By Jan H. Schut
ANTEC, the world’s premier technical conference for plastics, is 69 years old and still growing. Held May 1-4 this year in Boston, it featured 25% more papers than last year and 31% higher attendance. Here’s a look at some of the new technology that drew them. The letter and number in brackets after the title of a paper indicate the day of the week and session when the paper was given, i.e., [W25] was session 25 on Wednesday, May 4.
Part I below comprises papers on new process-related technologies for injection molding, extrusion, compounding, blow molding, and sintering, three of which used vibration. Part II below comprises papers on new materials and composites, with bio and eco polymers and fillers in both areas. A new hybrid grain, triticale, is tested both for starch and fiber. For non-attendees a copy of all ANTEC papers is available on a USB drive from the SPE (www.4spe.org) for $150.
Manipulation of Polymeric Biodegradation Characteristics by Vibration-Assisted Injection Molding [W25] by Burak Bekisli, Lehigh University (www.lehigh.edu). Injection molding biodegradable polymers with vibration applied through the injection screw can cause molecular alignment in the melt, which makes the part biodegrade more rapidly. This could allow medical parts to be made of the same polymer with different levels of degradability. PLA, both PLLA and PDLA, were tested.
Process Development of the Projectile Injection Technique (PIT) [T11] by Andre Potthoff, Institute of Plastics Processing (IKV) at RWTH Aachen University (www.ikv-aachen.de). Jointly developed with German machine builder Wittmann Battenfeld (www.wittmann-battenfeld.com) and introduced at an IKVopen house in Germany in 2010, PIT is a variation on fluid-assisted injection molding for hollow tubes. A fluid, such as water, forces a parabolic injection molded polyamide “projectile” into a mold cavity displacing melt to make the tubes with more uniform final wall thickness than water filling alone. The projectile can remain in the part or not. This is PIT’s U.S. debut.
Transient Mold Cooling Simulation for the Injection Molding Process [M13] by Franco Costa, Autodesk Australia Pty. (www.autodesk.com, http://www.SIMSquad.com). A new 3D finite element molding simulation introduced in March combines mold heating and cooling with filling and packing to improve molding prediction accuracy and optimize part design.
Producing Microlayer Blown Film Structures Using Layer Multiplication and Unique Die Technology [T28] by Joseph Dooley, Dow Chemical (www.dow.com). Microlayer cast films with 100s of layers have been made for years, but not blown film. Dow reports making 114-layer blown film with 108 microlayers on a 7-in. die. The technology combines Dow’s micro-layer-stacking feed block with layer encapsulation (first used for Dow’s corrosive PVDC film), and a modified cross-head die, which over-laps the ends of the flow channel instead of butting them.
Combinatorial Effects of Mechanical Vibration and Shear on the Cell Morphology of Microcellular Polymethyl Methacrylate [W16] by Hai-bin Zhao, South China University of Technology (en.scut.edu.cn). PMMA is foamed with supercritical CO2 using a high-shear screw and mechanical vibration from an electromagnetic field. Changing vibration frequency changes cell size and foam density.
Monolayer and Multilayer Polyolefin Films Incorporating Polymeric Microspheres [M25] by Sarah Schirmer, U.S. Army NSRDEC (nsrdec.natick.army.mil). Low loadings of 1.6, 2.4 and 3.3% polymeric microspheres (30MB120) from Expancel (www.akzonobel.com/expancel) in the core of a three-layer film lower density and improve Young’s modulus for HDPE film, but hurt tensile and tear strength for PP film. Microspheres have been tested in film before, but this may be the first published data.
Developing PHB/Wood Flour/Cell Debris Composites Through Extrusion [T3] by Meng-Hsin Tsai, Washington State University (www.wsu.edu). Wood composites made using unwashed PHB biopolymer avoid the high cost of removing dead bacteria cells from the bacterially produced biopolymer and reportedly get better properties than some commercial WPCs.
Study on Preparation of PP/PA6/OMMT Nanocomposites and Batching Foaming Process Conditions with Vibration Force Field [W31] by Haoyang Mi, South China University of Technology (en.scut.edu.cn). PP, nylon 6 and nano-organ-montmorillonite are reactively compounded with a compatibilizer and foamed with supercritical CO2, using vibration to achieve uniform micro foam.
Feed Enhancement Technology for Low-Bulk-Density Material into Co-Rotating Twin-Screw Compounding Extruders [T28] by Paul Andersen, Coperion Corp. (www.coperion.com). To increase the feed rate for fine and low bulk density fillers into an extruder, Coperion applied vacuum to the barrel wall in the feed zone. The filler adheres to pores in the barrel wall, increasing the coefficient of friction between filler and wall. Vacuum level depends on the size of the pores and filler. The new feed zone was introduced at K 2010 in Germany last year.
