By Jan H. Schut
New technologies at ANTEC 2013, the Society of Plastics Engineers (SPE) Annual Technical Conference in Cincinnati, OH, April 21-24 include the first “fractal structuring” of co-injected polymers not just into layers, but into geometric patterns of almost unlimited complexity. The technology comes from the Technical University of Eindhoven in the Netherlands (www.mate.tue.nl) and is the first 3-D structuring of any molded part. A new rheometer presented by Clemson University (www.clemson.edu) also creates and tests coex 3-D patterns for extrusion, using chaotic advection with independently turning stir rods–the only other known 3-D structuring.
Compounding news includes the first ultrasonic twin-screw extruder from the University of Akron in Ohio (www.uakron.edu), allowing comparison to ultrasonic single-screw extrusion and ultrasonic dies. South China University of Technology in Guangzhou (en.scut.edu.cn) reports a new co-rotating triple-screw extruder with vibrating middle screw, built by Guangzhou POTOP Experimental Analysis Instrument Co. Ltd. in China (www.potop-lab.com), a spin-off of the university, represented by Harden Industries Ltd., Hong Kong (www.hardenmachinery.com).
New materials include shape memory polymers with a range of temperature triggers and new biopolymer blends with polybutylene succinate (PBS), an emerging biopolyester. As five ventures around the world build plants to make bio succinic acid monomer for PBS, new PBS blends are timely (see this blog April 26, 2012). In biomaterials, soy and bone meal polymers show unusual benefits in pots and films for agriculture—as they degrade, they feed plants.
The letter and number in brackets after the title of a paper or poster indicate the day of the week and session when that paper was given, i.e. [T12] was session 12 on Tuesday, April 23. For people who didn’t attend ANTEC, all papers are available on CD from the SPE (www.4spe.org) for $200 to members and $250 to non-members. Student posters aren’t on the CD unless they were also presentations, so referenced posters not on CD are linked below.
‘STRUCTURING’ AND OTHER INJECTION MOLDING NEWS
Fractal Structuring in Polymer Processing [Plenary Speaker] by Han Meijer, professor of mechanical engineering & materials technology at Eindhoven Technical University in the Netherlands (www.mate.tue.nl). Flat tool halves with serpentine flow paths on the parting surfaces, similar to a static mixer, co-inject polymers into complex internal patterns. Patterns are made by cutting, rotating and combining horizontal and vertical stratified elements formed between the flat mold halves. The patterns are then preserved without compression in special runners into the mold. Meijer developed and verified the tooling using two colors of epoxy at room temperature before molding them with thermoplastics.
Fractal structuring can make repeatable 3-D patterns for the first time, including layers perpendicular to a part surface and “tree” shapes with trunk, branches, twigs, and leaves. “Extension to multiple trees with many branches in a forest is potentially possible, but here only making of one tree with 65,000 leaves is demonstrated,” Meijer explains modestly, adding that “compression of stratified structures is to be avoided.” The technology is also being developed for coextrusion, working with ETH Zurich University in Switzerland (www.ethz.ch).
2 PC-Recu-Module for Energy Recovery with Hydraulically Driven Injection Molding Machines [W11] by Marco Lenzen, Universitaet Duisburg-Essen in Germany (www.uni-due.de). A new “2 Plates Clamping Recuperation” hydraulic module is designed and simulated with a drive, three accumulators, valves, and controls. It’s expected to recover up to 50% of the energy typically lost in hydraulic clamping. The first prototype is being built now.
Dynamic Uni-Layer Melting Model [W11] by Trevor Spika, Spiral Logic Ltd., Hong Kong, China (www.spirallogic.com.hk). Spiral Logic’s unusual new injection screw and T-Rex barrel melt without a compression zone, boasting shorter residence and cooler temperature than conventional screws. Introduced at NPE 2012, the screw is shown for the first time at ANTEC.
An Investigation of Vibration-Assisted Injection Molding Manufactured Polymer Material and the Effect of Molecular Orientation on Biodegradation Activity [T12] by Qi Li, Lehigh University, Bethlehem, Pa. (www.lehigh.edu). PLA medical devices molded with more vibration-induced molecular orientation degrade more slowly in the body than ones with less orientation. Software controls vibration by opening and closing valves on the hydraulic screw.
