Mechanical Tests Research Articles

Synthesis, characterisations and applications of boron nitride based hybrid metal matrix composites

ABSTRACT This study focuses on how reinforcements impact the base material (specifically AA 6082) regarding its microstructure, mechanical behaviour& corrosion behaviour. Boron nitride (BN) & molybdenum disulphide (MoS2) employed as reinforcing materials ranged from 1% to 3% of BN & 1% to Constant MoS2. The composite materials were produced utilising the stir casting technique. X-ray diffraction (XRD), scanning electron microscope (SEM) with Energy Dispersive spectroscopy (EDAX) & an optical microscope (OM) were used to examine microstructural phase identification analysis. Tensile, compressive, impact, density& porosity fracture mechanisms were investigated by mechanical testing. BN & MoS2 reinforced particles’ presence in the samples is confirmed by XRD and microstructural pictures showing consistent matrix reinforcement distribution. According to the findings, incorporating BN & MoS2 reinforcements improved the mechanical & corrosion properties but slightly reduced the impact strength. The fractured samples revealed micro cuts, micro ploughing, cracks, trans-granular cleavage facets, dimples in the tensile & impact tests. Reduction in Corrosion rate was achieved gradually by adding reinforcement particles for the composites.AA6082, 3 wt: % BN, & 1 wt.% MoS2 composites have shown a decrease in corrosion current density by 1.901 mA/cm2 & an increase in charge transfer resistance by 99.934 Ω cm-2, attributed to passivation.

The Perception of Policy Uncertainty and the Labor Income Share of Firms: Empirical Research Based on Double Machine Learning

ABSTRACTBased on the double machine learning model, this study examines the impact of perception of policy uncertainty (PPU) on labor income share (LIS). We find that PPU negatively influences LIS. Mechanism test indicates that PPU not only results in a reduction in fixed asset investment, distorting human capital structure, but leads to a financing dilemma for firms, ultimately exerting a detrimental effect on LIS. Additionally, PPU primarily diminishes LIS of ordinary employees rather than executives. Furthermore, the inhibitory effect of PPU on LIS is significantly more pronounced in firms characterized by smaller union scales and those operating within monopolistic industries.

Directors from related industries and corporate diversification

ABSTRACT This paper aims to examine the impact of directors from related industries on corporate diversification. Director social networks, as a form of informal institution, have significant effects on firms’ production, operation, and strategic decision-making. However, few studies have focused on the economic effects of directors from related industries. We select Chinese A-share listed companies from 2012 to 2021 as our research sample and empirically examine the impact of directors from related industries on corporate diversification. The study finds that directors from related industries can promote corporate diversification. Mechanism tests that they can influence corporate diversification through the information channel. Heterogeneity analysis shows that the impact of directors from related industries on corporate diversification is more pronounced in firms with strong absorptive capacity, non-state-owned enterprises, and in regions with poor institutional environments. Additionally, directors from related industries can strengthen the positive correlation between diversification and corporate investment efficiency.

Artificial Intelligence and the Development of “Specialized, Refined, Unique, and Innovative” Small‐ and Medium‐Sized Enterprises

ABSTRACT“Specialized, Refined, Unique, and Innovative” (SRUI) enterprises are a crucial part of the national innovation system and play a significant role in enhancing national core competitiveness by leveraging strengths and addressing weaknesses. Given the limited quantitative analysis on the productivity of SRUI enterprises in the academic field, this paper constructs an enterprise‐level artificial intelligence index based on text analysis and machine learning. Using panel data from 2018 to 2022, we investigate the impact of artificial intelligence on the productivity of SRUI small‐ and medium‐sized enterprises (SMEs). The research findings indicate that (1) artificial intelligence significantly enhances the productivity of SRUI SMEs, and for each one standard deviation increase in artificial intelligence, the productivity level of SRUI enterprises will increase by 6.82%. (2) Mechanism tests reveal that artificial intelligence improves productivity by optimizing labor structure, improving labor resource allocation, stimulating endogenous motivation and innovation vitality within enterprises, and enhancing management level and investment efficiency. (3) Heterogeneity analysis indicates that at the regional level, artificial intelligence significantly boosts the productivity of enterprises with well‐developed network infrastructure and robust intellectual property protection systems. At the industry level, AI has a more pronounced effect on the productivity of technology‐intensive and competitive industries. Additionally, we also find that the impact of AI on productivity is more significant in enterprises with younger executive teams and executives with digital and intelligent education backgrounds. This study expands the research scope of productivity and provides valuable insights for the government to optimize digital economy policies and for enterprises to formulate digital innovation strategies.

