Influence of a bark-filler on the properties of PLA biocomposites

Abstract

In this study, wood plastic composites (WPC) made of poly(lactic acid) PLA and a bark-filler were manufactured. Two degrees of bark comminution (10–35 mesh and over 35 mesh) and varied content of bark (40, 50 and 60%) were investigated. The studied panels were compared with analogically manufactured HDPE boards. The manufacture of composites involved two stages: at first, WPC granules with the appropriate formulation were produced using the extruder (temperatures in individual extruder sections were 170–180 °C) and crushing using a hammer mill after cooling the extruded composite; secondly, the obtained granulate was used to produce boards with nominal dimensions of 300 × 300 × 2.5 mm3 by flat pressing in a mold, using a single daylight press at a temperature 200 °C. The study proved that comminuted bark can be applied as a filler in PLA composites. However, an increase in bark content decreased mechanical properties (MOR, MOE) and deteriorated humidity resistance (high TS and WA) of the panels. Along with the increase in bark content, an increase in the contact angle of the composite surfaces and a decrease in the total surface energy were noted. It was also found that PLA composites have higher strength parameters and lower moisture resistance compared to HDPE composites with the same bark content. Graphical abstract

Manufacturing and compatibilization of binary blends of superheated steam treated jute and poly (lactic acid) biocomposites by melt-blending technique

“…PLA is fermented from agricultural raw materials such as sugar, corn, beet, and potato in lactic acid [ 8 , 13 , 16 , 18 , 19 ] and has excellent mechanical properties [ 5 , 7 , 9 , 20 , 21 , 22 , 23 ], better biocompatibility [ 5 , 7 , 23 ], easily processable [ 7 , 23 ], transparency [ 20 ], and biodegradability [ 5 , 23 ]. Despite the properties, some modifications to PLA are required due to its brittleness, poor heat resistance, and low toughness properties [ 5 , 9 , 17 , 22 , 23 , 24 ].…”

Binderless Thermal Insulation Panels Made of Spruce Bark Fibres

“…Today, in Europe, the majority of the available bark is used for bioenergy production or is used for even less value-added purposes like composting and incinerating [ 4 ]. Tree bark can be superiorly utilised as raw material, for example, as a filler in urea formaldehyde adhesives [ 5 , 6 , 7 , 8 ] to replace wheat flour, reducing in this way the formaldehyde emissions.…”

PLA Biocomposites: Evaluation of Resistance to Mold

“…One of the directions of PLA modification is introduction lignocellulosic fillers, such as: wood fibers [ 5 , 6 , 7 ], wood flour [ 8 , 9 , 10 ], cork [ 8 ], bamboo fiber [ 11 ], abaca fibers [ 12 ], rubber wood sawdust [ 13 ], and bark [ 14 ]. The authors generally indicate an improvement in the mechanical properties of PLA composites filled with wood fibers with a filler content of up to 20% [ 5 , 7 ] or 30% [ 6 ].…”

“…Andrzejewski et al [ 8 ] reported the beneficial effect of cork filler (up to 30%) on the dimensional stability of PLA composites exposed to moisture. The use of wood flour or bark as a filler, on the other hand, deteriorates the resistance of PLA composites to moisture [ 10 , 14 ].…”

“…Schirp et al [ 31 ] reported that the influence of coloring and mold fungi on WPC was measured only by the visual method of assessment of microorganisms fouling the material. As part of the research, the mold growth on the samples was assessment using computer analysis of the image [ 14 ]. The tests were carried out on analogous WPC composites made of high-density polyethylene (HDPE).…”