Foam Density Research Articles

The Flammability and Thermal Stability of Filling Epoxy Foam Plastics for Construction Purposes

An effective type of polymer heat-insulating material (foams) based on reactive oligomers is casting epoxy foams with high technological and operational parameters. However, polyepoxide foams are highly flammable, which significantly restrains their application in the construction industry. The aim of this work was to develop effective methods for reducing the flammability of filling epoxy foams. In order to achieve the objective, the following objectives were addressed: determining the influence of the chemical nature and content of additive and reactive bromine- and phosphorus-containing compounds on the thermal stability, flammability and operational properties of filling epoxy foams, and the development of polyepoxy foams of reduced flammability with high-quality physical and mechanical characteristics. When estimating the flammability of epoxy foams, we used both state-approved methods and the methods described in scientific and technical literature. The thermal properties of epoxy foams were studied with the help of multimodular thermoanalytical complex DuPont-9900. The data on the influence of the apparent density of foams and oxygen concentration in the oxidant flow on the flame propagation speed on the horizontal surface of polyepoxy foams are presented. It was revealed that the chemical nature of amine hardeners does not affect the thermal stability and flammability of epoxy foams. It was established that phosphate plasticizers are ineffective flame retardants of foamed epoxy resin, and the chemical structure of additive organobromic flame retardants insignificantly affects their efficiency. It was shown that microencapsulated flame retardants are inferior in flame retardant efficiency to additive flame retardants. It was found that effective flame retardants for casting polyepoxy foams are phosphorus-containing oligoether methacrylate and epoxidized waste from the production of tetrabromodiphenylpropane. The results of this research will form the basis for the production of an experimental industrial batch of samples of pouring epoxy foams of reduced flammability.

Process Optimization of Pressure-induced Autoclave Foaming of Polylactide by Supercritical CO<sub>2</sub> Using Central Composite Design of Response Surface Methodology

A pressure-induced autoclave foaming assisted by supercritical CO2 of degradable polylactide (PLA) has been developed. A central composite design (CCD) of response surface methodology (RSM) is used to optimize three distinct process conditions: foaming temperature, pressure, and time. The mathematical model built for examining the effect of process conditions on the foam density and volume expansion ratio was verified and determined to be acceptable with an R-square value derived from the regression model of 0.930 and 0.934, respectively. The experimental and statistical results showed that of the three factors examined, the foaming pressure had the greatest impact on the density and volume expansion ratio of the PLA foams. The foaming temperature and time also had significant interaction impacts on both responses. It was observed that the following conditions are optimal for foaming of PLA, with a maximum VER of 10.107 and a minimum foam density of 0.123 g/cc: foaming temperature of 165.86 °C and foaming pressure of 152.4 bar for 2.38 h of foaming time.

Preparation and Properties of High‐Temperature‐Resistant and Low‐Dielectric Constant Silicon‐Containing Arylacetylene Resin/SiO2 Syntactic Foams

A silicon‐containing arylacetylene resin (PSA)/SiO2 syntactic foam was prepared through a chemical foaming approach, with PSA serving as the matrix, quartz sand (QS) and nanosilica (nSiO2) acting as fillers, and their structures and properties were characterized. The results show that the incorporation of appropriate amounts of QS and nSiO2 can reduce the cell size and apparent density of the syntactic foam, and improve its heat resistance, dielectric properties and wave transmission properties. The addition of QS can increase the compressive strength of the syntactic foam, while the addition of nSiO2 decreases the compressive strength. The apparent densities of the PSA/9QS and PSA/9nSiO2 syntactic foams with 9% filler addition are 0.242 g cm−3 and 0.157 g cm−3, respectively, and the temperatures at 5% weight loss (Td5) under a nitrogen atmosphere were 692 °C and 658 °C, respectively. The dielectric constants were 1.59 and 1.25, respectively. The wave transmittance within the frequency range of 8.2–12.4 GHz was 98.5% and 96.8%, respectively. PSA/SiO2 syntactic foam can be used as a lightweight and high‐temperature‐resistant wave‐transmission material in aerospace and other fields.

