Aramid Fiber Modified By Cryogenic Treatment

Cryogenic treatment as a heat treatment process,it can improve the materials' strength,toughness and wear resistance,also can improve the uniformity of the microstructure,dimensional stability,reducing distortion,thereby enhancing the service life of materials.And this method is easy to operate,not destroy the work piece,no pollution,low cost,shows considerable market prospect and commercial benefit.Cryogenic treatment is mainly used in metal and alloy,for the first time in this paper,we study the cryogenic treatment used in the fiber.Aramid fiber is formed from a rigid molecular chain with high crystalline and high degree of orientation.Aramid fiber has a range of advantages,not only its relative low weight and high strength,it is very stable at high temperatures and it is impact and scratch resistant.Aramid fiber reacts well under a tensile force(stretching force)but badly under a compressive force.There is a need for either new materials or new formulations and technology due to the ever increasing demands for high performance materials able to with stand drastic operating conditions such as high speeds,loads and temperatures with superior properties.This paper based on the cryogenic treatment on the properties of metal,determine the technological parameters of cryogenic treatment of aramid fiber,after discussion,eventually cryogenic treatment process as the cooling rate of 2?/min,-80? heat preservation for an hour,an hour at-120? heat preservation,the final heat preservation temperature is-196?,holding time is 12 h,natural.With this idea the commercially available aramid fiber is selected and subjected to quality improvement by cryo-treatment process.The mechanical,thermal and structural properties of 'un-treated' and'cryo-treated' Aramid fiber are studied in a comparative manner.Mechanical properties like wear performance and tensile properties are evaluated.Structural characterization by X-ray diffraction and Fourier transform infrared spectroscopy revealed the change in%crystalline,which is found to be the most important parameter responsible for enhancement of wear performance.In a similar way,thermal changes are also studied by using differential scanning calorimeter.The results show that the tensile strength of aramid filaments from the 3.09GPa up to 3.34GPa;wear resistance also increased 21.05%;Meanwhile,after cryogenic treatment of aramid fiber crystallinity and crystallite size has also been reduced,but little change in the thermodynamic properties.After cryogenic treatment,the interface properties of the aramid fibers are also improved.By scanning electron microscopy(SEM)test shows that the modified fiber surface modification are obviously rough,but there is no big groove,visible cryogenic treatment and no damage to the internal structure of the fibers,the fiber mechanical properties characterization results also confirm this.In fiber surface obtained by AFM test obviously rough,and the surface roughness increased significantly,and scanning electron microscopy(SEM)test results are consistent.Of the modified fiber is obtained by contact Angle test with water invasive is obviously improved,is beneficial to the combination of fiber and resin,improves performance of the interface.Of the modified fiber is obtained by contact Angle test with water invasive is obviously improved,is beneficial to the combination of fiber and resin,improves performance of the interface.IFSS values between aramid fibers and epoxy resin were increased by nearly 24%,which was mainly due to the creation of a more hydrophilic surface of aramid fibers by the cryogenic treatment.Finally,the paper studied the influence of different moisture content of cryogenic treatment,found that the increase of moisture content on the performance of the aramid fiber has both positive effect,also have a negative impact,can according to the different uses of fiber,choose different moisture regain,cryogenic treatment process parameters were optimized.