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Polymers are often blended to create compounds with new or enhanced properties in order to compensate for an individual polymer's weakness or lack of inherent properties. In the field of polymer foaming, polymer blends are also used to generate fine-cell structures via heterogeneous nucleation. Recently, an interest in physical blowing agents, such CO2 and N2, has increased because of their low impact on the environment. It has thus become additionally important to pursue research on the foaming of polymer blends employing these particular physical blowing agents in an effort to keep up with the demand for environmentally friendly products. In this study, thermoplastic polyolefin (TPO) blends were prepared with polypropylene (PP) and a metallocene-based polyolefin elastomer (POE) using twin-screw extruders and a batch mixer.

This research presents a fundamental study of the interaction between chemically modified wood fibers and high density polyethylene (HDPE) to develop wood fiber/HDPE composites with satisfactory performance. This paper investigates the effects of the interfacial properties of HDPE and wood fibers on the rheological properties and foaming behavior of the composites. The surface characteristics of wood fiber were modified by treating the fiber with trialkoxy silane. The effectiveness of chemical surface modifications of wood fiber was characterized using FT-IR. The effect of the interfacial interaction on the foaming behavior was studied via extrusion foaming with a physical blowing agent. The rheological property of the composites with a different interfacial structure were also evaluated by using dynamic oscillatory rheometer.

This research investigated the intercalation and exfoliation behaviors of polypropylene (PP)/clay nanocomposites. Different samples were prepared by melt blending with various combinations of PP, maleic anhydride grafted PP (PP-g-MAn), and nano-clay. The effects of key processing variables such as the mixing time, mixing temperature and screw rpm were investigated from the thermodynamic and kinetic point of view. The morphology was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Effective strategies for controlling intercalation and exfoliation of PP/clay nanocomposites are proposed and evaluated.

This research investigates the foaming behaviors of polypropylene (PP) and PP/clay nanocomposites blown with supercritical CO2. In this context, special attention is paid to the effects of varied clay content on the foamed structures. First, a master batch of nanocomposites with 1% and 5% clay are prepared; the nanocomposites are then characterized using X-Ray Diffraction (XRD) prior to and after their subjection to the foaming process. Subsequently, foaming experiments are conducted using supercritical CO2 as a blowing agent. The cell nucleation and expansion behaviors of the PP-based nanocomposite foams are studied at various clay contents and die temperatures. Finally, the effects of the clay content on the cell morphology, the cell density, and the expansion ratio of the PP/clay nanocomposite foams are identified.