Liquid high molar mass

Thermotropic liquid crystals may be classified as either low molar mass (i.e. non-polymeric), or high molar mass (i.e. polymeric) and within each of these broad classifications, there are several sub-classifications. 

In general terms, high molar mass liquid crystals are classified according to the location of the mesogenic unit in the polymer. Thus, they are either incorporated into the main chain (main-chain liquid crystal polymers - MCLCP Fig. 5A) or they are pendant from the main chain (side-chain liquid crystal polymers - SCLCP Fig. 5B). 

Separation of heat-sensitive materials. High molar mass material is often heat sensitive and will decompose if distilled at high temperature. Low molar mass material can also be heat sensitive, particularly when its nature is highly reactive. Such material will normally be distilled under vacuum to reduce the boiling temperature. Crystallization and liquid-liquid extraction can be used as alternatives to the separation of high molar mass heat-sensitive materials. 

In many aspects, the behavior of macromolecules substantially differs from the low-molar-mass substances. Therefore, it is necessary to briefly define the basic terms and explain the most important featnres of high-molar-mass systems related to liquid chromatography. To make the understanding as easy as possible, numerous simplifications have been adapted. This section is not intended for experts in polymer science and technology. 

Nature and amount of additives, which may be low- or high-molar-mass substances in liquid or solid state... 

The applicability of LC LC to the (ultra) high-molar-mass polymers. Contrary to liquid chromatography under critical conditions, LC LC likely exhibits no upper limit of the sample molar mass [234]. On the other hand, if the difference in elution rates of the barrier forming small molecules and the oligomeric species is too small, the LC LC separation becomes insufficient. As a result, LC CC and LC LC may be considered mutually complementary from the point of view of their applicability in the... 

Specifically, the general approximation / 0.079 m has been suggested [142] for a wide range of both polymer and small molecule liquids. This relation implies that high molar mass F-S polymers should have steepness index m of about m 100, which is consistent in order of magnitude with estimates [142] for the representative F-S polymer, polystyrene (PS). 

Pure liquid diisocyanates can be synthesized from the renewable resource furfural, and used with low and high molar mass diols also derived from furfural to form block copolyurethanes. 

Instantaneously deformed high molar mass polymer melts (long polymer chains in their liquid state) behave at intermediate times as networks with well-defined values of shear modulus, called the plateau modulus Ge, which is independent of molar mass for long-chain polymers. This rubbery plateau is seen for all polymer melts with... 

A polymer solution is a mixture of a solvent (usually a low-molar-mass liquid) and a solute (usually a high-molar-mass polymer). For dilute polymer solutions (from suspension theory and rf = 2.5cp) it is simple to show from geometric considerations that the viscosity varies as... 

Synovial fluids (SF) are highly viscous liquids that contain rather high amounts of high-molar-mass HA (normally about 2-3 mg/ml). Due to their profound biological significance, SF have been comprehensively studied. For instance, y-irradiation of SF results in a dose-dependent degradation of HA [71, 72]. This effect can be effectively suppressed by common free radical quenchers such as N-acetyl-L-cysteine [108] and is, thus, mediated by ROS, not by enzymes. 

According to recent investigations, cluster formation and bound solvent have to be considered, which will influence the phase behavior considerably. Also, the interpretation of careful measurements has to take into account the fact that a high molar mass fraction mixed into the sample will not turn into a liquid crystal, and a too low molar mass fraction may have an influence on the clearing temperature, as shown in Fig. 16. 

In low-molar-mass liquids, the diffusion coefficients of dissolved substances initially decrease strongly with increasing solvent viscosity (Figure 7-1). They then remain practically constant for solvents consisting of polymers of not too high molar mass. This allows the conclusion that the diffusion of the solute is only dependent on the segment mobility of the solvent molecules and not on the mobility of the molecular centers of gravity. 

A liquid/liquid transition is observed above the glass transition temperature with amorphous polymers (Figure 10-28). The molar mass dependence of this transition temperature proceeds parallel to that of the glass transition temperature. A simple relationship independent of the constitution appears to exist between the glass transition temperature and the liquid/liquid transition temperature for infinitely high molar mass. This relationship is Tn = 1.2 Tg (Figure 10-29). 

True liquids, in contrast, do not show an extensive order. Even with very slight stresses applied for a short time, they deform so completely that they very quickly adopt the form of the surrounding container. Low-molar-mass liquids thus behave in a purely viscous way under normal conditions. When stress is applied, the molecules are displaced irreversibly in relation to one another. In high-molar-mass substances above the glass transition temperatures, flow can be produced relatively easily. Deformations are much more difficult below the glass transition temperature of amorphous polymers. For this reason, and because of their lack of order, amorphous substances below their glass-transition temperatures are often termed supercooled liquids. 

Precipitation from substance Initiator Polymer Monomer is reaction medium, see third column So in M D in M PVC, PAN from liquid LDPE or LDPE made from gaseous monomer Powder Polymerization, is possible. LDPE is precipitated from the Separation of the polymer ethylene gas by means of high-from the reaction medium pressure polymerization. PAN causes no problems, even at is nonmeltable, is dissolved in high molar mass levels. dimethyl formamide and spun into threads... 

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