Study on foaming behavior of block copolymer/inorganic particles co‐construction of toughened epoxy resin foams

AbstractLow toughness and brittleness limit its application range of thermosetting epoxy resin (EP) based foams. In current research, inorganic particles are commonly utilized as heterogeneous nucleating agents to enhance foaming quality and EP toughness. However, the increasing inorganic particle content usually leads to particle agglomeration, which negatively impacts foaming quality and reduces EP performance. Block copolymers, which appear as liquid to effectively mitigate agglomeration, are employed as toughening materials for EP. In this study, a small number of modified calcium silicate particles (MCS) were used as anchor points to induce the distribution of block copolymers (P‐F68) to improve EP toughness and effectively enhance cell nucleation, thus, EP/MCS/P‐F68 foams performance was improved. The research results showed that EP foams obtained excellent cell structure and very small foam density (0.256 g/cm3) at the P‐F68 content of 10 wt%. The continuous increase of P‐F68 content would lead to the thickening of cell wall and the increase of cell size. Simultaneously, the core‐shell structure formed by P‐F68 in EP effectively enhanced the toughness of EP foams and mitigated its brittleness, offering crucial theoretical guidance for toughening and regulating the cell structure of EP foams.

Impact responses of steel–concrete–steel–gradient aluminum foam energy absorbing panels: Experimental and numerical studies

A novel steel–concrete–steel–gradient aluminum foam energy absorbing panel (SCSGF-EAP) has been proposed for improving the impact resistance of existing structures. The impact resistant performances of the SCSGF-EAP were evaluated through the drop weight impact tests and numerical simulations. The varying thickness of gradient aluminum foam and concrete core was considered in the drop weight impact tests. All the specimens presented a consistent failure mode, which included local indentation and global flexure of SCS panel and crushing of gradient aluminum foam. The Finite Element (FE) model was developed through adopting LS-DYNA for studying the impact resistance of SCSGF-EAP, and the comparisons exhibited that numerical results agreed well with experimental data. The internal energy of different components of specimen was determined by numerical model, and the gradient aluminum foam absorbed the majority of the impact energy. Finally, parametric studies were adopted to determine influences of the initial momentum and kinetic energy of impactor, as well as the density of gradient aluminum foam and impact location on the impact response of SCSGF-EAP.

Waste-to-resource: Employing lime mud as a foaming agent in glass foam manufacturing

The paper industry globally releases vast amounts of lime mud waste annually, raising environmental concerns. Composed mainly of calcium carbonate, lime mud has been utilized in various research works, including catalyst synthesis, cement production, and ceramic fabrication. This study investigates the use of lime mud as an eco-friendly foaming additive in the production of glass foam. Glass foams were prepared through a simple sintering method, utilizing glass cullet collected from households and incorporating different lime mud contents (0.5–2.0 wt%). The effects of lime mud concentration on the density, porosity, and pore size distribution of the glass foams were examined. Additionally, the thermal conductivity, compressive strength, and Weibull modulus were investigated in relation to the average porosity. The results revealed that the pore size distribution was dependent on the amount of lime mud, exhibiting three distinct distributions: a positively skewed distribution, a non-symmetric bimodal distribution, and a positively skewed distribution with a wide range. The Weibull modulus markedly decreased with increasing pore size. The compressive strength of the prepared glass foams ranged from 5.53±0.40–12.73±0.46 MPa, while the bulk density and porosity fell within the ranges of 0.41±0.02–0.70±0.04 g/cm3 and 72.12±1.45–85.38±0.98 %, respectively. The thermal conductivity could be as low as 0.07 W/m·K, approaching the upper limit for commercial glass foams used in thermal energy storage systems and meeting the requirements for Type I cellular glass thermal insulation classified by ASTM C552–16.