A Device for Simultaneous In-Situ Structuring and Measurement of Rheological Properties of Polymer Blends and Composites [T20] by David Zumbrunnen, S. Ramaswami, Clemson University, Clemson, S.C. (www.clemson.edu). This rheometer creates 3-D internal patterns by chaotic advection, and then measures their properties in situ. Chaotic advection uses rotating stir rods in a barrel to blend polymers into repeatable structures for blown and cast film.
Thermal and Morphological Behavior of PLA/PBS/CSW Blends Processed by Vane Extruder [Poster #1559206] by Rong-yuan Chen, South China University of Technology, Guangzhou (en.scut.edu.cn). PLA and PBS are blended with 5% calcium sulfate whiskers on a revolutionary new vane extruder invented at the university. The vane extruder, which elongates melt, was introduced at ANTEC last year (see this blog April 2012).
3D-CFD Simulation of Polymer Plastification in a Single-Screw Extruder Under High-Speed Conditions [M8] by Gregor Karrenberg, Johannes Wortberg, University of Duisburg-Essen in Germany (www.uni-due.de). This simulation of a 35-mm screw with a transition section depth going from 6 mm to 2 mm, extruding LDPE at up to 2000 rpm, shows high-speed extrusion melts without a melting mechanism.
A Mechanism for Solid Bed Break-up in Single Screw Extruders [T27] by Gregory Campbell, Clarkson University, Potsdam, NY (www.clarkson.edu); Mark Spalding, Dow Chemical Co., Midland, MI (www.dow.com). A fresh look at solid bed melting in a conventional screw finds that screw rotation physics carries melt under the solid bed, creating flow and pressure that breaks up the bed. The authors have a new book and photos to prove it.
NEW SHAPE MEMORY MATERIALS
Tunable Shape Memory Polymers Based on Compounds of Ionomers and Fatty Acids [New Technology Forums] by Robert Weiss, Jing Dong, Ying Shi, and Rostyslav Dolog of the University of Akron (www.uakron.edu). Instead of synthesizing a new polymer for every switching temperature, this technology blends an ionic polymer and fatty acid or fatty acid salt with the desired melting point. A patent-applied-for blend of sulfonated PEEK ionomer and fatty acid salt (U.S. Pat. Applic. # 20080287582) could be the first high temperature (>300 °C) thermoplastic shape memory polymer.
Thermoplastic Elastomers with Thermally Induced Shape-Memory Effect [New Technology Forums] by Liang Xu and Krishna Venkataswamy from the GLS Thermoplastic Elastomers division of PolyOne Corp., McHenry, IL (www.glstpes.com). This patent-applied-for (WO Pat. Applic. # 2012/166782) combination of a maleated styrenic block copolymer and polycaprolactone shows “manageable” shape memory characteristics.
Injection Molding of Novel PLA/Thermoplastic Polyurethane Blends with Shape-Memory Behavior [W10] by Xin Jing, Bionates Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI (wid.wisc.edu). A 70/30 blend of PLA and TPU deforms into temporary shapes at room temperature, then recovers its original shape “fairly quickly” at glass transition temperature. It’s believed to be the first PLA/TPU blend with shape memory.
ULTRASONIC TWIN- AND TRIPLE-SCREW COMPOUNDING NEWS
Preparation and Properties of Polyetherimide (PEI)/Graphite Composites with Ultrasound Assisted Extrusion [M6] by Jing Zhong, University of Akron (www.uakron.edu). A new ultrasound-assisted twin-screw extruder improves electrical conductivity of PEI/expanded graphite composites.
Continuous High Power Ultrasonic Extrusion of PEEK-CNT Nanocomposites [M4] by Todd Lewis, University of Akron (www.uakron.edu). The new ultrasonic twin-screw extruder mixes PEEK with only 1% carbon nanotubes and gets 16% higher tensile modulus and three times higher electrical conductivity.
