Biocomposites of Low-Density Polyethylene Plus Wood Flour or Flax Straw: Biodegradation Kinetics across Three Environments

Abstract

The purpose of this study was to assess the potential for biocomposite films to biodegrade in diverse climatic environments. Biocomposite films based on polyethylene and 30 wt.% of two lignocellulosic fillers (wood flour or flax straw) of different size fractions were prepared and studied. The developed composite films were characterized by satisfactory mechanical properties that allows the use of these materials for various applications. The biodegradability was evaluated in soil across three environments: laboratory conditions, an open field in Russia, and an open field in Costa Rica. All the samples lost weight and tensile strength during biodegradation tests, which was associated with the physicochemical degradation of both the natural filler and the polymer matrix. The spectral density of the band at 1463 cm−1 related to CH2-groups in polyethylene chains decreased in the process of soil burial, which is evidence of polymer chain breakage with formation of CH3 end groups. The degradation rate of most biocomposites after 20 months of the soil assays was greatest in Costa Rica (20.8–30.9%), followed by laboratory conditions (16.0–23.3%), and lowest in Russia (13.2–22.0%). The biocomposites with flax straw were more prone to biodegradation than those with wood flour, which can be explained by the chemical composition of fillers and the shape of filler particles. As the size fraction of filler particles increased, the biodegradation rate increased. Large particles had higher bioavailability than small spherical ones, encapsulated by a polymer. The prepared biocomposites have potential as an ecofriendly replacement for traditional polyolefins, especially in warmer climates.

Development of Wood Polymer Composites from Recycled Wood and Plastic Waste: Thermal and Mechanical Properties

“…In recent years, given the limits of natural resources, the materials and manufacturing sectors have gradually shifted their focus to the development of biodegradable and sustainable materials or products [1]. Wood is a renewable and low-carbon material [2,3]. It has been widely used in different interior and exterior applications [4,5], such as decking materials [6], fencing [7], landscaping timbers [8], furniture, and automobile products [9].…”

Construction, Physical Properties and Foaming Behavior of High-Content Lignin Reinforced Low-Density Polyethylene Biocomposites

“…However, most biopolymers produced with this technique, unfortunately, are immiscible with polyolefins, which drastically weakens their mechanical properties due to their physical and chemical differences. Polyolefin-based biocomposites have so far attracted extensive attention as an alternative approach [16][17][18][19][20]. Among their numerous biodegradable fillers, lignin is an important candidate because it is an inexpensive, natural, and biodegradable material obtained during the pulping and biorefinery processes [21][22][23][24][25]; nonetheless, since polyolefins and the lignin filler are still immiscible, chemical and physical methods have been proposed to modify the characteristics of lignin to enhance its dispersibility and interface adhesion in a two-phase composite system [26][27][28][29][30][31].…”

Investigation of the Orientational Mechanical Properties of Biodegradable Extrusion Films Based on Polyolefins and Beet Pulp

“…Filling polymers with vegetable fillers such as wood flour, straw, husk of cereal crops reduces the cost of polymer compositions and can significantly reduce the environmental burden after their use, which is especially important for disposable packaging materials [1][2][3][4][5][6][7][8][9][10][11][12]. Recently, there have appeared a lot of studies , which describe the compositions of biodegradable composites based on thermoplastic polymers and natural fillers such as starch, cellulose, rice husks, wood flour, and cereal straw.…”

“…Therefore, the development of compositions of biodegradable polymeric materials as well as the development of their production technological processes are currently the priority tasks [24]. The effect of biodegradability can be achieved by introducing vegetable fillers into synthetic thermoplastics [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In the Russian Federation, the main by-product of sugar beet production is beet pulp.…”

“…Studies [11][12][13][14][15] show the use of polyolefins, wood and flax flour to obtain biodegradable compositions. Malaysian scientists [16][17][18][19] studied the biocomposites based on various binders with plant waste from sugar palm.…”