Polymer related parameters

The effect of MW and MWD on the solid state properties have been extensively studied [11,12,82]. These studies have been made both on fractionated and whole polymer samples. Attempts have also been made to correlate the solution viscosity, melt viscosity, MFI and other related parameters, which represent the MW and MWD of the polymers, with the solid state properties. Table 6 summarizes the results of various studies on effect of MW and MWD on the properties of PEs. 

Light scattering from macromolecules is used routinely to obtain molecular weights, radii of gyration and polymer-solvent and polymer-polymer interaction parameters. A closely related technique, electric field induced light scattering (EFLS) (13,14) has received less attention, but is also potentially useful for polymer characterization. 

We have seen that two important lithographic parameters of a resist are sensitivity and contrast. This leads to a consideration of the design features that must be incorporated into the resist in order to optimize these parameters and, in turn, requires a fundamental understanding of the interaction of radiation with matter and how the polymer molecular parameters affect lithographic response. These aspects have been extensively covered in the literature, (5,6) and only the conclusions relating to lithographic performance will be summarized. 

Taking into account the modes in which the water can be sorbed in the resin, different models should be considered to describe the overall process. First, the ordinary dissolution of a substance in the polymer may be described by the Flory-Huggins theory which treats the random mixing of an unoriented polymer and a solvent by using the liquid lattice approach. If as is the penetrant external activity, vp the polymer volume fraction and the solvent-polymer interaction parameter, the relationship relating these variables in the case of polymer of infinite molecular weight is as follows ... 

Accurate temperature calibration using the ASTM temperature standards [131, 132] is common practice for DSC and DTA. Calibration of thermobalances is more cumbersome. The key to proper use of TGA is to recognise that the decomposition temperatures measured are procedural and dependent on both sample and instrument related parameters [30]. Considerable experimental control must be exercised at all stages of the technique to ensure adequate reproducibility on a comparative basis. For (intralaboratory) standardisation purposes it is absolutely required to respect and report a number of measurement variables. ICTA recommendations should be followed [133-135] and should accompany the TG record. During the course of experiments the optimum conditions should be standardised and maintained within a given series of samples. Affolter and coworkers [136] have described interlaboratory tests on thermal analysis of polymers. 

A review is presented of the electrical properties of polymers filled with different types of conducting particles. Following a theoretical description of a general effective media equation, experimental conductivity-volume fraction data for thermoplastic filled with vanadium oxide particles as well as thermosetting polymer composites, were fitted to the equation. The calculated property-related parameters in the equation are discussed. Data are given for PVC, HDPE, LLDPE, LDPE, and epoxy resin. 12 refs. 

The next step in the calculation of n(A) is the correlation of trimer peak intensities with the number of specific triads in the polymer. A parameter K can be assigned as a coefficient to express the relationship between the pyrolysis peak area and the triad number. These K values can be obtained by calibrating through copolymers with known composition. A random copolymer of known composition is the best choice in this case since it produces all trimer peaks allowing good calibration. For each trimer type, a simple relation of the type ... 

Interaction characteristics in polymer-related areas frequently make use of solubility parameters (16). While the usefulness of solubility parameters is undeniable, there exists the limitation that they need to be estimated either by calculation or from indirect experimental measurements. The thermodynamic basis of IGC serves a most useful purpose in this respect by making possible a direct experimental determination of the solubility parameter and its dependence on temperature and composition variables. Price (17) uses IGC for the measurement of accurate % values for macromolecule/vapor pairs, which are then used for the evaluation of solubility parameters for a series of non-volatile hydrocarbons, alkyl phthalates, and pyrrolidones. It may be argued that IGC is the only unequivocal, experimental route to polymer solubility parameters, and that its application in this regard may further enhance the practical value of that parameter. Guillet (9) also notes the value of IGC in this regard. 

Although the basic qualities of polysaccharides are determined by the chemical functionality of the glycosyl residues constituting the polymers, there is another specifically polymer-related dominating property a non-negligible excluded volume effect. Polysaccharides occupy volume in particular, in aqueous environment, they transform rather large compartments into functional phase spaces. At the molecular level, this performance is controlled by many parameters, in particular, the following ... 

The thermodynamic parameters 1/) and K introduced above, pertaining to polymer-solvent interactions in dilute solutions, may be determined from thermodynamic studies of dilute solutions of the polymer, e.g., from osmotic pressure or turbidity measurements at different temperatures. These parameters may also be determined, at least in principle, from viscosity measurements on polymer solutions (see Frictional Propcitics of Polymers). The parameter ij, which is a measure of the entropy of mixing, appears to be related to the spatial or geometrical character of the solvent. For those solvents having cyclic structures, which are relatively compact and symmetrical (e.g., benzene, toluene, and cyclohexane), xp has relatively higher values than for the less symmetrical acyclic solvents capable of assuming a number of different configurations. Cyclic solvents are thus more favorable... 

The energy of vaporization is not accessible for polymers, but cohesive energy density of polymers can be determined from PVT-data. However, common ways for determining polymer solubility parameters use thermodynamic properties of polymer solutions and their relations to excess enthalpy or excess Gibbs energy per unit volume. These excess quantities are related to the (square) difference between the solubility parameters of solvents and polymers, i.e. (d -... 

According to the Flory-Huggins theory, the equilibrium melting point depression can be related to the polymer-polymer interaction parameter, Xi2> by (46,47) ... 

Light scattering measurements can also be used to determine the molecular weight (M2) of solute molecules as well as interactional (second and third virial coefficients) and structural parameters (radius of gyration) [60, 61]. The reader is referred to Chapter 18 for more information on light scattering methods. The dependence of A2 and Rj) on M have been the subject of many research studies in polymer solution thermodynamics [29, 62]. Many other experimental techniques can been used to determine these and other related parameters [28, 35, 63]. 

BAK Bakshi, M.S., Kaur, N., Mahajan, R.K., Singh, J., and Sing, N., Estimation of degree of counterion binding and related parameters of monomeric and dimeric cationic surfactants from cloud point measurements by using triblock polymer as probe. Coll. Polym. Sci., 284, 879, 2006. 

An attempt was made to relate intriitsic viscosity [t]] to the solubility parameters of components. Also, 82 was calculated from the relationship [t]] = f(8i). The authors assumed that the maximitm value of [11] shoitld be obtained in a liquid in which its solubility parameter, 81, is eqital to the polymer solubility parameter, 82. Intrirtsic viscosity should be thus smaller for both smaller and larger values of 8[. From strrdies of [11] for polymethylmetacrylate in foirrteen different liqitids, a wide scattering of experimental points was obtained. The 82 value lies within 10% scatter. 

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