High Filler Content Research Articles

Enhancing mechanical properties of PLA‐based bio composite filament reinforced with horse gram filler for 3D printing applications

AbstractGreen composites for 3D printing have gained significant attention due to the potential of incorporating natural fillers to reduce costs and enhance performance while maintaining environmental benefits. The use of agricultural by‐products, such as horse gram (Hg), not only promotes waste utilization but also seeks to improve the mechanical properties of biopolymers like PLA. In this study, Hg powder was utilized as a natural filler to enhance the mechanical properties of PLA‐based composites. The composites were fabricated with 1%, 2%, 3%, and 4% Hg powder filler content, and the filament was processed through a single screw extruder machine. Their mechanical properties were systematically evaluated to determine the optimal filler ratio. The results indicate that the incorporation of 1% Hg filler into PLA provided superior mechanical performance compared to Neat PLA. Specifically, tensile strength increased by 11.19%, flexural strength improved by 5.32%, and compression strength increased by 5.94%. In contrast, composites with 2% and 3% Hg filler showed a reduction in these mechanical properties, highlighting that the 1% Hg/PLA composite achieves the best balance between strength and filler content. The findings suggest that the 1% Hg/PLA composite offers an optimized combination of tensile, flexural, and compression properties, making it a strong candidate for environmentally sustainable engineering applications such as lightweight structural components, automotive interior parts, and consumer product casings.Highlights One percent Hg filler improved tensile, flexural strength, and hardness through uniform dispersion. Higher filler content (3%–4%) led to agglomeration, reducing composite performance. XRD and SEM analyses revealed reduced PLA crystallinity and structural defects at higher filler levels.

Adding Mandarin Peel Waste to a Biodegradable Polymeric Matrix: Reinforcement or Degradation Effect?

In the current context, the use of fillers derived from fruit and vegetable waste is a crucial approach to mitigate waste and promote sustainable resource use, thus contributing to product life cycle completion and the achievement of sustainability goals. This study focuses on incorporating an endemic waste hitherto considered irrelevant within a biodegradable matrix. The resulting biocomposites were carefully characterized mechanically, rheologically, and morphologically to identify the connections between processability, structure, and properties. The results show that the presence of the filler results in an increase in the stiffness of the material (up to 27% in elastic modulus) accompanied by a decrease in tensile strength (approximately 50%) and elongation at break, which is on average about 7% at the highest filler content. This behavior was attributed to poor interfacial adhesion and the influence of a degradation process caused by the presence of citric acid and/or impurities in the filler.

Transforming Tree Bark Waste into a Green Composite: Mechanical Properties and Biodegradability

In this study, a “green composite” material made from 60% tree bark and 40% polylactic acid (PLA) was fabricated and evaluated according to its mechanical properties and biodegradability. Biodegradation tests were performed in compost, simulated aquatic environments, and natural soil. In compost, the composite degraded steadily and reached 47% biodegradation after 11 weeks. In soil, the material quickly lost much of its tensile strength, and after 6 weeks, there were signs that the surface and the internal structure had started to deform. Biodegradation in aquatic environments also caused a loss of tensile strength after only a few weeks. Because of the high filler content, excellent biodegradability, and light weight, the composite material has a low environmental footprint. The material could be used in agricultural equipment such as plant pots.

A near-single-ion conducting polymer-in-ceramic electrolyte for solid-state lithium metal batteries with superior cycle stability and rate capability

Composite solid-state electrolytes (CSE) represent a promising alternative to conventional porous separators and organic liquid electrolyte systems in commercialized lithium metal battery (LMBs), offering effective dendrite suppression, high interfacial compatibility and enhanced cycle life. This study introduces a polymer-in-ceramic electrolyte, which is synthesized by blending perovskite-type inorganic electrolyte Li1.5La1.5TeO6 (LLTeO) with polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF), denoted as PMMA/PVDF-LLTeO. The resulting CSE features a dense, non-porous structure, high mechanical strength, excellent thermal stability, and a broad electrochemical window. Notably, with the incorporation of a high ceramic filler content (up to 70 %), the CSE promotes a hybrid ion transport mechanism, yielding a near-single-ion conducting behavior with an ion transference number of 0.833, and a high elastic modulus of approximately 1 GPa. These attributes collectively contribute to the suppression of dendrite growth, as analyzed through multiphysics-based simulations. Li//Li symmetric cells using PMMA/PVDF-LLTeO-70 exhibit robust lithium stripping-plating stability, with a critical current density of 0.45 mA cm−2. Furthermore, the corresponding Li//LiFePO4 cells exhibit superior rate performance and cyclic stability, achieving over 150 cycles with a capacity retention rate of 92.2 % at high temperatures (60 °C). This research highlights the potential of the proposed CSE with high-temperature applications, significantly improving the safety and performance of LMBs

