Bamboo, a key symbol of traditional Chinese culture, embodies a unique oriental aesthetic and philosophical spirit in cross-cultural contexts. We focus on the visual interpretation and in-depth expression of bamboo culture in Chinese martial arts films, aiming to overcome the existing limitations of the attention paid to its symbolic meaning. We employed a methodology encompassing text analysis, semiotics, and film aesthetics to trace the evolution of ‘bamboo grove’ imagery in A Touch of Zen (by King Hu), Crouching Tiger, Hidden Dragon (by Ang Lee), and House of Flying Daggers (by Zhang Yimou). This analysis revealed the ethereal emptiness of Zen, the inner psychological obsession of characters, and spectacle-based systemic oppression, respectively, in each of the films. Additionally, it examined the isomorphism between the bamboo soundscape and female psychological resilience in The Banquet (by Feng Xiaogang), as well as the maneuver in the bamboo objects narrative as fragmented space, thereby projecting the Taoist philosophy of non-anthropocentrism in The Assassin (by Hou Hsiao-hsien). We found that directors across generations have successfully transformed the physical properties of bamboos ranging from natural bamboo groves to specific bamboo objects into a core visual mechanism representing Oriental philosophy. Our analysis clearly indicates the profound relational reflection among bamboo imagery, narrative space, character psychology and film aesthetics, which collectively provide a systematic interpretation and theoretical support for Chinese films to overcome prejudices and biases associated with the bamboo curtain while conveying Oriental values, such as the ‘unity of heaven and human’ and ‘softness over hardness’ to the world audience.
The Gibberellin-Stimulated Arabidopsis (GASA) gene family encodes small, secreted peptides transcriptionally regulated by gibberellin (GA). These play vital roles in plant growth, development, stress tolerance and hormone signaling. Although GASA families have been identified in many model plants, a comprehensive genome-wide analysis of this family has not yet been reported in Moso bamboo (Phyllostachys edulis), the most economically valuable bamboo species, which is known for its rapid growth. In this study, 11 GASA genes were identified from the Moso bamboo genome using bioinformatics tools. Their physicochemical properties, phylogeny, collinearity, chromosomal distribution, gene structure, conserved motifs, protein tertiary structures and cis-regulatory components were analyzed comprehensively. Transcriptome data were adopted to investigated their expression patterns during rapid shoot elongation and in response to exogenous hormones. The results suggest that several PeGASA genes may contribute to the rapid elongation of bamboo shoots, and some PeGASAs appear to respond to GA and NAA induction. These findings are based on transcriptomic and regulatory element analyses; functional validation remains to be performed. Furthermore, transcription factors associated with the regulation of GASA genes were predicted, and we constructed a preliminary heatmap of the GASA-related regulatory network. Our work presents a crucial theoretical framework that will assist advancing functional evolutionary investigations involving the GASA gene family in Moso bamboo and the complete genome. Additionally, it establishes a framework for the effective identification of GASA genes associated with stress tolerance and hormone responsiveness, with implications for bamboo and other grass species improvement.
Bamboo’s inherent material variability poses a major challenge for structural standardization compared with engineered materials such as concrete or steel. Our study evaluated the capability of multiple machine learning (ML) techniques to predict key mechanical properties, namely compressive, tensile and shear capacities, using non-destructive physical measurements, and to identify the principal variables governing variability through principal component analysis (PCA). Following experimental testing and data preprocessing, eight ML algorithms, including tree-based ensemble models and regularized linear regressions, were developed and comparatively assessed. Model performance was evaluated in terms of prediction accuracy and generalization capability. Regularized linear models outperformed ensemble approaches, demonstrating superior robustness against noise inherent in natural bamboo datasets. Subsequently, PCA was applied to investigate the multivariate structure of the data, with eigenvalues and eigenvectors revealing that density and linear mass were the dominant contributors to variance. Based on these findings, we propose a practical predictive framework for on-site quality assurance: Geometric measurements are first screened using PCA and Hotelling’s T² statistic to ensure consistency with the training domain, after which the trained ML models are employed for capacity prediction. This integrated methodology enhances reliability in assessing naturally variable bamboo, thereby improving its feasibility for structural applications.