Optimization of the foam-mat drying process to develop high-quality tomato powder: A response surface methodology approach

This research aimed to estimate the optimum formulation of process parameters in making tomato powder with optimal physicochemical properties using foam-mat drying. The egg albumin (EA) concentration (1–5%), carboxymethyl cellulose (CMC) concentration (1–1.5%), and drying temperature (60–70 °C) were employed as independent variables in optimizing through Response Surface Methodology (RSM) in combination with Box-Behnken experimental design (BBD). Based on the total 17 runs of BBD, foam-mat dried powder showed physicochemical properties such as 0.18–0.33 g/cm3 foam density, 178.54–350% foam expansion, 40–94% foam stability, 46.80–62% water soluble index (WSI), 1.13–2.96 water absorption index (WAI), 1.51–2 °Brix TSS, 2.30–3.98 mg/100mL ascorbic acid, 0.22–0.38% titratable acidity, and color (L*: 29.26–48.07, a*: 9.73–16.86, and b*: 6.81–21.56). Furthermore, the ANOVA findings revealed the correlation of determination (R2) exceeding 85% for the models, suggesting that the interaction between the responses and the prediction of the implied model is suitable. The optimal formulation from RSM was 4.59% EA, 0.70% CMC, and 60 °C drying temperature. Under the optimized conditions, the experimental values were 0.19±0.03 g/cm3 foam density, 346.60±3.35% foam expansion, 89.05±2.80% foam stability, 55.56±3.22% WSI, 2.49±0.09 WAI, 1.84±0.15 °Brix TSS, 2.93±0.10 mg/100 mL ascorbic acid, 0.39±0.02% titratable acidity, 46.95±6.35 L*, 17.54±1.50 a*, and 21.85±0.74 b*. The optimized parameters were verified, and there was good agreement between the experimental results and the predicted values (residual standard error (RSE) ≤ 5).

Developing a novel artificial model to predict the foaming properties and β-carotene content of lucuma (Pouteria lucuma) during foam-mat drying and process optimization

Drying fruit puree by the foam drying method has become popular due to its simplicity, low cost, short drying time, and low thermal degradation. The objective of the study was to investigate the effect of foaming conditions on foam properties (foam expansion, foam density) and content of β-carotene in lucuma powder using Box-Behnken design (BBD) with 3 factors and 3 levels, including water:lucuma ratio (1:1–3:1), egg albumin concentration (EA, 5–15%), and xanthan gum (XG, 0.1–0.3%). Response surface methodology (RSM) and artificial neural network (ANN) were used for model establishment. The results showed that as the EA increased, the foam volume increased significantly, while the foam density decreased. The ANN-coupled BBD model structure of 3-10-3 demonstrated a high level of accuracy in predicting the impact of foaming formulation on responses, with a coefficient of determination exceeding 0.99. The optimal conditions by stimulation multiple-objective RSM for lucuma foam-mat drying were achieved with a water:lucuma ratio, EA, and XG of 2.53:1, 10.8%, and 0.22%, respectively. Based on these ideal conditions, the foam density, foam expansion, and β-carotene content of the dried powder were found to be 0.23±0.04 g/mL, 228±2%, and 237.1±0.1 μg/g, respectively. The obtained experimental values were very close to the model-predicted results, with very low differences identified when the validation was performed. These findings provide information for controlling the drying process using an artificial model and further applying lucuma powder in various fields in the food industry.

Performance investigation of a thermoelectric generator for vehicle exhaust recovery using graded pore density foam metal

Improving the efficiency of thermoelectric generators (TEGs) used to harness residual heat from automobile exhausts is crucial for their widespread adoption. To enhance fluid heat transfer, the Kelvin tetrahedron model is employed for metal foam, and a multiphysical field model of the thermoelectric generator based on metal foam is established. The effects of inserting metal foam with uniform and gradient pore densities into the heat exchanger on the performance of the TEG are investigated. Experimental verification is conducted by constructing a test bench with dimensions identical to those of the model The findings suggest that inserting foam metal significantly enhances the output performance of the TEG, resulting in increases in both output power and efficiency as pore density rises. At Ta = 573 K and ma = 30 g/s, the output power of the TEG with inserted 20 PPI foam metal is enhanced by 140.46 %, while the efficiency experiences a remarkable increase of 197.50 % compared to a smooth pipe. Compared to the performance metrics of uniform foam metal, the positive gradient foam metal exhibits a maximum power increase of 7.89 % and a maximum efficiency increase of 34.46 %, along with an average pressure drop reduction of 27.29 %.

