Stinging nettle (Urtica dioica L.) has been observed to grow spontaneously on metal-contaminated soils marginalised by heavy industrial use, thereby presenting an opportunity for the economic utilisation of such lands. This study explores the potential of nettle as a fibre crop by producing short fibre-reinforced polylactic acid (PLA) composites through compounding and injection moulding. Whole stem segments from three nettle clones (B13, L18, and Roville), along with separated fibre bundles from the L18 clone, were processed. The fibre bundles were separated using a roller breaker unit and a hammer mill. From separation with the hammer mill, not only cleaned fibre bundles but also the uncleaned fibre-shive mixture and the undersieve fraction were processed. The Young's modulus of all composites exceeded that of unreinforced PLA, with mean values ranging from 5.7 to 8.1 GPa. However, the tensile strength of most composites was lower than that of pure PLA, except for the two composites reinforced with cleaned fibre bundles. Of these two, the reinforcement with fibre bundles from separation with the hammer mill led to superior mechanical properties, with a higher Young's modulus (8.1 GPa) and tensile strength (61.8 MPa) compared to those separated using the breaking unit (7.2 GPa and 55.9 MPa). This enhancement is hypothesised to result from reduced fibre damage and lower fibre bundle thickness. The findings suggest that nettle cultivation on marginal lands could be a viable option for producing short-fibre composites, thereby offering a sustainable use of these otherwise underutilised areas.

Melt blending is a reliable and well-demonstrated strategy for improving the mechanical, thermal, rheological, and surface properties of biopolymers. Poly(hydroxy-3-butyrate-co-3-hydroxyvalerate) (PHBV) and poly(butylene adipate-co-terephthalate) (PBAT) are the two popular choices for blending polymers due to their diverse properties and complementary soil biodegradable behaviour. Due to their immiscibility, however, blending with the help of processing additives is necessary to reap the most significant benefits from this process and to avoid immiscibility issues. This study utilized the additives (peroxides and epoxy-based chain extender) to compatibilize the biodegradable polymers PHBV and PBAT in a 60:40 blending ratio. The tensile strength and Young's modulus of the PHBV/PBAT(60/40) blend were improved by 32% and 64%, respectively, after adding a combination of peroxide (0.02 phr) and chain extender (0.3 phr) due to the formation of a complex network structure with increased chain length. The positive effect of an additive addition was also reflected by a 30 degrees C increment in heat deflection temperature of biodegradable blend due to its high modulus value as supported by mechanical properties. The combined action of a peroxide and chain extender demonstrated a significantly higher complex viscosity of the PHBV/PBAT(60/40) blend due to the formation of a crosslinked polymer network as analyzed by rheological analysis. Our research demonstrated the effect of additives and their combined impact on analytical properties of PHBV/PBAT(60/40) blend to guide future work in improving their candidature to serve as a drop-in solution in replacing non-biodegradable petro-based plastic products.

The present study examines the mechanical and morphological characteristics of a green composite reinforced with pineapple leaf fiber (PLF) under different environmental conditions. PLF underwent chemical treatment at optimal conditions, using a 1% w/v sodium carbonate solution for 6 hours, to produce an environmentally friendly pineapple leaf fiber (PLF)/polylactic acid (PLA)-based composite via injection molding. The optimal injection settings of 165 degree celsius (melting temperature), 50 mm/sec (injection speed), and 110 bars (injection pressure) to produce the PLF/PLA composite. The PLF/PLA composite was developed with a fiber loading of 20% and a length of 3 mm. The produced PLF/PLA composites were then exposed to a variety of environmental conditions, including water, soil, refrigeration, and room temperature. The impact of these diverse conditions on the mechanical properties (tensile, flexural, compression, and shear) was scientifically observed for four -week. Additionally, the morphology of the fractured specimens was assessed using a scanning electron microscope (SEM). The contact angle measurement was conducted to assess the hydrophilic characteristics of the PLF/PLA green composite. There has been a lack of comprehensive research on the effects of different environmental conditions on the mechanical, wettability, and morphological properties of green composites derived from PLF/PLA. Thus, in this study, emphasis is given for investigating the effect of various environmental conditions on the mechanical properties of PLF/PLA injection -molded green composite. The composite material demonstrated the highest water absorption and swelling thickness at 6.45% and 5.51%, respectively, in comparison to the dry PLF/ PLA samples. The green composite of PLF/PLA demonstrated excellent mechanical performance under ambient conditions compared to other environmental conditions. The PLF/PLA composite displayed a peak contact angle of 83.26 degrees when subjected to soil burial conditions. On the contrary, the initial samples of the PLF/PLA composite displayed the minimum contact angle of 56.72 degrees .

The present investigation evaluates the mechanical, thermal, morphological, and crystalline behaviour of green composite reinforced with bamboo fibre under recycling and various environmental conditions. The short bamboo fibre was chemically modified at an optimum condition by treating the fibre for 4 h using sodium hydroxide (2% w/v) to produce a sustainable bamboo fibre (BF)/polylactic acid (PLA) composite through injection moulding. The optimum injection conditions considered to develop BF/PLA composite were a melting temperature of 165 degrees C, injection speed of 60 mm/s, and injection pressure of 90 bars. The fibre length and loading of 4 mm and 20% were considered to fabricate the BF/PLA green composite. The developed BF/PLA composites were exposed to different environmental conditions like water, soil, refrigerator, and room temperature for four weeks. The fabricated BF/PLA green composite specimens were recycled five times by implementing the manual mechanical cutting process. The impact of various environmental conditions and recycling on the mechanical properties was systematically monitored. The morphology of the fractured recycled specimens and specimens exposed to different environmental conditions were also examined using a scanning electron microscope (SEM). The thermo gravimetric analysis (TGA) was performed on the recycled BF/PLA specimens to investigate the thermal degradation behaviour of the developed composites. The crystalline behaviour of the BF/PLA composite exposed to different environmental conditions and recycled samples was also analysed by using X-ray diffraction (XRD). The maximum water absorption and thickness of swelling of the developed composite were observed at 6.49% and 5.56% when compared to the dry BF/PLA specimens. The mechanical behaviour of the BF/PLA green composite was superior in room temperature conditions followed by refrigerating, soil burial, and water immersion conditions. The maximum degradation temperature of non-recycled and after the fifth recycled BF/PLA composite was perceived at 348 degrees C and 329 degrees C. The deterioration in PLA and BF was observed due to the thermo-mechanical recycling. The degree of crystallinity of the unexposed sample was observed as 57.75% with a semi-crystalline nature. The crystallinity of BF/PLA composite was changed to amorphous while exposed to water, soil, refrigerator, and room temperature with a degree of crystallinity of 9.41%, 18.62%, 31.62% and 37.93%. Meanwhile, the fifth recycled BF/PLA composite exhibited a degree of crystallinity of 12.71%.