Doctoral dissertation

Biodegradable materials can replace conventional plastics in a wider range of applications than before

Heidi Peltola
Increasing amount of plastic production as well as EU objectives towards circular economy and carbon neutrality promotes the use of novel bio-based material solutions. In biocomposites, fossil-based plastics are replaced by renewable raw materials, such as wood fibres. Wood fibre reinforced biocomposites can offer environmentally friendly options to several plastic products.

In conventional biocomposites, wood fibres are used to improve mechanical properties and appearance of the material, and at the same time, less plastic is needed. However, these typically non-biodegradable materials cannot be mechanically recycled due to lack of feasible recycling systems. Therefore, they often end up in incineration or landfills. Biocomposites based on compostable materials support the circular economy targets by offering an alternative end-of-life option for products that are hard to recycle.

“On the other hand, also compostable materials can be mechanically recycled into new products, if needed volumes for feasible recycling business are met”, says Heidi Peltola.

In her PhD dissertation, MSc (Tech) Heidi Peltola studied compostable wood fibre reinforced poly(lactic acid) (PLA) biocomposites. In addition to the possibility to industrial composting, these materials are totally bio-based, which enables detaching from fossil resources and decreasing carbon footprint. In the dissertation, the main objective was to gain more knowledge of the factors influencing characteristics of wood fibre reinforced PLA biocomposites to enable their wider use in commercial applications. By improving their properties, compostable biocomposites can be utilised in products that require even better performance, as well as in novel applications.

“As an example, we found out that wood fibre reinforced PLA biocomposites can be foamed using conventional processing equipment, which enables e.g. replacement of hard-to-recycle polystyrene foams”, explains Peltola.

As a conclusion, the dissertation shows that significantly improved properties can be reached by correct fibre selection, fibre treatments and certain additives. In addition to using virgin wood fibres from papermaking processes, also recycled newspaper or cardboard fibres can be utilised as reinforcement in biocomposites. Compostable products can actually have high mechanical properties and are suitable also for long lifespan products, such as furniture.

Peltola performed her PhD studies at VTT Technical Research Centre of Finland Ltd., acting as Senior Scientist in biocomposites and processing research team. Recently, she started working as R&D Manager at Sulapac Ltd, a company that develops recyclable, microplastic-free material solutions to replace conventional plastic in several applications, such as cosmetics packaging.

The doctoral dissertation of MSc (Tech) Heidi Peltola in the field of materials science titled Morphological Effects of Lignocellulosic Fibres on Poly(Lactic Acid) Biocomposites will be publicly examined in the Faculty of Engineering and Natural Sciences at Tampere University at 12 o’clock on Thursday 5th of December 2019, Sähkötalo S2 Auditorium, Korkeakoulunkatu 3, Tampere.  The Opponent will be DSc (Tech) Maiju Hietala, Brightpuls Oy. The Custos will be Professor Jyrki Vuorinen, Faculty of Engineering and Natural Sciences.

The dissertation is available online at

Photo: Samuli Peltola