Polymer nanocomposite foams

Poly (lactic acid) foaming

Enhanced acoustic damping in flexible polyurethane foams filled with carbon nanotubes

Extruded PLA/clay nanocomposite foams blown with supercritical CO2

Development of high void fraction polylactide composite foams using injection molding: Crystallization and foaming behaviors

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The microcellular nanocomposite processing was performed on an injection-molding machine equipped with a commercially available supercritical fluid (SCF) system. The molded samples produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscope (SEM) analyses. Molding conditions and nano-clays have been found to have profound effects on the cell structures and mechanical properties of polyamide-6 (PA-6) base resin and nanocomposite samples. The results show that microcellular nanocomposite samples exhibit smaller cell size and uniform cell distribution as well as higher tensile strength compared to the corresponding base PA-6 microcellular samples. Among the molding parameters studied, shot size has the most significant effect on cell size, cell density, and tensile strength. Fractographic study reveals evidence of different modes of failure and different regions of fractured structure depending on the molding conditions. Polym. Eng. Sci. 44:673–686, 2004. © 2004 Society of Plastics Engineers.

https://www.fpl.fs.fed.us/documnts/pdf2004/fpl_2004_yuan001.pdf

Study of injection molded microcellular polyamide-6 nanocomposites

This paper presents the effects of process conditions and nano-clay fillers on the microstructure (namely, size, density, and distribution of microcells within samples) and the resulting mechanical properties of microcellular injection molded polyamide-6 (PA-6) nanocomposite and its neat-resin counterpart. Based on the design of experiments (DOE) matrices, samples were molded at various supercritical fluid (SCF) levels, melt temperatures, shot sizes, melt plastication pressures (MPP), and injection speeds. These samples were then subjected to scanning electron microscope (SEM) analysis, tensile testing, and impact testing. For both materials, the microstructure and the mechanical properties of the molded samples were found to be dependent on the process conditions and presence of nano-clay, which could serve as microcell nucleating agent. At higher weight reductions, the nanocomposite samples exhibit much smaller microcells and higher cell densities than those obtained in the neat-resin samples. The SEM micrographs reveal noticeable differences in microcell surface roughness between the nanocomposite and the neat resin. A statistical design analysis was used to identify the optimal process conditions that would result in desirable cell size and density and, thus, better mechanical properties. For example, the highest tensile strengths have been observed at the highest levels of shot size, MPP, injection speed, and SCF level, and at the lowest level of melt temperature.

Effects of nano-fillers and process conditions on the microstructure and mechanical properties of microcellular injection molded polyamide nanocomposites

In this study, a cellulose-fiber-reinforced Polyamide-6 (PA-6) composite, a hybrid composite (PA6/cellulose/Wollastonite), and the neat PA-6 resin were injection molded into ASTM test–bar samples with conventional and microcellular injection molding. The impact and tensile strengths of molded samples were measured and the Scanning Electron Microscopy (SEM) images were taken at the fracture surfaces. The effects of filler systems and the

https://www.fpl.fs.fed.us/documnts/pdf2003/winat03a.pdf

Applications of Polyamide/Cellulose Fiber/Wollastonite Composites for Microcellular Injection Molding

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical Analysis (DMA), and X-ray Diffraction (XRD) analysis. Effects of processing conditions on the mechanical properties and microstructures have been studied. The results show that the supercritical fluid (N2 )h elps to further exfoliate and uniformly disperse the nano-clays in the matrix during the course of molding process. Compared to the corresponding base polyamide microcellular parts, the microcellular nanocomposites exhibit better cell structures and cell distributions as well as better mechanical properties.

https://www.fpl.fs.fed.us/documnts/pdf2003/yuan03a.pdf

Rick Spindler

Papers

Study of injection molded microcellular polyamide-6 nanocomposites

Effects of nano-fillers and process conditions on the microstructure and mechanical properties of microcellular injection molded polyamide nanocomposites

Applications of Polyamide/Cellulose Fiber/Wollastonite Composites for Microcellular Injection Molding

Microcellular nanocomposite injection molding process