Molecular weight decrease

An extra amount of free volume is associated with chain ends, which are capable of wagging in a way that is not possible in the middle of a chain. Accordingly, as molecular weight decreases, Vj- increases, which, in turn, decreases Tg. The following expression has been found to describe this molecular weight dependence ... 

The problem of solvent selection is most difficult for high molecular-weight polymers such as thermoplastic acryHcs and nitrocellulose in lacquers. As molecular weight decreases, the range of solvents in which resins are soluble broadens. Even though solubihty parameters are inadequate for predicting ah. solubhities, they can be useful in performing computer calculations to determine possible solvent mixtures as replacements for a solvent mixture that is known to be satisfactory for a formulation. 

Reactive groups have minimal auxochrome effect on color intensity, and color yield per molecular weight decreases with increasing numbers of reactive groups. Increased dye fixation and reduced environmental impact of hydrolyzed dye more than compensate for color reduction of additional reactive groups. 

Process 2-4 is main. With an increasing concentration of alkali the rate of polymerization increases and the molecular weight decreases. The nature of hydrolyzing agent and salt additions influence the acrylamide polymerization process. Various methods of the acrylamide polymerization in the presence of alkaline agents have been reviewed [12,16,17]. 

At temperatures 400-420°C the decomposition rate is so great that in 1 hour the molecular weight decreases from 27,100 to 3100, and within 5 hours the polymer is transformed into a mixture of liquid products [8]. 

Molecular weights were determined and the results for the weight average molecular weight are shown in Figure 12 for conversions of 30% and 50%. It is noted that molecular weight decreases with increasing (Nj e)e until just before the turbulence occurs. 

It has been noted previously that radiation exposure of a positive resist causes chain scission in its structure. As a result, its molecular weight decreases. According to Ku and Scala (3), the decrease in the number average molecular weight resulting from such irradiation is given by the expression ... 

The asymmetric 5,6-cyclopentyl-subsituted metallocene la/MAO shows a very low activity in toluene solution (around 150-320 kg PP mol 1 Hf h 1). In addition, the molecular weight is quite low (entry 1, Mw 5.5 x 104 g mol1). By increasing the temperature to 50 °C the activity more than doubled, but on the other hand the molecular weight decreased to 2.7 x 104 g mol-1 [5, 7, 11],... 

High quality xylan diacetate is insoluble in most reagents although the acetates of degraded xylan become progressively more soluble as the molecular weight decreases. Solubility in pyridine first appears, while with further decrease in molecular size, solubility in chloroform occurs. Because of their insolubility, the acetates of undegraded xylan cause filtration difficulties when present in commercial cellulose acetates. 

As the reaction proceeds beyond the gel point, the molecular weight of EANCs decreases and the fraction of material in the EANCs increases. The fraction of material in dangling chains passes through a maximum but their molecular weight decreases. Figure 5.5 characterizes the behavior of simple polyurethane systems. 

Variation of the length of the bridging chain —(C>I I2) — shows that both the productivity and molecular weight decrease in the order n = 3>n = 2>n = l, as found for the unsubstituted analogues. 

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