Effect of Cyclic Load Frequency on the Fatigue Crack Nucleation and Growth of Annealed and Prestrained Austenitic SS 304

ABSTRACTThe austenitic stainless steels are widely used in several engineering fields due to their high ductility, corrosion and high temperature performance. Despite its noble properties, components manufactured in austenitic stainless steel are subject to fatigue failure. Studies indicate that loading frequency can impact the austenitic stainless steel fatigue performance. In this scenario, the present study aims to evaluate the effect of frequencies of 3 and 30 Hz on the fatigue behavior of SS 304 alloy under load control in order to identify in which fatigue stage the effect is outstanding. Therefore, fatigue and fracture mechanics tests were evaluated on the alloy annealed at 1000°C. Furthermore, fatigue tests were also applied to the alloy after previous tensile plastic strain of 0.5. The analyses denoted a significant reduction in fatigue strength with increasing frequency, especially for the strained alloy. Fatigue crack nucleation is encouraged with greater load frequency. This behavior may be attributed to strain‐induced martensite and other strain mechanisms such as twinning and slip bands that are encouraged by lower strain rates but are relieved by auto‐heating achieved in higher frequencies, as mentioned in the literature, which decrease the strength to fatigue nucleation.

Local Government Debt and Corporate Fraud: Evidence from China

ABSTRACT Local government debt acts as a double-edged sword for economic development. While it has effectively stimulated local economic growth, it has also led to crowding-out consequences of crowding out corporate financing and investment. This study analyzes data of Chinese listed firms from 2007 to 2020, revealing the detrimental effects of local government debt on firms’ misconduct. We find that local government debt is positively related to corporate fraud, and the results remain robust to a series of sensitivity tests. The mechanism tests demonstrate that an increase in local government debt exerts pressure on firms’ financing and performance. Moreover, we observe that the adverse effects are more pronounced in private firms, and firms with poor governance systems.

Investigating the Impact of Long-Term Use on Mattress Firmness and Sleep Quality—Preliminary Results

Mattress comfort, often associated with firmness, is a complex construct influenced by factors such as material composition, construction, and personal preference. In this short communication paper, we indirectly investigated the effects of long-term mattress use on its hardness and sleep quality by observing the changes in the mattress. A mechanical durability test was performed on two structurally different mattress samples (with polyurethane core and pocket spring core) using a modified method based on the EN 1957 standard, aiming to understand the long-term effects of mattress characteristics on sleep quality. Preliminary results confirm that the mattress samples can maintain firmness and support during long-term use. The polyurethane foam mattress experienced initial compression but quickly stabilized, while the pocket spring mattress showed slight softening, maintaining overall firmness. For the polyurethane mattress, after the initial drop, the hardness value stabilized, varying between 7.53 and 9.03 N/mm, and at the end of the test, it stopped at 8.60 N/mm. The firmness rating stabilized at 4.3, showing minimal fluctuation between 4.0 and 4.6 throughout the process, while the total height loss was 3.79 mm. The hardness value of pocket spring mattresses generally decreased with increasing test cycles (it started at 5.86 N/mm and ended at 5.21 N/mm). The firmness remained relatively stable, varying between 7.3 and 7.1, and the total height loss was only 2.86 mm. The findings suggest that the firmness of a mattress can be changed with its use, highlighting the need for further research on a larger number of samples in the direction of the long-term implications of these changes on sleep comfort.

Anomalously High Apparent Young's Modulus of Ultrathin Freestanding PZT Films Revealed by Machine Learning Empowered Nanoindentation.

The mechanical properties at small length scales are not only significant for understanding the intriguing size-dependent behaviors but also critical for device applications. Nanoindentation via atomic force microscopy is widely used for small-scale mechanical testing, yet determining the Young's modulus of quasi-2D films from freestanding force-displacement curve of nanoindentation remains challenging, complicated by both bending and stretching that are highly nonlinear. To overcome these difficulties, a machine learning model is developed based on the back propagation (BP) neural network and finite element training to accurately determine the Young's modulus, pretension, and thickness of freestanding films from nanoindentation force-displacement curves simultaneously, improving the computational efficiency by two orders of magnitude over conventional brute force curve fitting. Using this technique, anomalously high apparent Young's modulus is discovered of 2.8nm thick PbZr0.2Ti0.8O3 (PZT) film as large as 229.4±12.1GPa, much higher than the bulk value. The enhancement can be attributed to the strain gradient-induced flexoelectric effect, and the corresponding flexoelectric coefficient is estimated to be ≈200nCm-1. The method is developed to enable an artificial intelligence (AI) system to study the mechanical properties of a wide range of low-dimensional materials.

