Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery.

Flocculation is a type of aggregation where the surfaces of approaching droplets are still at distances no closer than a few nanometers while still remaining in close proximity. In a high internal-phase oil-in-water (O/W) emulsion, the state of flocculation affects the bulk flow behavior and viscoelasticity, which can consequently control the three-dimensional (3D)-printing process and printing performance. Herein, we present the assembly of O/W Pickering high-internal-phase emulsions (Pickering-HIPEs) as printing inks and demonstrate how depletion flocculation in such Pickering-HIPE inks can be used as a facile colloidal engineering approach to tailor a porous 3D structure suitable for drug delivery. Pickering-HIPEs were prepared using different levels of cellulose nanocrystals (CNCs), co-stabilized using "raw" submicrometer-sized sustainable particles from a biomass-processing byproduct. In the presence of this sustainable particle, the higher CNC contents facilitated particle-induced depletion flocculation, which led to the formation of a mechanically robust gel-like ink system. Nonetheless, the presence of adsorbed particles on the surface of droplets ensured their stability against coalescence, even in such a highly aggregated system. The gel structures resulting from the depletion phenomenon enabled the creation of high-performance printed objects with tunable porosity, which can be precisely controlled at two distinct levels: first, by introducing voids within the internal structure of filaments, and second, by generating cavities (pore structures) through the elimination of the water phase. In addition to printing efficacy, the HIPEs could be applied for curcumin delivery, and in vitro release kinetics demonstrated that the porous 3D scaffolds engineered for the first time using depletion-flocculated HIPE inks played an important role in 3D scaffold disintegration and curcumin release. Thus, this study offers a unique colloidal engineering approach of using depletion flocculation to template 3D printing of sustainable inks to generate next-generation porous scaffolds for personalized drug deliveries.

Influence of 7-day subfreezing storage on physicochemical, nutritional, and microstructural attributes of porcine longissimus thoracis et lumborum muscle.

The effect of 7-day subfreezing storage on the physicochemical properties, nutritional composition, and microstructure of pork was investigated. After 7 days of chilling at 4°C, the meat exhibited color deterioration and the development of off-flavors. In contrast, the -12°C treatment significantly reduced the deterioration in water-holding capacity and color of samples (p < 0.05) and prevented changes in pH value. Similarly, the treatments at -12 and -18°C effectively preserved the meat's tenderness, thiobarbituric acid-reactive substances, protein solubility, and textural properties, maintaining these qualities close to those of fresh meat (p > 0.05). The nutrient content of samples stored at -12°C was comparable to those stored at -18°C (p > 0.05). Furthermore, subfreezing at -12°C was found to protect muscle integrity, promoting the formation of an elastic gel network and a homogenous muscle fiber structure. Therefore, the study concludes that 7-day subfreezing storage at -12°C can reduce protein denaturation and maintain thequality of pork, a result that is typically achieved under more extreme freezing conditions at -18°C.

Use of chia (Salvia hispanica L.) seed mucilage powder as a stabilizer in the preparation of salep beverage.

Salep, a traditional Turkish beverage, derives its name from its primary component: salep powder (SP), which is sourced from the tubers of certain orchid species. This study investigated various physicochemical attributes (including dry matter, protein content, pH, titration acidity, water activity, color, serum separation, and zeta potential), as well as rheological and sensory characteristics of salep beverages. These drinks were prepared by substituting SP with chia (Salvia hispanica L.) seed mucilage powder (MP) with different ratios (10%, 20%, 30%, and 40%). The substitution of SP with MP did not influence the dry matter and protein contents or the pH and acidity values of the drinks significantly (p > .05). The inclusion of MP in the formulation of salep drinks resulted in a decrease in lightness (L*) and a* color values while increasing the b* color values. However, consumer perception, as indicated by color difference values (∆E*), showed no distinguishable difference between drinks containing MP and control drinks. Furthermore, higher ratios of MP led to increased apparent viscosity values in the drinks and effectively prevented or significantly reduced serum separation observed in control drinks (p < .05). Remarkably, sensory evaluations revealed that substituting up to 30% of SP with MP did not negatively impact the overall sensory properties of the drinks (p > .05), suggesting that MP could be recommended as a feasible alternative. This substitution has the potential to contribute to the conservation of orchid plants, the primary source of salep, while also offering cost-saving benefits in the production of salep drinks.