In-plane density gradation of shoe midsoles for optimal energy absorption performance

Midsoles are important components in footwear as they provide shock absorption and stability, thereby improving comfort and effectively preventing certain foot injuries. A strategically engineered midsole designed to mitigate plantar pressure can enhance athletic performance and comfort levels. Despite the importance of midsole design, the potential of using in-plane density gradation (deliberate variation of material density across the horizontal plane) in midsoles has been rarely explored. The present work investigated the effectiveness of in-plane density gradation in shoe midsoles using novel polyurea foams as the material candidate. Different polyurea foam densities, ranging from 95 to 350 kg/m2 were examined and tested to construct density-dependent correlative mathematical relations required for optimizing the midsole design for enhanced cushioning and reduced weight. This study combined mechanical testing and plantar pressure measurements to validate the efficacy of density-graded midsoles. The methodology introduced here is relevant to realistic walking conditions, ensured by biomechanical tests supplemented by digital image correlation analyses. An optimization framework was then created to allocate foam densities at certain plantar zones based on the required cushioning performance constrained by the local pressure. The optimization algorithm was specifically tailored to accommodate varying local pressures experienced by different areas of the foot. The optimization strategy in this study aimed at reducing the overall weight of the midsole while ensuring there were no compromises in cushioning efficacy or distribution of plantar pressure. The approach presented herein has the potential to be applied to a wide range of gait speeds and user-specific plantar pressure patterns.

Blast impact on the density-based tri-layered polyurethane foam

Cellular solids are interesting materials for blast energy absorption because of their high porosity, cell structure, and unique mechanical properties. Also, it will undergo graded compression over the same foam density. Hence, in this study, an experimental investigation of blast pressure impact on the trilayered sequences made of three different polyurethane (PU) foam densities of equal thickness, such as D1-29.201 kg/m3, D2-59.692 kg/m3, and D3-107.720 kg/m3 is carried out. The force transmitted (FT) on the reaction plate and incident force on the blast impact face are recorded. The maximum force amplification (Famp) of the 63.79% was observed in the S5 and the minimum of 6.19% in S4. Thus the reduction in Famp in S4 compared to S5 is 90.3%. Similarly, the energy absorbed (Eabs) by the trilayer is a maximum of 24.80 J in S2 and a minimum of 3.60 J in S3. The Eabs increased to 85.48% in S2 solely by altering the layer sequences in S3. Hence, the location of the density in the layer sequences plays a key role in effective blast mitigation on different response measures.

Dynamic Response of Fiber-Metal Laminates Sandwich Beams under Uniform Blast Loading.

In this work, theoretical and numerical studies of the dynamic response of a fiber-metal laminate (FML) sandwich beam under uniform blast loading are conducted. On the basis of a modified rigid-plastic material model, the analytical solutions for the maximum deflection and the structural response time of FML sandwich beams with metal foam core are obtained. Finite element analysis is carried out by using ABAQUS software, and the numerical simulations corroborate the analytical predictions effectively. The study further examines the impact of the metal volume fraction, the metal strength factor between the metal layer and the composite material layer, the foam strength factor of the metal foam core to the composite material layer, and the foam density factor on the structural response. Findings reveal that these parameters influence the dynamic response of fiber-metal laminate (FML) sandwich beams to varying degrees. The developed analytical model demonstrates its capability to accurately forecast the dynamic behavior of fiber-metal laminate (FML) sandwich beams under uniform blast loading. The theoretical model in this article is a simplified model and cannot consider details such as damage, debonding, and the influence of layer angles in experiments. It is necessary to establish a refined theoretical model that can consider the microstructure and failure of composite materials in the future.

