Surface Modification Of PIPD Fibers For Improving Mechanical And Interfacial Performance

PIPD fiber or M5 is high performance fiber which have an outstanding properties such as high tensile strength and energy absorption that promote its application at weight sensitive applications.The PIPD fiber have an exceptional compressive properties that expand its usage at structural applications in fields such as aerospace,marine,automotive and construction industries.However,the smooth and inert surface of the fiber caused a lack of the interfacial adhesion with the matrix.For that reason plenty of surface modification methods has been suggested to overcome this shortcoming by improving the interfacial and mechanical properties.In this work,a surface modification methods has been proposed by grafting organic and inorganic nanomaterials in less severe conditions that result great enhancement of the mechanical and interfacial performance with the conservation of the initial tensile strength of the PIPD fiber.The multi-walled carbon nanotubes were introduced into the PIPD fiber after surface functionalization using the nitric acid to increase the PIPD performance.The effect of the acid treatment and the grafting method has been investigated.The evaluation of the fiber properties after the acid treatment in different conditions of concentration,time and temperature result the optimum condition of the surface functionalization without damaging the fiber.Moreover,grafting the multi-walled carbon nanotubes into the PIPD fiber surface enhanced the contact area with the resin and mechanical interlocking which improved the interfacial shear strength(IFSS)of the PIPD/ epoxy from 25.13 MPa to 40.63 MPa with increase amplitude of 62%.The surface wettability of MWCNTs-PIPD fiber showed a great elevation seeing that the surface energy of the grafted fibers was increased from 34.23 mJ/m2 to 52.04 mJ/m2 or by 52% of enhancement.Meanwhile,the degradation of the tensile strength has been controlled to be less than 3%.The introduction of two-dimensional inorganic Nano-sheets which is MXene(Ti3C2(OH)2)into the PIPD fiber via covalent bong grafting method after surface functionalization of both materials was examined.The presence of this nanosheets on the PIPD fiber surface improved the interfacial and the mechanical performance.In fact,the adhesion between the fiber and the epoxy resin was improved.Comparing the untreated fibers the IFSS was increased from 25.13 MPa to 40.54% or by 62%,meanwhile the retention of the tensile strength was less then 5%.Moreover,the surface wettability was greatly improved by 71%,and the ultraviolet and the hydrothermal aging resistance of PIPD grafted MXene fibers was boosted by 33% and 25% respectively.Growing CuO nanowires decorated with silver nanoparticles using the poly-dopamine as reduction layer on the PIPD fiber was presented.The application of this coating layer on the fiber surface provide a great protection to the PIPD fiber against cruel conditions such ultraviolet radiation and hydrothermal medium.Furthermore,a great mechanical and interfacial performance of the fiber was noticed by the increase of the IFSS between the fiber and the epoxy resin to 72% and the tensile strength of a single filament by 13%.Additionally,the presence of the silver nanoparticles on the fiber surface yields an antimicrobial property to the PIPD fiber against gram negative bacteria E.Coli.