Papers by Keyword: Aramid Fiber

Abstract: The poor ability of bonding performance of aramid fiber with epoxy resin limits its usage for wide range of applications. In this research work, an attempt was made to improve the bonding performance of aramid fiber with polymer matrix by performing nitric acid treatment on fiber. The role of functionalized multi walled carbon nano tubes (F-MWCNTs) reinforced in the base polymer matrix is also studied. Six composite sheets (AF0, AF1, AF2, AF3, AF4, and AF5) with varying content of F-MWCNTs from (0.1wt% to 0.5wt %) are fabricated using hand layup method having dimensions of 25cm x 25 cm x 0.8 cm . AF0 composite sheet is free from presence of F-MWCNTs. The remaining ingredients [80% epoxy resin, 0.2 % rubber powder, 0.2% graphite powder, and 0.2% BaSO₄, 0.2% Zirconium Silicate powder and 1.5 % fiber] are kept constant for achieving desirable properties of friction materials. After undergoing, curing process in atmosphere for 72 hrs, the specimens are cut according to ASTM standards to evaluate mechanical, thermal and bonding properties of the composites. Scanning electron microscope images (SEM) are observed for the samples to observe the grain distribution present in the composite. It was observed from results that, AF4 (aramid fiber reinforced composite friction material with 0.4% F-MWCNTs inclusions ) along with remaining ingredients exhibited better mechanical ,thermal and bonding properties compared to remaining formulations of materials.

Abstract: The chopped aramid fiber reinforced rubber composite (AFRC) has been widely used in the tire treads for its excellent characteristics. The viscoelasticity which is an important mechanical property for rubber matrix would be influenced by the adding of aramid fiber. In this study, the dynamic and quasi-static viscoelasticity were investigated via the dynamic thermal analysis experiment and the mullins experiment with multi-step relaxation, respectively. The frequency and temperature scanning were employed for AFRC with different fiber volume fractions, fiber aspect ratios and fiber orientation distributions. The effects of constituent parameters on the dynamic viscoelasticity were studied as well as the general rule of reinforcing effect of aramid fiber on rubber materials was presented. The stress relaxtion for AFRC were analysed basing on the experimental results. In addition, The ability of the viscoelastic constitutive model to describe the quasi-static viscoelastic behavior of AFRC were explored.

Abstract: The surface state of aramid fiber was modified by coupling agent to characterize the change of the state. The fiber / epoxy resin composites were prepared to study the mechanical and electrical properties and the internal mechanism of how different surface states affect. The results show that, after the treatment with the coupling agent, the surface roughness of the aramid fiber is increased，and the content of Si on the surface reach 5.8%, thus the surface activity is enhanced. At the same time, the treatment makes the properties of composites further improved. When the filling amount of aramid fiber reaches 30 strands, the tensile strength increase by 38.4% due to the coupling agent. In the test of two-layer samples, the breakdown field strength of the composites before and after treatment with coupling agent increased by 15.9% and 20.2%, respectively.Key words: aramid fiber; coupling agent; surface state; mechanical properties; electrical properties

Abstract: This paper studies the mechanical properties of the aramid fiber reinforced epoxy resin composite by varying the percentage composition. Three different compositions of aramid fiber are 30 %, 35 % and 45 % by weight. The aramid epoxy composite was manufactured by the vacuum suction method. The manufactured composites are then cured by the hot air oven for 180 minutes. The prepared composites undergo through various tests such as the tensile test, hardness test and impact test. The results of the tests on the three compositions analyzed and variation in its mechanical properties is noted.