Physico-chemical properties of natural actomyosin from breast and thigh meat of fast- and slow-growing chicken: a comparative study.

Physico-chemical behaviors of natural actomyosin (NAM) from slow-growing Korat chicken (KC) breast and thigh at low (0.2 M) and high (0.6 M) NaCl concentrations were evaluated and compared to those from their corresponding muscles in fast-growing broiler chicken (BC). NAM from KC breast and thigh meat showed higher solubility than their corresponding in BC (p < 0.05). Breast NAM from both chickens showed the highest solubility at 0.4 M NaCl, while thigh NAMs showed the highest solubility at 0.8 M (p < 0.05). SDS-PAGE revealed higher protein extractability for breast NAMs at low ionic strength, regardless of breed and structural protein, particularly troponin, appeared to vary within muscle and breed. NAM from KC showed higher Ca2+-ATPase activity, surface hydrophobicity, but lower total sulfhydryl groups content (p < 0.05). Particle size of NAM solutions varied with ionic strength, in which KC-NAM showed larger size than at lower ionic strength, while BC-NAM appeared to be greater at higher ionic strength. NAM from KC breast showed higher thermal stability as higher initial (T0) and maximum (Tmax) denaturation temperatures of 48.4 and 54.8°C, respectively, recorded by microdifferential scanning calorimetry. The KC-NAM, particularly from breast, exhibited lower turbidity within 40-50°C, while turbidity increased in BC samples at low ionic strength when heated at 60°C. Dynamic rheology revealed different storage modulus (G') depending on breed, muscle type and ionic strength. Breast BC-NAM formed more elastic gel with higher end point G' at 80°C (Ge'; p < 0.05). Ionic strength showed reverse effects on different breeds as a stronger Ge' value achieved in KC- NAM at low ionic strength, while high ionic strength induced stronger gel in BC samples. Aggregation of NAMs began at lower temperatures at higher ionic strength and actin dissociation probably occurred in breast NAM from KC as observed by a drop of G' at around 70°C. The results of this study revealed differences between NAM of the two breeds, by which higher gel elasticity are expected in KC at lower ionic strength.

Rheological properties of porcine organs: measurements and fractional viscoelastic model.

The rheological properties of porcine heart, kidney, liver and brain were measured using dynamic oscillatory shear tests over a range of frequencies and shear strains. Frequency sweep tests were performed from 0.1 Hz to a maximum of 9.5 Hz at a shear strain of 0.1%, and strain sweep tests were carried out from 0.01% to 10% at 1 Hz. The effect of pre-compression of samples up to 10% axial strain was considered. The experimental measurements were fit to a Semi-Fractional Kelvin Voight (S-FKV) model. The model was then used to predict the stress relaxation in response to a step strain of 0.1%. The prediction was compared to experimental relaxation data for the porcine organ samples, and the results agreed to within 30%. In conclusion, this study measured the rheological properties of porcine organs and used a fractional viscoelastic model to describe the response in frequency and time domain.

Technical-functional and surface properties of white common bean proteins (Phaseolus vulgaris L.): Effect of pH, protein concentration, and guar gum presence.

Legumes are abundant sources of proteins, and white common bean proteins play an important role in air-water interface properties. This study aims to investigate the technical-functional properties of white common bean protein isolate (BPI) as a function of pH, protein concentration, and guar gum (GG) presence. BPI physicochemical properties were analyzed in terms of solubility, zeta potential, and mean particle diameter at pH ranging from 2 to 9, in addition to water-holding capacity (WHC), oil-holding capacity (OHC), and thermogravimetric analysis. Protein dispersions were evaluated in terms of dynamic, interfacial, and foam-forming properties. BPI showed higher solubility (>80 %) at pH 2 and above 7. Zeta potential and mean diameter ranged from 15.43 to -34.08 mV and from 129.55 to 139.90 nm, respectively. BPI exhibited WHC and OHC of 1.37 and 4.97 g/g, respectively. Thermograms indicated decomposition temperature (295.81 °C) and mass loss (64.73 %). Flow curves indicated pseudoplastic behavior, with higher η100 values observed in treatments containing guar gum. The behavior was predominantly viscous (tg δ > 1) at lower frequencies, at all pH levels, shifting to predominantly elastic at higher frequencies. Equilibrium surface tension (γeq) ranged from 43.87 to 41.95 mN.m-1 and did not decrease with increasing protein concentration under all pH conditions. All treatments exhibited ϕ < 15°, indicating predominantly elastic surface films. Foaming properties were influenced by higher protein concentration and guar gum addition, and the potential formation of protein-polysaccharide complexes favored the kinetic stability of the system.

