Storage Modulus Research Articles

Abstract B041: Investigating the impact of extracellular matrix stiffness on macrophage function and organoid growth in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of only 11%. Current treatments mostly target the cancer cells themselves and have not been able to significantly improve survival rates, meaning there is an urgent need for novel therapies. PDAC is unique among solid tumors because it exhibits extensive desmoplasia that is characterized by an abundance of extracellular matrix (ECM) components. In recent years, an increasing body of work has shown that cancer tissue is stiffer than normal tissue by a factor of 3 or more. This increase in ECM stiffness has been shown to play an important role in affecting cell-to-cell communication as well as cancer progression and chemoresistance . However, how ECM stiffness affects tumor-associated macrophages, an important component of the pancreatic tumor microenvironment (TME), is still understudied. Previous studies have demonstrated that macrophages are highly responsive to mechanical cues, with the mechanical environment influencing macrophage polarization and function in a context- and disease-dependent manner. Elucidating these potential changes in PDAC can provide us with insights on how stiffness affects therapeutic outcome. Healthy pancreatic tissue typically exhibits a storage modulus of approximately 0.5-1 kPa, whereas PDAC tissue can range from 4-10 kPa. To study macrophage responses to varying stiffness, we cultured RAW264.7 mouse macrophage cell lines on 2D substrates with stiffness levels of 0.2, 2, and 8 kPa. We observed that macrophages cultured on stiffer matrices exhibited a trend toward a pro-inflammatory phenotype, with increased expression of M1 markers such as iNOS, IL-1β, and IL-6, compared to those cultured on softer matrices. However, conditioned media from macrophages cultured on both soft and stiff substrates similarly reduced the size of PDAC organoids, indicating a lack of functional difference between these groups. These findings suggest the need for more sophisticated models that better replicate the PDAC TME to fully capture the complex cell-to-cell interactions that are not evident in 2D cultures. To address this limitation, we developed a 3D tri-culture tunable biomimetic mouse model comprising PDAC organoids, host-matched cancer-associated fibroblasts (CAFs), and macrophages. This novel model allows us to modulate the stiffness of the 3D co-culture system through the addition of collagen I and CAFs. Rheometry data confirmed that the stiff tri-culture model had a significantly higher storage modulus than the soft tri-culture model. Using qPCR, we investigated the role of mechanosensitive ion channels, specifically Transient Receptor Potential Vanilloid-type 4 (TRPV4) and Piezo1, in mediating macrophage mechanosensing in response to varying levels of matrix stiffness. This study highlights the importance of 3D models that can recapitulate biophysical cues of cancer and will allow us to better understand how macrophages respond to stiffness, which may give rise to new therapeutic targets and development of new treatments in the future. Citation Format: Bayan Mahgoub, Weikun Xiao, Eileen Fung, Shannon Mumenthaler, Reginald Hill. Investigating the impact of extracellular matrix stiffness on macrophage function and organoid growth in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B041.

