| Popis: |
We studied the strueturat ion of rubbers in the presence of 2,6-dibromodimethyl-4-tert. butylphenol (DBP) and 2,6-diehlorodimethyl-4-tert.butylphenol (DCP). These substances were synthesized by passing the respective dry hydrogen halide through a saturated solution of 2,6-dimethylol-4-tert.butylphenol (DMP( in glacial acetic acid. The products were recrystallized from ligroir~, yielding white crystals, m.p. 71°C (DBP) and 68°C (DCP). The results of elemental analysis of these substances was in good agreement with the theoretical values. The extent of rubber structurat ion was expressed as the number of transverse bonds per c.c., and this was calculated on the basis of the swelling of samples in m-xylene using the Flory-Rener formula. The kinetics of DBP additior~ to rubbers were studied by using radioactive C ~4 from C ~ containing phenol. The samples for spectral analysis were prepared by a method described earlier [i]. The kinetics of HBr liberatior~ were established by heating the samples in a thermostat ampoule; the developing HBr, together with dry and heated argon entering the ampoule was bubled through an AgNO3 solution, which was then sampled at certain t ime intervals. The amount of liberated I-IBr was calculated from the results of the Folgart t i trat ion. The absence of a sudden change was verified by determining the Br-content in the dry residue after HBr liberation had. stopped [2] and by establishing the material balance. |
