8 research outputs found
Piezoelectric Polymeric Foams as Flexible Energy Harvesters: A Review
No full textPiezoelectric energy harvesters (PEHs) have the potential to power low-power electronic devices and can advance, self-powered, autonomous electronics to the next level. Conventional ceramic-based piezoelectrics have various properties such as fragility, rigidity, toxicity, high density, and lack of design flexibility which limit their use in more flexible environments. A ton of research has been carried out and published on novel piezomaterials, their transduction mechanisms, analytical models, and electrical circuits to improve various aspects of PEHs. Among these materials, studies on polymeric cellular (or foamed) ferroelectrets or piezoelectrets as PEHs have grown significantly since their discovery. Also, very limited or short reviews are available covering only few aspects. There is a necessity of recognizing their past and present advances in their various generation technology and polymer systems. Herein, a broader review of almost all conventional and recent polymeric foam-based piezoelectrics for PEH applications is summarized. These cellular polymer piezoelectric systems either in bulk, composite, layered, or film form can be fabricated, and depending on the application and conditions, different polymers groups, mainly, polyolefins, polyester, fluoropolymer, and others, are considered. Their applications and future perspectives are also presented and discussed.</p
Synthesis of cross‑linked polyurethane elastomers with the inclusion of polar‑aromatic moieties (BA, PNBA and 3, 5‑DNBA): Electrical and thermo‑mechanical properties analysis
No full textIn this work, we used the design strategy “doped nonpolar polymers” and synthesized the polyurethane elastomers (PUEs) by doping with highly polar aromatic molecules such as benzoic acid (BA), 4(para)-nitro-benzoic acid (PNBA), and 3, 5-dinitro- benzoic acid (3, 5-DNBA) by using the solution casting method. The effect of each molecule in three different weight percentages 2%, 4%, and 6% on electrical and thermo-mechanical properties of the material has studied. Experiments were carried out to determine electrical properties such as DC volume resistivity, dielectric constant, and loss factor. DMA and DSC measurements were done to assess thermo mechanical properties. Also, thermal conductivity measurement was carried out and a strong nitro group and doping percentage dependent results have been observed. A comparative analysis of the effect on the said properties was done among the doped and undoped PUEs.</p
Influence of mold temperature and annealing on the microstructure and mechanical properties of ESO-plasticized PP/CL composites
No full textComposites of polypropylene (PP) and calcium lactate (CL) with a constant weight percentage of 60% and 40%, respectively, were compounded with 3, 5 and 7 phr of epoxidized soybean oil (ESO) plasticizer using an internal mixer. The testing samples were prepared using an injection molding technique. The effects of the mold temperature and annealing treatment on the morphological and mechanical properties of PP-based composites using polarized optical microscopy (POM), differential scanning calorimetry (DSC), universal testing machines (UTM), and impact tester were performed. The results showed a remarkable increase in the elongation-at-break and impact strength, but a noticeable decrease in tensile strength and stiffness with increasing ESO contents. The experimental results also indicated that the higher mold temperature significantly improved the tensile strength and stiffness of samples due to an increase in spherulite size for neat PP, PP/CL composite and PP/CL composite with 3 phr of ESO. Additionally, annealing treatment enhanced the tensile and impact strengths of both neat PP and PP/CL composite, which was attributed to the increase in the crystal perfection and degree of crystallinity. These findings suggested that mechanical improvements using high mold temperature and annealing treatment were confined to the incorporation of an ESO plasticizer. The resulting performance of the plasticized PP composites after thermal treatment was described by two possibilities: the loss in the adhesion between the components and the migration of plasticizer
Improved thermal conductivity of polyurethane (PU)-/SiC composite fabricated via solution casting method and its mechanical model for prediction and comparison
No full textPolymer composites having high thermal conductivity (TC) gained great interest, including the advancement of electronic devices to become more functionalized, scaled, and integrated. In view of these, herein, highly thermal conductive polyurethane (PU)-/SiC composites are fabricated via the solution casting method. Silicon carbide is used as the filler in both flexible and rigid-polyurethane matrices to enhance the value of TC for electronic applications. A novel model has also been developed based on the Coran-Patel model for analysis and comparison of TC of as-synthesized composites. Calculated thermal conductivities by the model are found to be consistent with the experimental results. The highest measured TC for flexible as well as rigid-PU composites is 0.521 and 0.542 Wm−1K−1 representing improvements of 106% and 87% over their pure equivalents, respectively. SEM and DSC techniques are employed to analyze the samples' morphology, and other thermal properties, respectively
Thermo-mechanical properties of flexible and rigid polyurethane (PU)/Cu composites