Abstract A006: Investigating the effects of fibroblasts derived from the primary versus the metastatic organ on 3D biomimetic models of pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer death in the United States with a 5-year survival rate of only 13%. Early diagnosis is very difficult and thus 53% of patients are diagnosed after metastasis has already occurred, with the liver being the most frequently affected site. Both primary tumors and metastases have dense desmoplastic stroma due to a high percentage of fibroblasts within the tumor microenvironment (TME). Previously, we developed a tunable 3D biomimetic model of the liver metastatic niche (LMN) to investigate how local fibroblasts affect tumor growth and chemoresistance in PDAC liver metastasis. This study aims to investigate the contributions of fibroblasts at the primary versus metastatic sites. We used matched primary PDAC and liver metastatic (LM) organoids derived from the Kras+/LSL-G12D; Trp53+/LSL-R172H; Pdx1-Cre (“KPC”) genetically engineered mouse model. This allows us to compare the effects of primary PDAC cancer associated fibroblasts (CAFs) and liver metastasis associated fibroblasts (MAFs) on tumor cell growth and chemoresistance. Rheometry analyses were conducted to study the impact of local fibroblasts on the extracellular matrix (ECM) stiffness. Our results showed that both storage and loss moduli were enhanced only when PDAC CAFs were present in the co-cultured gels compared to gels with MAFs. Additionally, the 3D biomimetic model showed fibroblasts increased tumor growth and chemoresistance to gemcitabine, only when they were derived from the same site as the tumor cells. This highlighted the importance of studying the organ-specific microenvironment to develop better treatment options for patients with metastatic PDAC. To delve deeper into the molecular basis of these observations, we conducted RNA-sequencing to identify and compare the gene expression profiles in primary and metastatic tumor organoids exposed to conditioned media from CAFs and MAFs using a transwell membrane co-culture model. Our results showed significant differences in gene expression based on the type of fibroblasts co-cultured with the organoids. Moreover, we investigated the role of MAF-derived exosomes on LM growth and chemoresistance using exosome depletion and direct exosome addition to LM organoids. Lastly, we performed exosomes size and distribution characterizations using dynamic light scattering (DLS) analysis. Taken together, these findings highlight the critical role of the organ-specific microenvironment in tumor progression and the necessity of targeted therapies to improve patient outcomes in metastatic PDAC. Our results underscore the importance of developing a tunable 3D biomimetic model of the LMN, as it enables the testing of novel therapeutic strategies designed to disrupt interactions between MAFs and tumor cells, and potentially advancing treatments for metastatic PDAC. Citation Format: Mahsa Pahlavanneshan, Weikun Xiao, Eileen Fung, Vaidhyanathan Mahaganapathy, Chae Young Eun, Chang-Il Hwang, Shannon Mumenthaler, Reginald Hill. Investigating the effects of fibroblasts derived from the primary versus the metastatic organ on 3D biomimetic models of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A006.

The Photocleavable Protein PhoCl-Based Dynamic Hydrogels.

Dynamic protein hydrogels have attracted increasing attention owing to their tunable physiochemical and mechanical properties, customized functionality, and biocompatibility. Among the different types of dynamic hydrogels, photoresponsive hydrogels are of particular interest. Here, we report the engineering of a photoresponsive protein hydrogel by using the photocleavable protein PhoCl. We employed the well-developed SpyTag and SpyCatcher chemistry to engineer PhoCl-containing covalently cross-linked hydrogels. In the hydrogel network, PhoCl, which can be cleaved into two fragments upon violet irradiation, is employed as a dynamic structural motif to regulate the cross-linking density of the hydrogel network. The resultant PhoCl-containing hydrogels showed photoresponsive viscoelastic properties. Upon violet irradiation, the PhoCl hydrogels soften, leading to an irreversible reduction in the storage moduli. However, no gel-sol transition was observed. Leveraging this light-induced stiffness change, we employed this hydrogel as a cell culture substrate to investigate the mechanobiological response of NIH-3T3 fibroblast cells. Our results showed that 3T3 cells can change their morphologies in response to the stiffness change of the PhoCl hydrogel substrate dynamically, rendering PhoCl-based hydrogels a useful substrate for other mechanobiological studies.

Numerical FE Three-phasic Simulation to Predict the Effect of Air Voids on the Dynamic Modulus of Bituminous Composites

In this study, the mechanical performance of bituminous composites was predicted using an upscaling methodology that integrated both finite element analysis and analytical modeling. The FE approach was employed to incorporate intricate geometries and material characteristics. The dynamic modulus of the matrix and the elastic properties of aggregates served as inputs for the numerical models at various scales. This approach considers the distinctive attributes of the granular framework at each level. Furthermore, the investigation involved the influence of air void proportions on the composite's modulus. The numerical models encompassed the random incorporation of air voids within the matrix at varying levels. Notably, it was observed that at low frequencies air voids reduced the dynamic modulus of asphalt more than at high frequencies due to its effect on viscoelastic nature of the bituminous composite. Moreover, heightened temperatures intensified the impact of air void on the dynamic modulus of the asphalt mixture.