Development and validation of a new asphalt mixture to reduce tyre-road contact noise in interurban areas

Road transport is one of the most important sources of noise emissions having a serious impact on human health. Thus, the objective of this study is to develop an innovative asphalt mixture that decreases noise from tyre and pavement interaction on highways with average speeds of about 80 km/h. To achieve this, a series of mechanical and functional tests were conducted both in the laboratory and at the Gustave Eiffel University Accelerated Pavement Testing (APT) facility. The new experimental mixture achieves a balance between high void content and low macro-texture (wavelengths of 5–50 mm), which improves noise reduction while maintaining good mechanical performance. This is achieved thanks to its two-layer structure, with a top layer of reduced maximum aggregate size (4 mm) and a thickness suitable for optimum sound absorption. Various mechanical tests, including the particle loss test and the water sensitivity test, along with functional evaluations focusing on texture, flow resistivity and sound absorption properties, were performed. Measurements on the APT were taken at three different stages of the pavement service lifetime during the testing phase. The outcome was the production of an asphalt mixture that reduced noise up to 6.8 dB in comparison to an asphalt concrete road.

Busy Independent Directors and IPO Company Earnings Management: Evidence from China

This study investigates the effect of busy independent directors on earnings management in Chinese initial public offering (IPO) companies from 2010 to 2020. Using various measures of busy independent directors, the results indicate that directors in IPO companies play a significant role in supervision and governance, thereby significantly mitigating earnings management. Busy independent directors, serving on multiple boards, may face time constraints, but, intriguingly, companies with such directors show a lower inclination for earnings manipulation. This suggests that despite potential time pressures, the independent oversight provided by these directors serves as a deterrent to financial reporting manipulation in the context of Chinese IPOs, underscoring the importance of robust corporate governance structures for transparency and reliability. Additionally, this study identifies specific conditions that amplify the constraining effect and finds that the effect of busy independent directors on earnings management in IPO companies is more significant in companies with high compensation for independent directors, independent directors serving off-site, and companies that receive higher media attention. Mechanism testing indicated that busy independent directors mitigate IPO firms’ earnings management by engaging reputable audit firms and enhancing the effectiveness of internal controls. This nuanced analysis offers valuable insights into how busy, independent directors actively contribute to alleviating the risks associated with earnings management during the IPO process. This study enhances our understanding of the governance benefits of active independent directors in multiple roles and offers novel perspectives on how stakeholders can influence and constrain earnings management in IPO companies.

Multi-stage evolution characteristics and particle size effect of sandstone granules subjected to cyclic loads

Broken granules of different sizes and poor bearing capacities produced by repeated mining of coal seams contribute to natural disasters, such as rock strata movement. In this study, mechanical tests were performed on broken sandstone granules to explore their compaction and recrushing characteristics under repeated mining. The change characteristics of the relevant mechanical parameters of sandstone granules with different particle sizes and changes in energy density were examined, and compaction and recrushing mechanisms of sandstone granules under cyclic loading were identified. The results show that an increase in the initial particle size of sandstone granules has a significant effect on the increase in the strain under load. The cumulative dissipation energy corresponding to final crushing was greater for granules with larger initial sizes. The particle size of sandstone was found to be proportional to the fractal dimension after compaction and crushing. The probability of granular particles with larger initial particle sizes being broken into smaller particles is greater, resulting in the porosity attenuating most rapidly during the stress loading process of granular particles under repeated mining. Therefore, the degree of sample breakage was relatively severe. Particles were rearranged after compaction and crushing. Repeated mining results in dynamic evolution of the pore compaction, deformation, and fractur of the rock mass, as well as stable recombination. The study results provide important theoretical support for understanding of the movement mechanism of rock strata in the goaf under repeated mining.

