Improving the Processability and Performance of Micronized Fiber-Reinforced Green Composites through the Use of Biobased Additives

Abstract

Green composites made of bioplastics reinforced with natural fibers have gained considerable attention over recent years. However, the use of natural fibers in composites usually compromise some key properties, such as the impact strength and the processability of the final materials. In the present study, two distinct additives, namely an epoxidized linseed oil (ELO) and a sugar-based surfactant, viz. GlucoPure® Sense (GPS), were tested in composite formulations of poly(lactic acid) (PLA) or poly(hydroxybutyrate) (PHB) reinforced with micronized pulp fibers. Both additives showed a plasticizing effect, which led to a decrease in the Young’s and flexural moduli and strengths. At the same time, the elongation and flexural strain at break were considerably improved on some formulations. The melt flow rate was also remarkably improved with the incorporation of the additives. In the PHB-based composites, an increment of 230% was observed upon incorporation of 7.5 wt.% ELO and, in composites based on PLA, an increase of around 155% was achieved with the introduction of 2.5 wt.% GPS. ELO also increased the impact strength to a maximum of 29 kJ m−2, in formulations with PLA. For most composites, a faster degradation rate was observed on the formulations with the additives, reaching, in the case of PHB composites with GPS, a noteworthy weight loss over 75% under burial testing in compost medium at room temperature.

Flexible monolayer films of poly(lactic acid)/gallic acid for active food packaging: Preparation, characterization, and bioactive properties

“…339 C for both PLA_5ELO and PLA_7.5ELO. As disclosed in literature, similar results were previously reported for PLA plasticized with PEG 27 and ELO, 21,68 credited to the distinct maximum decomposition temperatures of the two plasticizers, namely below 300 C for PEG 27 and below 400 C for ELO. 69 Thus, there is a clear advantage of using ELO as plasticizer over PEG, which is in line the fact that epoxidized vegetable oils are known for being thermal stabilizers.…”

“…2 Despite the growing research activity in the use of natural polymers 5 for food packaging, such as nanocellulose, [6][7][8][9] chitosan, 10 starch, 11 pullulan, 12,13 and agar, 14,15 the majority of these natural polymers, although biodegradable, lack hydrophobic and thermoplastic properties that are relevant in the contexts of wet food packaging or dry food products that are sensitive to humidity during storage. Therefore, the application of bioplastics, 16 including biodegradable/sustainable polyesters, 17 for instance, poly (ε-caprolactone), 18,19 poly(lactic acid) (PLA), [19][20][21] poly (hydroxybuyrates), 20,21 or cellulose acetate, 22 has been gaining momentum as a viable alternative in the packaging sector. Amid the limited number of bioplastics currently produced at a commercial scale, the polyester PLA (classified as GRAS (generally recognized as safe) 23 ) stands out with a market size volume by 2035 of 2 million tons and a compound annual growth rate of 14.44% from 2023 to 2035, 24 with the packaging industry as the market growth driver.…”

Evaluation of Chemical and Biological Properties of Biodegradable Composites Based on Poly(3-hydroxybutyrate) and Chitosan

“…The moisture absorption of the polymer scaffolds was evaluated using the standard method described in [ 50 ]. The scaffolds were incubated at t = 50 °C until a constant weight was achieved (m0).…”

Biocomposites Based on Electrospun Fibers of Poly(3-hydroxybutyrate) and Nanoplatelets of Graphene Oxide: Thermal Characteristics and Segmental Dynamics at Hydrothermal and Ozonation Impact

“…%, H-5.6 wt. %, [23]. RGO was synthesized in the Institute of Chemical Physics, named after N. N. Semenov of the Russian Academy of Sciences, Moscow, Russia.…”

“…There are several ways to improve the operational parameters of PHB, among which the most effective are changing the chemical structure of polymer molecules through (bio)synthesis of its copolymers [15], mixing macromolecules to obtain new blends and composites [16,17] and introducing modifying agents [18][19][20], producing crucial effects on thermal, diffusional, and mechanical behavior of the given biopolymer. The introduction of plastifiers of different chemical structures as modifiers of mechanical and thermal properties has a long history of research and today remains one of the most effective ways to improve the structure and modulate the functional behavior of biopolyethers such as PHB, PLA, as well as their mixtures [21][22][23]. The next category of the modifiers comprises the compounds affecting diffusivity and solubility as well as the permeability of PHB membranes/films designated for separation and purification in liquid media [24] and food packaging materials against atmospheric gases [25].…”