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Topic: Number average molecular weight

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	Number Average and Weight Average Molecular Weight for Macrogalleria
		The number average molecular weight is the total weight of the sample divided by the number of molecules in the sample.
		This means that you multiply the weight of the molecule by the number of molecules of that weight.
		The distribution of molecular weights in a polymer sample is often described by the ratio of the weight average molecular weight to the number average molecular weight.
	www.pslc.ws /mactest/average.htm (531 words)

	New Page 1
		Consequently, molecular weight determinations are usually made indirectly by such physical means as measurement of viscosity, osmotic pressure, or light scattering, all of which are affected by the number, size, or shape of molecules in a suspension or in a solution.
		The "weight-average" molecular weight is particularly significant in the analysis of properties such as viscosity, where the weight of the molecules is important.
		Weight- average molecular weight and molecular weight distributions are determined from ultracentrifuge sedimentation, diffusion and light scattering.
	nersp.nerdc.ufl.edu /~soderho/D03.htm (512 words)

	United States Patent Application: 0030176615
		POLYOL B A propylene oxide-based diol having a number average molecular weight of 4,000 and a degree of unsaturation of 0.005 meq/g.
		POLYOL C A propylene oxide-based diol having a number average molecular weight of 4,000, with 15% internal ethylene oxide and a degree of unsaturation of 0.005 meq/g.
		POLYOL F A propylene oxide-based diol having a number average molecular weight of 4,000 with 40% internal ethylene oxide and a degree of unsaturation of 0.005 meq/g.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=20030176615.PGNR.&OS=DN/20030176615&RS=DN/20030176615 (6431 words)

	molecular weight. The Columbia Encyclopedia, Sixth Edition. 2001-05
		The molecular weight may be calculated from the molecular formula of the substance; it is the sum of the atomic weights of the atoms making up the molecule.
		Molecular weights of substances may be determined experimentally in various ways, the method employed usually depending on the state (solid, liquid, or gas) of the substance.
		The molecular weights of substances that are not normally gaseous and do not evaporate without decomposition are sometimes determined from their effects on the melting point, boiling point, vapor pressure, or osmotic pressure of some solvent (see colligative properties).
	www.bartleby.com /65/mo/molecwght.html (519 words)

	U.S. Patent: 6228551 - Toner for developing electrostatic image - May 8, 2001
		The toner of claim 3 wherein the molecular weight of polypropylene particle is 1,500 to 10,000, in number average molecular weight Mn, and ratio of weight average molecular weight Mw to Mn of the polypropylene particles is 1.5 to 3.
		The molecular weight of the low molecular weight polypropylene particle is preferably from 1,500 to 10,000, particularly from 1,800 to 4,000, in number average molecular weight Mn.
		The ratio of the weight average molecular weight Mw to the number average molecular weight Mn of the low molecular weight polypropylene particle Mw/Mn is preferably from 1.5 to 3, particularly from 2 to 3.
	www.everypatent.com /comp/pat6228551.html (5619 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		The number average molecular weight is the common, mean, average of the molecular weights of the individual polymers.
		It is determined by measuring the molecular weight of n polymer molecules, summing the weights, and dividing by n.
		An alternative measure of the molecular weight of a polymer is the weight average molecular weight.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=number_average_molecular_weight (185 words)

	U.S. Patent: 6023547 - Radiation curable composition comprising a urethane oligomer having a polyester backbone - ...
		It was unexpected that limiting the molecular weight of both the polyester backbone and the urethane oligomer within particular ranges, together with utilizing a diol component having a substituted carbon at the.beta.-position with respect to the hydroxyl groups, would provide polyester-based radiation cured coatings with improved hydrolysis resistance.
		It was further unexpected that such an improvement in hydrolysis resistance could be achieved by limiting the molecular weight of the polyester backbone, together with utilizing a diol component having a disubstituted carbon at the.beta.-position with respect to the hydroxyl groups, wherein the substituents on the.beta.-carbon total at least 3 carbon atoms.
		The molecular weight of these polyols, in terms of the number average molecular weight based on polystyrene standard, is usually 50-15,000, and preferably 100-8,000.
	www.everypatent.com /comp/pat6023547.html (6660 words)