Mechanism of sodium alginate synergistically improving foaming properties of pea protein isolate: Air/water interface microstructure and rheological properties

The synergistic effect of polysaccharides plays a crucial role in regulating the foaming properties of protein based aerated foods. In this study, the synergistic improvement mechanism of pea protein isolate (PPI)-sodium alginate (SA) composite on the foaming performance was determined through multi-component interaction, air/water interface adsorption behavior and foam properties. The results of interactions between PPI and SA indicated that SA and PPI could form smaller and more stable soluble composite through hydrogen bonding, hydrophobic interactions, and electrostatic interactions. The α-helix content of PPI significantly decreased, and PPI exhibited a more flexible secondary structure. In depth research on the air/water interfacial behavior and interfacial microstructure through adsorption kinetics, surface dilatational rheology and Lissajous plots indicated that the PPI-SA composite could accelerate the adsorption process, constructing a highly viscoelastic interface mainly based on elasticity. The results of foam properties showed soluble PPI-SA composite could prepare smaller and more dense foam with thicker and smoother interface film, which was beneficial to the foam stability. The results of small amplitude oscillatory shear and large amplitude oscillatory shear suggested that foam prepared by soluble PPI-SA composite showed stronger ability to resist deformation whether in linear or nonlinear viscoelastic region, revealing the good mechanical properties of these foam under extreme processing conditions and feasibility to improve the quality of aerated food. When the mass ratio of PPI/SA was 1:0.3, the foam properties was strongest. When the mass ratio of PPI/SA exceeded 1:0.3, insoluble substances appeared in the composite system, which was disadvantageous to foam properties and deformation resistance. Therefore, the complexation of PPI and SA was an effective way to improve the air/water interface and foaming properties of PPI, providing theoretical guidance for targeted regulation of the foaming properties of protein based aerated foods.

Optimized Eco-Friendly Foam Materials: A Study on the Effects of Sodium Alginate, Cellulose, and Activated Carbon.

This study focuses on optimizing the physical and mechanical properties of foam materials produced with the addition of sodium alginate as the matrix, and cellulose and activated carbon as fillers. Foam materials, valued for their lightweight and insulation properties, are typically produced from synthetic polymers that pose environmental risks. To mitigate these concerns, this study investigates the potential of natural, biodegradable polymers. Various foam formulations were tested to evaluate their density, compression modulus, and thermal conductivity. The results indicated that an increase in activated carbon content enhanced thermal stability, as indicated by higher Ti% and Tmax% values. Additionally, a higher concentration of sodium alginate and activated carbon resulted in higher foam density and compressive modulus, while cellulose exhibited a more intricate role in the material's behavior. In the optimal formula, where the sum of the component percentages totals 7.6%, the percentages (e.g., 0.5% sodium alginate, 5% cellulose, and 2.1% activated carbon) are calculated based on the weight/volume (w/v) ratio of each component in the water used to prepare the foam mixture. These results indicate that natural and biodegradable polymers can be used to develop high-performance, eco-friendly foam materials.

Dynamic properties of CO2-cured foam concrete at different loading rates: Effect of the foam admixtures and addition of polypropylene fiber

This paper investigated the dynamic mechanical properties of CO2-cured foam concrete under varying conditions, focusing on the effects of foam admixture and fiber reinforcement. The study tends to enrich the knowledge regarding the performance of CO2-cured foam concrete under different loading rates, especially in relation to density and matrix strength. The foam admixture of the specimens ranges from 26% to 55%, achieving density from 600 kg/m3 to 1,000 kg/m3. The specimens were loaded at strain rates from 80 s-1 to 398 s-1. Experimental results revealed the dynamic elastic modulus, dynamic compressive strength, and Dynamic Increase Factor (DIF) showed a strong correlation with the foam admixture and density. In addition, the incorporation of polypropylene (PP) fibers effectively improved the mechanical behavior of the foam concrete, achieving up to a 17% increase in dynamic compressive strength. This comprehensive analysis highlights the critical role of foam admixture and fiber reinforcement in determining the dynamic properties of CO2-cured foam concrete and provides valuable insights for optimizing the dynamic performance of foam concrete in various construction applications.