Influence of Stacking Sequence on the Mechanical Properties of Banana-Glass Fiber Hybrid Laminates for Automotive Shells

The development of composite materials using natural fibers has garnered significant global research interest. Banana fibers, due to their abundant availability and rapid growth cycle, present a promising option for composite material development. When combined with synthetic fibers to form hybrid composites, the resulting material may exhibit significantly improved properties, which is desirable for automotive body manufacturing. The hybrid properties of such composites, however, remain largely unexplored and require thorough evaluation. This study investigates the mechanical performance of hybrid laminated composites fabricated from banana and woven glass fibers bonded with epoxy resin. The composites were produced using non-crimp banana (B) fiber and woven glass (WG) fiber fabrics through the hand lay-up process with four distinct stacking sequences: [WG/B-0⁰/B-0⁰/WG], [WG/B-0⁰/B-45⁰/WG], [WG/B-0⁰/B-60⁰/WG], and [WG/B-0⁰/B-90⁰/WG]. Comprehensive mechanical testing, including tensile, flexural, impact, and hardness tests, along with environmental testing (water diffusion) was conducted in accordance with ASTM standards. Results indicated that the [WG/B-0⁰/B-0⁰/WG] configuration exhibited the highest tensile strength, while the [WG/B-0⁰/B-60⁰/WG] configuration achieved superior flexural strength. The [WG/B-0⁰/B-45⁰/WG] configuration demonstrated the highest impact strength and energy absorption. Rockwell hardness testing revealed that the average hardness numbers for all orientations were approximately 79, which is considered moderate for composite materials. Water absorption tests showed maximum water saturation in [WG/B-0⁰/B-90⁰/WG] of ∼5.5%, where the other laminates had water saturation between 4.5-4.9%. The microscopic analysis of the [WG/B-0⁰/B-45⁰/WG] laminate suggests fiber-matrix debonding and fiber pull-out as the major cause of failure under tensile and flexural loading. These findings suggest that the hybrid laminated composites, particularly the [WG/B-0⁰/B-0⁰/WG] and [WG/B-0⁰/B-45⁰/WG] configurations, exhibit mechanical properties suitable for automotive body applications.

New energy products going global: The impact of digital transformation amid trade frictions

New energy industry is the key field in which China has suffered from trade frictions. It remains to be explored whether digital transformation can enhance export resilience and alleviate the negative shock of trade frictions. Based on the export data of new energy products, this paper uses a panel two-way fixed effects model to explores whether digital transformation can alleviate the negative shock of trade frictions on the exports of new energy products. We find that (1) trade frictions lead to an average decrease of 11.45% in the export value of new energy enterprises and an average increase of 0.84% in the probability of exiting the export market. (2) Digital transformation can buffer the negative shock of trade frictions. For enterprises undergoing digital transformation, the negative shock of trade frictions on exports are relatively limited. (3) Mechanism test indicates that digital transformation accelerates the export products conversion and export markets transfer, thereby alleviating the negative shock of trade frictions. From the digital transformation perspective, this paper provides targeted policy implications for enhancing the export resilience of new energy enterprises and forming a sustained buffering mechanism to alleviate trade friction shocks.

Altered post-fracture systemic bone loss in a mouse model of osteocyte dysfunction

Abstract Femur fracture leads to loss of bone at uninjured skeletal sites, which may increase risk of subsequent fracture. Osteocytes, the most abundant bone cells, can directly resorb bone matrix and regulate osteoclast and osteoblast activity, but their role in systemic bone loss after fracture remains poorly understood. In this study we used a transgenic (TG+) mouse model that overexpresses human B-cell lymphoma 2 (BCL-2) in osteoblasts and osteocytes. This causes enhanced osteoblast proliferation, followed by disruption in lacunar-canalicular connectivity and massive osteocyte death by 10 weeks of age. We hypothesized that reduced viable osteocyte density would decrease the magnitude of systemic bone loss after femur fracture, reduce perilacunar remodeling, and alter callus formation. Bone remodeling was assessed using serum biomarkers of bone formation and resorption at 5 days post-fracture. We used micro-computed tomography, high resolution x-ray microscopy, mechanical testing, and Raman spectroscopy to quantify the magnitude of systemic bone loss, as well as changes in osteocyte lacunar volume, bone strength, and bone composition 2 weeks post-fracture. Fracture was associated with a reduction in circulating markers of bone resorption in non-transgenic (TG-) animals. TG+ mice exhibited high bone mass in the limbs, greater cortical elastic modulus and reduced post-yield displacement. After fracture, TG+ mice lost less trabecular bone than TG- mice, but conversely TG+ mice exhibited trends towards a lower yield point and reduced femoral cortical thickness after fracture, though these were not statistically significant. Lacunar density was greater in TG+ mice, but fracture did not alter lacunar volume in TG+ or TG- mice. These findings suggest that osteocytes potentially play a significant role in the post-traumatic systemic response to fracture, though the effects differ between trabecular and cortical bone.