	Weighted Average Cost Capital (Site not responding. Last check: )
		is the number of molecules of molecular weight
		Intuitively, if the weight average molecular weight is ''w'', and you pick a random monomer, then the polymer it belongs to will have a weight of ''w'' on average.
		An alternative measure of molecular weight for a polymer is the number average molecular weight; their ratio is called the polydispersity index.
	www.wwwtln.com /finance/202/weighted-average-cost-capital.html (1295 words)

	Number Average Molecular Weight, Mn
		Number Average Molecular Weight, Mn Slide 10 of 33
		Number Average Molecular Weight, Mn where Mi is the molecular weight of that species (on the x-axis)
		Example, What is the molecular weight of a polymer sample in which the polymers molecules are divided into 5 categories.
	www.csuchico.edu /~jpgreene/itec041/m41_ch03/sld010.htm (77 words)

	TEXT OF CLASS UPPER LIMIT PAPER
		The compound molecular weights described here were calculated with isotopically averaged atomic weights and are not necessarily equal to the mass of the molecular ion as used by mass spectroscopists.
		Plots of the cumulative number of class spectra vs. the difference between the true molecular weight and the reference average was used with statistical analysis of the data to establish the upper limits.
		The molecular weight range searched was 1 to 218 Daltons and the members with the highest molecular weight (218 Daltons) were [1-(1,1-dimethylethyl)-3,3-dimethylbutyl]benzene; (1-ethyloctyl)- benzene; (1-propylheptyl)benzene; (1-butylhexyl)benzene; decylbenzene; (1-methylnonyl)benzene; 1,4-bis(1-ethylpropyl)- benzene; p-di-tert-pentylbenzene; and 1-phenyl-1-nonane.
	www.donrscott.com /upclastxt.htm (2567 words)

	DS-820: Determination of Molecular Weights by Sedimentation Equilibrium (Site not responding. Last check: )
		Although several methods exist for obtaining molecular weights that appear to be simpler and less time consuming, the versatility and power of sedimentation analysis endows the analytical ultracentrifuge with a unique position in the array of alternative techniques.
		A downward curving plot, indicating that the molecular weight decreases with increasing concentration, is an indication that the solution is nonideal, and that the molecular weight exhibits concentration dependence.
		The inherent limitation of this method of determining molecular weights is the need to know not only the partial specific volume of the solute and the density of the solution, but also the sedimentation and diffusion coefficients of the solute.
	www.beckman.com /resourcecenter/labresources/sia/ds820.asp (2812 words)

	Determining Molecular Weight - (Site not responding. Last check: )
		The molecular weight of a substance is the weight in atomic mass units of all the atoms in a given formula.
		Analytical ultracentrifugation is a means for determining molecular weight and the hydrodynamic and thermodynamic properties of a protein or macromolecule.
		The molecular weight (MW) of a medication is a significant factor in determining the entry of a medication...
	molecular.fmqg.com /index.php?k=determining-molecular-weight (1045 words)

	Guidelines for the Notification and Testing of New Substances - Chemicals and Polymers - Appendix 6 (Site not responding. Last check: )
		Molecular weight is the physical parameter that is typically used to describe the size of a polymer.
		This correlation becomes the basis of molecular weight calibration and allows the molecular weight of an unknown sample to be calculated in relation to a known standard.
		Copolymers are difficult to analyze because the molecular size of random and block copolymers of the same molecular weight and comonomer composition in solution may not be the same.
	www.ec.gc.ca /substances/nsb/cpguide/eng/cp_x6_e.htm (2663 words)