Highly Filled Waste Polyester Fiber/Low-Density Polyethylene Composites with a Better Fiber Length Retention Fabricated by a Two-Rotor Continuous Mixer

A key challenge in the utilization of waste polyester fibers (PET fibers) is the development of fiber-reinforced composites with high filler content and the improvement of fiber length retention. Herein, the effects of a two-rotor continuous mixer and a twin-screw extruder on the structure and properties of waste polyester fiber composites were evaluated. The results revealed that the mechanical properties of the composites were improved significantly with increasing fiber content, especially when processed using the twin-rotor continuous mixer. This mixer facilitated the formation of a robust fiber network structure, leading to substantial enhancements in tensile strength, flexural strength, and heat resistance. Specifically, compared to those processed by the twin-screw extruder, with 60 wt% fibers content, the tensile and flexural strengths of specimens processed by the twin-rotor continuous mixer increase by 21% and 13%, respectively. The average fiber length in specimens processed by the twin-rotor continuous mixer was 32% longer than that in specimens processed by the twin-screw extruder, attributable to the lower shear frequency and the higher tensile ratio of the former. This blending technique emerges as an effective strategy, contributing significantly to promoting the development and practical application of waste textile fiber-reinforced polymer composites.

The Effect of Inorganic Filler Content on the Properties of BPA-Free Bulk-Fill Dental Resin Composites.

This study aimed to enhance the performance of dental resin composites (DRCs) by increasing the content of inorganic fillers while addressing potential health risks associated with Bisphenol A (BPA). To achieve this, the BPA-based resin monomer Bis-GMA was replaced with BPA-free Bis-EFMA. The study then explored the impact of varying inorganic filler contents on the physiochemical properties of Bis-EFMA-based bulk-fill dental resin composites (BF-DRCs). Four distinct Bis-EFMA-based BF-DRCs were formulated, each with different inorganic filler contents ranging from 70 wt% to 76 wt%. The study tested the depth of cure (DOC), double-bond conversion (DC), water sorption (WS), solubility (SL), and cytotoxicity of the system. It notably investigated the effects of increasing filler content on mechanical properties through flexural strength (FS), flexural modulus (FM), Vickers microhardness (VHN), and wear resistance, as well as the impact on polymerization shrinkage, including volumetric shrinkage (VS) and shrinkage stress (SS). To assess the commercial application potential of Bis-EFMA-based BF-DRC, the research used the commercially available BF-DRC Filtek Bulk-Fill Posterior (FBF) as a control. The results indicated that a higher filler content did not affect the DOC of Bis-EFMA-based BF-DRCs. Inorganic fillers at higher concentrations significantly enhanced overall mechanical properties while significantly reducing volumetric shrinkage (VS; p < 0.05). When the concentration of inorganic fillers in the resin system reached 76 wt%, most of the performance of the Bis-EFMA-based BF-DRC surpassed that of the commercial control FBF, except for FS, FM, and SS. These findings highlight the potential of Bis-EFMA-based BF-DRC as a long-term restorative material for dental applications.

Novel, Fluorine-Free Membranes Based on Sulfonated Polyvinyl Alcohol and Poly(ether-block-amide) with Sulfonated Montmorillonite Nanofiller for PEMFC Applications.

Novel blend membranes containing S-PVA and PEBAX 1657 with a blend ratio of 8:2 (referred to as SPP) were prepared using a solution-casting technique. In the manufacturing process, sulfonated montmorillonite (S-MMT) in ratios of 0%, 3%, 5%, and 7% was used as a filler. The crystallinity of composite membranes has been investigated by X-ray diffraction (XRD), while the interaction between the components was evaluated using Fourier-transform infrared spectroscopy (FT-IR). With increasing filler content, good compatibility between the components due to hydrogen bonds was established, which ultimately resulted in improved tensile strength and chemical stability. In addition, due to the sulfonated moieties of S-MMT, the highest ion exchange capacity (0.46 meq/g) and water uptake (51.61%) can be achieved at the highest filler content with an acceptable swelling degree of 22.65%. The composite membrane with 7% S-MMT appears to be suitable for application in proton exchange membrane fuel cells (PEMFCs). Amongst the membranes studied, this membrane achieved the highest current density and power density in fuel cell tests, which were 149.5 mA/cm2 and 49.51 mW/cm2. Our fluorine-free composite membranes can become a promising new membrane family in PEMFC applications, offering an alternative to Nafion membranes.

