Study On Surface Modification Of Aramid Tabby Fabrics And Its Anti-stab Properties

Aramid fabric is one of the main materials for fabrication of soft stab resistanceclothes. How to enhance puncture resistance and improve the usability of aramid fabrics inextreme environment is the key to the preparation of lighter, more reliable stab resistanceclothes. Surface modification is an effective way to improve the mechanical properties ofthe fabric, including fiber modification and fabric finishing.This paper modified aramid fiber by grafting process on carbon nanotubes, whichenhanced the tensile strength of single fibers and surfactivity; prepared a new type ofpolydispersity shear thickening (RLCP) fluid of graphene oxide/silica-polyethyleneglycol for aramid plain fabric by after-finishing, study on the properties of steady-state anddynamic rheological of RLCP system, speculated thicken mechanism of RLCPpolydispersity shear thickening system; compared single fiber mechanical properties anddynamic and quasi static puncture resistance of RLCP-Kevlar plain weave fabric andtraditional STF-Kevlar plain weave fabric, investigated the tolerance under extremeenvironments of two kinds of fabrics. Considering the defects of wet resistance of RLCPfluid, developed the technology of nylon coated aramid fabric. Systematic assesseddynamic and quasi static puncture resistance under NIJ standard tools of Nylon6,6-Kevlarfabric and Nylon6,12-Kevlar fabric, then compared with experiment results ofRLCP-Kevlar.1. A novel and efficient method was developed for surface-modification of Kevlarfibres by grafting carbon nanotubes (MWCNTs). Kevlar fibres were immersed in a solutionmixed with Hexamethylene diisocyanate,1,4-diazabi-cyclo [2,2,2] octane (DABCO) andtoluene to introduce pendant amine groups, and then the COCl-functionalized carbonnanotubes dispersed in NMP solution were chemically grafted to the surface of modifiedfibres under ultrasonic condition.7.2wt%MWCNTs was observed on the surface andinterior of the fibers. The mean value of tensile strength of Kevlar fibre was improved by12%compared with original one. The interlaminar shear strength (ILSS) of thefibre-reinforced bismaleimides composite was measured. The results show that the ILSS of the MWCNTs-grafted Kevlar sample can be increased by30%.2. Prepared graphene/SiO2-PEG polydispersity shear thickening system which bothhave high initial viscosity and high fluidity using space steric effect of oxide graphenenanoplatelets. The addition of trace multi-walled carbon nanotubes can significantlyincrease the maximum apparent viscosity of the thickened system. According to thesteady-state and dynamic rheological experiments, inferred thickening mechanism ofgraphene/SiO2-PEG polydispersity shear thickening system is: graphene nanoplateletsdivided silica particles into large amount of micro-structures like unit cell. Themicro-structures limit the movement of the spherical particles resulting in the increase incritical shear rate. The effect of carbon nanotubes is conection of independentmicrostructures via hydrogen bonding.“Microstructure cluster” effect instead of “particlecluster” effect become thickening mechanism of Graphene/SiO2–PEG polydispersesystem. Combining with the result of relationship between the energy consumption and thestress and strain, deduced the relationship between energy consumption and the strain ofRLCP fluid in the process of shear stress is (A, n are constant).3. Compared fabrics treated with RLCP fluid and general STF fluid via Single fibertest、 quasi-static and dynamic impact test、 UV aging test、 salt fog aging test: Enhancedadhesion of RLCP fluid made its tensile strength of single fiber is50%higher than STFprocessing fiber. RLCP-Kevlar fabric significantly outperforms the STF-Kevlar fabric indynamic test. Under4J impact energy the penetrated layers of paper reduces2layer in thesame areal density, but the advantage is not obvious in quasi-static test;4. Salt fog aging is more destructive than ultraviolet aging to RLCP-Kevlar fabric andSTF-Kevlar fabric. After salt fog aging, puncture depth reductions of more than100%inthe dynamic penetration test of two fabrics, while after UV aging test only fell by less than50%.5. A coating of Nylon6,6or6,12was used to improve the penetration resistance ofaramid fabric that would be potentially useful in the manufacture of flexible body armoragainst spike/knife threats. Quasi-static test results for the spike penetrator showed a77%and86%improvement in the puncture resistance of Nylon6,6and Nylon6,12coatedUHMWPE (respectively) over a neat fabric target of equivalent areal densities. Dynamic impact testing demonstrated dramatic improvement in the puncture resistance of nyloncoated fabrics while only a slight improvement in stab resistance was observed comparingsamples with equivalent areal densities. Photography of ruptured areas after quasi-statictesting revealed limited fiber motion or fiber stretching with no evidence of fiber pullout fornylon coated fabric samples in contrast to neat fabric. This suggests that there was asignificant increase in energy absorption by nylon coated fabrics at impact.6. Quasi-static and dynamic impact test results show: compared with RLCP-Kevlarfabric, Nylon-Kevlar fabric protective effect of P1type cutting tools is significantly lower,but in salt fog environment, retention of property is obviously better than that of RLCP-Kevlar fabric.