Additive manufacturing is distinguished from traditional manufacturing techniques such as casting and machining by its ability to handle complex shapes with great design flexibility and without the ...typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in direct manufacture of actual parts. For wide spread application of 3D additive manufacturing, both techniques and feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Here, we investigated short fiber (0.2–0.4mm) reinforced acrylonitrile–butadiene–styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructure and mechanical performance. The additive components are also compared with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ∼115% and ∼700%, respectively. 3D-printing yielded samples with very high fiber orientation in the printing direction (up to 91.5%), whereas, compression molding process yielded samples with significantly lower fiber orientation. Microstructure–mechanical property relationships revealed that although a relatively high porosity is observed in 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. This phenomenon is explained based on the changes in fiber orientation, dispersion and void formation.
Research and development activities directed toward commercial production of cellulosic ethanol have created the opportunity to dramatically increase the transformation of lignin to value-added ...products. Here, we highlight recent advances in this lignin valorization effort. Discovery of genetic variants in native populations of bioenergy crops and direct manipulation of biosynthesis pathways have produced lignin feedstocks with favorable properties for recovery and downstream conversion. Advances in analytical chemistry and computational modeling detail the structure of the modified lignin and direct bioengineering strategies for future targeted properties. Refinement of biomass pretreatment technologies has further facilitated lignin recovery, and this coupled with genetic engineering will enable new uses for this biopolymer, including low-cost carbon fibers, engineered plastics and thermoplastic elastomers, polymeric foams, fungible fuels, and commodity chemicals.
This work reports a scalable method to synthesize hierarchically porous, hetero-atom doped activated carbon nanosheet from waste biomass−human hair, and demonstrates the use of this carbon as an ...ultra-high performance electrode material for supercapacitor applications. Microscopic analyses reveal that sheet size ranges from 50 to 200 nm having a thickness of 15–27 nm. As-synthesized, carbon nanosheets possess a hierarchical porous structure having a specific surface area of 1548 m2 g−1. Heteroatom concentration (nitrogen, oxygen, and sulfur) of around 25% is confirmed from XPS analysis. Therefore, the novel interconnected hierarchical porous nanosheets structure enables fast adsorption and transportation of ions during electrochemical processes. Also, the abundant chemically available electroactive heteroatom species in the material enhance the wettability of ions and contribute to pseudocapacitance. The electrochemical analyses through cyclic voltammetry and galvanostatic charge-discharge measurements in 6 M KOH reveal the quasi-EDLC behavior of the activated carbons due to the presence of heteroatoms. A reprensentative KOH activated carbon shows an excellent specific capacitance value of 999 F g−1 at a current density of 1 A g-1. The symmetrically assembled two-electrode device also delivers a maximum energy density of 32 W h Kg-1 at a power density of 325 W Kg-1. In addition, excellent cyclic stability of 98% capacitance retention is observed after 10,000 continuous GCD cycles even at a high current density of 5 A g−1. Symmetric flexible supercapacitor device using KOH-PVA-K3FeCN6 as redox gel polymer electrolyte shows a synergistic specific capacitance of 145 mF cm−1 at a current density of 0.8 mA cm−1 exhibiting very less deviation in bending mode. Therefore, this waste biomass derived heteroatom doped hierarchical porous carbon nanosheets can be a promising material for cost-effective high- performance supercapacitor.
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•The modified route yields hierarchical, porous, interconnected heteroatom doped carbon nanosheets from waste human hair.•Isothermal holding during carbonization and activation increases crosslinking of aromatic compounds into carbon skeleton.•Around 25% of heteroatom doping concentration is achieved using a modified synthesis route.•The electrode material shows an excellent specific capacitance value of 999 F g−1 at a current density of 1 A g−1.•Symmetrically assembled supercapacitor device delivers energy density of 32 W h Kg−1 at a power density of 325 W kg−1
Transformer-based large language models have remarkable potential to accelerate design optimization for applications such as drug development and material discovery. Self-supervised pretraining of ...transformer models requires large-scale data sets, which are often sparsely populated in topical areas such as polymer science. State-of-the-art approaches for polymers conduct data augmentation to generate additional samples but unavoidably incur extra computational costs. In contrast, large-scale open-source data sets are available for small molecules and provide a potential solution to data scarcity through transfer learning. In this work, we show that using transformers pretrained on small molecules and fine-tuned on polymer properties achieves comparable accuracy to those trained on augmented polymer data sets for a series of benchmark prediction tasks.
Carbon fiber composite's high specific strength makes it incredibly useful for structural applications. However, their low strain-to-failure can be problematic in structural applications that can ...potentially see high strain conditions or high fatigue cycles resulting in sudden, catastrophic failure. This is further complicated by damage manifesting within the composite thus not showing damage indicators on the surface. Therefore, monitoring the structural integrity and strain history of the composite in application by itself―while maintaining positive composite performance―is vital to ensure safe operation. Here, a homogeneous dispersion of TiO2 nanoparticles on carbon fiber is demonstrated to generate a piezoresistive carbon fiber polymer matrix composite with enhanced self-sensing capabilities. The nanoparticle-embedded composites also exhibited superior strength and damping potential compared to the nanoparticle-free composites. The apparent interlaminar shear strength increased by up to 15% and the damping loss factor increased by an average of 150% while the piezoresistive sensitivity increased by up to 180% with the addition of a small weight fraction of nanoparticles to the fiber surface. These results demonstrate an approach to simultaneously improve the sensing capabilities, damping behavior and mechanical strength of carbon fiber composites by simply adding nanoparticles in the fiber sizing using a commercially scalable deposition method.