Comparative investigation of fillers loading effect on morphological, micromechanical, and thermal properties of polyvinyl alcohol/cellulosicfillers-based composites

Polyvinyl alcohol (PVA)-based biocomposites were fabricated by the incorporation of chitosan (Ch), cellulose fibers (CS), and their mixture (1:1 ratio). Fillers with various loading (2, 4, 8, and 10 wt.-%) were incorporated into PVA employing the solution casting method. The fillers and biocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), brightfield microscopy, tensile and microindentation tests, contact angle measurement and thermogravimetric analysis (TGA). FTIR spectra revealed the removal of lignin, and intermolecular H-bonding between PVA and fillers promoting their filler–matrix interfacial interactions. Crystallographic results showed varied crystallite sizes and crystallinity of composites. Microscopic techniques revealed a uniform filler distribution, attributed to their compatibility with PVA. Tensile and microindentation tests demonstrated a decreased tensile strength (3.3–8.2 MPa of the composites compared to 15.7 MPa of the matrix) and Martens hardness (HM) of biocomposites. However, their value was increased with higher filler concentration, signifying the mechanical reinforcement. Contact angle analysis confirms the decreased wettability (hydrophilicity) of biocomposites, attributed to higher compatibility of fillers with PVA and intermolecular H-bonding between them. A slightly decreased thermal stability of biocomposites with filler incorporation is implied by TGA results despite their uniform distribution and strong matrix–filler interfacial interactions.

Surface micro-welding strategy of h-BN assembled microspheres for composites with desirable thermal conductivity and a low dielectric constant

As electronic devices strive for higher integration and faster signal transmission, the demand rises for polymer composites with high thermal conductivity (TC) and low dielectric constant (εr). However, high TC composites often come with a high filler content, leading to a reduction in processibility and dielectric properties. Herein, by surface micro-welding strategy, we fabricated cohesive h-BN microspheres (SBO) with a quasi-hollow structure. The pre-constructed micro-nano network of h-BN inside the microsphere serves as a continuous pathway for heat transfer, while the internal space of the microsphere is divided into numerous gas chambers, establishing a foundation for low εr. Benefiting from this structure, the TC of the prepared composite is 2.12 W/m·K, and its εr is remarkably low at 3.24 (103 Hz), effectively balancing the TC and dielectric properties at a high filler loading. Furthermore, this designed structure significantly reduces the viscosity of the composite (measured 309 Pa s with a filler content of 50 wt% at 1s−1) due to the smooth surface of the microsphere. This strategy offers a facile approach for fabricating composites characterized by desirable TC, low εr and excellent processibility, showcasing promising prospects for advancement in the realm of microelectronics.

Properties of polyphenylene sulfide/multiwalled carbon nanotubes composites: a comparison between compression molding and microinjection molding

Abstract This work comparatively studied the electrical, morphological, and thermal properties of polyphenylene sulfide/multiwalled carbon nanotubes (PPS/CNT) composites which were prepared by compression molding (CM) and microinjection molding (μIM), respectively. The subsequent samples were termed as CM composites and microparts, respectively. Results revealed that the electrical conductivity of PPS/CNT microparts was lower than that of CM PPS/CNT composites, which was ascribed to the difference in shearing influence that affected microstructural evolution in resultant moldings. In addition, SEM observations revealed that the distribution of CNTs became better in the PPS/CNT microparts, which was related to the prevailing higher shearing effect in μIM. The tensile strength of PPS/CNT microparts dropped for filler concentrations ≤2 wt% and it started to increase after that reached 10 wt%; in comparison with the PPS/CNT microparts, the tensile strength of CM PPS/CNT samples exhibited an opposite trend when the filler concentration was ≤3 wt%. After that, the tensile strength of CM samples showed a monotonic increase with increasing CNT concentrations. Both the uniform distribution of CNT and increase of crystallinity were crucial to improving the tensile strength of PPS/CNT moldings. This work showed that PPS/CNT moldings with good electrical conductivity and mechanical performance can be molded at relatively high filler concentrations, which is critical for applications in demanding engineering sectors.

