Resin Functional Group

The most popular method by which epoxy thermoset structure is altered for structure-property investigations is the intentional variation of the curative/epoxy resin functional group ratio (A/E). Unfortunately, it is impossible to alter independently only one structural feature at a time using this technique. For example, the... 

The ion-exchange resin acts as a semipermeable membrane between the two aqueous phases, b and c. Ionized sample solutes are excluded from the interior water (b) and pass quickly through the column. Nonionic materials are not excluded and they partition between the two water phases, b and c. Thus, they pass more slowly through the column. Nonionic solutes differ in their degree of retardation by the resin phase because of (1) differing polar attraction between the solute and resin functional groups, (2) differing van-der-Waal forces between the solutes and the hydrocarbon portion of the resin. 

Note that the cupric ion is shown to be associated with two resin functional groups, releasing two sodium ions. Half the number of moles of doubly charged copper is equivalent on the basis of charge to sodium or hydrogen. If the copper were present as singly charged cuprous ion, the equivalents would contain equal numbers of moles. 

Cation-exchange resins Functional groups Chemical formula... 

Anion-exchange resins Functional Groups Chemical Formula... 

Our earlier attempts to identify both the formation and the stoichiometries of HAS(s) involv their retention on cation exchange resins and subsequent elution using dilute acid [1,9]. The technique relied on the assumptions that HAS,s) were small enough to enter the matrix of the resin (< 100 nm), that they were positively charged and that their retention by the resin functional groups would not alter the form in which they had entered the resin. We successfully applied this method in dilute mildly acidic solutions to identify HAS ) with Si Al ratios between ca. 0.2 and 0.7 and, at that time, we interpret these results as confirmation of the existence of one general form of HAS ) with an ideal Si Al ratio of 0.5. It was not until we had developed a method to... 

Esters. Most acryhc acid is used in the form of its methyl, ethyl, and butyl esters. Specialty monomeric esters with a hydroxyl, amino, or other functional group are used to provide adhesion, latent cross-linking capabihty, or different solubihty characteristics. The principal routes to esters are direct esterification with alcohols in the presence of a strong acid catalyst such as sulfuric acid, a soluble sulfonic acid, or sulfonic acid resins addition to alkylene oxides to give hydroxyalkyl acryhc esters and addition to the double bond of olefins in the presence of strong acid catalyst (19,20) to give ethyl or secondary alkyl acrylates. 

Ion-exchange resins are categorized by the nature of functional groups attached to a polymeric matrix, by the chemistry of the particular polymer in the matrix, and by the porosity of the polymeric matrix. There are four primary types of functionaHty strong acid, weak acid, strong base, and weak base. Another type consists of less common stmctures in specialty resins such as those which have chelating characteristics. 

The Hquid phase is free of Na" and the functional groups of the resin are converted to a sodium salt. Multivalent cations are removed in a similar manner. Electric charge neutraHty must be maintained in both the Hquid and soHd phases. 

Weak Base. Weak base anion-exchange resins may have primary, secondary, or tertiary amines as the functional group. The tertiary amine -N(CH2)2 is most common. Weak base resins are frequentiy preferred over strong base resins for removal of strong acids in order to take advantage of the greater ease in regeneration. 

Moisture and Water Content. Resins are thoroughly washed with water upon completion of manufacture and conversion (if necessary) to another ionic form. Excess water is removed by vacuum draining or filtration. Nevertheless, a significant quantity of water associated with the functional groups and adhering to the outer surface of the resin particles remains with the resin as it is discharged into shipping containers. No effort is made to dry the resin, except in a few appHcation areas, since the resins are used in aqueous processes in most installations. 

Temperatures should not exceed 60°C for the Type I resins, and 40°C for Type II and acryflc resins. Thermal degradation and the loss of functional groups occur when these temperatures are exceeded. Elimination of siUca from the resin bed is further improved by preheating the bed with warm water before injecting the NaOH solution. 

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