	PCHEM.TEX - Converted
		The numbers on the die represented six initiator molecules that might equally react and began polymerization, and the number of times each number was rolled for each of the five polymers represented the number of monomers in that chain.
		The purpose of this experiment is to synthesize an ideal, typical polymer statistically, determine the both the number average, Mn, and weight average, Mw, molecular weights, the root mean square end-to-end distance, and the distribution of individual chains.
		where Mo is the monomer molecular weight, k is the number of monomers in a given chain, and pk is the probability of finding a chain with k monomers in a polymer consisting of a total of N chains.
	www.elmhurst.edu /~chm/studentport/blaine/PCHEM.html (1724 words)

	molecular weight - HighBeam Encyclopedia
		molecular weight weight of a molecule of a substance expressed in atomic mass units (amu).
		Molecular evidence of an interaction between prenatal environmental exposures and birth outcomes in a multiethnic population.
		Processing of ultra-high molecular weight polyethylene by hot isostatic pressing, and the effect of processing parameters on its microstructure.
	www.encyclopedia.com /doc/1E1-molecwght.html (1103 words)

	Powder coating compositions based on mixtures of acid group-containing materials and beta-hydroxyalkylamides - US ... (Site not responding. Last check: )
		The molecular weights of the acrylic polymer are determined by gel permeation chromatography (GPC) using a polystyrene standard.
		Molecular weights greater than 2500 are undesirable because of a tendency to cause poor stability in the coating composition.
		Amounts greater than 25 percent by weight are undesirable because of a tendency to cause poor stability in the coating composition, whereas amounts less than 1 percent by weight are undesirable because of tendencies toward poor flow and poor flexibility in the coating.
	www.patentstorm.us /patents/4727111.html (5934 words)

	PCCM - Polymer Synthesis Lab Equipment
		Experimentally, several concentrations of solute are measured and the number average molecular weight is determined by the intercept of a plot of osmotic pressure divided by concentration vs. osmotic pressure.
		The molecular weight range of this technique is limited by the membranes used at the low end and the instrument's ability to measure tiny pressure changes at the high end, but is typically in the range of 10,000 to 500,000 Daltons.
		The relationship of refractive index to concentration is a necessary parameter for determining weight average molecular weight from light scattering.
	www.princeton.edu /~pccm/facilities-polymersynth-eq.htm (1012 words)

	New Page 1
		Determine the "number-average" molecular weight for the polymer of Example 1.
		As seen from the above example, the number-average molecular weight is 16,010, while the weight-average molecular, determined before, was 19,200.
		Whenever there is a distribution in sizes, the "number-average" molecular weight will be less than the "weight-average" molecular weight, because of the large numbers of small molecules in the smaller weight fractions.
	nersp.nerdc.ufl.edu /~soderho/d03b.htm (135 words)

	Molecular Weight
		This is an average that would account for the fact that a large city like Memphis holds a larger percentage of the total population of the four cities than Montrose, Colorado.
		Of course, the molecular weight obtained by measuring the viscosity is a different from either the number average or the weight average molecular weight.
		It plots molecular weight on the x-axis, and plots the amount of polymer at a given molecular weight on the y-axis.
	www.pslc.ws /mactest/weight.htm (1116 words)

	Determination of Molecular Weight
		In general, the number of distinct moments needed to fully describe a distribution is equal to the number of features in the distribution curve.
		The selectivity of this process for molecular weight is outstanding and the range of molecular weights which can potentially be characterized by this technique is only limited by the ability to produce controlled spaced gels.
		The output of a GPC is considered to reflect the number of chains at a given retention volume or molecular weight.
	www.eng.uc.edu /~gbeaucag/Classes/Characterization/MolecularWeighthtml/MolecularWeight.html (2323 words)