Crop damage by wild and stray animals is a major challenge for smallholder agriculture, underscoring the need for sustainable and affordable protective measures. Bamboo bio-fencing is a promising nature-based alternative. However, management interventions to accelerate barrier development are poorly understood. We evaluated the effects of soil mounding on growth, barrier formation, biomass production and carbon attributes of bamboo bio-fencing planted at 60cm plant-to-plant spacing under semi-arid conditions in India. Two species, Bambusa bambos and Dendrocalamus strictus, were evaluated under with-mounding (WM) and without-mounding (WoM) conditions using a quasi-experimental field approach. Soil mounding significantly improved the structural performance of the bio-fence by increasing closure percentage and reducing the gap fraction in both species. It also enhanced culm density, clump spread and culm diameter. However, the magnitude of these responses varied between the two species. Dendrocalamus strictus showed a stronger response in culm density, whereas Bambusa bambos produced larger culms and greater biomass accumulation. The highest total biomass was recorded in B. bambos under WM (3.66 t per 100m stretch), compared with 2.26 t per 100m stretch under WoM. Culm biomass increased by nearly 68–70% under mounding in both species. Carbon storage, sequestration rate, net O2 released and carbon credit value also increased markedly under mounded conditions. Among all treatments, B. bambos under WM recording the highest carbon stock (1.83 t per 100m stretch) and carbon credit value (US$ 83.98 per 100m stretch). The findings indicate that soil mounding is a practical management intervention for accelerating the structural development of bamboo bio-fences. It also improves biomass accumulation and enhances climate-mitigation potential, thereby strengthening the role of bamboo bio-fencing as a nature-based barrier with potential application in crop protection under semi-arid smallholder systems.
The transition to a circular bioeconomy has highlighted bamboo as a sustainable and high-yielding source of biomass for the production of functional carbon materials. We compile recent advances on the synthesis, functionalization, characterization, and application of bamboo-derived carbon materials comprising biochar, activated carbon, hydrochar, and nanostructured carbon. These materials exhibit tunable porosity, high surface areas and variable surface chemistries and are well-positioned for environmental remediation and energy storage. We discuss dominant adsorption processes such as electrostatic attraction, π–π stacking, pore filling and redox interactions as well as regeneration processes such as thermal, microwave and chemical treatment. We examine environmental life cycle factors, bibliometric trends and techno-economic assessments in order to identify research needs and commercial scalability. Gaps in long-term stability, scalability and standardization still exist despite tremendous advancements. We recommend areas of further research, including multidisciplinary creativity and legislative frameworks to accelerate the adoption of bamboo-based sustainable development solutions.