Enhanced electrorheological activity of rod-like Fe3O4@TiO2 particles in elastomers and their morphological effect

Abstract The properties of dielectric particles play the most important role in the electrorheological (ER) activity of elastomers, however, there is a lack of experimental research on the effect of particle morphology on the properties of electrorheological elastomers (EREs). In this study, spherical and rod-like Fe3O4@TiO2 core-shell particles were synthesized and used to prepare EREs. Particles characterization results showed that both spherical and rod-like Fe3O4@TiO2 exhibited an obvious core-shell structure and similar magnetic properties,with the aspect ratio of rod-like Fe3O4@TiO2 particles was approximately 7:1. Furthermore, the EREs filled with rod-like Fe3O4@TiO2 particles exhibit a higher dielectric constant and sharper dielectric loss peak than those filled with spherical particles, indicating that a larger aspect ratio enhances the dielectric performance. For EREs with the same volume fraction of particles or cured under the same external field, the storage modulus and relative ER effect of EREs filled with rod-like particles are both higher than those of EREs containing spherical particles. Additionally, it can be confirmed that the rod-like particle chain structures have a more significant strengthening effect on the ERE matrix, as evidenced by the rod-like Fe3O4@TiO2 particle filled elastomers exhibiting lower creep strain.

Effect of the Ratio of Protein to Water on the Weak Gel Nonlinear Viscoelastic Behavior of Fish Myofibrillar Protein Paste from Alaska Pollock

The linear and nonlinear rheological behaviors of fish myofibrillar protein (FMP) paste with 75%, 82%, and 90% moisture content were evaluated using small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests. SAOS revealed pastes with 75% and 82% moisture exhibited solid-like behavior, characterized by higher storage modulus (G′) than loss modulus (G″), indicative of weak gel properties with a strong protein interaction. In contrast, the 90% moisture content showed more viscous behavior due to weakened protein–protein entanglements. The frequency exponent (n′ and n″) from the power law equation varied slightly (0.24 to 0.36), indicating limited sensitivity to changes in deformation rate during SAOS. LAOS tests revealed significant structural changes, with Lissajous–Bowditch curves revealing early nonlinearities at 10% strain for 90% moisture content. Decomposed Chebyshev coefficients (e3/e1, v3/v1, S, and T) indicated strain stiffening at lower strains for the 75% and 82% moisture pastes (i.e., < 50% strain for 75% and < 10% strain for 82%), transitioning to strain thinning at higher strains. Additionally, numerical model confirmed the predictability of the 3D printing process from the nonlinear rheological data, confirmed the suitability of the 75% and 82% moisture pastes for applications requiring structural integrity. These insights are essential for optimizing processing conditions in industrial applications. The findings suggest that the 75% and 82% moisture pastes are suitable for applications requiring structural integrity, while the 90% moisture paste is ideal for flow-based processes. These insights are essential for optimizing processing conditions in industrial applications.

Mechanical Properties of Inflamed Appendix Tissues

Background/Objectives: Histopathological examination enables visualization of morphological changes in cells and tissues. In recent years, there has been increasing interest in assessing the mechanical properties of tissues that cannot be determined by standard histopathological examinations. Mechanobiology is crucial in human physiology and holds promise for uncovering new diagnostic markers for disease processes such as carcinogenesis and inflammation. In this study, we concentrated on measuring the mechanical properties of appendix biopsy specimens to identify potential mechanomarkers of inflammation. Appendix tissues provided the opportunity to measure mechanical properties both with an atomic force microscope and a shear rheometer. Methods: The atomic force microscope AFM—NanoWizard 4 BioScience JPK/Bruker was used for the evaluation of the elastic modulus (i.e., Young’s modulus) of appendix tissues. Young’s modulus was derived from the Hertz-Sneddon model applied to force-indentation curves. The rheological properties of macroscopic samples were measured on a parallel-plate, strain-controlled shear rheometer Anton Paar MCR302. Results: The data collected suggest that elasticity, expressed as Young’s modulus and the storage modulus, could be considered a marker indicating appendix tissue inflammation. Young’s modulus of inflamed appendix tissues was found to be significantly lower than that of healthy ones, with an average reduction of 67%. Furthermore, it was observed that inflamed appendix tissues, in comparison to healthy ones, respond differently under varying axial and shear stresses, enabling their identification. Conclusions: Our findings suggest that the specific mechanical properties of inflamed vermiform appendices could serve as novel mechanomarkers for the early detection and monitoring of appendicitis.