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Template-synthesized mesoporous carbons were successfully used in in vitro investigations of controlled delivery of three model drugs, captopril, furosemide, and ranitidine hydrochloride (HCl). ...Captopril and furosemide exhibited desorption kinetics over 30–40h, and ranitidine. HCl had a complete release time of 5–10h. As evident from the slow release kinetics, the mesoporous carbons have excellent potential for the controlled-release media of the specific drugs targeted towards oral delivery. The mesoporous carbons, synthesized from phloroglucinol and lignin, a synthetic and a sustainable precursor, respectively, exhibit BET surface area of 200–400m2g−1 and pore volume of 0.2–0.6cm3g−1. The synthetic carbon has narrower pore widths and higher pore volume than the renewable counterpart and maintains a longer release time. The release kinetics reveals that the diffusivities of the drugs from carbon media are of equivalent magnitude (10−22 to 10−24m2s−1). However, a tailored reduction of pore width in the sorbent reduces the diffusivity of smaller drug molecule by an order of magnitude. Thus, engineered pore morphology, along with its functionalization potential for specific interaction, can be exploited for optimal delivery system of a preferred drug.
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•Addition of 10wt.% nitrile rubber toughened the ABS/lignin blends dramatically.•Addition of 10wt.% of carbon fibers enhances the performance and lowers the degree of chemical ...crosslinking.•A highly interfused printed structure with 100% improved inter-layer adhesion strength was obtained.•3D-printed plastic composites with 40wt.% lignin content were produced.
We report the utilization of a melt-stable lignin waste-stream from biorefineries as a renewable feedstock, with acrylonitrile-butadiene rubber and acrylonitrile-butadiene-styrene (ABS) polymer to synthesize a renewable matrix having excellent 3D-printability. While the initial low melt viscosity of the dispersed lignin phase induces local thermo-rheological relaxation facilitating the composite's melt flow, thermal crosslinking in both lignin and rubber phases as well as at the lignin-rubber interface decreases the molecular mobility. Consequently, interfacial diffusion and the resulting adhesion between deposited layers is decreased. However, addition of 10wt.% of discontinuous carbon fibers (CFs) within the green composites not only significantly enhances the material performance but also lowers the degree of chemical crosslinking formed in the matrix during melt-phase synthesis. Furthermore, abundant functional groups including hydroxyl (from lignin) and nitrile (from rubber and ABS) allow combinations of hydrogen bonded structures where CFs play a critical bridging role between the deposited layers. As a result, a highly interfused printed structure with 100% improved inter-layer adhesion strength was obtained. This research offers a route toward utilizing lignin for replacement of petroleum-based thermoplastics used in additive manufacturing and methods to enhance printability of the materials with exceptional mechanical performance.
A new class of thermoplastic elastomers has been created by introducing nanoscale‐dispersed lignin (a biomass‐derived phenolic oligomer) into nitrile rubber. Temperature‐induced controlled ...miscibility between the lignin and the rubber during high shear melt‐phase synthesis allows tuning the material's morphology and performance. The sustainable product has unprecedented yield stress (15–45 MPa), strain hardens at large deformation, and has outstanding recyclability. The multiphase polymers developed from an equal‐mass mixture of a melt‐stable lignin fraction and nitrile rubber with optimal acrylonitrile content, using the method described here, show 5–100 nm lignin lamellae with a high‐modulus rubbery interphase. Molded or printed elastomeric products prepared from the lignin‐nitrile material offer an additional revenue stream to pulping mills and biorefineries.
A novel and powerful method for synthesizing a new class of high‐performance renewable thermoplastic elastomers is introduced. This new class of multiphase polymers shows 5–100 nm thick interconnected lignin lamellae with a high modulus rubbery interphase. The success in developing this unique morphology is the key innovation behind this first report on lignin‐based elastomers with unique yield stress.
Hard-carbon materials are considered as one of the most promising anodes for the emerging sodium-ion batteries. Here, we report a low-cost, scalable waste tire-derived carbon as an anode for ...sodium-ion batteries (SIBs). Tire-derived carbons obtained by pyrolyzing acid-treated tire at 1100 °C, 1400 °C and 1600 °C show capacities of 179, 185 and 203 mAh g−1, respectively, after 100 cycles at a current density of 20 mA g−1 in sodium-ion batteries with good electrochemical stability. The portion of the low-voltage plateau region in the charge-discharge curves increases as the heat-treatment temperature increases. The low-voltage plateau is beneficial to enhance the energy density of the full cell. This study provides a new pathway for inexpensive, environmentally benign and value-added waste tire-derived products towards large-scale energy storage applications.
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•Carbon composites were successfully prepared from waste tires for Na-ion batteries.•Tire-derived carbon anodes show good capacities and stabilities after long cycling.•The capacity plateau below 0.2 V increases drastically with pyrolysis temperature.•Demonstrated a low-cost and environmentally friendly anode for energy storage.
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