Materials Science Forum Vol. 1198

Abstract: Acrylonitrile–butadiene–styrene (ABS) is widely used for structural housings, but its stiffness and strength can be limiting. Here, a particulate-reinforced ABS composite was fabricated by casting using polymer-derived ceramic (PDC) powder as reinforcement. A liquid polysilazane (PSZ) precursor was cured, milled to ~1–10 μm powder, and pyrolyzed at 700–1200 °C to obtain SiCNO-based ceramic filler. ABS pellets and SiCNO powders were melt-mixed at 250 °C and cast into ASTM-standard specimens for tensile (ASTM D638), compression (ASTM D695), and flexural (ASTM D790) tests. For tensile specimens with 10 wt.% filler, tensile strength increased from 23.89 MPa (neat ABS) to 36.74 MPa at 1100 °C pyrolysis, while Young’s modulus increased from 1.71 GPa to 2.61 GPa. At higher pyrolysis temperature (1200 °C), tensile performance degraded, consistent with increased ceramic crystallization and/or interfacial weakening. Compression tests (5–30 wt.% filler) showed monotonic increases in modulus with filler loading, but resilience dropped sharply between 10–20 wt.%, indicating a brittle–ductile transition window. Flexural strength improvements were modest; the best case was 10 wt.% filler pyrolyzed at 900 °C, giving 55.05 MPa vs. 51.35 MPa for neat ABS. SEM fracture surfaces revealed a transition from ductile fibrillation in neat ABS to layered fracture with embedded ~1–5 μm ceramic particles in the composite. These results demonstrate that castable ABS/PDC composites can deliver substantial tensile stiffening and strengthening when carefully selected pyrolysis temperature and filler fraction are used.

Abstract: Natural fiber hybridization has been peaking across industries as it offers a promising approach for developing sustainable and eco-friendly alternatives. In this study, hybrid coconut coir and tiger grass fiber composites of weight ratio 1:1 were fabricated by encapsulating their strands into epoxy resin and hardener matrices. The hardness and flexural performance of the hybrid fiber composite were characterized based on ASTM standards D2240 Adapted and D790 Adapted and compared with composites reinforced with the individual fibers. Among the three fiber composites, the hybrid composite exhibited the highest flexural modulus (2.41 GPa), representing a 35.3% improvement over pure coir composites and an 11.6% increase relative to pure tiger grass composites. This improved flexural stiffness of the hybrid composite is attributed to the mechanical compatibility of coir and tiger grass, resulting in effective stress transfer upon hybridization. In contrast, shore durometer hardness results showed no significant differences among the composites, with the hybrid composite recording an average hardness reading of 71. These results support that the hybridization effectively mitigates the mechanical limitations of the individual fibers offering broader potential for sustainable industrial and structural applications.

Abstract: Applications of 3D printed metallic alloy materials like Ti6Al4V or Ti64 offer significant advantages for certain applications and incorporates complex geometries like lattice structures achieving material optimization. This study analyzes the thermal processing of i-SLS 3D-printed Ti6Al4V-PA12 composites with varying lattice structures (Solid, Gyroid, and Sinusoid). This paper analyzes the chemical barriers and morphological indicators of the sintered composites using SEM-EDX and Optical Microscopy, Pearson Correlation is calculated for statistical analysis. Results among the varying sintering profiles showed that sintering at 1250 °C (Intermediate Temperature Profile) has progress on initial Ti64 contact. Outcomes are dependent with the high surface-area-to volume ratio of the geometric shapes, leading to higher residual carbon decomposition, but prone to surface oxidation. Oxidation and carbon residues are factors interfering with the necking between Ti6Al4V particles. Thus, high temperature treatment for Ti6Al4V sintering under high purity argon atmosphere showed a lack of densification and failed to reach a sintered state.

Abstract: Natural materials used in broom-making like tiger grass fibers and midribs of coconut leaves have potential use in composites as alternative reinforcements due to their biodegradability and availability at lower prices while offering some possible enhancements on mechanical properties. In this paper, tiger grass fibers and coconut leaf midribs from locally made brooms were reinforced in epoxy resin in a unidirectional orientation. No chemical treatment was applied to the reinforcing materials. A hybrid fiber reinforced composite was also prepared using a manual casting process. The mechanical characterization performed are flexural and durometer hardness tests. Results revealed that all sample types of composites obtained lower mean flexural strength and hardness than the unreinforced sample. This could be linked to the absence of surface treatment that possibly led to a weaker adhesion between the fibers and the epoxy matrix. Moreover, all composites obtained almost similar flexural strength of about 74 MPa which might be primarily influenced by the epoxy strength since the load applied is in perpendicular direction with the unidirectional reinforcements. Nevertheless, an improvement of about 22 % was obtained in terms of the flexural modulus of the composite with coconut leaf midrib.

