Hydrophilic resin matrix

It was predicted, and subsequently confirmed, that an anion exchange resin based upon an acrylic matrix should demonstrate beneficial exchange equilibria and kinetics towards large organic ions compared with the styrenic structures. A simplistic explanation for this lies with the greater hydrophilic nature of the aliphatic skeletal structure of the acrylic matrix, which in turn means a weaker van der Waals type attraction between the resin matrix and the hydrocarbon structure of an organic counter-ion. 

Comparisons of commonly used XAD resins have been published for the isolation of both fulvic acid (Aiken et al., 1979) and humic acid (Cheng, 1977) from water. These resins differ in pore size, surface area, polymer composition, and polarity (Table 5) (Kunin, 1977). As with anion-exchange resins, hydrophobic styrene-divinylbenzene resins (XAD-1, XAD-2, XAD-4) were found more difficult to elute than hydrophilic acrylic-ester resins (Table 6). This is due to hydrophobic interactions, and possible tt-tt interactions with the aromatic resin matrix of styrene-divinylbenzene resins. In addition, ki-... 

Both hydrophilic and hydrophobic polymers have served as the matrix for ion exchangers. In the world of HPLC, only those polymers capable of withstanding the high operating pressures of HPLC are used. They comprise mainly poly(styrene-divinylbenzeneX which is a hydrophobic resin, and crosslinked polymethacrylate and polyvinylalcohol, both hydrophilic resins. 

The interphase in PE fibre/epoxy resin matrix composites was studied by FTIR microspectroscopy using a set-up for investigation of the matrix as close to the fibre as a few microns or less. It was shown that moisture present on the fibre surface could influence the polymerisation reaction of the epoxy/anhydride matrix in an irreversible manner. This effect was enhanced for composites from the more hydrophilic PVAl fibre. The fibre/matrix interaction in these thermoplastic fibre composites was also studied by DSC through characterisation of the fibre melting. A decreased DSC interaction parameter was found if the composition of the interphase was changed by moisture. For a composite with an epoxy/amine matrix, on the other hand, the DSC interaction parameter was unaffected by moisture from the fibre surface. 22 refs. (Pt.I, ibid, p.83-100)... 

IMA sorbents can be used in HPLC techniques. The metal-chelate adsorbent TSK gel chelate-5PW, suitable for HPLC, which was prepared by coupling IDA to a hydrophilic resin-based matrix (TSK gel G 5000 PW), later became commercially available (Fig. 1). 

Electrical properties of filled resin systems are also improved by filler treatment. Filler particles are naturally hydrophilic via their metal hydroxide surfaces, and the particles naturally seek to agglomerate with each other, and so transport electrical charges through resin composite. Treatment with silane-coupling agent alters the chemistry of the filler surface, allow better dispersion of the filler throughout the resin matrix, and imparts improved electrical properties to the composite. Table 15.13 indicates the improved electrical properties of a quartz-fiUed epoxy resin system with 0.3% silane admixed into the formulation. Improved insulation values, including reduced dielectric constant and reduced dissipation factor, are also denoted. 

Weight gain of the epoxy matrix cured with a catalyst, SarCat CD1012 (CD1012) cationic initiator from Sartomer was examined to compare with the hydrophilic cured matrix of GMAEVC and epoxy resin. The active molecule of the catalyst is the diaryl iodonium hexafluoroantimonate that decomposes imder thermal curing (140°C) [31]. 

From comparisons of the sorbed water effects on the polymer cured under different conditions, it can be concluded that the sorbed water in the polymer contributes to the changes of the thermomechanical properties differently depending on the crosslink structure. It is concluded that water absorption leads both to plasticization effects and chemical modification of the hydrophilic polymer matrix of GMAEVC and epoxy resin depending on the structure and crosslinks of the matrix. 

Duolite A-7 2.2 1.12 Phenolic type resin. High porosity and hydrophilic matrix. pH range is 0 to 6. 

Internal surfactant antistats ate physically mixed with the plastic resin prior to processing. When the resin is melted, the antistat distributes evenly in the polymer matrix. The antistat usually has some degree of solubiUty in the molten polymer. However, when the polymer is processed (extmded, molded, etc) into its final form and allowed to cool, the antistat migrates to the surface of the finished article due to its limited solubiUty in the solidified resin. The molecule of a surface-active agent is composed of a polar hydrophilic portion and a nonpolar hydrophobic portion. The hydrophilic portion of the surfactant at the surface attracts moisture from the atmosphere it is the moisture that has the static dissipative effect. 

The degradation of the matrix in a moist environment strongly dominates the material response properties under temperature, humidity, and stress fatigue tests. The intrinsic moisture sensitivity of the epoxy matrices arises directly from the resin chemical structure, such as the presence of hydrophilic polar and hydrogen grouping, as well as from microscopic defects of the network structure, such as heterogeneous crosslinking densities. 

The drug may be incorporated in a slowly eroding matrix of waxy materials, embedded in a plastic matrix, complexed with anion exchange resins or incorporated in a water-insoluble hydrophilic matrix. Drug release from these systems occurs by several mechanisms diffusion, dissolution, ionic exchange or osmotic pressure [1,2], depending on the type of polymeric excipient present and the formulation used. 

The use of the anion-exchange resin Duolite A-7 for concentrating organic acids was reported as early as 1965 by Abrams and Breslin (7) and more recently by Leenheer (8). A-7 is a high-surface-area, macro-porous, phenol-formaldehyde, weak-base resin. This resin combines weak-base, secondary-amine functional groups with the relatively hydrophilic phenol-formaldehyde matrix to effectively sorb and elute organic acids. 

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