Rheology of Cellulosic Microfiber Suspensions Under Oscillatory and Rotational Shear for Biocomposite Applications

This study investigates the rheological behavior of cellulose microfiber suspensions derived from kahili ginger stems (Hedychium gardnerianum), an invasive species, in two adhesive matrices: a commercial water-based adhesive (Coplaseal®) and a casein-based adhesive made from non-food-grade milk, referred to as K and S samples, respectively. Rheological analyses were performed using oscillatory and rotational shear tests conducted at 25 °C, 50 °C, and 75 °C to assess the materials’ viscoelastic properties more comprehensively. Oscillatory tests across a frequency range of 1–100 rad/s assessed the storage modulus (G′) and loss modulus (G″), while rotational shear tests evaluated apparent viscosity and shear stress across shear rates from 0.1 to 1000 s−1. Fiber-free samples consistently showed lower moduli than fiber-containing samples at all frequencies. The incorporation of fibers increased the dynamic moduli in both K and S samples, with a quasi-plateau observed at lower frequencies, suggesting solid-like behavior. This trend was consistent in all tested temperatures. As frequencies increased, the fiber network was disrupted, transitioning the samples to fluid-like behavior, with a marked increase in G′ and G″. This transition was more pronounced in K samples, especially above 10 rad/s at 25 °C and 50 °C, but less evident at 75 °C. This shift from solid-like to fluid-like behavior reflects the transition from percolation effects at low frequencies to matrix-dominated responses at high frequencies. In contrast, S samples displayed a wider frequency range for the quasi-plateau, with less pronounced moduli changes at higher frequencies. At 75 °C, the moduli of fiber-containing and fiber-free S samples nearly converged at higher frequencies, indicating similar effects of the fiber and matrix components. Both fiber-reinforced and non-reinforced suspensions exhibited pseudoplastic (shear-thinning) behavior. Fiber-containing samples exhibited higher initial viscosity, with K samples displaying greater differences between fiber-reinforced and non-reinforced systems compared to S samples, where the gap was narrower. Interestingly, S samples exhibited overall higher viscosity than K samples, implying a reduced influence of fibers on the viscosity in the S matrix. This preliminary study highlights the complex interactions between cellulosic fiber networks, adhesive matrices, and rheological conditions. The findings provide a foundation for optimizing the development of sustainable biocomposites, particularly in applications requiring precise tuning of rheological properties.

Effect of nano‐SiO2 dispersion on the mechanical properties and frost resistance of modified cement paste

AbstractThe dispersion of nano‐SiO2 (NS) in cement plays a critical role in enhancing the properties of cementitious materials. In this study, the combination of ultrasonic dispersion and polycarboxylic acid water reducing agent (PCE) was used to significantly improve the dispersion of NS. The effects of ultrasonic dispersion time, NS content, and PCE content on dispersion quality were investigated, alongside their impact on mechanical properties, electrical resistivity, and frost resistance. The results demonstrated that this synergistic method optimized the dispersion of NS, leading to superior mechanical properties and frost resistance. With an ultrasonic dispersion time of 40 min, NS content of 1.0 wt.%, and PCE content of 0.75 wt.%, the cement paste achieved its optimal performance. Compared to non‐dispersed samples, compressive strength increased by 33.7%. After 75 freeze–thaw cycles, the mass loss was 2%, the relative dynamic elastic modulus was 99.15%, and the strength loss was 13.74%.