	Nonwoven polyester fabric (Site not responding. Last check: )
		The polyester prepolymers to obtain the aliphatic polyesters used in the present invention are relatively high molecular weight saturated aliphatic polyesters having substantially hydroxyl groups at the ends thereof, number-average molecular weights of at least 5,000, preferably at least 10,000, and melting point of 60.degree.
		For preparation of the polyester prepolymer having a relatively high molecular weight, it is necessary to use deglycol-reaction catalysts in the deglycol reaction subsequent to the esterification.
		C., a number-average molecular weight (Mn) of 35,500 a weight-average molecular weight (Mw) of 170,000, a MFR (190.degree.
	www.90minuta.com /inventions/network_game_network_game_system/nonwoven_polyester_fabric.html (4808 words)

	Third Floor- Molecular Weight
		A desired property may improve with increasing molecular weight (the law of diminishing returns comes into play), but the processability of the polymer decreases with molecular weight, so a compromise molecular weight must be used for the product.
		Because weight average molecular weight is always equal to or greater than number average molecular weight, the polydispersity is eiether equal to or greater than unity.
		A close examination of the formula for weight average molecular weight and the formula for number average molecular weight shows that if the polydispersity is unity, then all the polymer chains must share the same degree of polymerization.
	web.umr.edu /~wlf/MW (160 words)

	EPA: Federal Register: Pesticides; Tolerance Exemptions for Polymers
		with poly(oxyethylene); molecular weight (in amu) 1,800- 16,000.
		hydroxypoly(oxyethylene); the poly(oxyethylene) molecular weight (in amu) averages 2,300.
		with poly(oxyethylene); molecular weight (in amu) 1,800- 9,000.
	www.epa.gov /fedrgstr/EPA-PEST/2003/February/Day-26/p4384.htm (4285 words)

	GPC
		However, each of these methods yields a single number for the molecular weight, and the absolute methods tend to be slow and cumbersome.
		While GPC has its greatest value for measuring the molecular weight and polydispersity of synthetic polymers, a closely related method, high-performance liquid chromatography, HPLC, is more useful for polymers containing functional groups, such as proteins and pharmaceutical polymers containing special active groups.
		Molecular weight sensitive methods include light-scattering, viscometry, etc. If two angles are used in the light-scattering detector, the radius of gyration, a measure of size of the chain, can be determined.
	www.polyacs.org /nomcl/pmse.gpc.html (940 words)

	180.1001 Exemptions from the requirement of a tolerance.
		Emulsifier hydroxypoly(oxyethylene), average molecular weight (in amu) of 600.
		Surfactant α-(carboxymethyl)- ω-(nonylphenoxy) produced by the condensation of 1 mole of nonylphenol (nonyl group is a propylene trimer isomer) with an average of 4-14 or 30-90 moles of ethylene oxide.
		Surfactant hydro-ω- hydroxypoly(oxyethylene); the poly(oxyethylene) molecular weight (in amu) averages 2,300.
	www.setonresourcecenter.com /40CFR/Docs/wcd0004b/wcd04bdd.asp (6676 words)

	Bloomer Plastics - Cast Film Glossary
		Average Molecular Weight: Molecular weight of polymers is determined by viscosity of the material in solution at a specific temperature.
		Melt Index: The number of grams, of a thermoplastic resin which can be forced through a 0.0825 inch orifice when subjected to 2160 grams force in 10 minutes at 190°C. Melting Point: The temperature at which a resin changes from a solid to a liquid.
		Molecular Weight (MW): The sum of the atomic weights of all atoms in a molecule.
	www.bloomerplastics.com /capabilities-glossary.html (3193 words)

	Viscotek - Light Scattering Detector
		M is the molecular weight of the polymer sample and C is the sample concentration.
		Equation 7 reveals that molecular weight elution profile is proportional to the ratio of the LALS detector signal to the RI detector signal.
		An elution profile for molecular weight on a broad distribution polystyrene sample is shown in Figure 2, overlaid with the RI and LALS signals.
	www.viscotek.com /technotes01.php4 (1342 words)

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