Simulation of the Vacuum Assisted Resin Transfer Molding Process
Abstract : A process model that includes the coupled phenomenon of resin flow and preform compaction was developed and used to simulate resin infiltration of a fibrous preform using the vacuum-assisted resin transfer molding (VARTM) process. Flow of resin through the distribution medium and preform were modeled as flow through porous media. The finite element/control volume method was used to calculate the infiltrating fluid pressure distribution and track the progression of the flow front. The simulation results were compared with data obtained during infiltration of a carbon fiber preform with an epoxy resin. The parameters measured include the flow front location, resin pressure, and preform thickness change. With accurate inputs, the flow front locations and resin pressure distribution can be accurately predicted. The predicted transverse displacements do not agree well with the experimental measurements. The reasons for the differences are discussed, and further investigations are recommended to develop a more accurate compaction model.
Flow and Compaction During the Vacuum Assisted Resin Transfer Molding Process
The flow of an epoxy resin and compaction behavior of carbon fiber preform during vacuum- assisted resin transfer molding (VARTM) infiltration was measured using an instrumented tool. Composite panels were fabricated by the VARTM process using SAERTEX(R)2 multi-axial non- crimp carbon fiber fabric and the A.T.A.R.D. SI-ZG-5A epoxy resin. Resin pressure and preform thickness variation was measured during infiltration. The effects of the resin on the compaction behavior of the preform were measured. The local preform compaction during the infiltration is a combination of wetting and spring-back deformations. Flow front position computed by the 3DINFIL model was compared with the experimental data.
Mucoadhesive Nanoparticles for Drug Delivery to the Anterior Eye
While the use of topical drops for the delivery of drugs to the anterior of the eye is well accepted, it is far from efficient with as little as 5% of the drug instilled on the eye actually reaching the target tissue. The ability to prolong the residence time on the eye is desirable. Based on the acceptability of 2-hydroxyethyl methacrylate based polymers in contact lens applications, the current work focuses on the development of a poly(2-hydroxyethyl methacrylate (HEMA)) nanoparticle system. The particles were modified to allow for degradation and to permit mucoadhesion. Size and morphological analysis of the final polymer products showed that nano-sized, spherical particles were produced. FTIR spectra demonstrated that the nanoparticles comprised poly(HEMA) and that 3-(acrylamido)phenylboronic acid (3AAPBA), as a mucoadhesive, was successfully incorporated. Degradation of nanoparticles containing N,N′-bis(acryloyl)cystamine (BAC) after incubation with DL-dithiothreitol (DTT) was confirmed by a decrease in turbidity and through transmission electron microscopy (TEM). Nanoparticle mucoadhesion was shown through an in-vitro zeta potential analysis.