As an important economic forest species, Moso bamboo (Phyllostachys edulis) possesses significant ecological and economic value. However, the intensification of environmental pollution has heightened concerns regarding the impact of heavy metal stress on the growth and ecological functions of Moso bamboo. The MTP (Metal Tolerance Protein) gene family, also referred to as the CDF (Cation Diffusion Facilitator) gene family, consists of integral membrane transporters that facilitate the translocation of metal ions across plant membranes. By sequestering cytoplasmic divalent cations into vacuoles or other endomembrane compartments, MTPs effectively mitigate metal toxicity and maintain ionic homeostasis. Nevertheless, the genomic repertoire, expression landscape and biological roles of MTP genes in Moso bamboo remain largely uncharacterized. We conducted a genome-wide scan that identified 16 non-redundant MTP loci within the Moso bamboo genome. Phylogenetic reconstruction classified the bamboo MTP complement into four distinct clades that are evolutionarily conserved across land plants. Comprehensive in-silico characterization, including conserved motif profiling, exon-intron architecture, chromosomal distribution, cis-regulatory element composition and micro-synteny analyses, revealed both conserved lineage-specific features and segmental duplication events that have shaped this gene family. Time-course expression mining of RNA-seq datasets using STEM algorithms indicated that selected MTP paralogues are dynamically co-expressed during the rapid elongation phase of bamboo shoots, implicating this family in both developmental and stress-responsive processes. Homology-based tertiary modeling recapitulated the canonical CDF fold, with signature zinc-binding and cation-transporting motifs positioned within the transmembrane helices, thereby providing structural insights into ion selectivity and efflux mechanisms. Protein–protein interaction networks and transcription-factor binding-site enrichment further predicted a core regulatory module centered on five hub MTPs. Subcellular localization of GFP fusions in transgenic Nicotiana benthamiana confirmed plasma membrane residency for the investigated isoforms. Collectively, these findings provide the first integrated framework for understanding the classification, structural properties and putative physiological functions of the MTP family in Moso bamboo, establishing a molecular basis for future genetic improvements in bamboo resilience to heavy-metal stress.
Bamboo-based cooking fuel is an alternative to the unsustainable or “black” firewood/charcoal that is currently used by over 95% of the East African population. The use of “black” energy sources has undesirable environmental and livelihood consequences, such as forest cover loss and related climate change, energy insecurity and poor health for kitchen workers who breathe smoke-filled kitchen air. Bamboo is attractive for several reasons, the main one being that it can mature in a short period of 4–5 years; it is tag-harvested, meaning that the stump is composed of poles (culms) of different age and only the mature ones are harvested, thus avoiding replanting; and it can grow in marginal lands. The challenge for the adoption of bamboo as an energy source has been that it releases its energy too fast, which is inconsistent with local cooking habits. We sought to devise a way in which bamboo firewood and/or charcoal can be configured to cook like the preferred hardwood-derived firewood or charcoal. The solution adopted was to crush and densify the bamboo particles, forming non-carbonized briquettes (branded as YAZINI firewood) followed by carbonizing to produce charcoal (branded as YAZINI charcoal). Here, we characterize YAZINI with respect to its cooking performance under controlled environments as well as in the hands of target users. Six bamboo species were screened for their Fuel Value Index, and Bambusa vulgaris and Dendrocalamus asper were selected for further study. The validity of the proof-of-concept was tested by using a modified water-boil test and showing that YAZINI released it energy in a manner indistinguishable from that of hardwood-derived firewood/charcoal. To demonstrate potential for adoption, the water-boil test results were further confirmed in the hands of target users through usability studies. The usability of YAZINI firewood and charcoal were scored (on a Likert scale) between 4 (above average) and 5 (high) and 3 (average) and 4 (above average), respectively. The results indicate that YAZINI firewood and charcoal are viable alternatives to black firewood and charcoal in terms of cooking characteristics. However, further studies (pilot-scale) are needed to confirm the cooking characteristics with a wider target audience and most importantly to demonstrate economic viability, as well as kitchen air quality improvement.
Sustainable structural options are needed as conventional materials face supply and carbon constraints. We examined laminated bamboo lumber (LBL) columns manufactured from Bambusa spinosa (kawayang tinik) and quantified how the slenderness ratio (7) and eccentricity-to-height ratio (e0/h) affected the ultimate capacity under eccentric compression. The mechanical properties used in the analysis were parallel to grain. Prismatic LBL columns (50 & times;50 and 25 & times;25 mm; clear heights, 300, 450, 600 mm) were tested under quasi-static displacement control (0.5 mm min-1). Axial load, including prescribed eccentricities, was introduced through bonded steel end brackets that provided uniform bearing and pinned-like end conditions; offsets were verified prior to loading. There was a clear inverse relation between 7 and capacity, reflecting increased buckling susceptibility with slenderness, and a pronounced sensitivity to e0/h consistent with combined compression-bending. Based on the dataset, a species-specific empirical equation is proposed that integrates 7 and e0/h. Predictions clustered near the identity line with MAE = 1.35 kN, RMSE = 1.69 kN, and MAPE = 9.09% over the tested range (approximately 7 approximate to 21-83; e0/h approximate to 0.042-0.167), exhibiting a small conservative bias desirable for design. A benchmark against a published model indicated comparable accuracy while preserving local calibration to B. spinosa. In contrast to prior LBL studies that largely feature Phyllostachys pubescens and single-eccentricity tests, this work provides a dedicated B. spinosa dataset, examines multiple eccentricities together with slenderness, and delivers a calibrated, validated capacity model with a stated domain of applicability. The findings offer design-oriented, species-appropriate guidance for the structural use of engineered bamboo in Philippine practice and similar contexts.
