Microcapsule Powder Research Articles

Dopamine as a bioinspired adhesion promoter for the metallization of multi-responsive phase change microcapsules

This work reports on an environmentally friendly method to produce encapsulated phase change material with a thin nickel coating, applicable for heat conversion, storage and thermal management of heat-sensitive components and suitable for active heating by electromagnetic radiation. A critical issue for the metallization is the adhesion between the polymer capsule shell and the metal layer. Based on previous studies using the bio-molecule dopamine as adhesion promoter in composites and for plastics metallization, commercial paraffin microcapsules were coated with an ultrathin polydopamine film via a simple wet chemical process. Subsequently, a thin, uniform and compact nickel layer was produced by electroless metallization. The successful deposition of both layers was verified with a broad range of imaging and spectroscopic techniques. For the first time, surface-enhanced IR spectroscopy was used to study the deposition of ultrathin PDA films. The combination of SEM and energy-dispersive X-ray spectroscopy allowed resolving the spatial distribution of the elements Ni, N, and O in the MC shell. Electrically conducting paths in the Ni shell were verified by conductive AFM. Thermal analysis revealed that the coated microcapsules show a phase change enthalpy of approx. 170 J/g, suitable for thermal storage and management. Additionally, the nickel layer enhanced the thermal diffusivity of the microcapsule powders and enables a fast heating of the PCM microcapsules by microwave radiation, demonstrating the applicability of the metallized MCs for controlled heating applications.Graphical abstract

Omega fatty acid-balanced oil formula and enhancing its oxidative stability by encapsulation with whey protein concentrate

The aim of this study is to design special blends of oils with a balance between the major fatty acid groups {(saturated (SFA): monounsaturated (MUFA): polyunsaturated (PUFA) SMP} and, at the same time, with a desirable balanced ratio between the essential fatty acids (omega-6/omega-3). The encapsulation techniques were used to protect these balanced omega oils from oxidative deterioration and to enhance their bioaccessibility. The efficiency of whey protein concentrates incorporation with various wall materials in the microcapsules by spray or freeze-drying methods was evaluated in terms of stability of internally trapped oil against oxidative degradation. An ultrasonic or microfluidizer was used to prepare nanoemulsions, which were then dried by freeze drying or spray drying to produce microcapsule powder in order to minimize lipid oxidation Whey protein concentrate was combined with maltodextrin and Arabic gum at 8:2:1 ratio. Particle size, zeta potential, emulsion stability, and oxidative stability were evaluated in the feed emulsions used in particle manufacturing. In addition, the encapsulation efficiency and in-vitro digestion and morphology of encapsulated powder were assessed. The highest level of encapsulation efficiency was achieved using a microfluidizer and drying with a spray dryer, these powders also showed the highest emulsion and oxidative stability; microfluidized powders dried with a freeze drier had the lowest encapsulation effectiveness. Some health benefits (particularly for maintaining human health and preventing or reducing certain diseases) are expected to come from consuming fatty foods that contain balanced fatty acids as well as a certain ratio of omega-6 and omega-3 fatty acids.

Effect of Emulsifiers and Wall Materials on Particle Size Distribution and Stability of the Blended Essential Oils Nanoemulsions

In the present work, microencapsulation of the essential oil blend (clove + lemon peel + thyme) was successfully used to produce a product that can be used as food additives or in the pharmaceutical industry for the manufacture of a food supplement or so-called nutraceutical of plant origin. The characterization of the powder of the microcapsules made it possible to observe that the essential oil was successfully incorporated into the coating matrix. This was designed by the wall material, namely maltodextrin represented a barrier allowing the protection of the active principle, the control of its release and the property retention of the encapsulated essential oil for a long time. This powder of microcapsules of essential oil mixture can be successfully used for medical purposes to remedy certain pathologies, in particular for its antioxidant, antibacterial and anti-inflammatory properties.

