Enzyme-Mediated Grafting Of AGE To Kevlar Fiber Using Horseradish Peroxidase

Kevlar fiber exhibits an excellent thermal stability, as well as superior tensile strength and modulus.And owing to its high tenacity, Kevlar fiber is widely used in manufacture of advanced composites. It is well known that themechanicalproperties of fiber reinforced composites depend on the effectiveness of the interactions between the fiber and the matrix, however, the adhesion between Kevlar fiber and most matrices is poor as a result of the high crystallinity resulting in a chemical inertness and smooth surface of the fiber. Therefore,surface modification is essential to enhance its reinforcing effect.Enzymatic technology has attracted much attention in recent years owning to its advantages such as milder reaction conditions and highly specific nondestructive transformations targeted to surfaces. The application of enzymes to modify the surface of natural polymer, such as wool has been widely researched by industry.However, enzymatic modification of synthetic polymer is quite a new technology, only a few works has been done on this subject.In order to improve the interfacial adhesion between Kevlar fiber and resin matrix, Kevlar fiberand diglycidyl ether of bisphenol A type epoxy (EP) resin were chosen as reinforced phase and resin matrix, respectively, to study the surface modification of Kevlar fiber,CF/EP composites and hot water aging experiment in this thesis.The research is the reaction of the high-performance fiber Kevlar grafted allyl glycidylether(AGE),in the process,we use the horseradish peroxidase(HRP) as the catalyst, H2O2as the oxidant of free radicals initiator system.The grafted fiber was made to do the following performance tests:element analysis, infrared, SEM, XRD, TG, Contact Angle, tensile strength, be pull out by monofilament. We can see from the infrared spectra, the peak of the grafted fiber in1510cm-1and1250cm-1increase apparently, it shows that the AGE has been grafted.There are new peaks in760cm-1and690cm-1, proved the grafted position is in benzene rings; from the SEM,we know the surface roughness of the grafted fiber increase apparently; the test result of TG showed the Yc increased regularly, both of them prove the succession of the grafting, moreover, the fiber also has the good thermal stability after grafted; the contact angle has been reduced from80to60, shows the content of fiber surface polar groups has been increased, enhance the wettability significantly; the monofilament pull out test shows after grafting the adhesion between the Kevlar fiber and the epoxide resin matrix has been improved.In Boiled water, virgin and grafted Kevlar fiber were carried out hot water aging experiments, and measured water absorption, degree of crystallinity and tensile strength. We analysised chemical structure changes in the water absorption process by FTIR, observed the fiber surface morphology changes by SEM and discussed the water absorbing mechanism.