Continuous Phase Structure Research Articles

Microstructure and characteristics of phase-separated gels of Type-A gelatin and hydroxypropyl starch: pH responsiveness

The impact of phase separation behavior on the performance of hydrogels has always been the research focus. This study explored the relationship of “pH-microstructure-hydrogel properties” of phase-separated hydrogels composed of type-A gelatin (GE, 5 wt%) and hydroxypropyl starch (HPS, 3 wt%). The results revealed that changes in the microstructure of the hydrogel at different pHs significantly impacted the gel properties. At pH 4.00 and 11.00, phase separation occurred in the GE/HPS gel with a microstructure of HPS-in-GE. In particular, at pH 5.00, 6.00, 7.00, and 9.00, severe phase separation resulted in the separation of substantial aggregates of HPS and GE, resulting in a continuous phase structure. At pH 2.00 and 3.00, phase separation was suppressed, resulting in a homogeneous microstructure. Compared to the phase-separated gels at pH 4.00–11.00, the homogeneous systems at pH 2.00 and 3.00 displayed a synergistic effect with higher gel strength. Analysis of intermolecular forces in the GE/HPS gel indicated that hydrogen bonding was the primary interaction force. Furthermore, the addition of GE/HPS into hawthorn jelly at about pH 3.00 effectively preserved the structural appearance and exhibited higher levels of hardness, thus improving the sensory properties of hawthorn jelly. In summary, phase separation decreased the storage modulus of GE/HPS gel, but the compatibility of GE/HPS macromolecules exhibited synergistic effects at 2.00 and 3.00 and improved the hydrogel mechanical properties. This work provides some new insights for GE/HPS-based gel foods.

Fabrication and investigation of graphene‐loaded triiron tetraoxide/silicone‐rubber electromagnetic shielding composites based on static magnetic‐field–induced orientation

AbstractGraphene‐loaded triiron tetraoxide/silicone‐rubber composites containing highly loaded graphene‐loaded Fe3O4 (Fe3O4@RGO) particles were fabricated using static magnetic field‐induced alignment. The Fe3O4@RGO particles were characterized through Fourier transform infrared, x‐ray diffraction, SEM, and XPS analyses. Subsequently, the influence of added material and the strength of the magnetic field on the alignment distribution of the filler were examined through a synergistic combination of SEM and Raman spectroscopy. The electrical conductivity and electromagnetic shielding properties of the composites were assessed. The electrical conductivity of the composites increased with increasing filler addition, the 25 wt% filler mixture had the fastest curing rate and the maximum torque, and the continued increase in filler addition led to the occurrence of many defects. Concurrently, the alignment distribution of the filler progressively enhances with the augmentation of magnetic field strength. The composites synthesized at 180 mT exhibit the most substantial alignment, facilitating the establishment of effective conductive pathways. This results in a notable enhancement in electromagnetic shielding effectiveness, approximately 400% greater than that of pure silicone rubber and around 40% higher than that of non‐aligned composites. This approach introduces a novel concept for shaping the structural design of flexible electromagnetic shielding materials.Highlights Highly loaded Fe3O4@RGO was prepared by self‐assembly. The continuous phase structure of Fe3O4@RGO oriented was assessed. Fully oriented Fe3O4@RGO promotes the formation of conductive pathways. Fully oriented Fe3O4@RGO reduced the SER by 13% and increased the SEA by 67%.

Investigation of the mechanism of gelatin to enhance 3D printing accuracy of corn starch gel: From perspective of phase morphological changes

The study examined the impact of phase morphological transformations within the corn starch/gelatin system, induced by varying gelatin content, on its rheological properties and 3D printing performance. Gelatin addition inhibited the gelatinization and retrogradation of starch, which leaded to the transformation of continuous phase structure. The transition process from starch continuous phase to gelatin continuous phase promoted a thinner wall structure of the gel and loosed its dense network, resulting in reduced flow stress (τf) and storage modulus (G′). These changes improved the extrusion and “extrusion swelling" of gel ink materials, which made the print size of printed product closer to the set model. The formation of a gelatin continuous phase in the gel was helpful in increasing τf and G′, resulting in enhanced support capacity of the printed product. This study presented meaningful information for the application of 3D printing to starch-gelatin complex foods.