Sourcing suitable fibres to take care of the deficit in the supply of fibre for pulp and paper production in some parts of the world is becoming increasingly difficult. Providing an alternative to the conventional species for fibre production requires investigation into the fibre characteristics of non-wood species, such as herbaceous field crops and shrubs. We evaluated the fibre characteristics of two cultivars of Bambusa vulgaris to assess their potential as a substitute for other fibre species. Culms of the two cultivars of bamboo were collected from the Forestry Research Institute of Nigeria at Jericho in Ibadan, Nigeria. Wood slivers from the base, middle and top were macerated using equal volumes (1:1) of glacial acetic acid and hydrogen peroxide inside an oven for 4 h at a temperature of 100 degrees C. Parameters assessed include fibre length (FL), fibre diameter (FD), lumen width (LW), cell wall thickness, Runkel ratio (RR), slenderness ratio (SR) and flexibility ratio (FR). The correlation between fibre length and other parameters was assessed. The mean FL of the two cultivars ('Vitata' and 'Wamin') were 2.76 f 0.73 and 2.46 f 0.75 mm, FD (17.77 f 4.87 and 13.93 f 2.15 & micro;m), LW (17.77 f 4.87 and 13.93 f 2.15 & micro;m), and CWT (4.57 f 1.36 and 2.34 f 0.68 & micro;m), respectively. FL had a strong and positive relationship with every other fibre characteristic. The fibres from the two cultivars are suitable for paper production given their respective fibre lengths.
Tanzania hosts a rich diversity of palms, bamboos and other woody species that are pivotal for ecosystem functioning, carbon sequestration and rural livelihoods. This study provides a comprehensive characterization of Tanzania’s palms and bamboo, integrating growth forms, ecological distributions and utilization patterns using the updated National Forestry Resources Monitoring and Assessment species list and field inventory data collected between 2015 and 2023. The revised dataset strengthens the foundation for national forest monitoring under the Measurement, Reporting, and Verification framework of the National Carbon Monitoring Centre, supporting transparent and robust carbon accounting aligned with the reduced emissions from deforestation and forest degradation, plus the role of conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries (REDD+) policy objectives. By combining extensive field surveys with modern monitoring approaches, this research not only identifies species-specific ecological requirements and conservation priorities but also informs sustainable management strategies, value chain development and climate mitigation planning. The updated species inventory establishes a critical baseline for long-term forest monitoring, providing a replicable model for tropical countries seeking to balance biodiversity conservation, carbon sequestration and socio-economic development.