MXene/Bacterial Cellulose Hybrid Materials for Sustainable Soft Electronics

This work evaluated bacterial cellulose (BC) as a possible biodegradable soft electronics substrate in comparison to polyethylene terephthalate (PET), while also focusing on evaluating hybrid MXene/BC material as potential flexible electronic sensor. Material characterization studies revealed that the BC material structure consists of nanofibers with diameters ranging from 70 to 140 nm, stacked layer-by-layer. BC samples produced are sensitive to post-treatment with isopropanol resulting in a change of structural and mechanical properties. The viscoelastic properties of the BC substrates have been studied experimentally in comparison with the PET film. Aged BC substrate showcased similar viscoelastic properties stability, while exhibiting better properties above 70 °C, with total storage modulus change of −15% and loss modulus change of 21%. MXenes prepared using the Minimally Intensive Layer Delamination (MILD) method were screen-printed onto BC substrates and PET films to form MXene/BC (MX/BC) and MXene/PET (MX/PET) devices. The electrical properties results showcased different resistive behavior on both BC and PET substrate samples with different impedance moduli. MX/PET presented lower sheet resistance of around 156 Ω·sq−1, while MX/BC was 2733 Ω·sq−1. Finally, the MX/BC and MX/PET devices were subjected to repeatable quasi-static load tests and the piezoresistive sensing behavior of the devices has been reported.

Research on mechanical properties and pore structure evolution process of steam cured high strength concrete under freeze thaw cycles.

With the widespread use of high-strength concrete structures (HC), the impact of pore structure on their performance has become a current research focus. The mechanism by which different curing conditions and freeze-thaw cycles influence the evolution of pore structure remains unclear. Therefore, this study systematically investigated the frost resistance of high-strength concrete under different curing conditions, measured the mass loss rate, compressive strength, and relative dynamic elastic modulus of concrete under freeze-thaw cycles. Utilizing low-field nuclear magnetic resonance (NMR) technology, this study analyzed the evolution of pore structure in HC under freeze-thaw cycles. Additionally, the fractal dimension was used to evaluate the change of concrete internal pore structure, so as to reflect the influence of pore structure on the mechanical properties of concrete subjected to freeze-thaw cycles, and then evaluated the freeze-thaw damage of HC. The experimental results indicated that the steam curing regimes led to an increase in the porosity of HC, thereby influencing its frost resistance. Steam-cured high-strength concrete (SMHC) exhibited a higher degradation rate under freeze-thaw cycles, resulting in a greater level of deterioration compared to standard curing high-strength concrete (SDHC), even under the same number of freeze-thaw cycles.

Multiphase Biopolymers Enriched with Suberin Extraction Waste: Impact on Properties and Sustainable Development

This manuscript explores the development of sustainable biopolymer composites using suberin extraction waste, specifically suberinic acid residues (SAR), as a 10% (w/w) reinforcing additive in polylactide (PLA) and thermoplastic starch–polylactide blends (M30). The materials were subjected to a detailed analysis using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) to assess their thermal, mechanical, and structural properties. The study confirmed the amorphous nature of the biopolymers and highlighted how SAR significantly influences their degradation behavior and thermal stability. M30 exhibited a multi-step degradation process with an initial decomposition temperature (T5%) of 207.2 °C, while PLA showed a higher thermal resistance with decomposition starting at 263.1 °C. Mechanical performance was assessed through storage modulus (E′) measurements, showing reductions with increasing temperature for both materials. The research provides insights into the potential application of SAR-enriched biopolymers in sustainable material development, aligning with circular economy principles. These findings not only suggest that SAR incorporation could enhance the mechanical and thermal properties of biopolymers, but also confirm the effectiveness of the research in reassurance of the audience.