Performance Investigations on All-Solid-State Polymer-Ceramic Sodium-Ion Batteries through a Spatially Resolved Electrochemical Model

Rechargeable batteries are crucial in modern energy storage, with lithium-ion batteries dominating the market. However, the scarcity and environmental concerns associated with lithium have spurred interest in alternative battery chemistries, particularly sodium-ion batteries (SIBs), which utilize abundant sodium resources. Despite extensive experimental research on all-solid-state SIBs (ASSSIBs), theoretical investigations have primarily focused on molecular-level analyses, overlooking the impact of cell composition on overall performance. This paper aims to address this gap by developing a physical model for simulating ASSSIBs at the particle scale. Our methodology involves integrating experimental data with simulation results to identify key factors influencing battery performance. The study reveals slow sodium ion transport as a significant bottleneck, attributed to factors such as low porosity of the half-cell and limited electrolyte ionic conductivity. Simulation outcomes emphasize the importance of advancing fast-ion-conducting solid electrolytes to enhance ASSSIB performance. Moreover, the results suggest that electrodes with high electrolyte active filler content and reduced thickness are necessary for achieving optimal battery capacity utilization. Overall, this research underscores the intricate relationship between electrode microstructure and battery performance, offering valuable insights for the design and optimization of sustainable sodium-ion battery systems suitable for stationary and mobile applications.

The realization of high filler loads in segregated boron nitride/polyethylene composites for efficient thermal management

The formation of segregated structure in thermally conductive polymer composites (TCPCs) is regarded as one promising strategy to improve their thermal conductivity. However, it remains a great challenge to incorporate high filler contents into TCPCs with a segregated structure. Herein, we realize the fabrication of segregated TCPCs with high filler contents by using butadiene rubber (NBR) as interface adhesive between boron nitride nanosheets (BN) and ultrahigh molecular weight polyethylene (UH). It is demonstrated the formation of segregated structure in the BN@NBR/UH and the BN loads could be as high as 50 wt%. A superior thermal conductivity of 4.36 W/(m·K) is achieved in the 50 wt% BN@NBR/UH, which is increased by 81.7 % compared to the composites with randomly distribution structure. The work provides valuable guidance to the development of high performance TCPCs for thermal management.

Effects of neat and silver coated fly ash cenospheres on the properties of styrene-butadiene-styrene block copolymer composites obtained by a solution mixing method

Utilization of industrial by-products to develop novel value-added materials while mitigating their environmental impact is a crucial issue. Fly ash (FA) microparticles are a common component of power plant waste. This work aims to investigate the impact of varying concentrations of neat/silver-coated FA on the morphology and thermal properties of styrene-butadiene-styrene/FA composites. Composite materials based on styrene-butadiene styrene triblock copolymer (SBS) with various volume fractions of as-received and silver-coated FA were prepared using a solution mixing method. Silver-coated cenosphere particles were prepared using an electroless plating method. Scanning electron microscopy and optical microscopy showed that the solution mixing method obtains composite materials characterized by uniform dispersion of filler without large particle aggregates and predominantly unbroken cenospheres. The tensile strength of the composite with 10% of both as-received and silver-coated fly ash remains at the level of the unfilled SBS sample. However, at higher filler concentrations (20% and 30%), a decrease in strength by 27% and 42% respectively is observed, possibly due to the agglomeration of FA, which leads to a poorer interface and dispersion at higher filler weights. Additionally, thermal analysis in an oxygen atmosphere showed that the introduction of both as-received and metallized cenospheres in the same quantity increased the thermal stability of the tested composition. The temperatures at 5% mass loss of SBS/FA composites were on average 70°C higher than those of the original SBS.

