Multi-scale Characterization Of Rubber And Its Composites Based On Atomic Force Microscopy And Chromatographic Techniques

With the rapid development of rubber industry,higher requirements are imposed on rubber products,and rubber materials should be developed in the direction of multifunctional and high performance.Researches on high-performance rubber matrix and rubber composites are of great significance.Studying on the compatibility of additives and rubber matrix,and the reinforcing mechanism of fillers,can guide the design of rubber formulations and obtain higher-performance rubber composites.To focus on the self-reinforcing mechanism of natural rubber(NR),develop the alternative NR resources and attempt to synthesize NR in vitro can relieve the resource pressure of NR and obtain the rubber matrix with wider sources and better performance.In the process of developing high-performance rubber and rubber composites,the microstructure and chemical composition will influence their macroscopic properties and application scope.Focusing on the multi-scale characterization of rubber and rubber composites,this paper mainly includes the following researches:(1)Based on the Peak-force Quantitative NanoMechanics AFM(PF-QNM AFM)technology,a new method was developed for the phase identification of complex rubber systems which can observe the phase distribution objectively and quantitatively.The compatibility of five functional resins with SSBR was compared by the new method.The molecular compatibility of different resins with SSBR was revealed by using AFM-IR.The migration of resins in different phase after softening was directly observed by PF-QNM AFM which resulting in a decrease in the concentration difference of each phase.In addition,it was found that the higher concentration of resin in the butadiene chain enriched region was beneficial to the dynamic performance of the tread rubber.(2)By using the new phase identification method,the microstructure evolution during stretching of each phase in peroxide-vulcanized isoprene rubber(IR)and NR systems,as well as sulfur-vulcanized NR systems was observed objectively and quantitatively.The structure evolution and mechanism related to crystallization during stretching were observed on a larger scale,so as to obtain a new understanding of strain-induced crystallization(SIC)of IR and NR.In addition,the effect of epoxidation on the SIC of NR was explored from molecular level,and it was found that the appropriate epoxidation degree could promote the SIC of NR and obtain a higher tearing strength.These studies play an important role in obtaining higher performance rubber matrix materials.(3)By using the phase identification method,the dispersion state of carbon nanotube(CNT)and graphene oxide(GO)in NR,and the interfacial interaction between the nano-fillers and rubber matrix were observed visually and quantitatively.Furthermore,the structural evolution of nano-fillers and rubber matrix during stretching was observed by using AFM visually.Combined with mechanical properties and XRD results,the different effect mechanisms of CNT and GO on SIC of NR,as well as the reinforcing mechanism was proposed which could provide a theoretical basis to prepare the high-performance rubber nanocomposites.(4)A rapid,nonradioactive method for the quantitation of DMAPP and FPP in natural rubber latex by liquid chromatography-tandem with mass spectrometry(LC-MS/MS)was established.By using this new method,the content of DMAPP and FPP in the biosynthesis process of hevea rubber tree and Eucommia ulmoides could be detected in real time and quantitatively.The method can be utilized to do some basic research for real-time monitoring the biosynthesis process in vitro,and useful for NR synthesis.(5)A bio-based reinforcing plasticizer-Eucommia ulmoides resin(EU-resin)was prepared by using ethyl acetate extraction from Eucommia ulmoides leaves.It was applied to be a modifier for the nonpolar rubbers,and the results illustrated that EU-resin could not only be used as a normal plasticizer to improve the processing properties but also can promote the vulcanization and improve the mechanical properties,especially greatly improve the tear strength and dynamic fatigue performance.The general properties of EU-resin were characterized and the further composition analysis was achieved by using the comprehensive two-dimensional gas chromatography-mass spectrometry(GCxGC-MS).As a functional plasticizer and reinforcing agent,EU-resin complies with the development trend of energy saving and consumption reduction in rubber industry.At the same time,the comprehensive development and utilization of EU-resin can effectively reduce the production cost of Eucommia ulmoides gum,so as to alleviate the demand pressure of NR.