Preparation of multiaxial glass fiber/epoxy prepreg and its mechanical properties in composites

AbstractThis study investigates the mechanical properties of composites made from biaxial warp‐knitted glass fiber/epoxy prepregs (BW‐GF/EP) in comparison to plain woven glass fiber/epoxy prepregs (PW‐GF/EP). The BW‐GF/EP composites demonstrated superior tensile strength, with an increase of 9.5%, and bending strength, with an increase of 12.2%, compared to the PW‐GF/EP composites. Despite having a lower tensile modulus, the BW‐GF/EP composites exhibited 8.7% higher interlaminar shear strength. Dynamic mechanical analysis showed that both materials had similar storage and loss moduli at lower temperatures, with PW‐GF/EP performing better at higher temperatures. Microscopy revealed that failure in PW‐GF/EP occurred at weave intersections, while BW‐GF/EP composites showed fiber rupture and delamination. The findings highlight the advantages of using biaxial warp‐knitted fabrics for improved composite performance.Highlights Developed biaxial warp‐knitted fabric prepregs to replace liquid molding techniques. Improved interlaminar shear strength, reducing delamination risks in composites. Achieved higher tensile and bending strength compared to plain weave composites. Enhanced resin impregnation and molding efficiency with biaxial warp‐knitted fabrics. Reduced environmental impact and costs by avoiding VOCs and minimizing waste.

Surface modified cellulose nanospheres with simultaneous nucleation and degradation-accelerating effects on poly(lactic acid)

As a novel type of nanocellulose material, cellulose nanospheres (CNSs) have gained significant attention and rapid development in recent years. In this work, the surface hydrophobic modification of CNSs was achieved by employing maleic anhydride as an esterifying agent. The effects of modified cellulose nanospheres (CNS-MA) on the crystallization and hydrolysis behaviors of polylactic acid (PLA)-based composites were systematically investigated. The results demonstrate that surface modification improves the dispersion of CNSs in the PLA matrix. Well-dispersed particles act as nucleation sites, which increases the crystallization rate and crystallinity of PLA and endows the composites with remarkable heat distortion resistance. The storage modulus of the PLA/CNS-MA composites exceeds 300 MPa, even at an elevated temperature of 90 °C. Furthermore, the hydrolytic degradation of PLA is dramatically accelerated with the addition of CNS-MA. Combining the morphology observations and theoretical calculations, it is speculated that the fast hydrolytic degradation is related to a transition in the main hydrolytic degradation mechanism from surface erosion to bulk erosion, because the presence of CNS-MA provides particular pathways for water molecules to diffuse into the interior of the composites. This research highlights the potential of CNSs as a multifunctional filler with both reinforcing and degradation-promoting effects, offering valuable insights for the study of other biomass nanomaterials.

Evaluation of SMA-13 Asphalt Mixture Reinforced by Different Types of Fiber Additives

This research aims at systematically evaluating the properties of SMA-13 asphalt mixture reinforced by several fiber additives including flocculent lignin fiber (FLF), granular lignin fiber (GLF), chopped basalt fiber (CBF), and flocculent basalt fiber (FBF). Firstly, the thermal stability, moisture absorption, and oil absorption property of these fiber additives were analyzed. Secondly, the property of SMA-13 reinforced using four types of single fibers and two kinds of composite fibers (FLF + CBF and FLF + FBF) was comprehensively analyzed. Specifically, the high-temperature performance was evaluated using the uniaxial penetration test and the rutting test, the medium-temperature anticracking property was evaluated using the IDEAL-CT test, the low-temperature property was analyzed using the beam bending test, and the water stability was studied by the freeze–thaw splitting test. Thirdly, the dynamic mechanical response of different-fibers-modified SMA-13 was evaluated using the uniaxial compression dynamic modulus test. Finally, correlation analysis between the results of dynamic modulus and the high-, medium-, and low-temperature mechanical performance was carried out. The research results reveal that the stability of CBF and FBF under thermal action is better than that of GLF and FLF, and FBF shows the best thermal stability. The oil absorption property of FLF is better than that of GLF, followed by FBF and CBF. The comprehensive mechanical properties of CBF- and FBF-reinforced SMA-13 are better than those of FLF- and GLF-modified SMA-13. CBF can better reinforce the mechanical property of SMA-13 under low and medium temperature, while FBF can better reinforce the performance of SMA-13 at high temperature. FLF/CBF- and FLF/FBF-composite-modified SMA-13 show better high-temperature mechanical performance than that of the single-fiber-reinforced mixture, and FLF has some negative impact on the properties of FLF/FBF-composite-modified SMA-13 at low temperature. Fibers have no significant influence on the water stability of the mixtures. Meanwhile, the linear correlation between the mechanical performance of all the fiber-reinforced SMA-13 and the dynamic modulus result is good.

