Transcrystallinity in Surface Modified Aramid Fiber Reinforced Nylon 66 Composites

Abstract

Aramid (kevlar‐49) fibers were surface treated by two different methods to induce roughness and then used to produce unidirectional nylon 66 based composites. The transcrystallinity generated around the treated fibers was characterized by SEM and polarized light microscopy and compared with the regular transcrystalline layers produced by pristine aramid under the same processing conditions. The treated fibers generated a double transcrystalline layer, the inner layer being thinner and more compact than the regular nylon 66 transcrystallinity. In addition, mechanical testing of the composites showed the longitudinal Young's modulus of the treated fiber composites to be significantly higher than the control in a wide range of fiber volume fractions.Polarized light microscopy picture of double transcrystallinity in Br/NH3 treated aramid fiber reinforced nylon 66.magnified imagePolarized light microscopy picture of double transcrystallinity in Br/NH3 treated aramid fiber reinforced nylon 66.

Structure–property relationships in isotactic polypropylene/multi-walled carbon nanotubes nanocomposites

“…This structure begins to develop on the walls of CNT before the most common supermolecular structure of spheroulites (T c,1 peak), which is observed thereupon during the cooling. The trans-crystallinity structure has been reported in various conventional polymer/fiber composites [38,39] and recently in nanocomposites. In particular, in Refs.…”

Effect of discontinuous long polyimide fiber on mechanical properties, fracture morphology, and crystallization behaviors of polyamide-6 matrix composites

“…A number of studies indicated that many of the thermoplastic composites based on semicrystalline polymeric matrices were observed to present some transcrystalline layers on the fiber surfaces due to the fact that the reinforcing fibers act as giant nucleation sites enhancing the nucleation and crystallization rates of polymeric matrices. 59 –61 Considering of a high nucleating ability of long PI fiber for the crystallization of PA6 matrix, the formation of transcrystalline layers is anticipated within the PA6/PI fiber composites. An observation of polarizing optical microscopy was performed to investigate the transcrystallinity of PA6/PI fiber composites.…”

Improvement of the Interfacial Adhesion Between Fiber and Matrix

“…Feldman [11] treated Kevlar 49 fiber surface with saturated aqueous bromine solution for 15 s then treated with 25% NH3 solution for 30 s. Scanning electron microscope images illustrated etched formation on fiber surface which tend to increase fiber surface roughness. Results show decrease in tensile strength and Young modulus in comparison with untreated Kevlar fiber reinforced composite.…”