The material model for a Multi-Walled Carbon Nanotube (MWCNT) reinforced poly-vinyl-ester-epoxy matrix composite material (carbon nanotube reinforced composite mats, in the following) developed in our recent work [1], has been used in the present work within a transient non-linear dynamics analysis to carry out design optimization of a hybrid polymer-matrix composite armor for the ballistic performance with respect to the impact by a Fragment Simulating Projectile (FSP). The armor is constructed from E-glass continuous-fiber poly-vinyl-ester-epoxy matrix composite laminas interlaced with the carbon nanotube reinforced composite mats. Different designs of the hybrid armor are obtained by varying the location and the thickness of the carbon nanotube reinforced composite mats. The results obtained indicate that at a fixed thickness of the armor, both the position and the thickness of the carbon nanotube reinforced composite mats affect the

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With society focusing more and more on environmental issues, the recycling of materials of all types has become an important concern. As a result of previous processing and usage, the properties of recycled materials are often significantly inferior when compared to their unrecycled counterparts. Recycled polymeric materials, for example, have lowered molecular weights caused by previous thermal and/or shear histories. Thus, the scope of application for recycled materials has traditionally been very limited. With the aid of a new processing concept known as vibration-assisted injection molding (VAIM), the mechanical properties of products containing recycled polymeric materials could be dramatically improved. The current paper presents the results of an initial experimental investigation into the application of VAIM for recycled polystyrene (Recycled-PS) products. A number of recycled/new material blends were studied, and in all cases significant product mechanical property enhancements were realized through the use of VAIM. It was concluded that VAIM molded products containing as much as 50% low-grade recycled material could be made stronger than products made using traditional molding with 100% new polymer. Detailed results are presented in the paper, along with some insight into the likely fundamental mechanism underlying the utility of the VAIM technique.

Due to the micro-scale dimensions in the microinjection molding proces, it is difficult to inspect the part quality without using costly microscopic observation methods. To address this issue, a suitable process monitoring method such as cavity pressure monitoring can be employed to detect any process deviation that causes defects in part quality. The objective of this study is to investigate how cavity pressure responds to different molding conditions that lead to varying part quality of a molded hollow cap.

The focus of this study is on the ability of amorphous polymers to replicate micron and sub-micron features when molded at an elevated mold temperature without externally applied pressure. Molding was performed using three different types of amorphous polymers: cyclo-olefin copolymer (COC), polystyrene (PS) and poly (methyl methacrylate) (PMMA) on a silicon mold containing surface features as small as 700 nm in depth and aspect ratios ranging from 5 to 0.02. In this study, processing temperatures were selected in order to match the viscosity for all polymers used. Polymer viscosity was characterized via cone and plate rheometry and wettability was characterized via contact angle analysis to quantify interfacial effects. Feature replication was assessed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to compare the molded feature depth ratio. It was observed that for the features with an aspect ratio (depth/width) bigger than 2 the depth ratio of the molded parts decreases. PS shows the best replication because of high wettability behavior. PMMA shows the intermediate replication because of dipole-dipole interaction and its lower diffusion coefficient than PS. COC has the worse replication especially in low aspect ratio because of sticking to the silicon oxide layer. PS has the best surface roughness among all polymers.