Study On The Aging Of Butadiene Rubber

Rubber material is a kind of polymer material with high elasticity and viscoelasticity,which plays an irreplaceable role in the development of national economy.Among them,butadiene rubber(BR)has become one of the world's three general-purpose rubbers due to its excellent comprehensive properties,and is widely used in the industrial manufacture of tires,wear-resistant and cold-resistant products.However,the rubber material is susceptible to light,heat and oxygen in practical applications,causing changes in its composition and structure,resulting in the destruction of its excellent properties.At present,the research on the aging of butadiene rubber mainly focuses on the physical and mechanical properties.There are few researches on the aging mechanism and chemical structure changes.Therefore,it is of great scientific value to study the aging of butadiene rubber and its anti-aging mechanism.In this paper,the rubber of cis-butadiene rubber was selected,and the aging study of butadiene rubber was carried out by FT-IR?1H-NMR and UV-Vis methods.The specific research contents were as follows;1.Study on thermal oxidation agingThe chemical structure changes of butadiene rubber(BR)and butadiene rubber(BRRD)with anti-aging agent RD at 120 ?C were studied and the aging mechanism was investigated.The obtained experimental results showed that BR had poor resistance to thermal aging.When aging at 120 ? for 0.5 d,its structure changed significantly,olefin content decreased significantly,alcohol and aldehydes and ketone compounds were formed,and ?-H had been reacted by about 97%when the double bond of butadiene rubber was aged at 15 d;the thermal aging resistance of BRRD had been greatly improved,and the induction period of 2d had appeared,and the aging effect had been delayed in the thermal oxidation aging of butadiene rubber at 120 ?during 15 days.The mechanism of thermal aging was that the double bond ?-H first oxidized to form a peroxyl hydroxyl group,which was then oxidized to an alcohol and an aldehyde ketone compound,and finally degraded to form a terminal acrolein,and a double bond underwent a radical addition reaction.According to the thermal oxidation aging curve established by nuclear magnetic resonance spectroscopy,and the aging equation of thermal oxidation aging process of BR and BRRD was obtained.2.Study on UV agingThe chemical structure changes of butadiene rubber(BR)and butadiene rubber(BRUV-531)with UV-531 were studied,and the aging mechanism was investigated.The obtained experimental results showed that the anti-UV aging ability of BR was poor.When the ultraviolet light was irradiated for Id,the aging began,and the chemical structure changed significantly.The UV-531 content in BRUV-531 was continuously volatilized with the aging time to decrease.Effective anti-aging time could reach 7 days.UV aging began with ?-H,first produced hydroperoxide(ROOH),and then formed oxygenates such as ketones and ethers.On the other hand,double bond addition reaction occurred under the action of ultraviolet light.According to the UV aging curve established by nuclear magnetic resonance spectroscopy,and the aging equation of UV aging process of BR and BRUV-531 was obtained.3.Study on media agingThe aging of butadiene rubber(BR)in 5%H2O2,5%KMnO4,5%HC1,5%NaCl and 5%NaOH solution was studied to observe the change of molecular structure and the aging mechanism was explored.The obtained result is that BR had strong aging resistance to 5%H2O2 solution medium.During the 0-15d aging of H2O2 solution,there was no obvious change of double bond,and no characteristic peak of carbonyl was found,and the molecular structure had no obvious change;compared H2O2 and KMnO4,BR was carbonized on the surface of KMnO4 solution and the powder layer was detached.The double bond reacted with KMnO4 to form the o-diol product,indicating that the anti-KMnO4 solution was weak;BR in HCl solution,with aging time The surface gradually yellowed,but the molecular structure did not change significantly,indicating that BR could stay in the medium environment of dilute hydrochloric acid solution stably;BR had strong anti-NaCl solution aging ability,and its molecular structure didn't appear obvious change,and the rubber state was stable,it could be stably present in the salt solution medium environment;BR produced white flocculent substance in the NaOH solution,this substance was due to the aging process,the solution volatilizes and precipitates NaOH,indicating the BR had anti-alkali solution medium environment ability;In the above five kinds of medium solutions,according to the change of appearance and the change of molecular structure,BR was resistant to acid and alkali salt solution medium environment,and it was not resistant to 5%KMnO4 solution;according to the medium aging curve established by nuclear magnetic resonance spectroscopy,the aging equation of BR in 5%KMnO4 solution was obtained.4.Study on natural agingThe natural aging process of butadiene rubber(BR)in Xiamen for 18 months was studied,and the chemical structure changes were observed,and the aging mechanism was explored.The result was that the anti-natural aging ability of BR was weak,the aging was basically completed within 15 days,and the cross-linking mainly occurred in the later stage,BR cracked;In the natural aging process,both ultraviolet light and heat(sun light),in which natural aging was greatly affected by ultraviolet light,and secondly by thermal oxygen;in the natural aging process,BR was affected by uv,double-bond ?-H was first oxidized to peroxyl hydroxyl group,and then dehydrogenated to form a ketone,or combined with an alkyl group to form an ether;the crosslinking process was a double bond opening to generate a radical addition reaction;in the natural aging anti-aging experiment,the anti-aging effect of the ultraviolet light absorber UV-531 was stronger than the anti-aging effect agent RD,therefore,in the actual application process of BR,it was necessary to prevent exposure to ultraviolet light environment;according to the natural aging curve established by nuclear magnetic resonance spectroscopy,the natural aging equation of BR was obtained.Innovatively established the relationship between natural aging time and 120 ? thermal oxidation aging,UV aging,5%KMnO4 media aging time.It was concluded that the natural aging of butadiene rubber was similar to the UV aging,which provided an important theoretical basis and support for the aging research of butadiene rubber and its service life prediction.