不同硫化体系对硫化天然橡胶改性沥青性能及微观结构的影响

Effect of Different Vulcanization Systems on Properties and Microstructure ofVulcanized Natural Rubber Modified Asphalt

天然橡胶是一种生物质聚合物,作为沥青改性剂在环境可持续性上具有明显优势。然而,其对沥青物理及流变性能的提升不显著。硫化可以改善天然橡胶改性沥青(Natural rubber modified asphalt,NRMA)的性能,但硫化是一个复杂的过程,硫化体系众多,不同硫化体系对硫化天然橡胶改性沥青(Vulcanized natural rubber modified asphalt,VNRMA)的影响尚不明确,这极大地影响了进一步开发高性能VNRMA以获得更广泛的应用。基于此,本研究通过普通硫化体系(Conventional vulcanization,CV)、半有效硫化体系(Semi-efficient vulcanization,SEV)和有效硫化体系(Efficient vulcanization,EV)制备不同的VNRMA,并探究硫化体系对VNRMA性能及微观结构的影响。结果表明:在高温性能和温度敏感性方面,SEV/VNRMA的复数模量、相位角、车辙因子以及温度敏感性系数VTS表现最好;在低温性能方面,三种硫化体系制备的VNRMA均能满足规范要求,但CV/VNRMA低温性能最佳,更适合在低温环境下使用;相容性方面,SEV/VNRMA的Han曲线在低频区斜率值(1.042)最大,相容性最好;施工和易性方面,SEV/VNRMA占据优势,其通过传统等黏度法确定的拌合温度比CV/VNRMA和EV/VNRMA最大分别降低5℃和5℃,压实温度最大分别降低5℃和6℃。通过FM和FTIR对VNRMA的微观结构和化学结构进行分析,结果显示,相比于CV/VNRMA和EV/VNRMA,SEV/VNRMA更加均匀且致密的网状结构是其在相容性和高温性能方面表现优异的主要内在原因。综上,SEV对NRMA的硫化效果最佳,推荐后续研究使用。

Natural rubber is a biomass polymer that offers significant advantages in terms of environmental sustainability as an asphalt modifier.However,its enhancement of physical and rheological properties of asphalt was not significant.Vulcanization can improve the performance of natural rubber modified asphalt(NRMA),but vulcanization is a complex process,there are many vulcanization systems,and the effect of different vulcanization systems on vulcanized natural rubber modified asphalt(VNRMA)is not clear,which greatly affects the further development of high-performance VNRMA for wider applications.Based on this,in this study,different VNRMAs were prepared by conventional vulcanization(CV),semi-efficient vulcanization(SEV),and efficient vulcanization(EV)systems,and the effects of vulcanization systems on the properties and microstructures of VNRMAs were investigated.The results show that SEV/VNRMA has the best performance in terms of high temperature performance and temperature sensitivity in terms of complex modulus,phase angle,rutting factor,and temperature sensitivity coefficient VTS.In terms of low-temperature performance,VNRMA under all three vulcanization systems meets the specification,but CV/VNRMA is best at low temperatures and is more suitable for use in low-temperature environments.In terms of compatibility,the Han curve of SEV/VNRMA has the largest slope value(1.042)in the low frequency region and has the best compatibility;In terms of construction ease,SEV/VNRMA dominates,with its mixing temperature determined by the conventional iso-viscosity method being reduced by a maximum of 5℃and 5℃,and its compaction temperature by a maximum of 5℃and 6℃,respectively,compared with CV/VNRMA and EV/VNRMA.The microstructure and chemical structure of VNRMA were analyzed by FM and FTIR,and the results showed that the more homogeneous and dense reticular structure of SEV/VNRMA is the main intrinsic reason for its excellent performance in compatibility and high temperature properties compared with CV/VNRMA and EV/VNRMA.In conclusion,SEV had the best effect on the vulcanization of NRMA and is recommended for subsequent studies.