Vacuum-assisted resin transfer molding (VARTM) process is one of the liquid composite molding (LCM) processes aimed at producing high-quality composite parts. The void content and fiber volume fraction of a VARTM part can be affected by many parameters and is critical to the mechanical properties and the quality of the part. In this paper, a series of experiments were conducted with a heated dual pressure control VARTM setup for investigating the effects of vacuum pressure, inlet pressure, and mold temperature on the void content and fiber volume fraction of polyester/E-glass fiber composite. It was found that stronger vacuum and higher mold temperature can better control and increase the fiber volume fraction; however, such a combination of strong vacuum and high mold temperature may also require a reduced inlet pressure for minimizing the void content. The need of pressure reduction can be explained with the compatibility between Darcy's flow and capillary flow in the fiber preform and can be calculated based on the room temperature VARTM results. The experimental results suggest that high mold temperature, high vacuum, and appropriately reduced inlet pressure can produce a VARTM part with high fiber volume fraction and low void content.

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Paraffin waxes are commonly used phase change materials for energy storage. However, the low thermal conductivity of the paraffin wax can limit the energy charging and discharging rate. In this research, a new nano-enhanced paraffin wax with dispersed conductive nanoparticles is tested for the thermal conductivity enhancement. A notable increase in the thermal conductivity has been measured from the carbon nanofiber enhanced paraffin wax.

A major weakness of laminated composite is the susceptibility to delamination. Having a good understanding of composite material resistance to interlaminar fracture and fatigue is important to establish design allowable and damage tolerance guidelines for structures. Previously reported static delamination test results have shown that there is about 100% improvement in the critical energy release rates GIC by adding 1wt% carbon nanofibers (CNFs) to glass fiber/polyester laminates. Hence, this paper presents the fatigue resistance characterization of glass fiber/polyester composite modified with CNFs. CNFs were surfactant treated and dispersed in the thermoset polyester. The matrix with suspended CNFs was infused into glass fiber preform through vacuum assisted resin transfer molding (VARTM). The crack development of the laminated specimens during fatigue delamination testing was recorded along with the displacement and cyclic load applied. The fatigue measurement results for the traditional composite laminate and the one modified with CNFs is compared to understand the role of CNFs in the fatigue delamination process. It was found that CNFs significantly improve the low cycle fatigue performance, but it provides minimal improvement to the high cycle fatigue performance.