Physicochemical properties of yogurt fortified with microencapsulated Sacha Inchi oil

Yogurt can be fortified with polyunsaturated fatty acids such as Sacha Inchi oil (SO) whose stability can be improved by microencapsulation. The comparison on yogurt properties after addition of microcapsules with hydrophobic and hydrophilic wall materials is scare. The aim of this work was to compare physicochemical properties of yogurt during 30-day storage at 4 °C after fortifying with 1 g SO/100-g-yogurt in the unencapsulated or microencapsulated form. Freeze-dried SO microcapsules (FDSOMs) were prepared with hydrophobic zein, and spray-dried SO microcapsules (SDSOMs) were prepared with hydrophilic maltodextrin and modified starch. Yogurt samples had a desirable pH from 3.88 to 4.23 during storage and had a light-yellow appearance. Microcapsules were homogeneously distributed in the yogurt, while big oil droplets were observed for the unencapsulated SO. The addition of SO and microcapsule powders weakened the yogurt network, most significant for FDSOMs due to the most incompatible hydrophobic zein. Syneresis of yogurt samples was 3.09–4.07 g/10-g-yogurt, lowest for the SDSOM treatment. The release of free fatty acids after simulated gastrointestinal digestions was significantly improved for FDSOMs (94.27%) and SDSOMs (103.29%) when compared to the unencapsulated SO (89.20%). Findings from this study may be significant to manufacturing functional yogurts with polyunsaturated fatty acids.

CURCUMIN MICROENCAPSULATION USING CHITOSAN–ETHYL CELLULOSE–GMS MIXTURE FOR PRESERVATION OF MUCOADHESIVE PROPERTIES AND CONTROLLED RELEASE KINETIC

Objective: This research aimed to prepare curcumin microcapsules by the spray drying method and to evaluate their characteristics. Methods: The microcapsules were prepared by the spray drying method. The generated microcapsules were evaluated for organoleptic, morphology, particle size, the percentage of curcumin and water content. Furthermore, the release of curcumin from the microcapsules was tested in vitro and compared to uncoated curcumin powder. In addition, the mucoadhesive properties of uncoated curcumin powder and curcumin microcapsules were also evaluated. Results: The results showed that the microcapsules had spherical shape with particle size in the range of 100–1009 µm and water content of 9.34% (w/w) (FIII) and 8.09% (w/w) (FVI). The release of curcumin from its uncoated powder and the microcapsules FVI within 8 h were 8.87% and 26.32% (w/w), respectively. It was found that the mucoadhesive properties of microcapsules FVI were better than those of FIII and uncoated curcumin powder. Microcapsules FVI rendered the cumulative amount of curcumin remaining on the intestinal mucosa of 55% (w/w) within 3 h. Conclusion: Accordingly, curcumin microcapsules generated by spray drying could be further formulated into various solid dosage forms for a better therapeutic effect.

Programming Semiconductor Nanowire Composition with Sub-100 nm Resolution via the Geode Process.

We demonstrate the vapor-liquid-solid growth of single-crystalline i-Si, i-Si/n-Si, and SixGe1-x/SiyGe1-y nanowires via the Geode process. By enabling nanowire growth on the large internal surface area of a microcapsule powder, the Geode process improves the scalability of semiconductor nanowire manufacturing while maintaining nanoscale programmability. Here, we show that heat and mass transport limitations introduced by the microcapsule wall are negligible, enabling the same degree of compositional control for nanowires grown inside microcapsules and on conventional flat substrates. Efficient heat and mass transport also minimize the structural variations of nanowires grown in microcapsules with different diameters and wall thicknesses. Nanowires containing at least 16 segments and segment lengths below 75 nm are demonstrated.

Cinnamon Essential Oil Microcapsules Made Using Various Methods: Physical Properties and Antimicrobial Ability

HighlightsCinnamon essential oil was microencapsulated using various methods.The most suitable method was determined by considering the powder recovery and product quality.The structure of freeze-dried microcapsules was examined using confocal laser scanning microscopy.The cinnamon essential oil microcapsules inhibited bacterial growth in minced chicken meat samples.Abstract. Cinnamon essential oil has enormous potential for use in foods, pharmaceuticals, and cosmetics; however, its applications are currently limited due to its volatility and rapid degradation. In this study, cinnamon essential oil was microencapsulated using four methods. The main aims were to determine a suitable method for producing cinnamon essential oil microcapsule powder and to examine the physical properties of the microcapsule powder. The results indicated that the powder recovery values for spray-drying were much lower than for the other methods. For the same encapsulation method, samples with higher oil concentration had lower powder recovery and were harder to dissolve. Freeze-drying provided the highest encapsulation efficiency (92.3% to 95.2%), followed by drum-drying, spray-drying, and a manual method. Freeze-drying with an oil concentration of 27% was the most suitable method for microencapsulation in this study due to its higher solubility and encapsulation efficiency and having the lowest surface oil content for the product. Confocal laser scanning microscopy demonstrated that the cinnamon essential oil was well encapsulated in the freeze-dried microcapsules. The cinnamon essential oil microcapsules significantly impeded bacterial growth in minced chicken meat samples during chilled storage for 12 days. Keywords: Cinnamon, Drum-drying, Encapsulation, Freeze-drying, Spray-drying.