Abstract: This paper presents an experimental study on bending behavior of aramid and steel fiber reinforced concrete (AFRC and SFRC) members. The objective is to investigate effects of two types of aramid fiber and one type of steel fiber in hybrid reinforced concrete (RC) beams. The term hybrid beam is defined as the beam with fiber reinforced concrete (FRC) cast in tension zone and normal concrete (without fiber) cast in compression zone of the beam. The diameter of aramid fiber (AF) is 0.5mm and the surface condition is twist fiber consisting of two single fibers. The fiber lengths are 30mm and 40mm for two types of aramid fiber. The diameter of steel fiber (SF) is 0.6mm and the length is 33mm with hooked ends. Four reinforced concrete (RC) beams with a dimension of 150×200×2100 mm³ were designed to undergo flexural failure. All the tested beams are with the same reinforcement ratio (0.93%), having a fiber volume fraction (V_f) of 1% for each type of fiber. One RC beam without fiber was prepared and tested as a controlled specimen. The height of the FRC tension zone at ultimate state was calculated to be 170mm. Load capacity, average and maximum crack widths of hybrid aramid and steel fiber reinforced concrete beams (HAFRCs & HSFRC) under four-point bending tests were discussed.

Abstract: The surface of aramid fiber is very smooth and chemical inert.The adhesiveness of aramid fiber with EPDM rubber materials is not good.So the tensile strength of EPDM rubber composite materials is influenced seriously.This paper modified the surface of aramid fiber with silicon coupling agentKH-550. We test the chang of fibers in surface with the ESCA,and the result is that content of carbon decreased ,while content of nitrogen and oxygen element increased.The activity of surface of fiber has been increased. Strength of composite materials increased from 2.58MPa to 3.22 MPa . The SEM photos of samples indicate that the weight of EPDM rubber on surface of EPDM rubber is more than untreated fiber composite materials .The treating effect on aramid fiber is best when the concentration of KH-550 is 5%,5hours.

Abstract: Based on the thermal stability test on the different fire resistance materials, this article study the Thermal protection property (TPP) of the different materials composite structure and analyses the effect that the materials changes on the TPP of the composite structure products. The results indicate that the thermal insulation batts made by Aramid fiber materials have excellent thermal stability, adding a certain percentage of Aramid fiber 1414 into the thermal insulation batts makes for the batts having stably insulation function, and it only needs 10% around additive amount to satisfy this demand, compared with polyimide and PPS, Aramid fiber 1414 have better thermal stability when encountered fire.

Abstract: The poor wetting property between aramid fiber and resin results in the low interfacial performance due to the inertia and smooth surface of aramid. 60Co gamma-ray was used to modify the surface of domestic aramid fiber in the medium of epoxy chloropropane and diethanolamine respectively. The properties of aramid/epoxy composites were characterized by interface shear strength (IFSS) and the effect of two graft polymerization systems on fiber surface was discussed. The results showed that in an irradiation dose of 400kGy, when chloropropane and diethanolamine were used respectively as the graft system, the IFSS value of the composite material reached 86.53MPa and 70.37MPa, and compared with the untreated sample, each increase of 31.23% and 6.72%. High-energy radiation treatment increased the surface energy of aramid. The original smooth surface was disappeared. Oxygen content on fiber surface greatly risen, and aramid surface activity increased.

Abstract: The crystal structure of aramid fibers is highly orientated. The structure of aramid fibers with various manufacturing processes and aramid paper sheets were analyzed and observed by using polarized light microscope (PLM). The change and its law of aramid fiber crystal structure in such processes as aramid fiber mamufaturing of aramid fiber/fibrids, forming of aramid paper sheets, and heat treatment were analysed. The relationship between the structural feature of aramid fibers and the performance of aramid paper was also discussed.

Abstract: A chemical modification was adopted to treat the surface of aramid fibers.The influences of aramid fibers on the friability and compression behavior of phenolic foam before and after modification were studied.Compared with unmodified aramid fiber-reinforced phenolic foam ,foam reinforced with modified aramid fibers exhibits significantly lower friability, higher compressive strength and compressive modulus. The thermal conductivity and Oxygen index of modified aramid fiber- reinforced phenolic foam hasn’t obviously been changed compared with the unmodified counterpart.