State of the art, challenges, and future prospects for the multi-material 3D printing of plant-based meat.

The emergence of innovative plant-based meat analogs, replicating the flavor, texture, and appearance of animal meat cuts, is deemed crucial for sustainably feeding a growing population while mitigating the environmental impact associated with livestock farming. Multi-material 3D food printing (MM3DFP) has been proposed as a potentially disruptive technology for manufacturing the next generation of plant-based meat analogs. This article provides a comprehensive review of the state of the art, addressing various aspects of 3D printing in the realm of plant-based meat. The disruptive potential of printed meat analogs is discussed with particular emphasis on protein-rich, lipid-rich, and blood-mimicking food inks. The printing parameters, printing requirements, and rheological properties at the different printing stages are addressed in detail. As food rheology plays a key role in the printing process, an appraisal of this subject is performed. Post-printing treatments are assessed based on the extent of improvement in the quality of 3D-printed plant-based meat analogs. The meat-mimicking potential is revealed through sensory attributes, such as texture and flavor. Furthermore, there has been limited research into food safety and nutrition. Economically, the 3D printing of plant-based meat analogs demonstrates significant market potential, contingent upon innovative decision-making strategies and supportive policies to enhance consumer acceptance. This review examines the current limitations of this technology and highlights opportunities for future developments.

Effects of enzymatic hydrolysis combined with glycation on the emulsification characteristics and emulsion stability of peanut protein isolate.

Peanut protein isolate (PPI) has high nutritional value, but its poor function limits its application in the food industry. In this study, peanut protein isolate was modified by enzymatic hydrolysis combined with glycation. The structure, emulsification and interface properties of peanut protein isolate hydrolysate (HPPI) and dextran (Dex) conjugate (HPPI-Dex) were studied. In addition, the physicochemical properties, rheological properties, and stability of the emulsion were also investigated. The results showed that the graft degree increased with the increase of Dex ratio. Fourier transform infrared spectroscopy (FTIR) confirmed that the glycation of HPPI and Dex occurred. The microstructure showed that the structure of HPPI-Dex was expanded, and the molecular flexibility was enhanced. When the ratio of HPPI to Dex was 1:3, the emulsifying activity and the interface pressure of glycated HPPI reached the highest value, and the emulsifying activity (61.08 m2/g) of HPPI-Dex was 5.28 times that of PPI. The HPPI-Dex stabilized emulsions had good physicochemical properties and rheological properties. In addition, HPPI-Dex stabilized emulsions had high stability under heat treatment, salt ion treatment and freeze-thaw cycle. According to confocal laser scanning microscopy (CLSM), the dispersion of HPPI-Dex stabilized emulsions was better after 28 days of storage. This study provides a theoretical basis for developing peanut protein emulsifier and further expanding the application of peanut protein in food industry.

Bubble ascent and rupture in mud volcanoes.

Large gas bubbles can reach the surface of pools of mud and lava where they burst, often through the formation and expansion of circular holes. Bursting bubbles release volatiles and generate spatter, and hence play a key role in volcanic degassing and volcanic edifice construction. Here, we study the ascent and rupture of bubbles using a combination of field observations at Pâclele Mici (Romania), laboratory experiments with mud from the Imperial Valley (California, USA), numerical simulations and theoretical models. Numerical simulations predict that bubbles ascend through the mud as elliptical caps that develop a dimple at the apex as they impinge on the free surface. We documented the rupture of bubbles in nature and under laboratory conditions using high-speed video. The bursting of mud bubbles starts with the nucleation of multiple holes, which form at a near-constant rate and in quick succession. The quasi-circular holes rapidly grow and coalesce, and the sheet evolves towards a filamentous structure that finally falls back into the mud pool, sometimes breaking up into droplets. The rate of expansion of holes in the sheet can be explained by a generalization of the Taylor-Culick theory, which is shown to hold independent of the fluid rheology.

