There are millions of tons of post-food processing residues discarded annually. Currently, these waste materials are discarded to landfill, used as animal feed or incinerated. This suggests that ...there are potential uses for these materials in value-added applications. This work focuses on the characterization and valorization of peanut hulls through the generation of green composites. Peanut hulls were pyrolyzed at 500 °C and analyzed to discover their unique surface morphology and relatively low ash content. Raman spectral analysis determined I
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values of 0.74 for the samples, suggesting greater graphitic content than disordered carbon content. Such results were confirmed in X-ray diffraction analysis by the presence of (002) and (100) planes. Partially biobased engineering thermoplastic, poly(trimethylene terephthalate) (PTT), was combined with 20 wt.% biocarbon. The tensile and flexural moduli improved with the addition of biocarbon, and the bio-content increased from 35 to 48 wt.% as compared to neat PTT. The higher temperature biocarbon was found to have superior performance over the lower temperature sample. The enhanced sustainability of these materials suggested that peanut hulls can be valorized via thermochemical conversion to generate value-added products. Future works could focus on the optimization of these materials for non-structural automotive components or electrical housings.
A mixture design of experiment (DoE) was used to guide the fabrication and analysis of sustainable poly(lactic acid) (PLA) and biobased poly(butylene succinate) (BioPBS) 3D-printing filaments. The ...statistical DoE approach was employed to investigate the correlation between the mechanical properties of the PLA/BioPBS blends at different PLA and BioPBS wt % and to obtain the linear regression models of the mechanical properties. The statistical models help to design PLA/BioPBS blends with the desired mechanical properties. The PLA/BioPBS filaments with different composition ratios were 3D-printed via fused deposition modeling (FDM). The 3D-printability of the polymer blends was determined by the flowability and dimensional stability of the filaments, provided by fundamental rheological and coefficient of linear thermal expansion (CLTE) studies. Preliminary research found that the 3D-printability of PLA/BioPBS filaments with BioPBS content higher than 50 wt % was unsuccessful due to high viscosity and low thermal stability. These findings were verified with rheological tests for a range of PLA/BioPBS blend ratios and thermomechanical studies. Rheological results show a significant increase of the blend viscosity when BioPBS content in the blend was >50%. Additionally, the CLTE drastically increased with higher contents of BioPBS, making the PLA/BioPBS filaments thermally unstable during FDM processing. These results confirmed that the 3D-printability of PLA/BioPBS filaments is greatly influenced by the blend viscosity and the printing temperature. Rheological studies revealed that the viscosity range of a 3D-printable PLA/BioPBS filament lies within 1000–100 Pa·s. Scanning electron microscopy (SEM) and polarized optical microscopy (POM) images confirmed that PLA and BioPBS are immiscible. However, the addition of BioPBS improved the ductility and the crystallinity of PLA. The 3D printed PLA/BioPBS (90/10) blend showed an interesting result in that it obtained higher tensile and impact strengths than the neat PLA, which was attributed to crystallinity and morphological factors.
A considerable amount of powder residue is generated during the selective laser sintering (SLS) process. Processing the powder residue into filaments for extrusion-based additive manufacturing (EAM) ...provides an opportunity to recycle SLS residue without significantly reducing its value. In this study, the feasibility of using a milled carbon fiber (mCF)/recycled polyamide12 (rPA12) composite filament for EAM was demonstrated. A microscopic study on the morphology of mCF showed that mCF is a short and smooth fiber. The mCF did not significantly change the melting temperature, crystallization temperature or crystallinity of rPA12 as measured by differential scanning calorimetry (DSC). A morphological study on the fracture-surface of the composites revealed that there was moderate interfacial interaction between the mCF and PA12. Tensile strength, tensile modulus, flexural strength, flexural modulus and impact strength of rPA12 were improved by 35%, 163%, 61%, 138% and 23%, respectively with the addition of 30 wt.% mCF.