Effect of drying method and wall material composition on the characteristics of camellia seed oil microcapsule powder

AbstractCamellia seed oil (CSO) is one of the richest sources of oleic acid (75–80%) and it is considered to provide beneficial health effects to humans. However, its susceptibility to oxidative degradation prevents its widespread use in the food industry. This study was aimed to improve the stability of camellia seed oil by microencapsulation. CSO was microencapsulated using whey protein concentrate (WPC) and maltodextrin (MD) or starch sodium octenylsuccinate (SSOS) as wall materials. The produced oil‐in‐water emulsion was subsequently dehydrated to produce microcapsule powder using spray and freeze drying techniques, respectively. Various characteristics of oil‐in‐water emulsion and final microcapsule powder including particle size distribution, encapsulation efficiency, morphology, rheological properties of reconstituted emulsions, in vitro digestion behavior and oxidative stability were determined to investigate the effect of wall material composition and drying method on these microcapsule powder characteristics. The spray‐dried powder had significantly higher bulk density and smoother surface compared to freeze‐dried powder while the freeze‐dried CSO microcapsule powder with WPC/SSOS as wall material had the highest encapsulation efficiency and the lowest surface oil. The subsequent in vitro digestion test suggested the microencapsulated CSO could be successfully controlled‐released in the simulated gastric (10.28–13.03%) and the subsequent intestinal fluid (72.89–89.61%). Oxidative stability of camellia seed oil was significantly improved by microencapsulation. The freeze dried CSO microcapsule powder in WPC/SSOS wall material exhibited highest encapsulation efficiency (95.17%) and best oxidative stability (peroxide value and p‐anisidine values of 3.57 meq/kg oil and 3.01, respectively, during the 45 days storage at 25°C.

Preparation of Melamine/Rice Husk Powder Coated Shellac Microcapsules and Effect of Different Rice Husk Powder Content in Wall Material on Properties of Wood Waterborne Primer.

The melamine/rice husk powder-coated shellac microcapsules were prepared by in-situ polymerization with melamine resin mixed with rice husk powder as microcapsule wall material and shellac as microcapsule core material. The effect of the addition amount of microcapsules with different wall material ratios on the performance of wood waterborne primer coating was investigated. The results show that the most important factor affecting the performance of microcapsules is the content of rice husk powder. Through the preparation and analysis of shellac microcapsule primer coating coated with melamine/rice husk powder, when the content of microcapsule powder is 0–6%, it has little effect on the optical properties of wood waterborne primer coating, and the microcapsule with 5.5% rice husk powder has little effect on the color difference of primer coating. The coating hardness increases with the increase of rice husk powder content in wall material. When the rice husk powder content in wall material is more than 5.5%, the coating hardness reaches the best. When the content of microcapsule powder is 3.0–9.0%, the adhesion of the coating is better, and the coating with rice husk powder content of 5.5% in microcapsule wall material has better impact resistance. When the content of rice husk powder was 5.5% and the content of microcapsule powder was 6%, the elongation at break of the primer coating was the highest and the tensile resistance was the best. The composition of wood waterborne primer did not change after adding microcapsule. The water-based primer with microcapsule has better aging resistance. The water-based primer coating with rice husk powder content of 5.5% and the addition amount of 6% had the best comprehensive performance, which lays the technical reference for the toughness and self-repairing of the waterborne wood coatings.

Supercritical Fluid CO2 Extraction and Microcapsule Preparation of Lycium barbarum Residue Oil Rich in Zeaxanthin Dipalmitate