Imitating Spiders to catch flying insects: Realizing high-strength bonding of bamboo scraps/magnesium oxychloride lightweight composite interface

Compatible interface is the key to designing low-carbon building materials containing plant fiber. Moisture migration causes steric hindrance at interfaces, resulting in materials with poor two-phase interface compatibility and low mechanical strength. Drop load presents a serious threat to the structural safety of future houses. Firmer cementation in composite becomes an urgent problem. We report on a strategy using polysaccharide chains between two different phases, and design high-strength adhesion interface. This new design is inspired by the behavior of spiders to catch flying insects. The presence of hydroxyl and amino groups on the spider silk surface allows binding of flying insects with high strength and using only small contact area. To mimic that strategy, MgO was used for orderly crystallization on the polymer chain and active hydroxyl groups with high specific surface area achieves multidimensional and multi-site adhesion of bamboo scraps. Improved interfacial compatibility facilitates the formation of heterogeneous but continuous phase structure. The compressive stress reaches 4.66 MPa and softening factor is 0.74 for density of 0.37. The designed material is an advanced composite in construction and decoration. Its low-loading characteristic can reduce carbon footprint calculations, suggesting this strategy has significant potential for future development.

Investigation of bubble structure in a microchannel under microgravity conditions: Effects of discontinuous wettability with dynamic contact angle

A thorough understanding of the dynamics of bubble/liquid two-phase flows under microgravity conditions is essential for achieving efficient heat transfer between spacecraft and space stations. This paper examined the influence of the discontinuous wettability of a microchannel's wall on bubble structure movement under microgravity conditions. The volume-of-fluid methodology involving a dynamic contact angle code was employed by considering wall-adhesion equations to predict the form of the bubble/liquid interface at and near the wall. The flow field's governing equations were numerically solved utilizing the finite volume method. Initially, the results were compared to previously reported data for validation. Subsequently, the effects of discontinuous wettability with different configurations on the structure of bubbles were investigated; new insights were obtained into the size and shape of generated bubbles, as well as the slug length as a function of the wall wettability. The results showed that for a uniformly hydrophilic surface, the bubble had a concave shape under microgravity conditions, while for a uniformly superhydrophobic surface, the bubble had a convex shape. A microchannel wall surface with discontinuous wettability led to the generation of an asymmetric bubble, a variation in slug length, changes in the bubble's length and shape, and a continuous phase structure. Furthermore, variations in the wall wettability caused the flow upstream to vary and affected all four stages of bubble generation, namely lag, filling, necking, and the starting point of detachment.

Effect of compositions on physicochemical properties and rheological behavior of gelatinized adzuki-bean cake (Yokan)

Gelatinized adzuki-bean cake (commonly known as Yokan or Yanggaeng) is one of Asia's favorite bean snacks. This product as a continuous phase structure, which is embedded with the dispersed phase formed by adzuki bean paste, which is prepared by the combination of agar and sugar. The gel characteristics of gelatinized adzuki-bean cake are influenced by the physical properties of agar, sugar, and the adzuki bean paste and are highly correlated to its product quality. An analysis was carried out using a Rapid Visco Analyzer on the adzuki bean powder to investigate the feasibility of simplifying its preparation process and reducing the amount of agar used in it. The effect of starch contained in the adzuki bean powder on the gelling capacity was also investigated. The gelatinous properties and viscoelasticity of gelatinized adzuki-bean cake were affected by the textural properties of adzuki bean paste, agar, and sugar. The results showed that the structured bean paste particles were distributed in the continuous phase formed by agar and sugar. These particles formed a gelatinous product with a homogeneous dispersion system following a long cooking period and concentration.

Effect of hybrid wall contact angles on slug flow behavior in a T-junction microchannel: A numerical study

This study investigates the effects of hydrophilic-to-superhydrophobic discontinuous wall contact angles on gas-liquid slug flow in a T-junction microchannel. The two-phase volume-of-fluid model with dynamic contact angle are used by solving wall-adhesion equations, which determine the shape of the fluid’s interface at and close to the wall. The governing equations of the flow field are solved numerically using a finite volume method. The obtained results are first validated against previously reported experimental data. Subsequently, the effects of changes in the wall contact angles on the slug flow behavior are examined resulting in the new insights into the size, shape, and velocity of slug flow as a function of the wall contact angle. Using a hydrophilic-superhydrophobic hybrid surface leads to the formation of an asymmetric bubble and separation of the bubble from the hydrophobic part. It also causes adhesion to the hydrophilic part, a change in slug length, a reduction in pressure drop, and a variation in the heat transfer characteristics and continuous phase structure. It is shown that using a particular pattern significantly increases the thickness of the liquid wall film.

Structure and impact properties of a thermoplastic elastomer/silly putty blend

AbstractThe structure and impact properties of a thermoplastic elastomer/silly putty blend are explored. The impact‐resistant materials are made with polyolefin‐based thermoplastic elastomer HYBRAR™ 5127 and silly putty DOWSIL™ 3179. The peak impact force decreases with the content of silly putty, as part of the impact energy might be dissipated by the dissociation of boron–oxygen dynamic dative bonds in silly putty. It is also observed that the crack behavior of samples under impact is related to the phase structure of silly putty in the samples. For the samples with high content of silly putty, a macroscopic crack is observed for these samples under impact, as a crack can spread in the continuous phase structure of silly putty. Different energy dissipation ratios in rheological, compression and impact experiments are also observed. It is concluded that the results of linear dynamic oscillatory shear and compression at a low strain rate cannot give a direct predication of energy dissipation ratios of samples under impact at a high strain rate. © 2021 Society of Industrial Chemistry.

