Volatile organic compounds (VOCs) reduce indoor air quality. They are associated with negative effects on human health and wellbeing. In terms of legislation requirements and consumer pressure, VOCs from engineered wood materials are reduced due to use of water based additives and adhesives in their formulation. Therefore, the main source of VOCs remains the raw material—the wood itself. Alternatives to wood strands, annual plant materials, are tested nowadays due to their advantages: The short cycle; the raw material is sourced naturally and can be produced more sustainably; and faster sequestering atmospheric carbon. The aim of this work was to investigate volatile organic compounds emitted from untreated and chemically treated hemp shive and compare the emission characteristics to soft wood strands. Simple, yet effective chemical treatments, like tartaric acid, citric acid and sodium bicarbonate were used in order to reduce VOC emissions. Gas chromatography-mass spectrometry (GC-MS) combined with headspace solid-phase microextraction (HS-SPME) was used to analyse the volatile compounds emissions. Specific VOCs like acetic acid; Benzaldehyde; hexanal, α-, β-pinenes; limonene and camphene were monitored before and after the treatments. Non-target screening was performed to identify the most responsible compound for differentiation of samples according to their treatments. Comparing untreated samples, spruce strands showed highest amounts of total VOCs, while untreated hemp shive showed the lowest. Further, due to the chemical modification of hemp woody core components, such as hemicelluloses, lignin, and extractives, the key VOCs showed significant changes leading to an increase in the amount of total emissions.

Common wheat is currently the most widely grown cereal and its grains are mainly used to produce white bread. Contrary to plant seeds, the plant itself may be considered an agricultural waste which is used as an animal feed, soil fertilizer, or pelletized solid fuel to produce heat energy. While wheat straw is used widely in sustainable building construction, mostly as straw bales, the use of the thin dry husk around the grain, the wheat chaff, remained unexplored. An insulation panel made of a medium-density fiberboard (MDF) envelope and wooden studs was manufactured. The 150-mm gap between the MDFs was filled with dry wheat chaff. The thermal transmittance of the panel was determined under static and dynamic thermal conditions using a modified guarded hot box method. The results were compared to an insulation panel of the same construction that was filled with mineral wool. The thermal transmittance of wheat chaff under steady-state and dynamic conditions was 0.307 W m⁻² K⁻¹ and 0.298 W m⁻² K⁻¹, respectively. While in steady-state conditions the mineral wool outperforms the wheat chaff insulation, after a period of dynamic thermal loading, the ability of both insulations to resist heat-energy dissipation becomes similar. In conclusion, wheat chaff agrowaste seems to be a promising environmentally friendly alternative to artificial thermal insulation. Moreover, the determination of the thermal transmittance of bio-based materials with relatively high specific heat capacities under dynamic thermal loading, provides more accurate results, compared to steady-state conditions.

Hot-stage microscopy was used to characterise crystal growth at the interface between sisal fibre bundles and a polylactic acid (PLA) matrix in order to better understand the mechanical properties of sisal fibre–PLA composites. Cooling rates and crystallisation temperatures and times were varied to influence crystalline morphology at the interface. Single sisal fibre bundles were evaluated in their as received state or treated with 6 wt.% caustic soda solution for 48 h at room temperature. A microbond shear test was used to characterise the shear strength of the interface as a function of fibre surface treatment. These tests were performed on sisal fibre bundles carefully embedded in flat films of PLA supported on card mounts. Fibre bundles in a PLA matrix were cooled from 180 °C at rates from 2 to 9 °C/min and then crystallised isothermally. For as received fibre bundles uneven growth of PLA spherulites occurred at all cooling rates and crystallisation temperatures. For caustic soda treated fibres, uneven spherulitic growth was observed at crystallisation temperatures at and above 125 °C. In contrast, transcrystalline growth was observed for samples cooled to 120 °C at cooling rates from 2 to 6 °C/min and then allowed to crystallise. The microbond shear strengths of untreated and caustic soda treated fibre bundles were evaluated using Weibull statistics and the caustic soda treated fibres exhibited higher interfacial shear strengths in comparison to untreated fibres, reflecting the development of a transcrystalline layer at the fibre to matrix interface.