| At present,although the recycled rubber industry has adopted various means to reuse rubber.However,the recycling degree of recycled rubber is low,the molecular chain degredation is serious,the environmental pollution is serious,the application scope and direction are narrow.There are the problems to be broken through in the recycled rubber industry at present.Therefore,it is urgent to find a method that can reduce pollution and recycled rubber efficiently.In this work,the effect of reclaimed rubber(RR)and environmental friendly aromatic oils(EAO)on the mechanical properties of natural rubber(NR)composites was investigated in comparison,taking advantage of the low viscosity and certain plasticity of the RR body.Fourier transform infrared spectrometer(FTIR),thermogravimetric analyzer(TG)and rotorless rheometer were used to characterize the RR body.It was found that the RR body contained60.25% NR rubber hydrocarbons with recrosslinking ability,27.66% carbon black and 4.62%small molecule oils.In addition,the effects of RR and EAO on NR vulcanizates were characterized by transmission electron microscopy(TEM),crosslinking density measurement and dynamic and static macroscopic mechanical tests.The experimental results showed that RR itself could provide additional reinforcement while being used to replace EAO as a plasticizer.Compared to the NR-EAO10 composite,the NR-RR10 composite had a 16.4% higher MH,approximately 18.3% faster vulcanization,17.5% higher cross-linking density,7% higher hardness and approximately 5% higher 100% modulus.On the basis of this,NR matrix was replaced with different proportions of RR in order to further investigate its reinforcement effect in the composite.It was found that with the presence of RR,a two-phase structure began to appear in the composite material,in which the NR/RR(60/40)and NR/RR(40/60)systems showed a bicontinuous phase,and the NR in the NR/RR(20/80)system changed into a dispersed phase in the RR continuous.The vulcanization data showed that the t10 and t90 values of the composties were almost inversely proportional to the RR content.When RR content was less than 60 phr,the MH-ML and cross-linking density of NR/RR system increased with the increase of RR content,but decreased when the RR content reached 80 phr.The change in tanδ confirmed the occurrence of a high crosslink density structure with the incorporation of RR in the composite,which became more pronounced with increasing RR content.The stress-strain behaviour showed that the 100% modulus was positively correlated with the amount of RR when the content of RR in the system is below80 phr.Meanwhile,the elongation at break and the rebound coefficient of the composties decreased with the increase of RR content in the system.Finally,RR was prepared using four regeneration processes in combination with regeneration methods such as thermo-mechanical shearing and thermal oxidation without involving chemical reduction reagents;the physical and mechanical properties of the RR bodies prepared by the different processes and their filled NR composites were investigated in comparison.The results showed that the sol content(45.2%)and regeneration degree of the reclaimed rubber prepared by mechanical shear and thermal oxidation(RKH)were the highest.In addition,the vulcanisation properties of RR filled NR composites were investigated and the NR-RRH20 system was found to have a faster vulcanisation rate,higher torque values and the highest crosslink density values.In the strain sweep,the NR-RRH20 system had the highest E’.Compared to the NR-RR composites prepared with other regeneration method,the NR-RRH20 composites had the best comprehensive mechanical properties. |
PDF Full Text Request