WILMINGTON, DE.–An advanced polymer modifier could speed growth of polylactic acid (PLA) polymers in packaging. Carol Casarino, global technology manager for DuPont Packaging & Industrial Polymers, is reporting that, “Our latest trials show that DuPont™ Biomax® Strong 120 overcomes limitations that have held back widespread use of bio-based PLA. Not only does it deliver remarkable toughening effects in brittle PLA materials, it also reduces crinkly film noise and cuts power consumption while increasing thermal stability during extrusion.”
Until now, the crinkly sound of PLA-based films has limited their acceptance in flexible packaging applications, such as snack bags. Preliminary testing of monolayer films shows that Biomax® Strong 120 reduces such noise even at just a few percent loading. Furthermore, by combining PLA containing Biomax® Strong 120 with layers of flexible materials, it’s feasible to design PLA-based packaging structures that produce no more noise than conventional packages, according to Casarino.
“During extrusion, Biomax® Strong 120 melts quickly and acts as a lubricant in the solids conveying sections of the extruder,” Casarino reports. “That can result in an increase of up to 21 percent in extruder energy efficiency with just 2 weight percentof Biomax® Strong 120.” Major improvements in thermal stability during processing are seen with the addition of just 2 to 5 percent of Biomax® Strong 120 to PLA. That can pay off with greater use of regrind during extrusion. It also could help expand the use of PLA in extrusion coating, which uses relatively high processing temperatures.
Biomax® Strong 120 was originally developed as a toughening modifier. It sharply reduces brittleness, as indicated by flexural fatigue tests showing a nine-fold improvement with just 1 percent of the modifier in amorphous sheet. In crystallized sheet, dramatic reductions in brittle behavior also are seen. In addition, the modifier produces major improvements in elongation with loading levels of just a few percent, according to Casarino.