Bamboo is a fast-growing, renewable forest resource with the potential to address interconnected social, economic and environmental challenges in Sub-Saharan Africa (SSA). Despite this promise, the bamboo sector remains underdeveloped, and its contributions to sustainable livelihoods and the UN Sustainable Development Goals (SDGs) are not fully realised. This review systematically synthesises evidence on how bamboo enhances rural livelihoods in the five SSA countries with the most significant bamboo resources and sector activity: Ethiopia, Ghana, Nigeria, Tanzania and Uganda. Examining peer-reviewed articles, technical reports, and case studies from 2014 to 2026, I identify four promising bamboo value chains: (1) sustainable energy (charcoal and briquettes) advancing SDG 7 (Affordable and Clean Energy); (2) construction and engineered materials supporting SDG 11 (Sustainable Cities and Communities); (3) furniture and handicrafts fostering SDG 1 (No Poverty) and SDG 5 (Gender Equality); and (4) edible shoots contributing to SDG 2 (Zero Hunger). My comparative analysis reveals distinct national trajectories: Ethiopia possesses vast latent potential constrained by infrastructure deficits; Nigeria demonstrates market-driven construction sector disruption but lacks coherent governance; Tanzania leverages indigenous knowledge for diversified rural livelihoods; and Ghana and Uganda exemplify policy-led value addition where institutional coherence compensates for modest resource endowments. Cross-cutting barriers, fragmented policies, weak processing infrastructure, limited technical capacity and insecure land tenure impede sectoral advancement across all five nations. To overcome these challenges, I propose a ''Bamboo-livelihoods nexus'' approach emphasizing differentiated, context-specific interventions: Infrastructure investment in Ethiopia, pro-poor value chain formalization in Nigeria, scaling of Ghana's balanced model, and technology transfer in Tanzania and Uganda. My findings underscore that bamboo’s ultimate contribution to the 2030 agenda depends less on hectares of standing stock than on the coherence of institutions, policies, and the value chains constructed around it.
Agroforestry is vital for sustainable land and tree management, enhancing rural livelihoods while addressing environmental degradation. In northwestern Ethiopia, bamboo is a key component of agroforestry systems, commonly cultivated in homesteads and along farm boundaries. We investigate the factors that influence farmers' bamboo practices, traditional management techniques and the socio-economic significance of bamboo in Banja District, Awi Zone, northwestern Ethiopia. Data were collected from 270 households across three kebeles, categorized by their distance from the main road: within 4 km, 4-8 km, and beyond 8 km. The findings reveal a robust tradition of bamboo cultivation, with households averaging over twenty years of experience. Bamboo is primarily planted in homesteads and along farm boundaries, serving as an essential resource for crafting handicrafts, furniture and tool handles. Despite its significance, most households allocate less than 5% of their land to bamboo cultivation. Management practices include selective thinning, mulching, fencing and manuring, but formal technical support is lacking. Three bamboo landraces were identified: Tikur, Key and Zeger, with Tikur being the most preferred due to its adaptability and economic value, as evidenced by its advantages in growth parameters such as internode length and branch number. Proximity to roads positively correlated with better management practices and increased bamboo-related income. The age distribution of bamboo culms indicated that 42% were 1-3 years old, 34% were over 3 years old and 24% were less than a year old. Despite a rise in bamboo plantations over the past two decades, challenges such as limited extension services and unequal market access persist. Farmers located closer to main roads benefit from improved practices due to better access to information and markets. Our study underscores bamboo's potential for enhancing income and sustainability, highlighting the need for improved resource management, genetic research and strengthened extension services to maximize the benefits of bamboo cultivation for rural communities in Ethiopia.
