TECHNOLOGY | BIOPLASTICS


Building better bioplastics


Pricing and performance issues mean bio-based plastics are not yet drop-in replacements for traditional polymers. Peter Mapleston finds compounding and additive developments are addressing the problem


Bioplastics will only become a true alternative to traditional polymers made from non-renewable sources when their performance reaches the same level – and for many applications that is still not the case. However, important progress is being made, not only with bioplastic polymers themselves but also in the additives and compounding technolo- gies that help improve and expand their property profiles. This article takes a look at some of the latest developments in biopolymer modification at technology suppliers and users. Polylactide (PLA) – more often described less


accurately as polylactic acid – is now the most well-established of the commercially available modern bioplastics. The bio-based and biode- gradable polyester is increasingly used in food packaging and a wide variety of other more niche applications. But despite its favourable perfor- mance attributes, significant improvement in performance is still required to make it fully competitive with conventional polymers during processing, according to speciality ester producer Condensia Quimica.


www.compoundingworld.com


Based in Barcelona, Spain, Condensia Quimica counts itself among the growing number of additive manufacturers working to develop solutions to overcome some of the limitations of PLA, as well as other biopolymers. Technical Manager Stefano Fiori says these include poor thermal stability and their susceptibility to degrada- tion as well as loss of properties during processing and reprocessing. “Biologically-based polymers and blends have less flexibility in polymer design than copolymers,” he says. “PLA is rigid and brittle with low plastic deformation capacity below the glass transition temperature (Tg is 50-60°C), and it is necessary to plasticise PLA in order to produce flexible films.”


Existing plasticisers have limited compatibility


with PLA. In addition, their non-degradable nature is a clear disadvantage in many PLA applications. “The combination of these circumstances means that the plastics industry cannot currently offer thin, flexible PLA films to the food industry,” Fiori says. That could soon change, however. Fiori and two colleagues have patented a method for plasticising


September 2019 | COMPOUNDING WORLD 25


Main image: Bioplastic


compounding technology is closing the performance gap. Italian PHA producer Bio-On made these bricks to demonstrate the resins’s dimension stability


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