PH-sensitive aminated chitosan/carboxymethyl cellulose/aminated graphene oxide coated composite microbeads for efficient encapsulation and sustained release of 5-fluorouracil

The application of smart pH-sensitive carriers has become an ideal choice for administering drugs with desired release profiles. Although pH-sensitive microbeads offer distinct benefits for delivering anticancer drugs orally, they encounter drawbacks, including low encapsulation efficiency, weak mechanical stability, biocompatibility concerns, and the risk of abrupt release. This study focuses on developing pH-sensitive coated composite microbeads for effective encapsulation and sustained release of 5-fluorouracil (5-FU). Aminated graphene oxide (AmGO) was integrated into carboxymethyl cellulose (CMC) microbeads, which were subsequently coated with an aminated chitosan (AmCs) derivative. Various analysis techniques, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analyzer (TGA), zeta potential (ZP), and mechanical testing, were utilized to characterize the microbeads. The AmCs@CMC@AmGO composite microbeads demonstrated a compact structure with enhanced mechanical properties, achieving a maximum Young's modulus value of 35.99 N/mm2 compared to 25.95 N/mm2 for pure CMC microbeads. Moreover, pH-sensitivity and water uptake studies (at pH 1.2 and pH 7.4) revealed significant tunability of the composite microbeads by altering the AmGO and AmCs ratios. The coated composite microbeads encapsulated approximately 86.4 % of 5-FU compared to 47 % for CMC microbeads. The burst release of 5-FU at pH 7.4 was significantly reduced, with sustained release reaching 51 % over 24 h. The predominant release mechanism was Fickian diffusion, which well-described by the Peppas-Sahlin kinetic model. The developed microbeads exposed improved biodegradability and non-toxicity toward normal colon cells, while exhibiting notable toxicity against cancerous cells, emphasizing its potential for anticancer drug delivery.

Assessing the Effect of Minimally Invasive Lipid Extraction on Parchment Integrity by Artificial Ageing and Integrated Analytical Techniques.

To assess the short and long-term effect of a newly developed minimally invasive lipid extraction method on parchment, sacrificial pieces of parchments were subjected to artificial ageing and investigated using various analytical methods. Lipids were extracted using our novel vacuum-aided extraction method and characterised by high-temperature gas chromatography (HTGC-FID). Lipids were identified as arising from degraded animal fats. The physical, molecular, and mechanical properties of the parchment samples before/after lipid extraction, and before/after ageing were assessed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pure shear single notch fracture testing. SEM imaging allowed for an assessment of potential structural changes of the collagen fibres while FTIR was used to investigate the possible molecular changes indicated by changes in amide I and II bands. Mechanical tests were used to record the changes in brittleness and stiffness occurring in the materials through lipid extraction and ageing. The multimodal investigation did not highlight measurable changes in the structural, molecular, and mechanical properties of the lipid-extracted parchment, thus indicating the suitability for the minimally invasive lipid extraction method to be applied to historical parchments.

Improved mechanical and microscopic properties of ultra-high-performance concrete with the addition of hybrid alkali-resistant glass fibers

Ultra-high-performance fiber-reinforced concrete (UHPFRC), wherein steel fibers are a primary component, is a new cementitious material with high tensile strength and impact resistance. However, steel fibers are susceptible to corrosion in the alkaline environment of concrete matrices. By contrast, alkali-resistant glass fiber (ARGF) exhibits better corrosion resistance. However, few studies have explored the effects of ARGF on UHPFRC, leaving the optimum ARGF content and its enhancement mechanism unclear. Therefore, this study proposes a UHPFRC design that utilizes AR-GF in place of steel fibers. The effects of different types, lengths, and admixtures of AR-GF are investigated using mechanical tests, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the splitting tensile strength and flexural strength of the UHPFRC increase with fiber length and fiber dosage. The optimum fiber mixing ratio is 30 kg/m3 of 12 mm-long Anti-Crak® 62.4 combined with 0.05 kg/m3 of 6 mm long Anti-Crak® HD, leading to a 23.3 % increase in splitting tensile strength and 15.8 % increase in flexural strength compared to those of undoped concrete. By analyzing the ARGF dispersion pattern at the fracture surface of the flexural test, the ARGF dispersion analysis method was proposed. SEM shows that the ARGF is coated with C-S-H, which increases its adhesion to the concrete matrix. XRD confirms that ARGF does not affect the hydration reaction of the cement in the UHPFRC. Finally, a model of ARGF-reinforced UHPFRC is established to elucidate the reinforcing mechanism. This study provides guidance and a reference for the application of UHPFRC in engineering projects.