We investigated the biomass fuel characteristics, thermal degradation behaviour and iso-conversional kinetics of raw and carbonized Philippine giant bamboo (Dendrocalamus asper) under inert (N2) and oxidative (air) atmospheres using simultaneous TG-DTG-DSC analyses at heating rates of 5-20 degrees C min-1. Carbonization significantly enhanced fixed carbon content (up to 64.60%), increased gross calorific value (26.96 MJ kg-& sup1;) and energy density (4.59 GJ m-& sup3;), and substantially reduced volatile matter. In nitrogen, raw bamboo exhibited devolatilization within 200-400 degrees C corresponding to hemicellulose and cellulose degradation, whereas carbonized bamboo showed delayed and broadened high-temperature degradation (300-750 degrees C) associated with aromatic carbon restructuring. In air, raw bamboo underwent volatile oxidation followed by char combustion, while carbonized bamboo displayed a dominant oxidation stage attributed to char oxidation within 300-650 degrees C. Iso-conversional analyses using the Ozawa-Flynn-Wall, Starink and Friedman methods revealed conversion-dependent apparent activation energy (EA) evolution, confirming multi-step kinetics. Under inert conditions, carbonization increased EA at intermediate to high conversions (alpha = 0.6-0.8), indicating enhanced structural stability of the condensed carbon matrix. Conversely, in air, carbonized D. asper exhibited markedly lower activation energies (approximate to 42.60-98.64 kJ mol-& sup1;) compared to raw bamboo (approximate to 73.21-176.25 kJ mol-& sup1;), suggesting a potential mineral-associated catalytic effects supported by Fe2O3 enrichment in ash. Overall, carbonization induced an atmosphere-dependent shift in degradation mechanisms, and the validated conversion-dependent kinetic parameters provide intrinsic inputs for mechanistic modeling of bamboo-based biomass energy systems.
Ethiopia has suitable and untapped areas with high potential for bamboo resources, primarily located in the highlands, particularly in Amhara, Oromia, and the Southern Nations, Nationalities, and Peoples' Regional State. Ethiopia encompasses approximately 9.9 million hectares, suggesting a large potential for the development of this species. The species typically grows in backyards and homesteads, along farm boundaries, on gully sides, in woodlots, and along roadsides. I examined the distribution, determinants, opportunities, and challenges related to the development of highland bamboo in Ethiopia. Socioeconomic, demographic, and institutional factors, including farmers' perceptions, access to extension services and training, market demand, road availability, silvicultural management techniques, competition with other plantation forests, and bamboo culm prices, are factors that influence the establishment, expansion, and marketing of bamboo. Although affordable opportunities and a positive policy environment exist, there are still issues with coordination, implementation gaps, market challenges, and limited government support for sector development. The sector has received limited attention as a potential sector for the country's economic growth. Market-related constraints and knowledge gaps in bamboo production and processing were the most significant challenges that I identified in this study. Actors need to be empowered by improving their awareness, establishing better linkages, and accessing information to facilitate effective value addition and increase commercialization. Creating an enabling environment, building a value chain, and applying regulations locally are essential steps to boost the development of highland bamboo plantations.
The sustainable management of food-service waste requires innovative upcycling strategies to mitigate environmental accumulation. This study valorizes two problematic waste streams-post-consumer polypropylene (rPP) from diverse packaging and discarded bamboo chopsticks (rB)-into high-performance bamboo-plastic composites (BPCs). The novelty of this work lies in eliminating synthetic coupling agents by utilizing endogenous oxidation products in the rPP matrix to enhance interfacial compatibility with hydrophilic bamboo fibres. Thermal analysis revealed that beverage-grade rPP exhibited a higher crystallinity (49.18%) than its food-grade and virgin counterparts. Crucially, FTIR spectroscopy identified oxidative degradation products in the recycled matrices which, rather than compromising performance, functioned as intrinsic adhesion promoters. This increased surface polarity significantly enhanced interfacial bonding with the hydrophilic bamboo fibres compared to virgin PP systems, as corroborated by scanning electron microscopy. Although the rB fibres underwent a reduction in cellulose crystallinity and increased hygroscopicity due to prior service life, the resulting composites maintained robust mechanical and physical integrity. All rPP-rB formulations successfully complied with the Thai Industrial Standard (TIS 2998-2019) for exterior-grade applications, achieving densities > 0.90 g & sdot;cm(-3) , flexural strengths > 20 MPa, and 24-hour water absorption < 5%. These findings suggest that the cumulative thermal history and intrinsic oxidation of recycled polymers could be strategically leveraged to engineer compatible, value-added circular materials, offering a scalable route for upcycling contaminated foodservice waste.