Morphological evolution of self‐assembled PS‐g‐PA6 graft copolymer via in situ polymerization

AbstractThe self‐assembly behaviors of polystyrene graft polyamide‐6 (PS‐g‐PA6) copolymer obtained through incorporation of PA6 and PS segments with exact lengths via in situ polymerization were studied in this work. Copolymers were obtained via the bulk polymerization induced self‐assembly process without any external template or stabilizer. The morphological characteristics of PS‐g‐PA6 copolymer were probed using SEM and TEM techniques. Particular attention was paid to changing the PS‐g‐PA6 morphology from a simple nanospherical to the combined nano/microspherical phase structure by varying the [PA6]/[PS] mass ratio. At a [PA6]/[PS] mass ratio of 80:20, PS‐g‐PA6 copolymer revealed a specific phase structure, where the PS backbones formed a continuous phase and the PA6 side chains ensured the microspheres with dispersed nano‐scale inclusions. The grain diameter of a dispersed PA6 sphere phase was found to be about 75 nm. When the PS backbone mass ratio decreased to 10 wt%, the copolymer structure was self‐assembled into the 1–3 μm large microspheres with uniformly distributed nanospherical particles. A further decrease in the PS backbone content to 5 wt% led to the failure of phase inversion in the copolymers. The main feature of this project is that the structure of the main chain and branch chain of PS‐g‐PA6 copolymer can be reversed. The branched chain forms spherical phase and the main chain forms continuous phase structure. The strategy was proved to be effective to obtain the novel structure of graft copolymer.

Swelling and Degradation Characteristics of Crumb Rubber Modified Asphalt during Processing

The existence of cross-linked structure in crumb rubber modified asphalt (CRMA) leads to the complexity of its system. According to the preparation test of CRMA under different processing technology, the influence of processing temperature and time on the properties and cross-linking structure of CRMA was analyzed. By analyzing the volume expansion rate of the rubber powder after swelling and the toluene insoluble content attenuation rate, the formation conditions of the macro-level cross-linked structure were determined, and the relationship model between the cross-linked structure and the rubber asphalt performance was established. The results show that the rubber particles can form a continuous phase structure after swelling. At this time, the expansion ratio of the swollen rubber powder was 1.76–2.14. Too high temperature (above 200°C) and too long time (above 60 min) caused serious degradation of rubber. The suitable processing technology was stirring at 180–190°C for 45–60 min.

Sandwich-structure styrene-butadiene-styrene block copolymer (SBS)/polypropylene (PP) blends: The role of PP molecular weight

Abstract

Phenolic Resin-Induced Dynamically Vulcanized Polylactide/Natural Rubber Blends

ABSTRACTBlends based on polylactide (PLA) and natural rubber (NR) were prepared through phenolic resin-induced dynamic vulcanization. The cross-linked NR had a continuous phase structure in PLA. The incorporation of NR sacrificed the tensile strength but only had a limited increase in the impact strength of PLA. The viscoelasticities of the PLA melts were largely improved by the cross-linked NR phase, however, the crystallization of the PLA phase was restricted by the continuous NR phase. The initial decomposition temperature of the blends was lowered by the incorporation of NR.

Influence of methyl methacrylate-co-glycidyl methacrylate copolymers on the compatibility, morphology and mechanical properties of poly(butylene terephthalate) and polycarbonate blends

Abstract Methyl methacrylate-co-glycidyl methacrylate copolymers (MMA-co-GMA) were prepared to compatibilize the poly(butylene terephthalate) (PBT) and polycarbonate (PC) blends. The chemical reactions between the PBT and the epoxy groups and the good miscibility between the PC and the poly(methyl methacrylate) (PMMA) phase were responsible for the excellent compatibilization effect of the MMA-co-GMA copolymers. The MMA-co-GMA copolymers decreased the melting and crystallization temperature of the PBT phase in the PBT/PC blends. Dynamic mechanical analysis result showed that the exchange reactions were inhibited due to the compatibilization reactions owing to the consumption of the carboxyl/hydroxyl end groups of the PBT phase. MMA-co-GMA copolymers decreased the phase domain size of the PBT/PC blends, and with the increase in GMA content in the MMA-co-GMA copolymers, the blends changed from a double continuous phase to a single continuous phase structure. Tensile test indicated that the yield stress, elongation at break and elastic modulus of the PBT/PC blends increased due to the addition of MMA-co-GMA. The impact strength of the blends changed unnoticeably.