Hybrid Handwash with Silver Nanoparticles from Calotropis gigantea Leaves and Patchouli Oil: Development and Properties

When washing hands, handwashing is one way to prevent diseases caused by bacteria such as Staphylococcus aureus and Escherichia coli, the most common bacteria that can cause infections. The production of handwash utilizing silver nanoparticles as an active antibacterial agent remains a relatively infrequent practice. The synthesis of silver nanoparticles from the leaves of Calotropis gigantea, which grows in the geothermal area of Ie Seu-um Aceh Besar, has been carried out using the green synthesis method and hybrid green synthesis with patchouli oil. Handwash with active ingredients such as silver nanoparticles was successfully formulated, evaluated, and tested against S. aureus and E. coli. The organoleptic characteristics, pH, viscosity, foam height measurements, density, irritation, and antibacterial activity against S. aureus and E. coli were evaluated. The results showed that the organoleptic properties of the handwash with silver nanoparticles were not changed during a 30-day storage period, with pH values in the range of 9.7-10.3, and did not cause irritation upon using silver nanoparticle handwash. The best formula for handwashing with silver nanoparticles in inhibiting the growth of S. aureus and E. coli bacteria was F2, with inhibition zones of 12.9 ± 2.85 mm and 10.95 ± 0.8 mm, respectively. The formulated handwash with silver nanoparticles met the requirements of good liquid soap according to the Indonesian National Standard (SNI) with potent antibacterial activity.

Mechanical Properties of Polyurethane Foam Reinforced with Natural Henequen Fibre

Polymeric foams are used in many applications, from packaging to structural applications. While polymeric foams have good mechanical performance in compression, they are brittle in tension and bending; fibre reinforcement can enhance their tension and flexural behaviour. This work reports a novel investigation of the mechanical properties of fibre-reinforced polyurethane (FRPU) foams with natural henequen fibres. Pull-out tests were performed with 10 mm fibres and various foam densities to identify the optimal density of 100 kg/m3. Thus, FRPU foams with this density and fibre contents of 1, 2 and 3 wt% were manufactured for mechanical testing. Compression tests showed an increase in the elastic modulus of the FRPU foam specimens compared to the unreinforced PU foam. The FRPU foams also exhibited higher yield stress, which was attributed to the reinforcing effect of the fibres on the cell walls. A maximum increase of 71% in the compressive yield stress was observed for the FRPU foam specimens with a fibre content of 2%. In addition, FRPU foam specimens absorbed more energy for any given strain than the unreinforced PU foam. Flexural tests showed the FRPU foams exhibited increased flexural strength compared to the unreinforced PU foam. A maximum increase of 40% in the flexural strength was observed for the FRPU foam with a fibre content of 1%. The findings reported here are significant because they suggest that FRPU foams incorporating natural henequen fibre exhibit promising potential as sustainable materials with enhanced mechanical properties.

Multi-scale experimental study on properties of compressed air foam and pressure drop in the long-distance vertical pipe

Compressed air foam has been gradually applied in super high-rise buildings due to its high extinguishing efficiency and great transportation ability. However, the transport characteristics of compressed air foam are unclear because the foam is a complex gas-liquid two-phase fluid. In this study, multi-scale experiments were conducted to investigate the foam properties of compressed air foam and pressure drop in the long-distance vertical pipe. The results show that the foam is compressed as a whole when pressure increases, resulting in a significantly increased foam density. At higher pressures, the bubble coarsening degree decreases, accompanied by a narrower particle size distribution and an increased foam size homogenization. Moreover, a critical pressure phenomenon is observed in foams with different foam expansion ratios. The average foam diameter stabilizes gradually with pressure changes after exceeding the critical pressure. A theoretical model for foam density is developed, considering various pressures, temperatures and foam expansion ratios. When the compressed air foam is transported in the vertical long-distance pipe, the pressure decreases in a slightly downward curve, which is due to the decrease in foam density. Finally, a prediction model for the pressure drop of compressed air foam in the long-distance vertical pipe is proposed, which considers changes in foam density. The accuracy of the prediction model is verified by the multi-scale experimental results. The results deepen the understanding of foam flow in the long-distance vertical pipe and provide useful guidance for applications of compressed air foam in super high-rise buildings.

Improving the acoustic performance of flexible polyurethane foam using biochar modified by (3-aminopropyl)trimethoxysilane coupling agent.

