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The aim of the study was to assess the usefulness of agricultural biomass residues as reinforcement in recycled polymer matrices. In this study, recycled polypropylene and high-density polyethylene composites (rPPPE) filled with three types of biomass residues, sweet clover straws (SCS), buckwheat straws (BS) and rapeseed straws (RS), are presented. The effects of the fiber type and the fibers content on the rheological behavior, mechanical properties (including tensile, flexural and impact strength), thermal stability and moisture absorbance were determined, in addition to morphological analysis. It was revealed that the addition of SCS, BS or RS increased the materials' stiffness and strength. The reinforcement effect increased as the loading of the fibers was increased, especially for BS composites in the flexural test. After the moisture absorbance test, it was found that the reinforcement effect slightly increased for the composites with 10% fibers but decreases with 40% fibers. The results highlight that the selected fibers are a feasible reinforcement for recycled polyolefin blend matrices. [ABSTRACT FROM AUTHOR]

Lignocellulosic fibers have been used in polymer composites for a long time but their treatment process is still challenging due to insufficient efficiency and environmental impact. This research analyses the influence of N-methylmorpholine N-oxide (NMMO) on the structure and properties of three types of lignocellulosic fibers - sweet clover (SCS), buckwheat (BS) and rapeseed straws (RS). The fibers were treated with an NMMO solution at 90 °C for different periods of time (80 min, 180 min, 300 min and 30 h). It was detected that after treatment in a dilute NMMO solution, non-cellulosic substances were removed, the morphology and aspect ratio were affected and the fibers were characterized by higher thermal stability. However, the results show that before using NMMO for the production of microfibers, additional research on the pretreatment process will be necessary because an insufficient aspect ratio value and surface morphology were obtained. The current research shows that it is not economically feasible to process fibers using NMMO for the production of reinforcement for polymer composites. [ABSTRACT FROM AUTHOR]

Lignocellulosic fibers have been used in polymer composites for a long time but their treatment process is still challenging due to insufficient efficiency and environmental impact. This research analyses the influence of N-methylmorpholine N-oxide (NMMO) on the structure and properties of three types of lignocellulosic fibers – sweet clover (SCS), buckwheat (BS) and rapeseed straws (RS). The fibers were treated with an NMMO solution at 90 °C for different periods of time (80 min, 180 min, 300 min and 30 h). It was detected that after treatment in a dilute NMMO solution, non-cellulosic substances were removed, the morphology and aspect ratio were affected and the fibers were characterized by higher thermal stability. However, the results show that before using NMMO for the production of microfibers, additional research on the pretreatment process will be necessary because an insufficient aspect ratio value and surface morphology were obtained. The current research shows that it is not economically feasible to process fibers using NMMO for the production of reinforcement for polymer composites. [ABSTRACT FROM AUTHOR]

In the context of sustainable materials, this study explores the effects of accelerated weathering testing and bacterial biodegradation on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/rapeseed microfiber biocomposites. Accelerated weathering, simulating outdoor environmental conditions, and bacterial biodegradation, representing natural degradation processes in soil, were employed to investigate the changes in the mechanical, thermal and morphological properties of these materials during its post-production life cycle. Attention was paid to the assessment of the change of structural, mechanical and calorimetric properties of alkali and N-methylmorpholine N-oxide (NMMO)-treated rapeseed microfiber (RS)-reinforced plasticized PHBV composites before and after accelerated weathering. Results revealed that accelerated weathering led to an increase in stiffness, but a reduction in tensile strength and elongation at break, of the investigated PHBV biocomposites. Additionally, during accelerated weathering, the crystallinity of PHBV biocomposites increased, especially in the presence of RS, due to both the hydrolytic degradation of the polymer matrix and the nucleating effect of the filler. It has been observed that an increase in PHBV crystallinity, determined by DSC measurements, correlates with the intensity ratio I1225/1180 obtained from FTIR-ATR data. The treatment of RS microfibers increased the biodegradation capability of the developed PHBV composites, especially in the case of chemically untreated RS. All the developed PHBV composites demonstrated faster biodegradation in comparison to neat PHBV matrix. [ABSTRACT FROM AUTHOR]