This review provides a current summary of the major sources and distribution of ocean plastic contamination, their potential environmental effects, and prospects towards the mitigation of plastic ...pollution. A characterization between micro and macro plastics has been established, along with a comprehensive discussion of the most common plastic waste sources that end up in aquatic environments within these categories. Distribution of these sources stems mainly from improper waste management, road runoff, and wastewater pathways, along with potential routes of prevention. The environmental impact of ocean plastics is not yet fully understood, and as such, current research on the potential adverse health effects and impact on marine habitats has been discussed. With increasing environmental damage and economic losses estimated at $US 1.5 trillion, the challenge of ocean plastics needs to be at the forefront of political and societal discussions. Efforts to increase the feasibility of collected ocean plastics through value-added commercial products and development of an international supply chain has been explored. An integrative, global approach towards addressing the growing ocean plastic problem has been presented.
Ocean plastics are of utmost global concern due to their impact on the environment, society, and economy. This perspective addresses the major contributing sources of ocean plastic pollution, their effects, and promising mitigation strategies.
A sustainable green composite based on poly(3-hydroxybutyrate) (PHB) and agave fibre was produced. The synergy between PHB bioplastic and agave natural fibre was investigated in the presence of an ...organic peroxide through one step reactive extrusion processing. The work focuses on controlling the crystallinity of PHB to tailor the mechanical properties, especially for improving the impact properties of highly brittle PHB. Optical microscopy showed a decrease in spherulite formation, and hence controlled reduction of the crystalline region of the PHB matrix, with the addition of agave fibre and peroxide treated fibre. Scanning electron microscopy showed the role of organic peroxide in improving the interfacial interaction in fibre matrix adhesion, and hence resulting in improved mechanical properties. An expected reduction in tensile strength of PHB was found with the addition of 25 wt% of agave fibre due to the reduction in crystallinity induced by the treated agave fibre. Interestingly, optimal composition of composites having 25 wt% agave fibre with 0.1 phr peroxide improved the flexural strength by 46%, impact strength by 45% and heat deflection temperature (HDT) by 39% compared to the neat PHB. An effective reactive extrusion of agave fibre and PHB in the presence of peroxide can provide a sustainable and cost-effective alternative to petroleum-based plastics for food packaging applications.
A sustainable composite based on poly(3-hydroxybutyrate) PHB and agave fibre was produced.
The effect of three different types of cellulose nanofillers on the morphology, mechanical, and thermal properties of flexible polyurethane foam was studied. Cellulose nanocrystals (CNC), cellulose ...nanofibrils (CNF), and cellulose filaments (CelFil) were used as fillers at 0.1–0.8 wt% loading levels. The comparison of the results showed that smaller loading levels resulted in foams with better performance in almost all cases. In the next step, the properties of foams containing CNC, CNF, or CelFil at 0.025%–0.1% loading levels were compared with those made with inorganic nanofillers including nanosilica (nSi), reduced graphene oxide, and halloysite nanotubes (HNT). Among all the properties evaluated, the tensile modulus of the foams was improved up to 40% by adding HNT at 0.05 wt% loading level whereas the addition of CNF resulted in a 44% increase in the compressive modulus of the foams at 0.1 wt% loading level.
In this work the influence of different organic and inorganic fillers on the mechanical and thermal properties of flexible polyurethane foams was compared.
Advanced hybrid biocomposites are engineered from nylon 6, waste wood biosourced carbon (biocarbon) with a low content of synthetic fiber for lightweight auto‐parts uses. The novel engineering ...process through direct injection molding of only 2 wt% synthetic fibers in the form of masterbatch with 20 wt% biocarbon, results outstanding performance of the resulting nylon biocomposites. Such uniquely developed biocomposites show tensile strength of 105 MPa and tensile modulus of 5.14 GPa with a remarkable heat deflection temperature (HDT) of 206 °C. The direct injection molding of synthetic fiber retains the length ≈3 times higher as compared to traditional extrusion and injection molding; resulting greater degree of entanglement and composite reinforcement effectiveness in the hybrid biocomposites. Highly dimensionally stable nylon 6 biocomposites with a very low coefficient of linear thermal expansion results through reinforcing ability of the sustainable biocarbon and small amount of synthetic fiber.