Tribological properties of real foods using extended Stribeck curves and their relationship with nutritional and rheological parameters.

The tribological properties of 19 commercial food products, grouped into six categories (yogurt, dressings, spreads, porridges, emulsified sauces, and syrups) were investigated in relation to their rheological (dynamic oscillatory shear test) and nutritional properties (fat, carbohydrate, and protein). A tribological system (a glass ball and three polydimethylsiloxane pins) generated the extended Stribeck curve, monitoring friction factors (f) over an extended range of sliding speed (v) (10-8 to 100 m/s). Tribological parameters (f, v) at four inflection points dividing the frictional regimes (X1, breakaway point between the static and kinetic regimes; X1-X2, boundary; X2-X3, mixed; X3-X4, hydrodynamic regimes) and the slope between X3 and X4 (s) were subjected to principal component analysis and hierarchical clustering on principal components, using rheological and nutritional parameters as quantitative supplementary variables. Tribological patterns were predominantly influenced by viscosity, viscoelasticity, yield stress, fat content, and the presence of particles (e.g., sugar, proteins, and fibers) and pasting materials (e.g., starches and modified starches). The 19 tribological patterns were classified into 3 clusters: low f and s for fat- and/or viscoelastic-dominant foods (Cluster 1), low f and high s for food emulsions and/or those with low extent of shear-thinning (Cluster 2), and high f at the boundary regime either for the most viscous foods or for those in the presence of particulates (Cluster 3). These results suggest that the compositional and rheological properties have a more profound impact on the classification of complex tribological patterns than the categories of food products.

Performance evaluation of the nano-biodegradable drilling fluid using the greenly synthesized zinc nanorods and gundelia seed waste.

Addressing the increasing demand for green additives in drilling fluids is essential for the sustainable development of the oil and gas industry. Fluid loss into porous and permeable formations during drilling presents significant challenges. This study introduced an innovative, environmentally sustainable drilling fluid known as nano-biodegradable drilling fluid (NBDF). The NBDF formulation incorporates greenly synthesized zinc nanorods (ZNRs) and gundelia seed shell powder, with ZNRs derived from Cydonia oblonga plant extracts using an eco-friendly method. The research developed multiple drilling fluid variants for experimentation: a reference drilling fluid (BM); biodegradable drilling fluid (BDF) with particle sizes of 75, 150, 300, and 600 µm at concentrations ranging from 0.5 to 1 wt% (GSMs); a drilling nanofluid (DNF) with ZNRs at a 0.1 wt% concentration (ZNR); and NBDF combining both nano and gundelia waste (GS-ZNR). Experimental tests were conducted under various temperature and pressure conditions, including low temperature and low pressure (LTLP) and high temperature and high pressure (HTHP). Rheological and filtration measurements were performed to assess the impact of the nano-biodegradable additives on flow behavior and fluid loss. Results indicated that incorporating 1 wt% of gundelia seed shell powder with a particle size of 75 µm led to a 19.61% reduction in fluid loss compared to BM at 75 °C and 200 psi. The performance of the same GSM improved by 31% under identical conditions when 1 wt% of zinc ZNRs was added. Notably, the GS-ZNR formulation demonstrated the most effective performance in reducing fluid loss into the formation, decreasing mud cake thickness, and enhancing the flow behavior of the non-Newtonian reference drilling fluid. This study highlights the relevance of particle size in the effectiveness of biodegradable additives and underscores the potential of NBDF to address environmental concerns in the oil and gas drilling industry.

Effect of viscosity of gelatin methacryloyl-based bioinks on bone cells.