Producing Microlayer Blow Molded Structures Using Layer Multiplication and Unique Die Head Technology [M20] by Sam Crabtree, Dow Chemical Co. (www.dow.com). In the first known demonstration of nano-layered blow molding, Dow blew a bottle with 33 micro layers and two encapsulation layers. The most layers known to be blow molded commercially before is seven for an automotive part. Dow used its own layer-stacking feedblock and encapsulation technology (see Joseph Dooley’s paper [T28] above) with a modified heart-shaped die, over-lapping the ends of the flow channel instead of butting them.
Barrier Property and Characteristics of Polyglycolic Acid for Un-Oriented Sheets and Oriented Films [T35] by Daisuke Ito, Kureha Corp. (www.kureha.co.jp). Kureha first tested oriented and unoriented sheets of PGA for barrier properties, then made stretch-blown multi layer PET bottles with a layer of 1 and 3 wt % PGA. The PGA-layered bottles showed 1.5 and 2.5 times better gas barrier properties respectively.
Laser Sintering Processes: Practical Verification of Particle Coalescence for Polyamides and Thermoplastic Elastomers [W30] by Mike Vasquez, Loughborough University (www.lboro.ac.uk). Polyamides and TPEs are tested for potential in laser sintering. Researchers at Loughborough are also developing high-speed sintering, using inkjet print heads, polymer powder and i.r. curing to build parts, potentially for higher volume.
Manufacturing of Micropellets Using Rayleigh Disturbances [T28] by Martin Launhardt, University of Wisconsin-Madison (pec.engr.wisc-edu). Micropellets can be made without a die and holes. Uniform spherical micro pellets are formed using a special nozzle to break up the melt stream with a jet of hot air. The University of Wisconsin is also researching use of Rayleigh disturbances to make nylon 12 micropowders, potentially for serial production of parts by laser sintering.
Properties of Poly(propylene carbonate) Produced via SK Energy’s GreenPol Technology [M15] by Minho Jeon, SK Energy (www.skenergy.com). SK started pilot plant production of PPC, a new amorphous copolymer made from carbon dioxide and propylene oxide, in late 2009 in Korea. This is its first presentation of material data here. Novomer (www.novomer.com) is the only other known company developing PPC polymer (see Plastics Engineering blog, December 2010). PPC properties include oxygen barrier, transparency, and printability.
Triticale Starch-Based Bioplastics [M19] by Hongbo Li, Canadian National Research Council (imi.cnrc.gc.ca). The rheology of starch made from triticale, a hybrid of wheat and rye, is tested for potential blending with PLA biopolymer in blown film. Triticale is used as a commercial crop mostly for fodder, but with potential for energy.
Structure and Properties of Pentablock and Triblock Copolymer Blends [INT3] by Eugene Joseph, Virginia Tech (www.vt.edu). Blending a styrenic pentablock copolymer, poly (t-butyl styrene-b-(ethylene-r-propylene)-b-styrene-(ethylene-r-propylene)-b-(t-butyl styrene (Nexar) from Kraton Polymers LLC (www.kraton.com) with styrene-ethylene/butylene-styrene block copolymers makes an elastomeric film that wicks moisture. The ethylene/propylene in Nexar bonds to ethylene/butylene in SEBS without compatibilizing.
Effect of Hybrid Compatibilizers on Mechanical Properties of a Ternary Blend of Polypropylene, Poly(Lactic Acid) and TPO [W20] by Hyn-sup Lee, Daedeok R&D Institute, Honam Petrochemical Corp. (English.hpc.co.kr). Melt blending PLA with normally incompatible PP and TPO elastomer plus 3 wt% of a hybrid compatibilizer improves thermal stability and properties.
Hybridization of Thermoplastic Poly(Lactic Acid) and Polyoxymethylene Composites Through Micro-Braiding [W5] by Patcharat Wongsriraksa, Kyoto Institute of Technology (www.kit.ac.jp/english). A composite of immiscible PLA and POM thermoplastics is made by micro braiding PLA and POM threads over jute yarn, then wrapping the yarn around a steel frame and compression molding it.
New Polypropylene/Triticale Composites: Relationship Between Formulation and Properties [T24] by Mihaele Mihai, Canadian National Research Council (imi.cnrc.gc.ca). Triticale straw has potential as filler too (see Hongbo Li’s paper on triticale starch [M19] above). PP is reactively compounded in a twin-screw extruder, with up to 40 vol % triticale straw and 3.75 vol % coupling agent and tested.
Comparison of Properties of Extruded PVC/VAc Foams and PVC Foams Filled with Coffee Husk [T18] by Diego Dominguez, Universidad de los Andes (www.uniandes.edu.co). Rigid PVC/vinyl acetate copolymer was extrusion foamed with a chemical blowing agent both with and without coffee bean husks as a filler. The copolymer with coffee husks foamed at lower temperature and got better properties. Another use for Colombian coffee!