Abstract: Additive manufacturing techniques such as Fused Deposition Modelling (FDM) and Stereolithography (SLA) enable the production of smart composites with complex geometries. In these materials, the bonding strength between ferromagnetic shape memory alloy (FSMA) microparticles and the polymer matrix is critical for efficient strain transfer. Matrix stiffness also plays a key role: it must be high enough to transmit stress, yet soft enough to allow magnetic twin boundary motion without exceeding the blocking stress. This study analyses the temperature-dependent shear modulus of composites containing Ni₄₅Mn_36.7In_13.3Co₅ microparticles embedded in polycaprolactone (PCL) and photocurable bisphenol A-glycidyl methacrylate (Bis-GMA) matrices using dynamic mechanical analysis (DMA). The experimental results were fitted using modified Rule of Mixtures (ROM) and Halpin-Tsai (HT) models. The elastic energy transfer was also calculated to evaluate the strain transfer capability from the microparticles to the matrix during the martensitic transformation. These results underscore the substantial impact of matrix properties on mechanical response and provide modelling tools for the design of FSMA-based actuators, sensors, energy generation devices based on the harvesting of vibrational energy and damping systems.

Abstract: Three-dimensional (3D) printing enables the fabrication of smart composite materials by embedding ferromagnetic shape memory alloy (FSMA) microparticles into a ductile polymer matrix, thus overcoming the intrinsic brittleness of most FSMA materials. In this work, the effects of thermal treatments near the melting temperature upon the damping mechanism in the low-temperature region are studied both in the 3D-printed PCL samples and in the 3D-printed (PCL/Ni₄₅Mn_36.7In_13.3Co₅) composites, focusing on the interactions processes between the microparticles and the polymer chains. 3D-printed PCL and 3D-printed composites were obtained by means Fused Deposition Modelling (FDM) and were studied by mechanical spectroscopy (MS). The deconvolution of the damping spectra revealed the appearance of two relaxation mechanisms in 3D-printed PCL samples and three relaxation mechanisms in 3D-printed composites.

Abstract: As the climate challenges worsen and the need to reduce carbon emissions becomes more urgent, timber is undergoing a remarkable revival as a sustainable material, driven by shifting societal attitudes. However, this renewed reliance on wood also raises important questions about how to reforest in ways that are ecologically responsible. With global demand for timber projected to rise, the expansion of managed plantations has become inevitable, positioning agroforestry at the centre of both commercial and scientific attention.Paulownia, renowned as the fastest-growing tree species globally, plays a pivotal role in this transition. Its dense foliage enables unparalleled CO₂ sequestration, earning it the moniker of a "climate tree". While native to China, it is now cultivated across the globe, though not without controversy - its invasive tendencies have spurred demand for domesticated strains with reduced ecological impact. Crucially, such cultivars must retain robust mechanical performance, including vibration damping properties, a key determinant of acoustic suitability.This research evaluated strain-dependent damping characteristics through analysis of the logarithmic decrement in free-decaying flexural vibrations. Specimens included a conventional Paulownia variant (cultivated in Georgia, Italy, and Spain) alongside a novel German-cultivated strain - notably the first such harvest recorded in the country.Given the microstructure’s reliance on local soil nutrients and its critical role in damping behaviour, the study quantified the resulting variability in strain response. The results identified distinct regimes within the damping curves: a strain-independent plateau followed by a strain-dependent area. Calculated bending moduli, derived from resonant frequencies, ranged from 1024 N/mm² to 5873 N/mm². This wide dispersion is attributed to heterogeneity in the fibril alignment - a factor that also influences energy dissipation.

Abstract: Conventional crosslinking agents for Epoxidized Natural Rubber (ENR) are typically synthesized chemicals that pose toxic threats to living organisms and the environment. Glycerol, a major byproduct from waste palm oil biodiesel production, remains largely underutilized. This study aims to identify a novel, environmental-friendly crosslinking agent for Epoxidized Natural Rubber (ENR). While waste palm oil is commonly utilized for biodiesel production, its major byproduct, glycerol, remains largely underutilized. Consequently, this research investigates the potential of glycerol to serve as a crosslinking agent for ENR. Experimental results confirm that a crosslinking reaction successfully occurs between ENR and glycerol. This is substantiated by Fourier Transform Infrared Spectroscopy (FTIR) analysis, which reveals crosslinking via the opening of the ENR oxirane rings. Significant peaks observed at 1032 cm⁻¹, 3340 cm⁻¹, and 2900 cm⁻¹ correspond to C-O-C, O-H, and C-H bonds, respectively. Furthermore, results from gel fraction analysis and Moving Die Rheometer (MDR) testing corroborate the crosslinking interaction between ENR and glycerol, indicating that crosslinking density increases with higher glycerol loading. Mechanical property testing further demonstrates that the tensile strength of glycerol-crosslinked ENR improves in correlation with the increased degree of crosslinking.

Abstract: Microelectromechanical systems (MEMS) are widely used in flexible and stretchable applications employing polymeric substrates such as PDMS, PET, and Polyimide. In this study, the mechanical behavior of PVDF thin films on PDMS substrates is numerically investigated under uniaxial tensile loading using Finite Element Analysis (FEA). The developed FEA model is first validated using established experimental results before being applied to the main specimen. Mesh-independent analyses are performed for PVDF film thicknesses of 50, 75, 100, and 125 µm with a 1 mm thick PDMS substrate under different elastic modulus conditions. Results show that thicker PVDF films require higher elastic strain to reach yielding. Furthermore, interfacial shear stresses are maximum at the laminate ends and decrease toward the center. These findings provide useful insights into the mechanical behavior and failure characteristics of PVDF–PDMS laminates for flexible MEMS applications.