Multifiller carbon nanotube, graphene, and carbon black composite filaments: A path to versatile electromaterials

Addressing the growing demand for conductive and flexible composites, this research focuses on producing thermoplastic composite fibers made of polyurethane and carbon nanomaterials featuring the highest possible electrical conductivity. Based on a recently developed methodology enabling the formation of very high filler contents of 40% w/w, this work presents a systematic investigation of the role of all the materials used during the manufacturing process and selects the materials that ensure the best electrical performance. The results show that the highest electrical conductivity and current-carrying capacities are obtained when dimethylformamide is used as a solvent, and small amounts of AKM surfactant aid the de-agglomeration of carbon nanomaterials. It is also shown that the hybridization of MWCNTs filler with graphene nanoplatelets and small amounts of carbon black is beneficial for the electrical properties. However, the highest performance is achieved with SWCNTs as fillers, exhibiting two orders of magnitude higher electrical conductivities of 6.17 × 104 S/m.Impact statementThe article presents a pioneering exploration into the synthesis and application of a novel composite material. This research significantly impacts the field of electromaterials by introducing a cutting-edge approach that leverages the synergistic properties of carbon nanotubes, graphene, and carbon black within a single filament. The impact of this research extends beyond the laboratory, influencing the development of next-generation materials that bridge the gap between conventional materials and advanced nanomaterials. The presented composite filaments open avenues for the creation of innovative devices and systems that demand good mechanical strength, electrical conductivity, and thermal stability. Moreover, the versatility of these filaments allows for the optimization of materials properties, enabling customization based on specific application requirements. In addition to its technological significance, the paper contributes to sustainability efforts by facilitating the production of lightweight, energy-efficient materials. The insights provided by this research have the potential to reshape the landscape of materials science, inspiring further exploration and innovation in the quest for versatile and high-performance electromaterials.Graphical abstract

The Critical Role of Ca2+ in Improving the Transparency and Strength of High-Filler-Content Nanocellulose/Montmorillonite Nanocomposite Films.

Strong and transparent nanocellulose/montmorillonite (MMT) nanocomposite films with high filler content (≥50 wt %) are emerging as versatile materials for advanced applications due to their excellent optical, barrier, mechanical, and thermal properties, and environmental friendliness. Nonetheless, these films undergo a notable decline in optical and mechanical properties at high MMT loadings. This study first demonstrates that calcium-ion-induced tactoids are the key factor causing disordered structures in nanocomposite films, leading to the degradation of optical and mechanical properties. We then address this issue by employing a Ca2+ removal strategy─dialysis. Through removing 43% of free Ca2+, simultaneous improvements in both properties are observed. For example, in a nanocomposite film with 70 wt % MMT, light transmittance increases from 75.9 to 91.6%, and the tensile strength rises from 100.4 to 139.4 MPa. This work offers insights into developing strong and transparent nanocomposite films with high MMT contents.

Electric-field-induced assists fabrication of micro-SiC/Epoxy coating with low additive amount to improve surface insulating performance of HVDC insulator

The micro-SiC/Epoxy composite coating has huge potential for application in the insulator of high voltage direct current (HVDC) gas insulated switchgear (GIS) since it can effectively suppress charge accumulation at gas–solid interface and adaptively regulate resistive electric field distribution. However, achieving stable and fruitful properties often requires high filler concentrations, which can compromise processability and long-term stability. Thus, a new method is proposed for preparing SiC/Epoxy composite coatings based on in-situ electric-field-induced assist (EFIA). The alignment process of SiC induced by the in-situ electric field, the effects of in-situ field on the physical and chemical properties of cured composites were studied. Even at concentrations far below the percolation threshold, the alignment of SiC particles along the in-situ electric field direction can induce significant non-linear conductive properties along that specific direction in the composite. Furthermore, the EFIA-coating leads to a 59.43% reduction in surface charge accumulation, more than a 50% decrease in charge dissipation time, and a 17.3% increase in surface flashover voltage. The coating discussed in this paper will be helpful in insulation design of DC components.

Mechanical and physical properties of attachments employed in clear aligner treatments. A critical appraisal

Clear aligners have become a viable option for orthodontic treatment. Unlike conventional orthodontic brackets, aligners are not directly bonded to teeth and thus, have a different application of forces. Attachments are a type of auxiliary for aligner treatment that creates points in which pressure can be applied on the tooth surface, acting to transmit forces from the aligner tray to the teeth. Currently, there is no consensus on what material should be used to fabricate attachments and how they behave clinically. Material and methods: The present study is a critical appraisal of data already published on the subject up to now: from 1784 records initially screened, 11 reports were included, mostly in vitro studies and with variable methodology. Results: Surface wear of attachments can vary from 9,6% to 100%. Attachment loss is roughly the same for upper and lower arches, but posterior teeth tend to present more losses. Patient-related variables might account for more failures than operator and material-related failures, but it has been shown that conventional composites might present better resistance, aligner fitting, and less surface wear. Conclusion: Clinicians might expect some degree of attachment surface wear and losses. Patient orientation and use of conventional composites with high filler content might reduce such failures and improve treatment results.

