Study On Dispersibility And Bloming Prediction Of Insoluble Sulfur In Natural Rubber

Insoluble sulfur is an important curing agent for unsaturated rubbers except CR.The vulcanizates crosslinked by insoluble sulfur had good comprehensive properties,uneasy blooming and high adhesive strength between rubber and framework.Insoluble sulfur had already been widely used in radial tyre and wire braided hose.Although insoluble sulfur made in China had rapid growth,the quality of insoluble sulfur made in China was less than the same kind of insoluble sulfur made from abroad.This thesis studied the thermostability of insoluble sulfur in NR compounds used by DSC and dispersibility of insoluble sulfur in NR compounds used by stereomicroscope.It also studied the modified technology and granulation by polymer of insoluble sulfur in order to improve the dispersibility of insoluble sulfur in NR compounds.This thesis studied the influence of process conditions such as mill run times,mixing time or dump temperature and the formula components such as Zinc oxide,DZ and 4020 on the thermostability of insoluble sulfur in NR compounds.The results showed that mill run times and mixing time at low tempperature had little influence on the thermostability of insoluble sulfur.The transform amount from insoluble sulfur to soluble sulfur was under 1.6 phr.The compounds didn't bloomed.However,the dump temperature had more influence on the thermostability of insoluble sulfur.The transform amount from insoluble sulfur to soluble sulfur increased when the dump temperature rised.The transform amount from insoluble sulfur to soluble sulfur exceeded 1.6 phr when the temperature reached 110 centigrade.The compounds bloomed obviously.The formula components such as Zinc oxide,DZ and 4020 decreased the thermostability of insoluble sulfur.Among the three components,antioxidant 4020 was the most one.This paper studied different modifiers modified insoluble sulfur and the application of modified insoluble sulfur in NR compounds.The results showed that not only the modifiers containing Boron had little influence on the melting point and thermal stability of insoluble sulfur,but also they could improve the dispersibility of insoluble sulfur in NR compounds.Compare with the vulcanizates used raw insoluble sulfur,the tensile strength,elongation at break and fatigue resistance of vulcanizates used modified insoluble sulfur were improved.Other physical mechanical properties and dynamic properties had little changed.Among the four modifiers,the modifier whose trade name was B200-1 was better than the other three kinds of modifiers.Insoluble sulfur granulated by polymer obviously improved the dispersibility of insoluble sulfur in NR compounds and the properties of vulcanizates made by granulated insoluble sulfur also improved obviously.