Ultrasonic Devulcanization of Tire Rubber of Different Particle Sizes in Twin-Screw Extruder [M6; also Poster # 1657660] by Tian Liang, University of Akron (www.uakron.edu). The patent-applied-for ultrasonic twin-screw (WPO # 2012142562) devulcanizes 10- and 30-mesh rubber particles at 40 kHz, with more devulcanization and fewer gels for the smaller 30-mesh size. Revulcanized 30-mesh rubber also has higher elongation at break and tensile strength.
Decrosslinking of Crosslinked HDPE via Ultrasonically Aided Extrusion [W7] by Keyuan Huang, University of Akron (www.uakron.edu). Decrosslinking increases with ultrasonic amplitude in both single- and twin-screw extruders, but mechanical properties of HDPE are better from the ultrasonic single-screw. This is the first reported comparison of materials from ultrasonic single- and twin-screw extruders.
Preparation and Microcellular Foaming Investigation of PLA/Talc Composites [M19] by Peng Xiang-Fang, South China University of Technology in Guangzhou (en.scut.edu.cn). A new 22 mm, 40 L/D triple-screw extruder and patent-pending foaming device are used to make this bio composite with CO2 blowing agent. The triple-screw extruder is built by Guangzhou POTOP Experimental Analysis Instrument Co. Ltd. in China (www.potop-lab.com).
Preparation and Characterization of Poly(lactic acid)/Poly(vinyl alchohol) Blend [P2] by Peng Yu, South China University of Technology in Guangzhou (en.scut.edu.cn). POTOP’s new triple-screw extruder (www.potop-lab.com) is used to make more biopolymer blends.
PBS BLENDS AND OTHER BIO MATERIAL NEWS
Mechanical Properties and Crystallization of Talc-Filled PLA/Poly(butylene succinate) Blend Composites [T1] by Weraporn Pivsa-Art, Rajamangala University of Technology Thanyaburi, Thailand (www.eng.rmutt.ac.th). Blending up to 30 wt % PBS and up to 20% talc into PLA improves PLA’s tensile modulus, crystallinity, and impact strength.
Effect of Poly(butylene adipate-co-terephthalate) Contents on Crystallization and Mechanical Properties of Polymer Blends of PLA and Poly[(butylene succinate)-co-adipate] [T1] by Sommai Pivsa-Art, Rajamangala University of Technology Thanyaburi, Thailand (www.eng.rmutt.ac.th). Adding up to 50% PBAT to an 80/20 blend of PLA and PBSA also increases crystallization and improves properties.
The Role of Surface Interactions in Renewable Poly(butylene succinate)-Silica Nanocomposites [M21] by Margaret Sobkowicz; Poly(butylene succinate) Fumed Silica Nanocomposite: Functionality and Rheology [Poster # 1628517] by Xun Chen, University of Massachusets Lowell (www.uml.edu). Mechanical properties of PBS improve when it’s blended with fumed silica, whether the silica is surface treated or not.
Mechanical Properties of HDPE/Pennycress Press Cake Composites [M35] by Louis Reifschneider, Illinois State University, Normal, IL (www.ilstu.edu); Rogers Harry-O’Kuru, National Agricultural Utilization Research Center, Peoria, IL (www.ars.usda.gov). HDPE with 25 wt% fibers from Pennycress, a potential new oilseed crop for biodiesel, and 5% coupling agent gets 42% higher tensile modulus, 12% higher tensile strength. Impact strength drops 15%.
Blended Meat & Bone Meal Bioplastic and Polyethylene Sheets: Enhanced Moisture Resistance and Mechanical Properties [T21] by Sam Lukubira, Clemson University, Clemson, SC (www.clemson.edu). Cross-linking plasticized bone meal polymer and blending with LLDPE makes moisture-resistant film with potential for composite seed germination mats.
Sustainable Materials for Horticultural Application [T21] by Gowrishankar Srinivasan, Iowa State University, Ames, IA (www.iastate.edu). Plants grown in soy polymer/PLA pots grow better than plants grown in PP or natural fiber pots. Apparently, as soy polymer degrades, it feeds the plants, while the soy polymer/PLA blend retains moisture. The university reported this in a symposium in 2012, but ANTEC was its first public presentation.