Molecular weight relative

ASTM, Standard Test Method for Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils from Viscosity Measurements, ASTM Standard D-2502-92, 1992. 

Ma Molecular weight (relative molecular mass) of A kg/kmol MN- ... 

In the author s laboratory, it has never been found necessary to resort to matrices other than glycerol or 1-thioglycerol for the analysis of saccharides and glycoconjugates. Nevertheless, alternative matrices are often equally effective, and, in some laboratories, they are preferred. The most widely used include tetraethyleneglycol (4) and its higher-molecular-weight relatives, the poly(ethyleneglycol)s, and such basic matrices as N,N -bis(2-aminoethyl)ethylenediamine ( triethylenetetramine, 5), 2,2 -... 

For any given macromolecule (polymer), no matter whether it occurs naturally or is the result of some synthetic procedure, there is no unique molecular weight (relative molar mass, R.M.M.) as there is for small organic molecules such as the alkanes. Because of the randomness of the reactions which take place to produce the macromolecule, there will always be chains of differing length (R.M.M.) which give rise to the polymer sample having an R.M.M. distribution (Fig. 5.6). 

Number average molecular weight Relative molecular mass Weight average molecular weight Meter... 

Table I. Yields and Molecular Weights (Relative to Polystyrene) for Both Fractions of the Bimodal Distribution from Gel Permeation Chromatography in THF of Organosilane Polymers.

Figure 26 shows a typical GPC elution curve of the ethanol insoluble polymers obtained at 0 °C, (b), together with the GPC curve of the original iodine-terminated polypropylene, (a). Curve b clearly shifted toward higher molecular weights relative to curve a, but retained a narrow molecular weight distribution (Mw/Mn = 1.14), indicative of the formation of a propylene-THF diblock copolymer. The 13C NMR spectrum of the block copolymer is shown in Fig. 27. 

Small size (10-100 nm) is one ofthe most interesting features of polymeric micelles. Besides allowing the extravasation of the carriers, it permits the sterilization of the preparation to be done simply by Lltration and minimizes the risks of embolism in capillaries, contrary to larger drug carriers (Kwon and Okano, 1996). Micellar size seldom exceeds 100 nm, but depends on several factors including copolymer molecular weight, relative proportion of hydrophilic and hydrophobic chains, and aggregation number (Yokoyama etal., 1990 Trubetskoy and Torchilin, 1996 Shin etal., 1998). 

Scheme 6.8 Cyclization of 57 under high-dilution conditions (molecular weights relative to PS standards).

Scheme 6.15 Tether length dependence of half-rings (molecular weights relative to PS the intramolecular dimerization of templated standards).

In all cases except perhaps the second you need a quick and reliable answer. Suppose you are trying to identify the heart drug propranolol, one of the famous beta blockers used to reduce high blood pressure and prevent heart attacks. You would first want to know the molecular weight and atomic composition and this would come from a mass spectrum propranolol has a molecular weight (relative molecular mass) of 259 and the composition C16H21NO2. Next you would need the carbon skeleton-—this would come from NMR, which would reveal the three fragments shown. 

Mass spectrum weighs the molecule molecular weight (relative... 

Condensation type routes have been used to prepare low molecular weight, relatively poorly defined poly(ferrocenylphosphines) 21 and poly-(ferrocenylphosphine oxides) 22 (7/,72). For example, the products M ... 

The two kidneys are situated at the back of the abdomen on either side of the vertebral column. They carry out many functions in the body, the most important of which is the production of urine and the excretion from the body of low-molecular-weight (relative molecular mass less than 68 000 daltons) water-soluble compounds, including many drugs. Each kidney contains approximately one million urine-producing structures called nephrons. The nephron in turn consists of a bundle of blood capillaries termed a glomerulus, which functions as a very efficient filter to remove waste products and impurities from the blood, and a long tube-like structure called a tubule (see Figure 2.10). 

For typical thermal plastic, not only the viscosity has temperature dependence, but it also strongly depends on the polymer s molecular weight relative to the so-called critical molecular weight of a given polymer M. can be interpreted as the molecular weight at which a temporary network of entanglements... 

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