New polymer modifier could drive greater PLA take up in packaging - DuPont

Latest trials by the US-based company have shown its Biomax Strong 120 delivers “remarkable toughening effects”​ in brittle PLA materials, cuts power consumption and increases thermal stability during extrusion, Dr Carol Casarino, packaging and consumer global technology manager, told FoodProductionDaily.com.

Noise reduction​

The modifier can also have a dramatic effect in reducing crinkly film noise – which has so far restricted its acceptance in flexible packaging application such as snack bags, said DuPont.

Last year, Frito Lay made global headlines when it withdrew five of its six SunChips brand bags​ after consumer feedback indicated the 100 per cent plant-based PLA packaging was too noisy.

DuPont said preliminary testing of monolayer films had shown that inclusion of the substance cuts such noise even at just a few percent loading.

“We believe it does this by allowing the material to dissipate more energy as heat rather than sound and that can have a substantial effect on noise,”​ said Dr Casarino.

The firm said recent testing had revealed the new benefits from this PLA modifier that “could speed the growth of ​PLA​ polymers in packaging​”.

Toughening ​

Dr Casarino said the company's track record for toughening materials led it to develop a new modifier for PLA that produced significant improvements to the material properties.

In a flex fatigue cycle trial, which involves the folding of a substrate until it breaks, Biomax demonstrated a performance step change, said the packaging expert.

PLA monolayers that contained none of the chemical broke after 100 repetitions, while adding 1 per cent of the modifier increased this five-fold. An addition of 5 per cent saw this rise to 1,000 bends, she added.

The elongation of break, which measures PLA’s ability to stretch, found that adding 2 per cent of Biomax to the material meant it could be pulled to two and half times its original size – 15 times more than modifier-free PLA.

Energy efficiency and thermal stability​

Use of the modifier can also promote energy efficiency in the extrusion process.

"During extrusion, Biomax Strong 120 melts quickly and acts as a lubricant in the solids conveying sections of the extruder,"​ said the global packaging technology manager. “The addition of 2-5 per cent improves energy efficiency in the extruder by between 20-30 per cent in controlled lab experiments. We have heard anecdotally from customers that this also happens in commercial applications.”​

Major improvements in thermal stability during processing are seen at the same levels of inclusion.

That can lead to with greater use of regrind during extrusion and help expand the use of PLA in extrusion coating, which uses relatively high processing temperatures, said DuPont.