Phase-separated porous nanocomposite with ultralow percolation threshold for wireless bioelectronics.

Realizing the full potential of stretchable bioelectronics in wearables, biomedical implants and soft robotics necessitates conductive elastic composites that are intrinsically soft, highly conductive and strain resilient. However, existing composites usually compromise electrical durability and performance due to disrupted conductive paths under strain and rely heavily on a high content of conductive filler. Here we present an in situ phase-separation method that facilitates microscale silver nanowire assembly and creates self-organized percolation networks on pore surfaces. The resultant nanocomposites are highly conductive, strain insensitive and fatigue tolerant, while minimizing filler usage. Their resilience is rooted in multiscale porous polymer matrices that dissipate stress and rigid conductive fillers adapting to strain-induced geometry changes. Notably, the presence of porous microstructures reduces the percolation threshold (Vc = 0.00062) by 48-fold and suppresses electrical degradation even under strains exceeding 600%. Theoretical calculations yield results that are quantitatively consistent with experimental findings. By pairing these nanocomposites with near-field communication technologies, we have demonstrated stretchable wireless power and data transmission solutions that are ideal for both skin-interfaced and implanted bioelectronics. The systems enable battery-free wireless powering and sensing of a range of sweat biomarkers-with less than 10% performance variation even at 50% strain. Ultimately, our strategy offers expansive material options for diverse applications.

Enhancing Thermal Conductivity in Polymer Composites through Molding-Assisted Orientation of Boron Nitride.

Incrementing thermal conductivity in polymer composites through the incorporation of inorganic thermally conductive fillers is typically constrained by the requirement of high filler content. This necessity often complicates processing and adversely affects mechanical properties. This study presents the fabrication of a polystyrene (PS)/boron nitride (BN) composite exhibiting elevated thermal conductivity with a modest 10 wt% BN content, achieved through optimized compression molding. Adjustments to molding parameters, including molding-cycle numbers, temperature, and pressure, were explored. The molding process, conducted above the glass transition temperature of PS, facilitated orientational alignment of BN within the PS matrix predominantly in the in-plane direction. This orientation, achieved at low filler loading, resulted in a threefold enhancement of thermal conductivity following a single molding time. Furthermore, the in-plane alignment of BN within the PS matrix was found to intensify with increased molding time and pressure, markedly boosting the in-plane thermal conductivity of the PS/BN molded composites. Within the range of molding parameters examined, the highest thermal conductivity (1.6 W/m·K) was observed in PS/BN composites subjected to five molding cycles at 140 °C and 10 MPa, without compromising mechanical properties. This study suggests that compression molding, which allows low filler content and straightforward operation, offers a viable approach for the mass production of polymer composites with superior thermal conductivity.

Enhancement of spent coffee grounds as biofiller in biodegradable polymer composite for sustainable packaging

AbstractThis study explores the utilization of Spent Coffee Grounds (SCG), a residual product of the coffee industry, as a microfiller reinforcement in Poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) biopolymer composites at varying concentrations (1%, 3%, 5%, and 7%). Melt compounding via a twin‐screw extruder and subsequent compression molding were employed in the fabrication process. The SCG microfiller, with particle diameters ranging from 1.11 to 1.28 μm, exhibited a significant negative charge (zeta potential: −20 mV). Hydrophobicity increased up to 5% filler concentration, as indicated by higher water contact angles, but diminished at highest concentration likelihood of agglomeration of the spent coffee grounds within the biopolymer matrix. The addition of SCG enhanced overall mechanical properties, particularly at a 5% filler concentration. Field Emission Scanning Electron Microscopy (FE‐SEM) and Atomic Force Microscopy (AFM) confirmed the successful incorporation of SCG microfiller, improving structural characteristics. Schematic drawings illustrated the interphase bonding of microfiller and matrix. However, properties diminished at the highest filler content (7%) due to coffee grounds' agglomeration. Despite this, SCG incorporation enhanced functional properties, making the biopolymer composite a promising material for sustainable packaging and various applications.Highlights Enhancement of properties of spent coffee grounds in PHBV biocomposites. Characterization of Biocomposites for multifunctional properties. Fracture and 2D analysis of the tensile fractured surface of biocomposites. A promising material for sustainable and biodegradable packaging.