Modifiers for the preparation of starch composites under mechanochemical activation: An extended set of criteria

Modification of starch with synthetic polymers under mechanochemical activation is a convenient way to regulate the operational properties of composite materials. The widespread use of this approach is limited by the lack of data on the influence of synthetic polymer nature on the properties of starch and the absence of clear criteria for modifiers selection in the form of aqueous dispersions. To eliminate existing problems, the work proposes to use five integral criteria − polarity, hydrophilicity, and flexibility of synthetic modifiers, as well as particle size and ζ-potential of their aqueous dispersions. To achieve this goal, we studied the dielectric constant, contact angles, IR spectra, and dynamic mechanical properties of four acrylic copolymers and an aliphatic polyurethane. Using the mechanochemical activation, blends and composite films based on corn starch and synthetic modifiers (80:20) were manufactured. Methods of rotational viscometry, X-ray diffraction analysis, DMA, mechanical tests, and moisture permeability allowed us to reveal the influence of the modifier integral parameters on the rheological characteristics of the molding blends and the impact of joint mechanical activation on them, as well as on the crystal structure of the composites, their storage modulus, strength, and transport characteristics.

Design and experiment of a deviation information detection mechanism for sugar beet harvesters based on agricultural machinery and agronomy integration

To address large geometric shape differences, poor ridge distribution straightness and the uncertain spatial distribution of beet roots during the harvesting period, as well as damage caused by the inaccurate row correction detection mechanisms of combine harvesters, this study conducts a design analysis and performance tests of deviation information detection mechanisms based on the integration of agricultural machinery and agronomy. The agronomic process of mechanized sugar beet production was analyzed, the geometric dimensions of root tubers under typical planting patterns of typical varieties in main sugar beet production areas were measured, and a three-dimensional geometric model of beet root tubers was established. A device for measuring ridge shape and root tuber distribution was designed, and agronomic parameters during the harvesting period, such as plant spacing, ridge height, unearthed height, and deviation distance of beet root tubers, were measured and analyzed. A spatial model of ridge shape and beet root tuber growth distribution on the ridge during harvesting was established. The overall structure of the deviation information detection mechanism was analyzed and designed, and the structural forms and key parameters of key mechanisms, such as left‒right swing detection and up‒down floating profiling, were designed on the basis of agronomic parameter analysis. Using the missed detection rate as the evaluation index, field performance tests of the deviation information detection mechanism were conducted. The results revealed that when the average forward speed of the harvester was 0.84 m/s, the average missed detection rate of the deviation information detection mechanism was 0.56%. This method has high adaptability and detection accuracy and achieves a high level of integration for agricultural machinery (detection spatial region of the detection mechanism) and agronomy (beet root distribution spatial region). This study provides a technical basis and methodological reference for improving the quality and efficiency of automatic row correction combined with harvesting operations for crops such as sugar beets.

Physical and thermal improvement of bioplastics based on potato starch/agar composite functionalized with biogenic ZnO nanoparticles

This study investigated potato starch/agar-based bioplastics' structure, properties, and biodegradability by adding ZnO nanoparticles (NPs) biogenically synthesized using Coriandrum sativum extract. ZnO NPs presented crystalline structure, good optical properties, and a size of 6.75 ± 1.4 nm, which were added at various concentrations (419.66–104.23 ppm) in bioplastics and their presence was confirmed via EDS elemental analysis and X-ray fluorescence. The highest NPs concentration contributed to a smoother surface, while FTIR and Raman analyses suggested interactions between the NPs and functional groups of the biopolymeric matrix. ZnO NPs addition slightly reduced bioplastic transparency but significantly improved UV-A and UV-B blocking capacities. It also increased hydrophobicity, evidenced by a 22 % reduction in water absorption and a 55 % increase in contact angle. Thermogravimetric analysis (TGA) indicated that NPs raised the bioplastic's thermal stability. Mechanical property tests showed that ZnO NPs concentrations had negligible or negative effects probably due to the heterogeneous distribution of NPs, or the non-isotropic characteristic of the bioplastic. Finally, biodegradability assays in seawater and soil revealed over 43.5 % and 66 % degradation after 15 and 28 days, respectively. Therefore, biosynthesized ZnO NPs mainly enhanced the bioplastic's UV-blocking capacity, hydrophobicity, and thermal properties, offering an eco-friendly option for future studies/applications.