| Compatibilizer has an important application value in short fiber reinforced rubber composites.Selecting suitable compatibilizer can greatly improve the comprehensive properties of the composites.This paper mainly researched and analyzed the properties of heat treated aramid fibers or aramid pulp reinforced natural rubber composites,through the use of MLPB,epoxy resin and epoxidized natural rubber as compatibilizers,and the compatibilizing effects of the various compatibilizers on high performance of the composites were examined.Structure and characteristics of the composites such as rheology,mechanical cutting,interfacial layer of fiber and rubber matrix were evaluated.The main contents are as follows:(1)Batch of aramid fiber/rubber was prepared by two steps method after thermal oxidation treatment.Small molecular epoxy resin,MLPB and the amide group on the fiber surface interacted with each other in composite system,thus improving the bonding between the fiber and the rubber matrix.The addition of different kinds of epoxy compatibilizer can promote the vulcanization of rubber and reduce the curing time.RPA analysis showed that the interfacial bonding between fiber and matrix was improved by addition of compatibilizer,and the tensile modulus at 100% and tensile modulus at 300% and tear strength properties were obviously improved.The results of rubber composite anti cutting performance and tensile fracture morphology indicted that the bonding of fiber and rubber matrix was improved.The results of DMA showed that the maximum of the loss factor decreases with the addition of compatibilizer,reflecting the interfacial adhesion of aramid short fiber and rubber matrix to improve.(2)Through the research of adding content of ENR,it is found that curing time decreased,and the tensile modulus at 100% and tensile modulus at 300% were increased by 19.7% and 21.3% at the maximum values when the dosage of 12 phr ENR was added.RPA analysis of vulcanizate showed that the energy storage modulus and loss modulus of composites decreased,indicating that the addition of ENR increased the polarity of matrix rubber,which resulted in increasing the dispersion of filler and weakening the Payne effect of rubber composite.DMA analysis showed that the loss factor tan delta was obviously decreased,which indicated that the interface of composite was improved.The two loss peaks were observed when adding ENR,which also showed that the composite had two phase structure.(3)The addition of epoxy(EP)improved the processability of the rubber compound and the dispersion of the filler.The tensile strength and tear strength were greatly improved,especially,the F51 specimens increased by 12.1% and 19.8% respectively,and the longitudinal tear strength increased by 15.1%.But the small molecules in composite materials play a plasticizing effect,which resulted in tensile modulus decreasing slightly.The result of RPA analysis of the vulcanizate showed that the loss factor tan? decreased,indicating the interfacial adhesion between fiber and rubber matrix was improved.From DMA data analysis,tan?NR and tan?ENR peak position were closer,which indicates that the addition of epoxy resin made compatibility of NR and ENR part increased by adding EP.(4)Through the study on the natural rubber reinforced by carbon black and aramid pulp,it is found that carbon black and fiber had a synergistic effect on reinforcing NR/ENR.With the decrease of carbon black content in NR/ENR,the mechanical properties of composites were improved when ENR was added.From the analysis of RPA and the microscopic morphology of the cross section,the interfacial bonding of fiber and matrix was enhanced by ENR,and the tan? of vulcanizate was decreased obviously.The experimental results showed that the composite had the best comprehensive properties when ENR was added to 12 phr and carbon black content was 44 phr.The addition of F51 improved the processability of the composites.But the RPA analysis of vulcanizate showed that tan? has increased.The longitudinal tear strength reached the maximum when the content of F51 was 0.6phr,and the transverse tear strength decreased somewhat compared with the control group,indicating that F51 made the fibers tended to orientation.It was seen from the morphology of longitudinal tear transect that the adhesion of the fiber root interface became better and the fiber damage was aggravated by the addition of F51.The results of RPA analysis and cutting resistance showed that the interfacial bonding was improved.In the DMA spectrum,the loss factor peak of AP reinforced NR decreased greatly with the addition of ENR,and the Tg moved to low temperature.The addition of F51 leaded to a decrease of tan?ENR. |
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