Impact of statistical poly(propylene co-ethylene) on the thermo-mechanical properties of high-density polyethylene

A series of high-density polyethylene and a statistical copolymer of poly(propylene-co-ethylene) blends in a wide range, namely (0, 10, 20, 30, 40, 50, 60,70, 80, 90, 100) abbreviated as HDPE/VM were systematically investigated by using a rheometer, differential scanning calorimetry (DSC) measurements, polarized optical microscopy (POM) and tensile tests. Rheometer results show that adding VM decreases dynamic viscosity, storage, and loss modulus. Han plot shows that HDPE and VM are compatible and miscible in the range from 20 to 60 VM % in the molten state. DSC results show little nucleation effect of VM on HDPE (HDPE’s melt crystallization temperature shifts 2 °C higher). Moreover, a linear composition dependence of ∆cp ∆Hc, ∆Hm shows that PE and VM are most probably compatible in the molten state in composition range from 20 to 60%. However, upon crystallization, the VM and PE domains occur distinctively. The results of the tensile tests demonstrated a decrease in elastic modulus, yield stress, and ultimate tensile strength as VM content increased. At low VM content (less than 20%), high elongation at break was detected for the blends, and very fine spherulites of HDPE were found across the sample by POM.

Impact of Graphene Nano particles on static and dynamic mechanical properties of basalt-glass fibre reinforced epoxy polymer hybrid composites

ABSTRACT This paper investigates the structure-property relationships in basalt – glass fabric reinforced hybrid polymer composites doped with graphene nanoplatelets. Basalt Glass fabrics were reinforced with 0.2 wt.% − 0.8 wt.% graphene using hand layup and compression moulding to fabricate laminated plates. The mechanical, morphological, and thermomechanical properties were characterised using tensile, flexural, impact, SEM, FTIR, XRD, and DMA testing. Results showed that low graphene loadings of 0.2 wt.% − 0.4 wt.% led to small, isolated graphene platelets decorating the basalt fibres. At 0.8 wt.% loading, extensive wrinkling, folding, and stacking of graphene sheets on the basalt was observed. FTIR revealed increasing sp2 C=C vibrations and XRD showed rising graphene peak intensities with higher loadings. While tensile and flexural strengths improved up to 0.6 wt.% graphene due to efficient stress transfer, impact energy increased consistently until 0.8 wt.% graphene owing to reinforcement effects. DMA exhibited enhanced storage modulus and restricted mobility with more graphene. An optimum graphene loading of 0.6 wt.% was found to maximise the mechanical performance through uniform dispersion and strong interfacial adhesion. The results demonstrate that graphene incorporation can substantially augment the strength, toughness, and thermomechanical properties of the composites at appropriate compositions prior to aggregation.

Study on chloride ion penetration performance of recycled composite micro powder concrete under freeze-thaw environment

With the increasing generation of construction waste, the rational utilization of recycled micro powder has become crucial for the efficient development of construction waste resource recycling. This study investigates the chloride ion penetration performance of Recycled Composite Micro Powder Concrete (RCMPC) under freeze-thaw conditions. By incorporating Recycled Concrete Powder (RCP) and Recycled Brick Powder (RBP) in a ratio of 2:8 to replace various proportions of cement, specimens with different water-to-binder ratios (0.35, 0.45, 0.55) were designed and subjected to freeze-thaw cycles (FTC), pore structure analysis, rapid chloride ion migration, and diffusion tests. The results indicate that the frost resistance of the concrete decreases with the addition of Recycled Composite Micro Powder (RCMP). As the RCMP content increases, the mass loss rate and relative dynamic modulus decline, while the thickness of the damage layer increases. Moreover, the chloride ion migration coefficient and diffusion coefficient exhibit a linear increase with the number of FTC, with specimens containing higher RCMP content showing poorer chloride ion penetration performance. Based on the experimental results, this paper establishes a chloride ion diffusion model for RCMPC considering freeze-thaw damage, which demonstrates good predictive capability for the chloride ion diffusion behavior of RCMPC in freeze-thaw environments, providing a theoretical basis for its application in cold and marine regions.