The viscosity of gelatin methacryloyl (GelMA)-based bioinks generates shear stresses throughout the printing process that can affect cell integrity, reduce cell viability, cause morphological changes, and alter cell functionality. This study systematically investigated the impact of the viscosity of GelMA-gelatin bioinks on osteoblast-like cells in 2D and 3D culture conditions. Three bioinks with low, medium, and high viscosity prepared by supplementing a 5% GelMA solution with different concentrations of gelatin were evaluated. Cell responses were studied in a 2D environment after printing and incubation in non-cross-linked bioinks that caused the gelatin and GelMA to dissolve and release cells for attachment to tissue culture plates. The increased viscosity of the bioinks significantly affected cell area and aspect ratio. Cells printed using the bioink with medium viscosity exhibited greater metabolic activity and proliferation rate than those printed using the high viscosity bioink and even the unprinted control cells. Additionally, cells printed using the bioink with high viscosity demonstrated notably elevated expression levels of alkaline phosphatase (ALP) and bone morphogenetic protein-2 (BMP-2) genes. In the 3D condition, the printed cell-laden hydrogels were photo-cross-linked prior to incubation. The medium viscosity bioink supported greater cell proliferation compared to the high viscosity bioink. However, there were no significant differences in the expression of osteogenic markers between the medium and high viscosity bioinks. Therefore, the choice between medium and high viscosity bioinks should be based on the desired outcomes and objectives of the bone tissue engineering application. Furthermore, the bioprinting procedure with the medium viscosity bioink was used as an automated technique for efficiently seeding cells onto 3D printed porous titanium scaffolds for bone tissue engineering purposes.

Understanding the textural enhancement of low-salt myofibrillar protein gels filled with pea protein pre-emulsions through interfacial behavior: Effects of structural modification and oil phase polarity.

This study investigated the effects of pea protein pre-emulsions containing triglyceride- or diglyceride-oil on the emulsifying and gelling properties of low-salt myofibrillar protein (MP). Pea protein isolates treated with pH12-shifting (PPIpH) or ultrasonication (PPIU) demonstrated superior initial interfacial adsorption and higher final interfacial pressure than native pea protein. Within MP/PPI blends, an increased ratio of MP led to a decrease in interfacial pressure, while simultaneously enhancing film elasticity at both polar and non-polar interfaces. Polar diglyceride promoted protein adsorption and fostered interfacial interactions between modified pea proteins and MP, enhancing the cross-linking of transglutaminase (TG) in the composite emulsion gels. Combining diglyceride-type PPIU and PPIpH emulsions with TG increased gel strength to 0.58 N and 0.63 N, respectively, from an initial 0.33 N, yielding a denser protein network with uniformly dispersed oil droplets. Therefore, the utilization of diglyceride and modified PPI can serve as structural enhancers in comminuted meat products.

Feruloylation and Hydrolysis of Arabinoxylan Extracted from Wheat Bran: Effect on Dough Rheology and Microstructure.

Feruloylated arabinoxylan (AX) is a potential health-promoting fiber ingredient that can enhance nutritional properties of bread but is also known to affect dough rheology. To determine the role of feruloylation and hydrolysis of wheat bran AX on dough quality and microstructure, hydrolyzed and unhydrolyzed AX fractions with low and high ferulic acid content were produced, and their chemical composition and properties were evaluated. These fractions were then incorporated into wheat dough, and farinograph measurements, large and small deformation measurements and dough microstructure were assessed. AX was found to greatly affect both fraction properties and dough quality, and this effect was modulated by hydrolysis of AX. These results demonstrated how especially unhydrolyzed fiber fractions produced stiff doughs with poor extensibility due to weak gluten network, while hydrolyzed fractions maintained a dough quality closer to control. This suggests that hydrolysis can further improve the baking properties of feruloylated wheat bran AX. However, no clear effects from AX feruloylation on dough properties or microstructure could be detected. Based on this study, feruloylation does not appear to affect dough rheology or microstructure, and feruloylated wheat bran arabinoxylan can be used as a bakery ingredient to potentially enhance the nutritional quality of bread.

Effects of Cactus Polysaccharide on Pasting, Rheology, Structural Properties, In Vitro Digestibility, and Freeze-Thaw Stability of Rice Starch.

