Mechanical Interlocking between Porous Electrospun Polystyrene Fibers and an Epoxy Matrix

Abstract

An epoxy matrix filled with nonwoven mats of porous polystyrene (PS) fibers processed by an electrospinning was compression tested at quasi-static (1 × 10 −3 s −1 ) and high strain (315 s −1 ) rates. The electrospun PS fibers with a diameter between 6 and 9 μm, accommodated spherical pores on the surface with the sizes ranging from 0.1 to 0.2 μm. The filling epoxy matrix with 0.2 wt % PS fibers increased the compressive elastic modulus and compressive strength over those of neat epoxy resin. The microscopic observations indicated that the surface pores facilitated the resin intrusions into the fiber, enhancing the interlocking between resin and fibers, and increased the deformation energy expenditure of the polymer matrix. KEYWORDS: electrospinning, epoxy matrix, composite, compression, high strain rate T he fields of application for fiber-reinforced polymer composites (FRPCs) over the last few decades have widened in aerospace, defense, transportation, and automotive industries. 1 The strength of FRPCs is derived to a large extent from the inclusion of 10−100 μm size strong fibers or fiber networks into complaint polymer matrices. The effectiveness of fibers in enhancing the mechanical properties of FRPCs is also affected by the interface between fibers and the matrix. The recent rapid progress and pace taken in the field of nanotechnology has resulted in novel techniques of processing submicron and nanometer size fibers of a relatively high surface area. 2 The high fiber surface area associated with small fiber size causes nanometer-scale interlocking between the fiber and the matrix, enhancing the load transfer from the fiber to the matrix, which requires additional energy expenditure to deform the polymer matrix. 3−7 Ultrathin fibers may conveniently be processed by electrospinning. 8 In electrospinning, a charged jet is ejected from a droplet of a solution through grounded collector under a high electrical field when the electrical force overcomes the surface tension of the droplet. By altering the electrospinning parameters including the spinning atmosphere, 9 solvent composition, 10 and calcination, 11 randomly oriented mechanically integrated nonwoven fibrous polymer mats with tunable fiber sizes and surfaces, internal porosities, and pore sizes are processed.There has recently been a rise in interest in exploring electrospun fibrous mats as reinforcement in FRPCs as these mats have the potentials of efficient stress transfer to matrix, high strength to weight ratio, and excellent multifunctional properties. The significant improvement in the mechanical response of FRPCs was also attributed to the nature of the interfacial bonding between nanofibers and polymeric matrices. 12−15 The cross-linked polystyrene-co-glycidyl methacrylate P(St-co-GMA)/ethylenediamine (EDA) nanofiber filled epoxy matrix showed 2.5 times higher storage modulus than P(St-co-GMA) nanofiber filled epoxy matrix, proving the substantial effect of cross-linking between the nanofibers and polymer matrix on the mechanical pro...

Synergistically enhanced ultraviolet aging resistance and interfacial adhesion of poly (p‐phenylene benzobisoxazole) fiber with soluble naphthalimide sizing

“…The surface morphologies and roughness of pristine PBO and NDI‐PBO fiber were further observed by AFM images as shown in Figure 4. In contrast to the relative smooth surface of pristine PBO fibers (Ra = 24 nm), the roughness was gradually increased to 35, 47, and 65 nm for 1.5%NDI‐PBO, 2.0%NDI‐PBO, and 2.5%NDI‐PBO fiber, which was helpful for generating of stronger interlocking and chemical interaction in interface region of PBO fiber composites [24].…”

Utilization of Electrospun Polystyrene Membranes as a Preliminary Step for Rapid Diagnosis

“…The inset presents a higher‐magnification image showing the surface feature of the constituent fibers. PS fibers exhibit a porous and rough surface morphology most probably due to phase separation between DMF and moisture in air associated with rapid solvent evaporation from the spinning jet …”

Potential of Electrospun Nanofibers for Biomedical and Dental Applications

“…Electrospun polyacrylonitrile and polyamide containing nano-diamonds have shown to increase the mechanical properties of polymeric composites when fused with each other [91] that can be used as a means to reinforce dental composites. Similarly, incorporation of electrospun polystyrene fibers to epoxy has also been shown to improve the mechanical properties of the polymers [92]. Electrospun carbon nanotubes and nylon fibers have been successfully used to reinforce resin composites [93].…”