The pyrolysis temperature dependence on the properties of Moso bamboo (Phyllostachys edulis) charcoal was investigated over temperatures ranging from 200 degrees C to 900 degrees C. With increasing the pyrolysis temperature, the yield, hydrogen and oxygen contents of the charcoals decreased. The XPS result showed that the O/C ratio decreased with increasing the pyrolysis temperature. The N2 adsorption isotherms revealed a maximum value of BET specific surface area of 537 m2 g-1 at 800 degrees C of the pyrolysis temperature. The micropore volumes estimated from CO2 adsorption isotherms at 298 K using the DA method were larger than those estimated from N2 adsorption isotherms at 77 K using the t-plot method. The sample prepared at 400 degrees C had a very large difference (around 2000%). The potassium ion concentration of the bamboo charcoal slurry increased with increasing the pyrolysis temperature. The pH value of the slurry-dispersed bamboo charcoal increased with increasing pyrolysis temperature up to 9.5 at 400 degrees C and then remained at a similar value up to 900 degrees C. This study offers foundational insights into the application potential of bamboo charcoal by examining its properties across a wide range of pyrolysis temperatures.
We determined the major predictor of the compressive load capacity of Oldeania alpina. This may enable the use of intact whole culms in the construction sector, given the increasing popularity of bamboo in structural applications. An extensive experimental investigation of compressive properties was conducted in two independent laboratories (AASTU and AAiT). Data normality tests were carried out prior to the datasets being pooled for a comprehensive analysis, and then regression analyses were used to identify the optimal physical properties. Additionally, the effects of culm height location and node presence on compressive and physical properties were evaluated. Linear mass, wall thickness, diameter, moisture content and density had the strongest relationships with compressive performance. While density predicted compressive strength inefficiently, linear mass performed best in simple regression (R² = 0.553 for ultimate load), and multiple linear regression significantly improved predictive accuracy. The position of the culm had a greater impact on mechanical properties (ultimate load, strength, stiffness) than the existence of a node. Nodes did not lower the culm's ultimate load capacity (p = 0.507). Despite having a lower compressive strength, bottom portions demonstrated a significantly higher ultimate load due to their bigger cross-sectional area. The exceptional mechanical potential of Oldeania alpina was confirmed by its mean compressive strength of 62.79MPa, which makes it ideal for contemporary load-bearing structures. 95% confidence bands were used to develop strength and load-capacity grading systems, and we found that capacity-based grading, which uses linear mass, was more reliable and trustworthy for commercial grading.
The effects of multiple recycling cycles on bamboo flour-thermoplastic polyurethane filaments and their properties in fused filament fabrication were investigated. Successive recycling induced progressive thermomechanical degradation of the thermoplastic polyurethane matrix, decreasing the average number and average molecular weight, while increasing polydispersity as shown by chain scission. Scanning electron microscopy images revealed increasingly rough and irregular filament surfaces with recycling, whereas gel permeation chromatography and differential scanning calorimetry confirmed reduced chain length and crystallinity, followed by partial recrystallization after three recycling cycles due to increased chain mobility. Mechanical testing indicated significant property deterioration, with the tensile strength, modulus and elongation at break decreasing by more than 50% after three recycling cycles. The decline in tensile properties was attributed to reduced thermoplastic polyurethane molecular weight, thermal degradation of bamboo flour, and persistent porosity, despite some compensatory effects from improved the adhesion between bamboo flour and matrix. With respect to printing by fused filament fabrication with bamboo flour-thermoplastic polyurethane parts from recycled filaments, additional property losses occurred because of weakened layer bonding, although the change in tensile modulus was not influenced significantly. Additionally, correlations between weight-average molecular weight and tensile properties highlighted molecular weight as a reliable processing-structure-property indicator. Despite property reductions, the recycled parts maintained mechanical properties comparable to those of elastomers and leather, underscoring their potential for applications in additive manufacturing and footwear applications.