This study combined rice starch (RS) with cactus polysaccharide (CP) at different composites (0.6%, 1.2%, 1.8%, 2.4%, and 3.0%, w/w), and analyzed the variations in the complex gelatinization properties, rheological properties, thermal properties, structural properties, digestibility, and freeze-thaw stability. As a result, the pasting parameters (p < 0.05) and storage modulus (G') together with the loss modulus (G″) decreased as the CP concentration increased; meanwhile, the RS and the CP-RS gels were pseudoplastic fluids. As revealed by differential scanning calorimetry (DSC), incorporating CP into the starch elevated the starch gelatinization temperature while decreasing gelatinization enthalpy, revealing that CP effectively retarded long-term retrogradation in RS. The gel microstructure and crystallization type altered after adding CP. Typically, CP inclusion could enhance the proportion of resistant starch and slowly digestible starch (SDS), thereby slowing RS hydrolysis. Concurrently, adding CP promoted the RS freeze-thaw stability. These findings could potentially aid in the innovation of CP-based food products.

Revealing the Impact of Viscoelastic Characteristics on Performance Parameters of UV-Crosslinked Hotmelt Pressure-Sensitive Adhesives: Insights from Time-Temperature Superposition Analysis.

This study emphasizes the influential role of rheology in decoding the viscoelastic properties of pressure-sensitive adhesives (PSAs) vital to predicting key application features such as shear, tack, and peel, depending on the flow characteristics of PSAs during bonding and debonding processes. By applying the principle of time-temperature superposition (TTS), we extend the scope of our frequency analysis, surpassing the technical constraints of the available apparatus. Our exploration aims to uncover the general correlations between PSAs' viscoelastic properties and their performance in end-use applications. Initially, the adhesive performance and viscoelastic properties of a UV-crosslinkable styrene-butadiene-styrene (SBS) model adhesive prior and subsequent to UV irradiation were examined. The subsequent crosslinking reaction increased cohesive strength and heat resistance, although tack and peel strength observed a substantial decline. We successfully demonstrated these effects by logging the viscoelastic properties, specifically the storage modulus G' at lower frequencies, which mirrors the shear strength at higher temperatures and the shift in the tan δ peak to represent each PSA's tack. These correlations were partially reflected in three commercial UV crosslinkable acrylic PSA products, although the effect of UV irradiation was less distinctive. This study also revealed the challenges in predicting tack and peel strength, which result from a complex interplay of bonding and debonding processes. Our findings reinforce the necessity for more sophisticated analysis techniques and models that can accurately predict the end-use performance of PSAs across different physical structures and chemical compositions. Further research is needed to develop these predictive models, which may reduce the need for labor-intensive testing under real-life conditions.

Crosslinking and Swelling Properties of pH-Responsive Poly(Ethylene Glycol)/Poly(Acrylic Acid) Interpenetrating Polymer Network Hydrogels.

This study investigates the crosslinking dynamics and swelling properties of pH-responsive poly(ethylene glycol) (PEG)/poly(acrylic acid) (PAA) interpenetrating polymer network (IPN) hydrogels. These hydrogels feature denser crosslinked networks compared to PEG single network (SN) hydrogels. Fabrication involved a two-step UV curing process: First, forming PEG-SN hydrogels using poly(ethylene glycol) diacrylate (PEGDA) through UV-induced free radical polymerization and crosslinking reactions, then immersing them in PAA solutions with two different molar ratios of acrylic acid (AA) monomer and poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker. A subsequent UV curing step created PAA networks within the pre-fabricated PEG hydrogels. The incorporation of AA with ionizable functional groups imparted pH sensitivity to the hydrogels, allowing the swelling ratio to respond to environmental pH changes. Rheological analysis showed that PEG/PAA IPN hydrogels had a higher storage modulus (G') than PEG-SN hydrogels, with PEG/PAA-IPN5 exhibiting the highest modulus. Thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated increased thermal stability for PEG/PAA-IPN5 compared to PEG/PAA-IPN1, due to higher crosslinking density from increased PEGDMA content. Consistent with the storage modulus trend, PEG/PAA-IPN hydrogels demonstrated superior mechanical properties compared to PEG-SN hydrogels. The tighter network structure led to reduced water uptake and a higher gel modulus in swollen IPN hydrogels, attributed to the increased density of active network strands. Below the pKa (4.3) of acrylic acid, hydrogen bonds between PEG and PAA chains caused the IPN hydrogels to contract. Above the pKa, ionization of PAA chains induced electrostatic repulsion and osmotic forces, increasing water absorption. Adjusting the crosslinking density of the PAA network enabled fine-tuning of the IPN hydrogels' properties, allowing comprehensive comparison of single network and IPN characteristics.

