction temperature, amount of catalyst, content of the end capping agent, etc, on the molecular weight of PLLA were discussed. Fourier transform infrared and 1H nuclear magnetic resonance were used to characterize the PLLA prepolymers. The results indicated that the polycondensation was performed under an optimum reaction condition as following: the amount of the catalyst was 500 ppm based on the mass of lactic acid, the amount of the end capping agent was 1% (the molar amount of the lactic acid), and the polymerization temperature was 170 °C. The viscosity-average molecular weight of the product reached 2.826×104 at this polymerization temperature and the yield was 73.34%.

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