Enhancement of mechanical properties of the fiber‐reinforced composites are mostly restricted due to the fiber breakage during extrusion and compounding. In this work, a superior mechanical and thermal properties enhancement of polyamide 6/biocarbon composites co‐reinforced with synthetic fiber (glass fiber or carbon fiber) masterbatch through direct injection molding is presented.
Recycled newspaper cellulose fiber (RNCF) reinforced poly(lactic acid) (PLA) biocomposites were fabricated by a microcompounding and molding system. RNCF-reinforced polypropylene (PP) composites were ...also processed with a recycled newspaper fiber content of 30 wt % and were compared to PLA/RNCF composites. The mechanical and thermal−mechanical properties of these composites have been studied and compared to PLA/talc and PP/talc composites. These composites possess similar mechanical properties to talc-filled composites as a result of reinforcement by RNCF. The tensile and flexural modulus of the biocomposites was significantly higher when compared with the virgin resin. The tensile modulus (6.3 GPa) of the PLA/RNCF composite (30 wt % fiber content) was comparable to that of traditional (i.e. polypropylene/talc) composites. The DMA storage modulus and the loss modulus of the RNCF−PLA composites were found to increase, whereas the mechanical loss factor (tan δ) was found to decrease. Differential scanning calorimetry (DSC) thermograms of neat PLA and of the composites exhibit nearly the same glass transition temperatures and melting temperatures. The morphology evaluated by scanning electron microscopy (SEM) indicated good dispersion of RNCF in the PLA matrix. Thermogravimetric analysis (TGA) thermograms reveal the thermal stability of the biocomposites to nearly 350 °C. These findings illustrate that RNCF possesses good thermal properties, compares favorably with talc filler in mechanical properties, and could be a good alternative reinforcement fiber for biopolymer composites.
This work features the first-time use of poly(trimethylene terephthalate) (PTT), a biobased engineering thermoplastic, for fused deposition modeling (FDM) applications. Additives such as chain ...extenders (CEs) and impact modifiers are traditionally used to improve the processability of polymers for injection molding; as a proof of concept for their use in FDM, the same strategies were applied to PTT to improve its printability. The filament processing conditions and printing parameters were optimized to generate complete, warpage-free samples. The blends were characterized through physical, thermal, viscoelastic, and morphological analyses. In the optimal blend (90 wt % PTT, 10 wt % impact modifier, and 0.5 phr CE), the filament diameter was improved by ∼150%, the size of the spherulites significantly decreased to 5% of the ∼26 μm spherulite size found in neat PTT, and the melt flow index decreased to ∼4.7 g/10 min. From this blend, FDM samples with a high impact performance of ∼61 J/m were obtained, which are comparable to other conventional FDM thermoplastics. The ability to print complete and warpage-free samples from this blend suggests a new filament feedstock material for industrial and home-use FDM applications. This paper discusses methods to improve hard-to-print polymers and presents the improved printability of PTT as proof of these methods’ effectiveness.
The effects of soy-based oil on the constitutive behavior of EPDM rubber have been investigated. Soy polyols with various hydroxyl numbers as well as unmodified soybean oil have each been ...incorporated in the EPDM rubber as a partial replacement for petroleum oil. Tensile tests have been performed at low and high rates, and hysteresis and stress relaxation tests have been performed at low rates. It has been found from the tensile tests that the rubber with soy polyol of low hydroxyl number can provide very similar constitutive characteristics as the control. On the other hand, the constitutive characteristics are significantly changed by using soy polyol of high hydroxyl number or unmodified soybean oil. For example, the rubber with unmodified soybean oil elongates substantially up to stretch ratios of 13, which is approximately 100% greater than that of the control. It has also been found from the tensile and hysteresis tests that the soy-based rubbers generally have better energy storing and dissipation characteristics than the control, such as storing more energy while maintaining lower peak stress, for an impact application. The test results indicate the potential for application based tuning of soy rubber properties by selecting an appropriate soy oil/EPDM blend or a polyol/EPDM blend with optimized functionality.
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