Rhubarb and berry bio-additives as natural UV absorbers and stabilizers for biodegradable polylactide and polycaprolactone
Malgorzata Latos-Brozio
, Aleksandra Drzazga, Anna Masek, Zdzisława Mrozińska, Marcin H. Kudzin
, Aleksandra Drzazga, Anna Masek, Zdzisława Mrozińska, Marcin H. KudzinVol. 20., No.7., Pages 742-760, 2026
DOI: 10.3144/expresspolymlett.2026.56
DOI: 10.3144/expresspolymlett.2026.56
Corresponding author: Malgorzata Latos-Brozio 
GRAPHICAL ABSTRACT
ABSTRACT
We investigated the effectiveness of plant-based bio-additives – rhubarb, lingonberry, and blueberry (0.1–1%) – as natural UV absorbers in biodegradable polymers polylactide (PLA) and polycaprolactone (PCL). A novelty of this work is the direct use of plant-based raw materials as UV absorbers in polymers. We performed Fourier transformed infrared spectroscopy (FT-IR) and UV-Vis analysis of the bio-additives, determined the ultraviolet protection factor (UPF) for the polymer samples, and evaluated their physicochemical properties (structural changes, colour, hardness, surface energy) after weathering (PLA) and thermo-oxidative (PCL) aging. Spectroscopic tests confirmed the presence of UV-A/UV-B-absorbing chromophores in the additives. Samples with 1% berries had excellent UV protection (UPF 40–50+), while PLA and PCL containing 1% rhubarb had lower UPF values (around 22), indicating good UV blocking properties. After aging, PLA-containing berries showed a significantly lower carbonyl index (CI), indicating reduced photodegradation. For PCL with lingonberry, this additive gave the greatest reduction in thermo-oxidative degradation (lowest CI). All plant additives increased material hardness by acting as nucleating agents; they increased the crystallinity of polyester, and aging further strengthened this effect. Bio-additives, especially berries, can increase the hardness and UV resistance of polymers and limit material aging. These polymer compositions are suitable for packaging materials.
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