Study On Characterization Methods Of Resins Structure

Every year, we buy tons of ion-exchange resins from foreign countries. Contraposing this situation, experiments were carried out in order to find effectively characterizing methods for ion-exchange resins among the existing domestic methods. According to the domestic ion-exchange resins, two kinds of resins were chosen for the study. They are cinnamic and acrylic resins. Polymer particles were synthesized by suspension polymerization with divinylbenzene as the crosslinker. This article reviews studies on the characterization of styrene-divinylbenzene, methyl acrylate-divinylbenzene and styrene-methyl acrylate -divinylbenzene copolymers, and it also reviews studies on the characterizing methods of ion-exchange resins which are based on those copolymers. The results that we found are as follows.Analysis by infrared spectrum: the three kinds of copolymers mentioned can be easily identified by its characteristic absorption spectras; this method can be used as a quantitative analysis method when the crosslinkages of acrylate-divinylbenzene and styrene-methyl acrylate-divinylbenzene copolymers are 10%~40%; the strong acid resins, alkali resins and weak base resins which all have structures of styrene-divinylbenzene can be identified from absorption spectras, and also the weak acid resins, weak base resins which all have structures of methyl acrylate-divinylbenzene can be identified; amphoteric resins with structure of styrene-methyl acrylate-divinylbenzene can be identified too, and snake-cage resins which have the same structure only can be recognized after washing by acid and alkali.Analysis by TG-DTG: one weight lost step exists in the three kinds of polymers; the crosslinkage of those polymers are linearly relateded to indexers that are obtained from the TG-DTG curves; quantity of weight lost steps which depends on the functions are 2 to 3.DSC was used to quantitative analysis crosslinkage of polystyrene-divinylbenzene whose crosslinkage are less than 23%.Analysis of element: exchange capacity of strong acid and alkali ion-exchange resins can be quantitative analysised by this method.Chemical titration can be used to quantitative analysis exchange capacity of ion-exchange resins with acid-base properties already known.Macroporous resins and gel-type resins with the same structure and function groups were characterized by same methods and got similar results.Two unknown foreign resins were characterized by methods of infrared spectrum, TG-DTG analysis, element analysis and chemical titration, and the results are that: the resins of Janpan are macroporous resins which have a structure of high divinylbenzen quantity and the S element; the resins of France are macroporous resins which have a structure of styrene-divinylbenzene and weak base function groups.