卵白・寒天共存ゲルのミクロおよびマクロ相分離の連続相構造と破断特性の相関

卵白・寒天共存ゲルのミクロおよびマクロ相分離の連続相構造と破断特性の相関

Preparation and characterization of the covalent-integrated poly(lactic acid) and scrap leather fiber composites

Scrap leather fibers (SLFs) modified with active silane containing epoxide groups were incorporated into poly(lactic acid) (PLA) modified by vinyl trimethoxysilane, i.e., the PLA/SLF composites were prepared for bio-composites by solvent compounding technology in this article. The effects of silane coupling agents on the structures of PLA and SLF molecules were examined, and the mechanical properties and thermal stability of PLA/SLF composites were also measured. The results of Fourier-transform infrared spectroscopy (FTIR) had proved that silane had been incorporated successfully to PLA and SLF molecules by means of the solvent technology. Scanning electric microscopy (SEM) was used to investigate both the changes in shapes between the pristine SLFs and the treated SLFs and the microscopic structures of composites. According to SEM results, it was shown that there were some significant differences between the untreated and treated SLFs, and a double continuous phase structure had occurred in PLA/SLF composites due to the excellent dispersion of SLFs in matrix. The addition of the treated SLFs into PLA resulted in a distinct improvement of the impact and tensile strengths. When the mass fraction of the treated SLFs was 15%, the notched impact strength and tensile strength of PLA/SLF bio-composites were improved by 34.4% and 21.2% compared with the pristine PLA, respectively. Additionally, with the increase of the modified SLFs content, the thermal stability of PLA/SLF bi-composites was apparently improved. The macroscopic properties of bio-composites were found to be strongly dependent on their components, concentration, dispersion and resulted morphological structures.

Carbon Black Selective Dispersion and Electrical Properties of Epoxy Resin/Polystyrene/Carbon Black Ternary Composites

Carbon black (CB) selective dispersion and conductive properties of immiscible thermoplastic/thermosetting polymer blends consisting of polystyrene (PS) and epoxy resin (EP) were investigated in this paper. The results showed that CB particles are preferentially localized in EP phase in PS/EP blends. The blend with 10 pbw (parts by weight) PS presented an EP continuous phase structure, and both blends with 20 pbw and 30 pbw developed into a bi-continuous phase structure. The selective dispersion of CB particles was explained by thermodynamic parameters. The phase structures of blends have important influences on both conductive and dielectric properties. The blends with 10 pbw PS has a very low percolation threshold nearly 0.25wt%.

Hydrogel-elastomer composite biomaterials: 2. Effects of aging methacrylated gelatin solutions on the preparation and physical properties of interpenetrating polymer networks

This study was conducted to understand the effects of aging methacrylated gelatin solutions on the properties of gelatin-HydroThane Interpenetrating Polymer Network (IPN) films. The latter were prepared from methacrylated gelatin solutions that were either freshly made or stored at different concentrations and temperatures for various periods. The morphology, swelling stability and mechanical properties of the IPNs were then accordingly characterized. The IPNs prepared with aged solutions showed a reduced phase separation; changed from a network-like structure to a continuous phase structure; and demonstrated higher swelling stabilities and higher elasticity under optimal aging conditions, compared to the IPN prepared with a fresh methacrylated gelatin solution. An increase in viscosity and a change in phase transition of aged methacrylated gelatin solutions were also observed, presumably due to the physical structuring of methacrylated gelatin chains (e.g., by the formation of a helix structure), thus altering the resulting IPN characteristics. A better understanding of the effects of aging methacrylated gelatin solution on the formation and properties of gelatin-HydroThane IPNs should enable us to further develop our composite biomaterials for different dressing applications.

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

AbstractA novel vibration internal mixer was used to prepare polypropylene/ultra high molecular weight polyethylene PP/UHMWPE blends with two additional adjustable processing parameters (vibration frequency and vibration amplitude) as compared with those prepared in the steady mode. Microscopy, mechanical tests, and differential scanning calorimetry showed that vibration influenced the blend morphology and the product properties. The good phase homogeneity of the blends might be due to the variation of shear rate either spatially or temporally in blending. Additionally, the vibration internal mixer could be used to analyze the dependency of viscosity on the shear rate. Vibration enhanced the interpenetration of UHMWPE into PP and vice versa. Subsequently, the formed crystals of two components were connected, and there was epitaxy between PP and UHMWPE crystals. Moreover, the crystalline aggregates, with the amorphous UHMWPE, formed a complex network‐like continuous structure, which improved the elongation ratio at the break and the yield strength. The higher the vibration frequency and/or the larger the vibration amplitude at a fixed average rotation speed of the mixer, the more significant these effects were. The larger amount of the connected crystals, especially of β form of PP in the bulk α form PP as well as with the continuous phase structure, led to a higher tensile properties of PP/UHMWPE vibration blended. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 164–176, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/adv.10020