Surface modification of Kevlar by grafting carbon nanotubes

Abstract

A novel and efficient method was developed for surface-modification of Kevlar fibers by multi-wall carbon nanotubes (MWCNTs). Kevlar fibers were immersed in a solution mixed with Hexamethylene diisocyanate, 1,4-diazabi-cyclo [2,2,2] octane (DABCO), and toluene to introduce pendant amine groups before the COCl-functionalized carbon nanotubes were chemically grafted onto the surface of modified fibers under ultrasonic condition. The characterization of resulting fiber involved in SEM, infrared spectroscopy, and tensile measurement. Results indicated over 20% of the fiber surface were coated by MWCNTs even after washing, which indicated a good adhesion. Furthermore, the mean value of tensile strength of Kevlar fiber was improved by 12% compared with original one. And the interlaminar shear strength (ILSS) of the fiber-reinforced bismaleimides composite was increased by 30%.

Influence of diaminobenzoyl‐functionalized multiwalled carbon nanotubes on the nonisothermal curing kinetics, dynamic mechanical properties, and thermal conductivity of epoxy–anhydride composites

“…The XPS survey spectra of the AS‐MWCNTs and DA‐MWCNTs are displayed in Figure . The major peaks of the C1s and O1s photoelectrons were observed in all of the survey spectra at about 285 and 534 eV, respectively . This result revealed that the surface of the unmodified MWCNTs had a small amount of oxygen‐containing functionalities, which were unintentionally produced from carbon impurities during the purification of the as‐produced MWCNTs, for example, during the use of strong oxidizing agents, such as concentrated acids .…”

Effect and origin of the structure of hyperbranched polysiloxane on the surface and integrated performances of grafted Kevlar fibers

“…Cheng's group found that the tensile properties of modified fibers treated with rare earth element were almost similar as those of original fibers, but those of fibers treated with epoxy chloropropane decreased by about 5% [27]. Therefore, how to effectively conquer the disadvantages on the basis of maintaining the outstanding performance of original PPTA fibers is still a challenge [28], that is, designing and synthesizing new grafting materials with unique structure and properties become the key to overcome the two disadvantages of PPTA fibers. Polysiloxane is famous for its excellent UV resistance because the attractive bonding energy of -Si-O-bond (446 kJ/mol) is much higher than the UV irradiation power (314-419 kJ/mol) [29], so polysiloxane may be the right material for improving the UV resistance of PPTA fibers.…”

“…Tensile properties, thermal stability and flame retardancy As described in the introduction part that how to effectively overcome the disadvantages on the basis of maintaining outstanding performances of original PPTA fibers is still a challenge [28]. As the mechanical, thermal and flame-retarding properties are the most important and outstanding properties for KF fibers [50], so it is important to discuss them for evaluating the effectiveness of the modification method developed herein.…”

“…Typically, chemical etching [17,18], chemical grafting [19][20][21], plasma modification [22,23] and ray irradiation [24] have been done to modify fibers. Among them, the chemical grafting exhibits big potential of getting expected performance by adjusting the sorts of the grafting materials over a wide range.…”

Enhancing the dispersion and adhesion of short aramid fibers in bromo‐isobutylene‐isoprene rubber using maleated polybutadiene resin via co‐vulcanization with 4, 4’ bis(maleimido)diphenylmethane

“…As a result, the interaction between the aramid fiber and the polymer matrix is generally weak. Therefore, various chemical and physical methods like acid treatments , bromination , polymer coating , polymer grafting , carbon nanotube grafting , heat treatments , plasma treatment , and so on have been practiced on the aramid fiber surface to improve its adhesion with the rubber matrix. In addition to the above‐mentioned methods, the use of coupling agents was also been employed to enhance the fiber‐matrix adhesion.…”