Molecular weight most probable

Molecular weight reduction probably plays a role even in pretreatment processes that are not intended to cause this effect (19). The most common method of molecular weight reduction is the addition of dilute acid to hydrolyze the acetal groups (I). The acid may be generated in situ by the liberation of acetic acid from acetate groups by steam or hot water. 

The fractionation scheme shown in Figure 3 was applied to the reaction products. The benzene-ethanol soluble fraction consisted primarily of a dozen individual compounds of low molecular weight, which probably come from condensation reactions of phenol. It is the large number, but small mass, of these low-molecular-weight materials that dominates the number average molecular weight Most of the... 

Polyacrjiates (3), where R = H, CH n < 100, 000 and Y = OH, OCH, O, etc, or copolymers with compatible monomers, are probably the most flexible dispersant products, because they are produced in a variety of molecular weights and degrees of anionic charge. Moreover, reaction of acryflc acid with other monomers confers additional properties that make them more adaptable for niche appHcations. 

Analysis of data pertaining to the modulus of PEO gels obtained by the polyaddition reaction [90] shows that even in this simplified case the network structure substantially deviates from the ideal one. For all samples studied, the molecular weight between crosslinks (M p) exceeds the molecular weight of the precursor (MJ. With decreasing precursor concentration the M xp/Mn ratio increases. Thus, at Mn = 5650 a decrease in precursor concentration from 50 to 20% increases the ratio from 2.3 to 12 most probably due to intramolecular cycle formation. 

This distribution is known as the Schultz-Flory or most probable distribution.2S The moments of the molecular weight distribution are ... 

Because of the absence of chain limiter, the catalyst itself may initially act as the chain limiter (Fig. 8.22). The catalyst reacts with the olefinic regions of the polymer backbone and causes chain scission to occur, forming two new chains. The reactive carbene which is produced then moves from chain to chain, forming two new chains with each scission until the most probable molecular weight distribution is reached (Mw/Mn = 2), producing linear chains end capped with [Ru] catalyst residues. 

Development of several new siloxane-imide copolymers for commercial applications have also been reported by Lee 181) and Berger58). Although no information was given in terms of the chemical compositions of these materials, most of these polymers were reported to be processable by solution or melt processing techniques, most probably due to their high siloxane contents. However, due to the presence of low (—20 to —120 °C) and high (>230 °C) temperature Tg s, it was clear that multiphase copolymers have been synthesized. Molecular weights and thermal stabilities, etc, were not reported. 

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