Average molecular weight between

The presence of long chain branches in low density polyethylene (LDPE) accounts for the difference in properties e.g. higher melt strength, greater toughness for the same average molecular weight) between LDPE and linear low density polyethylene (LLDPE, made by coordination polymerization). 

Iron dextran injection contains a complex of iron hydroxide with dextrans of average molecular weight between 5000 and 7000, and is used for the treatment of iron-defieiency anaemia in situations where oral therapy is ineffeetive or impractical. The sodium salt of sulphurie aeid esters of dextran, i.e. dextran sodium sulphate, has anti-eoagulant properties eomparable with heparin and is formulated as an injection for intravenous use. 

For seawater muds, another example [139] is a copolymer of 10% by weight AMPS and 90% by weight acrylic acid in its sodium salt form. The polymers have an average molecular weight between 50,000 and 1,000,000 Dalton. 

Copolymers of mainly acrylic acid and 2% to 20% by weight of itaconic acid are described as fluid loss additives for aqueous drilling fluids [138]. The polymers have an average molecular weight between 100,000 and 500,000 Dalton and are water dispersible. The polymers are advantageous when used with muds containing soluble calcium and muds containing chloride ions, such as seawater muds. 

The unbranched polymer produced by P. polycephalum and related Physarum strains has a weight average molecular weight between 40,000 and 60,000 Daltons and a polydispersity of 1.5-3.0 depending on the culture conditions and the age of the samples [111]. The acid form of poly-/ -malate does not show either a Tg or a Tm in the solid state, by DSC analysis, below its thermal decomposition temperature of 185 °C. 

Condensation in acid medium gives soluble, fusible phenolic resins, with an average molecular weight between 600 and 1,500, and a structure consisting essentially of phenol residues linked by methylene groups in the ortho- and para-positions they are called Novolaks. No further condensation occurs on heating... 

Mc number average molecular weight between crosslinks... 

Fig. 5. Relation between the average molecular weight between cross-links, Mc, and the volume fraction of gelatinized collagen (gelatin), v2. The swelling agent is 0.19 mol/1 citric acid - phosphate buffer solution, pH 7.4 at 80 °C. Experimental data obtained after cross-linking with various aldehydes solid circles, formaldehyde open circles, glutaraldehyde squares, glyoxal. The curve is predicted by Eq. (2) with X = 0.52 0.04 [38]...

Number average molecular weight between cross-links. 

At present all commercial polystyrene (with average molecular weights between 100,000 and 400,000) is manufactured by radical polymerization, which yields atactic polymers.476 Peroxides and azo compounds are commonly used initiators. The suspension process (usually as a batch process in water at 80-140°C) produces a product with relatively high residual monomer content.223 More important is the continuous solution process (usually in ethylbenzene solvent at 90-180°C), which yields high-purity product. Styrene can be copolymerized with numerous other monomers.477 One of these copolymers, the styrene-divinylbenzene copolymer produced by free-radical polymerization, has a crosslinked stucture and is used in... 

Plateau moduli are commonly expressed in terms of Me, the apparent average molecular weight between coupling junctions. The modulus equation from the... 

According to this method, the sample is calibrated by calculating the volume fraction of the polymer, v%, from the weight changes, or the dimensions of the sample, after immersion in a liquid for which ft is known (this is the case for many polymer-solvent systems). From V2 and /z, one obtains Met the average molecular weight between cross-links, according to the relation ... 

Fig. 42. Comparison of the experimental and calculated Hartmann-Hahn mismatch sideband patterns for polybutadienes with the average molecular weight between crosslinks M = 6810 (A), Mc = 2730 (B) and Mc = 1020 (adapted from Ref. 250>)...

Figure 15.1 a 2H NMR spectrum of perdeuterated crosslinked chains in a PDMS network (average molecular weight between junctions Mn= 10500 g.mol 1, i.e.,... 

Figure 15.8 2H NMR spectra obtained in a randomly crosslinked, deuterated PB network. Precursor chain molecular weight 115700 g.mol"1, 1.2% crosslink agent, the average molecular weight between junctions is 27400 g.mol 1 (as determined by swelling experiments) or 11600 g.mol"1 (elastic measurements). The smooth curves are fits with a most probable distribution of chain lengths with number average molecular weight Mc = 11600 and with non-Gaussian chain statistics...

The number of repeating units between crosslinks, N, a parameter appearing in equation (1), can be simply defined as the jratio of the number average molecular weight between crosslinks, Mc, to the average molecular weight of the clusters, Mq. 

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