Molecular weight, influence

Elharfaoui N., Djabourov M., Babel W.. Molecular weight influence on gelatin gels structure, enthalpy and rheology. Macromolecular Symposia 256 (2007) 149-157. 

The properties of TPUs, COPEs, and TPAs are also influenced by the molecular weight and molecular weight distribution, e.g., molecular weight influences the kinetics of phase separation,... 

Molecular weight. The molecular weight influences the melt viscosity, tensile strength, the low temperature brittleness, and the resistance to tearing. 

As mentioned in Sect. 2.2.3, the biodistribution of HPMA copolymers depends on many factors. Molecular weight influences the uptake in the isolated tissue of yolk sac [266] as well as the elimination in vivo [124, 125,267,268]. Nonspecific increase in the rate of polymer uptake can be achieved by incorporation of positively charged or hydrophobic comonomers into the HPMA copolymer structure, such as methacryloyloxyethyltrimethylammonium chloride [22], N-methacryloyltyrosinamide [21], or N-[2-(4-hydroxyphenyl)ethyl]acrylamide [267]. The incorporation of hydrophobic moieties may influence the solution properties of the HPMA copolymer conjugates [132,134,269]. The interaction with the cellular surface may depend on the association number and the stability of the micelles. 

For these reasons the selection of an appropriate oil is limited to some extent by the need to use metabolizable long-chain triglycerides. These are represented by natural oils such as olive or soy oil or the short-chain triglycerides obtained from coconut oils. The chain length and degree of unsaturation of the oil, as well as the molecular weight, influence the droplet diameter and polarity once formed. 

Since they act as surfactants, copolymers are added in only small amounts, typically from a thousandth parts to a few hundredth parts. Theoretically, Leibler [30] showed that only 2% of a diblock copolymer may thermodynamically stabilize an 80%/20% incompatible blend with an optimum morphology (submicronic droplets). However, in practice kinetic control and micelle formation interfere in this best-case scenario. To a some extent, compatibilization increases with copolymer concentration [8,31,32], Beyond a critical concentration (critical micellar concentration cmc) little or no improvement is observed (moreover, for high amounts, the copolymer can act as a plasticizer). Copolymer molecular weight influence is similar to that of the concentration effect. For example, in a PS/PDMS system [8,31,32], when the copolymer molecular weight increases, domain size decreases to a certain extent. Hu et al. [31] correlated their experimental results with theoretical prediction of the Leibler s brush theory [30]. Leibler distinguishes two regimes to characterize the behaviour of the copolymer at the interface... 

Table 2.3 Density, melt index, and molecular weight influence PEs performances...

Not only molecular weight influences the interfacial activity of the PS-hPBD diblock copolymers but also the internal structure. Instead of a single covalent bond between PS and hPBD, a more or less random copolymer sequence can form the transition between the two blocks resulting in the so-called tapered diblock copolymers. The effect of the tapered structure (12,22) and its superiority over the pure diblock (18) have been documented elsewhere and discussed in terms of a change in the interface itself and the melt viscosity of the interfacial agent. 

Molecular Weight Influence on the Isotachophoretlc Separation of Sulfonate-Group-Contalnlnq Polymers... 

The numbers 50S, 30S, etc. refer to a relative rate of sedimentation in an ultracentrifuge and cannot be added directly. Many things besides molecular weight influence the sedimentation characteristics, such as shape and density. 

A similarity can be established between the polymorphism of mannan and that of cellulose, as with both polysaccharides, one observes a molecular weight influence on the polymorphism, even though this influence is more pronounced in the case of mannan than in the case of oe llulose. It was shown that with mannan and glucomannan polymers, the mannan I structure was obtained more easily with low molecular weight material, whereas mannan II corresponded to higher molecular weight (4,8). A close resemblance... 

In North America, relative or inherent viscosities are more frequently used. In Europe, the Fikentscher number (or K number) is more frequently used. Figure 2.1 shows that there is excellent agreement between all three methods of expression of molecular weight influence on viscosity of PVC solutions. 

The molecular weight influenced the PUs thermomechanical behaviour. The best results were obtained with Mw = 2000. The type of SS macrodiol (polyether PTHF or polyester PBA) also influenced the PU thermomechanical behaviour. Numerous phase transformations were observed in the material obtained with PBAiooo (curve 8) as compared to the material with PTHFiooo (curve 3). Both materials were based on the same chain extender, DEG and diisocyanate DBDI. 

MOLECULAR WEIGHT INFLUENCES ON THE PHYSICAL PROPERTIES OF POLYETHYLENE ADIPATE-BASED ELASTOMERS (WITH NDI)... 

The above-mentioned behaviour, related to the initial molecular weight influencing the scission process, has been confirmed for melts of PS [273], PP [756] and PET [757]. 

Calderon et al. found that the surfactant s isometry and molecular weight influenced the thermal stability of phosphonium-containing clays that is, isometric phosphonium... 

Kozlov, G. V., Belousov, V. N., Mokaeva, K. Z., Gazaev, M. A., Mikitaev, A. K. (1995). The Molecular Weight Influence on Polyary latesulfone Forced Elasticity Stress. Manuscript deposited to VCSIIll RAN, Moscow, August 09,2407-V95. 

The molecular weight influences the degree of skin and hair adsorption, the penetration power and the interactions with other components. In general, the higher the molecular weight, the larger the fihnogenic effect and the weaker the penetration power (Swift et al, 2000). 

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