Influence of Carbonyl Iron Particles (CIP) and Glass Microspheres on Thermal Properties of Poly(lactic acid) (PLA).

In this investigation, composite poly(lactic acid) (PLA) systems of hollow glass microspheres (MS) and carbonyl iron particles (CIP) were processed and characterized to investigate the effects of using conductive and insulating particles as additives in a polymer system. PLA-MS and PLA-CIP were set at the two levels of 3.94 and 7.77 vol.% for each particle type to study the effects of the particle material type and loading on neat PLA's thermal properties. It was observed during the twin-screw extrusion that the addition of CIP greatly decreased the viscosity of the PLA melt during processing. Correlations determined using thermogravimetric analysis, differential scanning calorimetry, thermal conductivity, and shear rheology provided insights into how thermal stability was affected. The incorporation of MS and CIP altered thermal properties such as the glass transition temperature (Tg), melting temperature (Tm), and cold crystallization temperature (Tcc). The metal CIP-filled systems had large increases in their thermal conductivity values and viscoelastic transitions compared to those with PLA that were correlated with the observed overheating during extrusion.

Synergistic effects of cellulose nanocrystal on the mechanical and shape memory properties of TPU composites.

Cellulose nanocrystal is a nanomaterial that has a large specific surface area, high surface energy, and high strength. As well, it is biocompatible, environmentally friendly, nontoxic, and can be extracted from biomass resources. Because of these features, cellulose nanocrystals can be used to improve the mechanical properties of polymer matrices with a shape memory effect and as a shape memory switch. In this study, a polytrimethylene ether glycol-based thermoplastic polyurethane (TPU)/cellulose nanocrystal (CNC) composite was prepared via an in-situ polymerization process to create a self-healing polymer matrix. Also, the effect of CNC doses in low concentrations (≤2 wt%) on the different properties of the resulting bio-nanocomposite was investigated. The results showed that the introduction of CNCs affects the hydrogen bonding within the polymer matrix and provides better thermal stability in the high temperature range than pure TPU. Furthermore, the samples with 0 wt%, 0.75 wt%, 1 wt%, and 2 wt% of CNC exhibited an increasing trend in tensile strength with values of 11.71 MPa, 18.95 MPa, 17.88 MPa, and 26.18 MPa, respectively, which indicates a remarkable improvement in mechanical strength. The shape memory behavior was also notably prominent in this polymer composite, where the composite containing 2 wt% of CNC showed the fastest recovery time (240 s) at 75 °C with the highest shape retention. Moreover, their flow behavior and deformation capacity were examined through rheology tests. Besides, docking simulations were conducted in silico to assess the interaction of the TPU/CNC composite with the DNA gyrase enzyme. The interaction between CNC/TPU composite and DNA gyrase was meticulously analyzed across 10 distinct conformations, yielding docking scores ranging from -6.5 Kcal/mol to -5.3 Kcal/mol. Overall, the physico-mechanical properties of the TPU/CNC composites were substantially enhanced with the incorporation of nanofillers.

Structure-property relations in rheology of cellulose nanofibrils-based hydrogels.

Hydrogels prepared from self-assembled cellulose nanofibrils (CNFs) are widely used in biomedicine, electronics and environmental technology. Their ability to serve as inks for extrusion-based 3D printing is conventionally evaluated by means of rheological tests. A model is developed that describes the response of CNF gels in small- and large-amplitude oscillatory tests in a unified manner. The model involves a reasonably small number of material parameters, ensures good agreement between results of simulation and observations in oscillatory tests and correctly predicts the stress-strain Lissajous curves, experimental data in hysteresis loop tests, and measurements of the steady-state viscosity. The model is applied to analyze how composition and preparation conditions for CNF gels affect transition from shear thinning to weak strain overshoot in large-amplitude shear oscillatory tests. Based on the model, simple relations are derived for the fractal dimension of CNF clusters and the storage modulus of gels prepared in aqueous solutions of multivalent salts. The validity of these equations is confirmed by comparison of their predictions with observations in independent tests.