Synergistic Integration of α-Ag2WO4 into PLA/PBAT for the Development of Electrospun Membranes: Advancing Structural Integrity and Antimicrobial Efficacy.

The rising resistance of various pathogens and the demand for materials that prevent infections drive the need to develop broad-spectrum antimicrobial membranes capable of combating a range of microorganisms, thereby enhancing safety in biomedical and industrial applications. Herein, we introduce a simple and efficient technique to engineer membranes composed of polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) biopolymers and α-Ag2WO4 particles using an electrospinning technique. The corresponding structural, thermal, mechanical, and antimicrobial properties were characterized. X-ray diffraction (XRD) patterns confirmed the integration of crystalline α-Ag2WO4 within the polymer matrix. Scanning electron microscopy (SEM) and Raman confocal microscopy revealed uniformly dispersed α-Ag2WO4 particles in the electrospun fibers, influencing their diameter and surface roughness. Thermal analysis indicated adjustments in the thermal stability and crystallinity of the composites with an increasing α-Ag2WO4 content. Dynamic mechanical analysis (DMA) highlighted variations in storage modulus and glass transition temperatures due to interactions between α-Ag2WO4 and polymer chains, with tensile tests showing an increase in elastic modulus and ultimate tensile strength as the α-Ag2WO4 content increased. Antimicrobial assessments revealed that PLA/PBAT membranes with α-Ag2WO4 showed pronounced antibacterial activity, forming inhibition halos across all samples against Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Mycobacterium smegmatis (a surrogate for Mycobacterium tuberculosis). These membranes also exhibited potent antiviral activity against bacteriophage phi 6, a surrogate for SARS-CoV-2, suggesting potential applications in combating infections caused by enveloped viruses. The antimicrobial activities are attributed to the generation of reactive oxygen species (ROS) and the controlled release of Ag+ ions. This work underscores the multifaceted capabilities of α-Ag2WO4-enhanced PLA/PBAT membranes in combating bacterial and viral growth, where both durability and microbial resistance are critical. Taken together, our findings provide a solution for obtaining advanced materials to be applied in a wide range of industrial applications, such as filtration systems, food preservation, antimicrobial coatings, protective textiles, and cleaning products.

The Peculiarities of Acoustic Normal Waves Propagation in Thin Porous Sheets of Thermally Expanded Graphite

Thermally expanded graphite belongs to a new class of graphite materials with unique physical, chemical and mechanical properties. Acoustic wave velocity is one of the most important characteristics for study of porous materials including thin porous sheets of thermally expanded graphite. In this paper peculiarities of symmetric mode S0 Lamb wave propagation and SH-wave with horizontal polarization in sheets of thermally expanded graphite are experimentally investigated. To determine their velocities a differential measurement scheme on the base of a low-frequency acoustic flaw detector DIO1000 LF and specialized piezoelectric transducers with dry point contact was used. Additionally the longitudinal wave velocity in direction of sheet thickness was determined using piezoelectric transducers based on polyvinylidene fluoride. Indicatrices of normal wave velocities in the rolling plane were plotted and it was shown that the maximum acoustic anisotropy is characteristic for the S0-mode. The velocity minimum corresponds to the longitudinal direction of the rolling plane in which the maximum elongation of gas pores was observed. Influence of thickness and density of thermally expanded graphite sheets on the velocities of normal waves was investigated and presence of the thickness range where the minimum velocity values were observed due to the maximum inhomogeneity of layers formed in the rolling process. Method for determination of dynamic elastic moduli of porous thermally expanded graphite sheets using experimentally measured velocities of normal waves was proposed. It was shown that in the longitudinal direction of the rolling plane the Poisson's ratio took negative values which allow to attribute the specified material to auxetics ones.