This study aims to investigate the potential of integrating natural biochar (BC) derived from eggshell waste into flexible polyurethane (FPU) foam to enhance its mechanical and acoustic performance. The study explores the impact of incorporating BC at various weight ratios (0.1, 0.3, 0.5, and 0.7wt. %) on the properties of the FPU foam. Additionally, the effects of modifying the BC with (3-aminopropyl)trimethoxysilane (APTMS) at different ratios (10, 20, and 30wt. %) and the influence of diverse particle sizes of BC on the thermal, mechanical, and acoustic characteristics of the FPU composite are investigated. The functional groups, morphology, and elemental composition of the developed FPU composites are analyzed using Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) techniques. Characteristics such as density, gel fraction, and porosity were also assessed. The results reveal that the density of FPU foam increased by 4.32% and 7.83% while the porosity decreased to 50.22% and 47.05% with the addition of 0.1 wt. % of unmodified BC and modified BC with 20wt. % APTMS, respectively, compared to unfilled FPU. Additionally, the gel fraction of the FPU matrix increases by 1.91% and 3.55% with the inclusion of 0.1 wt. % unmodified BC and modified BC with 20 wt. % APTMS, respectively. Furthermore, TGA analysis revealed that all FPU composites demonstrate improved thermal stability compared to unfilled FPU, reaching a peak value of 312.17°C for the FPU sample incorporating BC modified with 20 wt. % APTMS. Compression strength increased with 0.1wt. % untreated BC but decreased at higher concentrations. Modifying BC with 20% APTMS resulted in an 8.23% increase in compressive strength compared to unfilled FPU. Acoustic analysis showed that the addition of BC improved absorption, and modified BC enhanced absorption characteristics of FPU, reaching Class D with a 20 mm thickness. BC modified with APTMS further improved acoustic properties compared to the unfilled FPU sample (Class E), with 20% modification showing the best results. These composites present promising materials for sound absorption applications and address environmental issues related to eggshell waste.

A Novel PAMAM G3 Dendrimer-Based Foam with Polyether Polyol and Castor Oil Components as Drug Delivery System into Cancer and Normal Cells.

One of the intensively developed tools for cancer therapy is drug-releasing matrices. Polyamidoamine dendrimers (PAMAM) are commonly used as nanoparticles to increase the solubility, stability and retention of drugs in the human body. Most often, drugs are encapsulated in PAMAM cavities or covalently attached to their surface. However, there are no data on the use of PAMAM dendrimers as a component of porous matrices based on polyurethane foams for the controlled release of drugs and biologically active substances. Therefore, in this work, porous materials based on polyurethane foam with incorporated third-generation poly(amidoamine) dendrimers (PAMAM G3) were synthesized and characterized. Density, water uptake and morphology of foams were examined with SEM and XPS. The PAMAM was liquefied with polyether polyol (G441) and reacted with polymeric 4,4'-diphenylmethane diisocyanate (pMDI) in the presence of silicone, water and a catalyst to obtain foam (PF1). In selected compositions, the castor oil was added (PF2). Analogs without PAMAM G3 were also synthesized (F1 and F2, respectively). An SEM analysis of foams showed that they are composed of thin ribs/walls forming an interconnected network containing hollow bubbles/pores and showing some irregularities in the structure. Foam from a G3:G441:CO (PF2) composition is characterized by a more regular structure than the foam from the composition without castor oil. The encapsulation efficiency of drugs determined by the XPS method shows that it varies depending on the matrix and the drug and ranges from several to a dozen mass percent. In vitro biological studies with direct contact and extract assays indicated that the F2 matrix was highly biocompatible. Significant toxicity of dendrimeric matrices PF1 and PF2 containing 50% of PAMAM G3 was higher against human squamous carcinoma cells than human immortalized keratinocytes. The ability of the matrices to immobilize drugs was demonstrated in the example of perspective (Nimesulide, 8-Methoxypsolarene) or approved anticancer drugs (Doxorubicin-DOX, 5-Aminolevulinic acid). Release into the culture medium and penetration of DOX into the tested SCC-15 and HaCaT cells were also proved. The results show that further modification of the obtained matrices may lead to their use as drug delivery systems, e.g., for anticancer therapy.