Study on the structure and properties of chlorinated natural rubber from latex

摘要

The structures of two chlorinated natural rubbers(CNR) prepared from solution process(CNRS) and latex process(CNRL) as well as the chlorination kinetics and mechanism of natural latex for preparing CNR and the contents and stabilities of the gel in CNRL had been studied by High Resolution Pyrolysis Gas Chromatography-Mass Spectrometry(HRPyGC-MS), ~(13)C-NMR and FTIR coupling with chemical analysis and thermal analysis techniques. The results indicated that the fine structures of CNRS and CNRL are different while their basic structures are similar. The rings on CNR molecular chains should be hexatomic rings. The molecule of CNRL contains a few carboxyl and carbonyl groups. The chlorination of CNR from latex is similar to that of CNR from solution. The main reason why the structure of CNR from latex is not as regular as CNR from solution is that there are some HOCl addition at the initial stage of chlorination, more 3℃—Cl bands formed, and ClC—C=O and RClC—COOH group produced at the later stage of chlorination. Furthermore, a conclusion could be induced that is the chlorination reaction was occurred evenly on all NR molecules in the chlorination of production CNR from latex. The gel in CNR from latex mainly was the intermolecular cross-linking product from CNR. The structure of the gel was similar to that of the sol in CNR, but the chlorine content of the gel was slightly lower than that of linear CNR. The thermal and thermooxidative stabilities of gel were poorer than those properties of the sol, and the formation of the gel showed adverse effects on the thermal and thermooxidative stabilities of CNR. The chlorination reaction mechanism and kinetics parameter of natural latex at the present technical process were introduced.