Polyamides solubility parameter

The SEC mechanism demands only an isocratic (constant composition) solvent system with normally a single solvent. The most frequently used organic solvents are THF, chloroform, toluene, esters, ketones, DMF, etc. The key solvent parameters of interest in SEC are (i) solubility parameter (ii) refractive index (iii) UV/IR absorbance (iv) viscosity and (v) boiling point. Sample solutions are typically prepared at concentrations in the region of 0.5-5 mg mL-1. In general an injection volume of 25-100p,L per 300 x 7.5 mm column should be employed. For SEC operation with polyolefins chlorinated solvents (for detector sensitivity and increased boiling point) and elevated temperatures (110 to 150 °C) are required to dissolve olefin polymer. HFIP is the preferred solvent for SEC analysis of polyesters and polyamides. 

A new class of hydrophilic polyamides, poly(tetrahydropyran-2,6-diylimino-carbonyl) 1 was prepared by the anionic polymerization of a bicyclic oxalactam (abbreviated as BOL, 2) 38-42). The resulting polyamide / has glass transition, fusion, and decomposition points at 130,260-285, and 315 °C, respectively, and its membrane can be obtained by casting from a polyBOL solution. The solubility parameter... 

T,his work uses the solubility parameter concept to describe the solu- bility of a typical polyamide ink resin used in flexographic printing. The entire resin concentration solubility is described by coordinates of resin solubility concentration vs. solvent solubility parameter. An interpretation of the interaction between the dispersion force, dipole moment, and the hydrogen bonding force of the polyamide resin and industrially important alcohols is made from the data. 

In terms of polymer matrices for composite materials, there will be a compromise between solvent and water resistance. Thus non-polar resins are likely to be less resistant to hydrocarbon solvents, which have low polarity, but more resistant to moisture absorption. Polar resins behave in the opposite way. Strongly polar solvents, such as dimethyl sulphoxide or similar, can interact with polar structures in the resin and are difficult to resist. Crystalline thermoplastic polymers are often better for such applications. For example, polyethene will only dissolve in hydrocarbon solvents (of similar solubility parameter) at temperatures above the crystalline melting point. Polar semi-crystalline polymers such as the polyamides or nylons can be dissolved in highly polar solvents, such as cresol, because of a stronger interaction than that between molecules within the crystallites. High performance thermoplastic polymers such as polyether ether ketone (PEEK) have been promoted for their resistance to organic solvents (see Table 3.5) [12], The chemical resistance of unsaturated polyester and vinyl ester and urethane resins is indicated in Table 3.6 [15]. 

Polyamides are another group of highly polar polymers which are successfully plasticized with sulfonamides. Sulfonamides and polyamides have similar ranges of solubility parameters. Figure 2.33 shows the effect of addition of N-butyl benzene sulfonamide on fatigue resistance of monofilaments. ... 

Calculate the solubility parameters of (I) aromatic polyamide, (2) aromatic polyhydrazide, and (3) aromatic polyamidehydrazide. 

Permeability is so low that, in sorption experiments, large pressure differences and membranes of small thickness have to be employed. These restraints do not apply to condensable vapours or highly permeant gas. In the last case, relaxation processes in the polymer matrix cause changes in the transport behaviour and make the permeability time-dependent. In contrast, only vapours of sufficiently high solubiUty are suitable for the gravimetric measurements used in the sorption experiments. Consequently, there are only few systems for which both sorption and permeation results have been reported. Low et al. conducted the two types of moisture transport experiments on a polyamide 6/elay nanocomposite. The authors found that the activation energy of moisture permeation obtained from the sorption experiment is lower than that derived from the permeation measurement. They concluded that the interaction and contribution of the diffusion and solubility parameters show complex transport behaviour in these nanocomposite films. 

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