No full textIn this article, flexible and rigid polyurethane (PU)/copper (Cu) composites are prepared via a simple and cost effective solution casting process. The filler dispersion and chemical bonding of composites are investigated by SEM and FTIR techniques. The results showed the homogeneous dispersion of Cu microparticles. Furthermore, thermal properties are investigated using DMA, DSC, and thermal conductivity measurements. The maximum improvement in thermal conductivity for flexible and rigid PU composites is 24%, and 48%, respectively, as compared to their pure counterparts. The obtained thermal
conductivity values are also compared and analyzed with the mechanical property model (Corans and Patel model) and found in good agreement with the output of the model. DMA results showed enhancement in the storage modulus
with filler loading while the DSC results revealed the endothermic temperature did not significantly change with adding Cu filler in both flexible and rigid PU matrices. The mechanical properties of composites were studied using
tensile and hardness (Shore A and Shore D) test. For flexible PU composites an improvement in tensile strength (43%), Young's modulus (111%), Shore A hardness (6%), Shore D hardness (27%) as compared to pure flexible PU. For rigid PU composites a reduction in tensile strength (23%), Young's modulus (32%), and an increase in Shore A hardness (3%), Shore D hardness (5%) as compared to pure rigid PU. As a result of the current study, TC of rigid PU is found doubly enhanced compared to flexible PU at the same filler concentration. Copper microparticles can act as active filler in both flexible and rigid PU matrices.</p
Effects of Modified Silicon Carbide on The Physical Properties of Bioplastic Blends
No full textThe study’s goal is to improve the physical properties of biodegradable plastics by mixing poly(lactic acid) (PLA), polybutylene succinate (PBS), and silicon carbide (SiC) to make composites that could be used as filaments for 3D printing. Polymer blends and composites were fabricated using an internal mixer. The fraction of SiC was varied from 10 to 40 phr and filled in PLA/PBS blends with a retained ratio of 80/20 wt.%. Then, the mechanical properties, thermal properties, melt flow rate and morphology of PLA/PBS/SiC composites were investigated. Field emission scanning electron microscope images present a uniform dispersion of silane-treated SiC particles throughout the PLA/PBS matrix. The morphology showed better adhesion between PLA/PBS and treated SiC particles. Therefore, this was also the reason for the improvement of Young’s modulus and impact strength when the SiC fraction was increased, which were improved by 33% and 104%, respectively, compared to neat PLA. Furthermore, the melt flow rate increased with an increasing SiC fraction. This might be because adding SiC reduces the viscosity of the composites, which affects the molecular chain movement of the PLA/PBS and the crystallinity of PLA, therefore decreasing the ΔHm of PLA and Xc,PLA. However, Tg and Tm of PLA and PBS remained relatively stable with an increasing fraction of SiC particles
Characterization of Banana Fiber-Reinforced Bioplastics for Environmentally Friendly Packaging Applications
No full textThis study explores the biocomposites composed of poly(butylene succinate) (PBS) reinforced with alkali-treated banana sheath and banana leaf fibers. The fibers were treated with 5% sodium hydroxide (NaOH) and incorporated into the PBS matrix at varying mesh sizes (40 and 60) and fiber contents (1, 2, and 5 parts per hundred resin (phr)). The composites were evaluated for melt flow rate (MFR), melt volume rate (MVR), tensile properties, impact strength, hardness, and microstructural characteristics using X-ray tomographic microscopy (XTM). The addition of both banana sheath and banana leaf fibers resulted in decreased MFR and MVR, while significantly improving the Young’s modulus, which reached up to 280 MPa in the composite containing 5 phr of fine banana leaf fibers. Impact strength was found to depend on both fiber size and loading, with the highest value of 10.8 kJ/m² observed in the composite reinforced with 2 phr of coarser banana sheath fibers. Microstructural analysis revealed that fiber dispersion, agglomeration, and void formation were key factors influencing mechanical performance. Furthermore, a prototype plant pot was successfully fabricated using the composite with the highest fine fiber and content, demonstrating the composite’s potential for sustainable product applications
Strengthening Natural Rubber with Activated Carbon from Cassava Rhizome Waste: Cure Characteristics, Physical, Thermal, and Mechanical Properties
No full textThis study aims to develop a bio-reinforcing filler from cassava rhizome waste, a common agricultural residue in northeastern Thailand that generates a significant amount of waste annually. The waste was turned into activated carbon (AC) by activating it with potassium hydroxide (KOH) and microwave irradiation. AC was then used as a reinforcing agent in natural rubber (NR) composites. The effects of KOH concentration and AC content on the cure characteristics, as well as the physical, thermal, and mechanical properties of the composites, were investigated. At optimal AC content, scorch time decreased by 13.74%, torque difference increased by 17.20%, and cure time was reduced by 2.90%. Mechanical properties improved with higher AC content, with AC prepared at lower KOH concentration exhibiting superior performance. The swelling index decreased with increasing AC content, indicating enhanced solvent resistance. Utilizing cassava rhizome-derived AC offers significant environmental benefits by repurposing agricultural waste. Future research could optimize preparation processes to further enhance performance and explore industrial applications. This study highlights the potential of cassava waste as an eco-friendly and sustainable filler for rubber composites
