Characterization Of VOCs And Study On Odor In Diene Rubber Composites

Diene rubbers such as natural rubber(NR),styrene-butadiene rubber(SBR),and butadiene rubber(BR)are mainly used in tires,which emit toxic and odorous volatile organic compounds during storage.In this study,the VOCs in the diene rubber composites were analyzed by ultrasound-assisted solvent extraction(UASE)coupled with gas chromatography-mass spectrometry(GC-MS).The source of VOCs were traced from the raw materials to the reaction compounds during the manufacturing process;the malodorous substances in vulcanizates were analyzed by headspace(HS).The main research contents are as follows:Firstly,the effects of different pretreatment methods were explored.HS only had a good effect on the detection of low boiling substances,the volatile content had a great impact on it,so it is difficult to analyze a wide range of Volatiles.In contrast,UASE was more suitable for VOCs analysis of vulcanizates.The VOCs components of the main raw materials such as NR,SBR,BR and modified phenolic resins were studied.Among them,the VOCs of NR are widely distributed and the degradation of non-rubber hydrocarbon components may contribute more to their VOCs and odors.From this,VFAs(such as acetic acid),aroma Group compounds(such as styrene,phenol,benzothiazole)and other substances were detected.Compared with NR,the composition of VOCs in SBR and BR are simpler and the smell are weaker which mainly due to the large amount of volatilization of polymerized monomers and polymerization additives.Styrene and octyl mercaptan in SBR and octyl mercaptan in BR.The three modified phenolic resins VOCs for tackifying are mainly composed of alkenes such as 2,4,4-trimethyl-l-pentene and 2,2,4,6,6-pentamethyl-3-heptene.Among them,the decomposition and volatilization of the alkyl-phenol were detected in SL1801 and R7510H,while the types of VOCs in T5600 was smallest and no volatilization of phenolic substances was found and the TVOCs was also the lowest.It is recommended to be used.Secondly,it was found that the VOCs component in the vulcanizate was mainly the reaction product of the additives during the vulcanization process by analyzing the complete formula and combining the analysis results of the raw materials.Among them,dicyclohexylamine has the largest volatility,accounting for about 65.44%of TVOCs,which is derived from the thermal decomposition of the promoter DZ.2,2,4,6,6-pentamethyl-3-heptene and its isomers account for about 11.60%.In addition,ketones and aromatics are also present.Due to the interaction between the active groups of the filler surface and specific VOCs,the filler has a significant adsorption effect on VOCs.The introduction of carbon black and white carbon can significantly reduce the content of dicyclohexylamine in the vulcanizate.Carbon black also has a good adsorption effect on substances which contain the benzene ring structure.Finally,the odor compounds of vulcanizate were studied by headspace incubation 2h at 80?.The influence of gas chromatography columns on the detection results were explored.HP-INNOWAX is more suitable for headspace analysis of vulcanizates.Among the many odor components,acids(such as acetic acid,heptanoic acid)and phenols(such as phenol)generally have an odor threshold below 10'3 mg/m3 and all have malodorous;amines(such as tert-butylamine,aniline,dicyclohexylamine)have higher olfactory thresholds but greater volatility and have an unbearable amine odor.The above may be the main substances that constitute the malodorous of vulcanizates.