Plastics News reporter Bill Bregar has recapped a few of the more than 600 technical papers presented at the Society of Plastics Engineers' Annual Technical Conference, held May 8-11 in Boston. For people who did not attend ANTEC, the complete, three-volume proceedings are available from Technomic Publishing Co. Inc. of Lancaster, Pa. Cost is $525.
Water-soluble polyethylene oxide polymers with a high molecular weight can increase surface lubricity of polystyrene, polycaprolactone, polyethylene and PVC significantly, according to a paper by Ramesh Ramachandran, market manager in Union Carbide Corp.'s Specialty Polymers and Products unit.
The paper reviews modifications that allow processing of PEO, which has high moisture sensitivity and low melting temperatures.
Union Carbide Corp. of Danbury, Conn., markets PEO as Polyox resins. Union Carbide says information reported in Ramachandran's paper opens the door to new applications in water-soluble packaging, personal-care products and time-release applications.
PE already is widely used in such lubricious razor strips, pharmaceutical excipients and in water-soluble packaging. The resins also serve as flocculants polymers, adhesives, drag reducers and antistatic additives.
Cabot Corp. facility tests carbon black
Michael Wu, a scientist at Cabot Corp., presented ``The Effect of Carbon Black Dispersion on Polymer Performance.''
Research conducted at Cabot's research and development facility in Billerica, Mass., investigated how to obtain optimal carbon black jetness and impact performance in ABS resin. Cabot determined that low-intensity mixing is sufficient to disperse low-surface-area carbon black.
Carbon blacks with a higher surface area require high-intensity mixing.
Other authors of the paper were Mark Bissell and Bob Whitehouse.
Flexible membranes tests carbon black
A paper by Heinz Gross of Kunststoff-Verfahrenstechnik of Rossdorf, Germany, describes how to replace choker bars with flexible membranes in flat sheet dies.
Use of choker bars has been the standard way to achieve uniform melt flow across the die width when processing different polymers. The experiments used a bent membrane instead.
Gross concludes that the membrane technology opens up new consistency in sheet extrusion, with fine-tuned flow channel resistance and, therefore, melt streams.
Exxon Chemical tests PP extrusion rates
The main properties that make extruding PP difficult are its high crystallinity and stiffness. C.Y. Cheng of Exxon Chemical Co. of Baytown, Texas, reported that the extrusion rate increases with decreasing crystallinity of PP.
Cheng tested four samples with different crystallinity and stiffness - two homopolymers, a copolymer and an impact copolymer - and extruded them using two sizes of extruders and barrel temperature settings.
Cheng concluded that, for PP, the lower heat input resins such as impact copolymer and random copolymer have a higher extrusion rate.
Factors to determine interfacial instability
When coextruding polyethylene in blown film, the molecular weight distribution of the materials is a significant factor to determine the onset of interfacial instability.
Materials with a broad molecular weight distribution have a greater tendency to exhibit interfacial instability, more because of layer ratio than processing conditions or die geometries, according to a technical paper by John Perdikoulias of Brampton Engineering Inc. of Brampton, Ontario, and Costas Tzoganakis of the University of Waterloo, Ontario.
On the other hand, materials with more narrow molecular weight distribution tend to show instability that appears to be related to stress at the interface.
Future work, the authors said, will focus on geometry at the merge point and the interaction of materials with different molecular properties.
Infrared pyrometers used in press nozzle
A paper by Venkat Reddy of Ford Motor Co.'s Advanced Injection Molding Division, and Nick Schott, director of the Institute for Plastics Innovation at University of Massachusetts at Lowell, describes the use of infrared pyrometers in the nozzle of the injection press.
They conclude that the device can be used to monitor melt temperature measurements and homogeneity of the melt for a particular machine/mold/material combination.
Bozzelli studies resin packability
A paper by John Bozzelli of Injection Molding Solutions of Midland, Mich., studied resin packability.
To determine packability - or how a resin packs out a mold - Bozzelli said to measure the pressure loss from the nozzle of an injection unit to a place on the part near the end of fill during the pack and hold stages of molding.
Three case studies are shown where the dynamic viscosities were compared and then correlated to their packability.