QUANTITATIVE-DETERMINATION OF MALEIC-ANHY DRIDE CONTENT IN ACRYLONITRILE COPOLYMERS IN THE PRESENCE OF INITIAL CARBOXY GROUPS

Three different titration methods were proved with respect to accuracy , reproducibility and handling for the determination of maleic anhydri de (MSA) content in acrylonitrile (AN) copolymers in form of poly(AN-c o-MSA) and poly(AN-co-styrene-co-MSA). The comparison comprises (i) th e combined method A/H characterized by the reaction of anhydride group s (AG) with aniline and titration of the formed monoacid with methanol ic KOH (A) and the complete hydrolysis of AG and titration of acid gro ups (SG) with aqueous NaOH (H), (ii) method B based on the conversion of AG with n-butylamine (BA) and back-titration of unreacted amine wit h HClO4 in glacial acetic acid and (iii) method C consisting of the re action of AG with p-chloroaniline (pCA) followed by Cl-determination a fter the Schoniger-decomposition. Whereas all mentioned methods are su itable for the determination of AG in the presence of initial SG, the combination of A/H additionally allows the simultaneous determination of AG and SG. In comparison with the other methods the combination of A/H is to be favoured due to the possibility to obtain additional info rmation about SG and because of the better results in accuracy, reprod ucibility and handling. By means of FTIR spectroscopy the content of A G and SG was estimated qualitatively and a correlation between the spe ctroscopic and potentiometric data of AG was discovered.