| Styrene-butadiene rubber(SBR),derived from two monomers,styrene and butadiene,is the earliest synthetic rubber of industrial production,and the consumption and production of SBR is the largest one in the world until now.The mechanical properties,processability and application fields of SBR are all close to these of natural rubber(NR),while the abrasion performance of SBR is better than that of NR.Besides,the thermostability,aging resistance and cure speed of SBR is superior to these of NR.It could be mixed with NR by any ratios and was widely used in varieties fields,which including tires,tapes,wires,cables and medical instruments and so on.In order to improve the application performance of rubbers,kinds of processing aids were needed during the process of rubber.Among them,reinforcing agent is the most consumable one.The main effect of reinforcing agent is to improve the physical and mechanical properties of rubber materials.The commercial reinforcing agents are carbon black(CB)and white carbon black(WCB)nowadays.While the energy consumption for producing CB and WCB is very high,besides the CB and WCB particles would assemble together and hence reduce the compatibility between the reinforcing agents and rubber matrix.Developing new types of reinforcing agent is the urgent agenda in rubber industry.Lignin is a three-dimension network based on phenylpropane units.Lignin is mainly obtained from papermaking wastewater,and it is now used as water reducing agent,flocculants and dispersants.However most of lignin in papermaking black liquid were poured into rivers and lakes or burned after concentrated.It will lead to severe environmental pollution and waste of resource as well.Owing to the network structure and phenylpropane units,lignin is hardly to be degraded and believed to be a suitable reinforcing agent for rubber.Besides,the low density of lignin would reduce the density of rubber and the consumption of rubber.In this thesis,wood hydrolysis lignin was chosen as the raw material.We prepared kinds of lignin/NR composite.First,the original lignin were dispersed into natural rubber latex,then this composite were used to reinforce SBR;besides,small molecule weight modifiers as formaldehyde were used to modify the lignin/natural rubber composite,different modification conditions were studied to optimum the experiment;meanwhile,high weight molecule polymers as starch and its’ derivatives were mixed with lignin/rubber composite,and then used to study the reinforcing effect for SBR;at last,the reinforcing effect of oxidized-lignin and different parts per hundreds of rubber(phr)for SBR were investigated.The results were show below:(1).The partial substitution of WCB by unmodified lignin/natural rubber composite will lead to good reinforcing effect to SBR,the tensile-strength of SBR is increased after reinforced by lignin/natural rubber composite.The tensile-strength increased about 17%reinforced by lignin composite partial instead of White Carbon Black.Besides,the improved breaking elongation indicated that the toughness of SBR was improved as well.Meanwhile,the dynamic mechanical analysis(DMA)result reveals that the storage and loss modulus and of the reinforced rubber increased.Besides,the rubber’s cold resistance and rolling resistance were improved also.But the wet skid resistance of SBR was reduced after reinforcing.(2).Small molecule weight modifiers were of no beneficial for lignin/natural rubber composite in reinforcing SBR.For formaldehyde,the orthogonal test showed that the amount of its usage had no effect on the final result and the modification reaction temperature should be controlled around 70 degree,while the reaction time was about 1 hour.For the other types of modifiers such as glutaraldehyde,epichlorohydrin and hexamethylenetetramine,Glutaraldehyde seems to be a good modifier among them.But the properties of Glutaradehyde modified lignin reinforced SBR can’t compare with unmodified ones(3).High molecular weight polymer mixed lignin/rubber composite also had no obvious reinforcing efficient for SBR.Two types of Polyvinyl alcohol were selected to modify lignin and the result showed that polyvinyl alcohol had no reinforcing efficient for its high melting point and large particle sizes.The reinforcing efficient of two kinds of modified starch was not as good as unmodified starch.(4).High substitute parts per hundreds of rubber(PHR)of lignin composite would reduce the reinforcing efficient evidently.Besides,the oxidation of lignin had no positive effect on reinforcing SBR also,which still needs further systematic investigation.Above all,the modified lignin/rubber composites had no evident reinforcing effect for SBR,while the original lignin could be an effective reinforcing agent for SBR.The control of lignin particle size and the surface modification will make lignin to be a potential reinforcing agent in rubber industry. |
PDF Full Text Request