Solid State Processing
2. Pellet Forming
U.S. Patent 8,557,160 (October 15, 2013), “Direct Forming of Non-Textile Fabric Elements from Plastic Pellets,” Gregory W. O'Connor, and James S. Gregg (Samsonite IP Holdings S.a.r.l., Luxembourg, Luxemborg).
Traditional plastic forming such as injection molding, blow molding, and extrusion involves melting and shaping the melt, requiring complex equipment and precise control. Forming processes can be simplified by solid phase forming using ultra high molecular weight polymers. This process produces articles having high heat distortion temperatures as well as porous layers with integrally formed skins. However, solid phase forming has not been used to form connected separately formed units. O'Connor and Gregg formed a non-textile fabric by coining single polymeric pellets into an individual element in a single forming step which can be simultaneously linked to form a continuous structure. This includes positioning a pellet in a mold cavity, and forcing the pellet into the shape of the mold cavity. The forcing step preferably uses an energy and speed where the pellet superplastically deforms to fill the mold cavity. This process is best carried out with four mutually interengaging rollers.
1. Solid State Shear Crystallization
U.S. Patent 8,410,245 (April 2, 2013),”Enhancing the
Physical Properties of Semi-Crystalline Polymers via Solid-State Shear
Pulverization,” John M. Torkelson, Cynthia Pierre, and Amanda Flores
(Northwestern University, Evanston, Ilinois, USA).
Solid-state processing methods, such as ball milling, mechanical alloying, pan milling, and solid-state shear pulverization, have recently been used to blend and form nanocomposites, leading in some cases to materials that cannot be produced via conventional processing. While much work involving solid-state processing has focused on heterogeneous mixtures, relatively little has been done on homopolymers. Torkelson, Pierre and Flores showed that solid-state shear pulverization using a modified twin screw extruder with cooling zones increases isothermal crystallization rates 27% for polypropylene, 85% for low density polyethylene and 92% for poly(butylene terephthlate). The Young's modulus of polycaprolactone increased by 65% after pulverization, and comparable or lesser changes were observed in the other polymers.
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Roger D. Corneliussen
Maro Polymer Links
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Copyright 2013 by Roger D. Corneliussen.
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** Date of latest addition; date of first entry is 4/12/2013.