The scope of this investigation aimed at obtaining and stabilizing bioactive products derived from Lycium barbarum seeds and peels, which were the byproducts in the processing of fruit juice. Zeaxanthin dipalmitate is a major carotenoid, comprising approximately 80% of the total carotenoid content in the seeds and peels. The method of obtainment was supercritical fluid CO2 extraction, studying different parameters that affect the oil yield and content of zeaxanthin dipalmitate. The optimized protocol to enact successful supercritical fluid CO2 extraction included optimum extraction pressure of 250 bar, temperature at 60 °C over a time span of 2.0 h, and a CO2 flow of 30 g/min, together with the use of a cosolvent (2% ethanol). The yields of oil and zeaxanthin dipalmitate under these optimal conditions were 17 g/100 g and 0.08 g/100 g, respectively. The unsaturated fatty acids were primarily linoleic acid (C18:2), oleic acid (C18:1), and γ-linolenic acid (C18:3), with their contents being as high as 91.85 ± 0.27% of the total fatty acids. The extract was a red-colored oil that was consequently microencapsulated through spray-drying with octenylsuccinate starch, gum arabic, and maltodextrin (13.5:7.5:3, w/w) as wall materials to circumvent lipid disintegration during storage and add to fruit juice in a dissolved form. The mass ratio of core material and wall material was 4:1. These materials exhibited the highest microencapsulation efficiency (92.83 ± 0.13%), with a moisture content of 1.98 ± 0.05% and solubility of 66.22 ± 0.24%. The peroxide content level within the microencapsulated zeaxanthin dipalmitate-rich oil remained at one part per eight in comparison to the unencapsulated oil, following fast-tracked oxidation at 60 °C for 6 weeks. This indicated the potential oxidation stability properties of microcapsule powders. Consequently, this microencapsulated powder has good prospects for development, and can be utilized for a vast spectrum of consumer health and beauty products.

Application of Caseinate Modified with Maillard Reaction for Improving Physicochemical Properties of High Load Flaxseed Oil Microcapsules

AbstractHigh‐load flaxseed oil microcapsule is prepared with the Maillard reaction products (MRPs) of sodium caseinate and isomaltooligosaccharide as wall material. It is found that the emulsifying activity index and emulsion stability index of MRPs are increased by 31.32% and 34.11% respectively at the appropriate degree of graft (26.30%) compared with the mixture of sodium caseinate and isomaltooligosaccharide. Smaller droplet size and lower polydispersity index can be achieved in the flaxseed oil emulsions coated by MRPs, due to the change of sodium caseinate molecular weight and spatial structure. The microencapsulation efficiency of the microcapsules coated by MRPs is highly improved up to 98.22% at oil load of 58.43%, compared with the control group. Furthermore, MRPs as coating material can protect flaxseed oil against lipid oxidation at 50 °C for 4 weeks. More importantly, the smooth, round, and compact external surface structures of microcapsule powder support its physical necessity for industrial usage. Due to its high microencapsulation efficiency and good oxidation stability, MRPs formed with sodium caseinate and isomaltooligosaccharide show great application potential in preparing high load oil microcapsule.Practical Applications: Findings in this research could be utilized for developing microencapsulation loaded with higher concentration of flaxseed oil, a rich source of α‐linoleic acid and lignans. Application of MRPs (Maillard reaction products) formed through interaction between sodium caseinate and isomaltooligosaccharide by heating improved both its physicochemical properties and oxidative stability. It is a novel approach for developing microcapsule with higher percentages of oils with better oxidative stability.

Preparation and drying of water-in-oil-in-water (W/O/W) double emulsion to encapsulate soy peptides

Soy peptide solution (40%, w/w) was successfully encapsulated in a W1/O/W2 double emulsion produced by a two-step emulsification process. Polyglycerol polyricinoleate (PGPR) was found to be an effective inner emulsifier compared to Span 60 and lecithin to produce stable W1/O primary emulsion. The primary emulsion was subsequently emulsified into an outer aqueous phase (W2) containing octenyl succinic anhydride (OSA) starch and maltodextrin. The droplet size and encapsulation efficiency of the peptide solution in W1/O/W2 emulsion were found to depend on the W1:O ratio, peptide concentration in the inner W1 phase and homogenization condition of the secondary emulsification step. The double emulsion with the highest encapsulation efficiency (>80%) was prepared by: (i) using 40% (w/w) soy peptide solution as W1 phase; (ii) controlling W1:O ratio at 3:7 (w/w) and (iii) homogenizing the emulsion at 10,000 rpm for 3 min. The freeze-dried microcapsule powder of W1/O/W2 emulsion showed higher encapsulation efficiency (>70%) compared to spray-dried one. The freeze-dried microcapsule of W1/O/W2 double emulsion developed in this study is a promising delivery matrix to encapsulate hydrophilic ingredients including peptides. Fourier-transform infrared spectroscopy (FTIR) spectra of the microcapsule powder indicated good compatibility between peptide and encapsulants.

Effect of Dextrose Equivalent on Maltodextrin/Whey Protein Spray-Dried Powder Microcapsules and Dynamic Release of Loaded Flavor during Storage and Powder Rehydration.

The preparation of powdered microcapsules of flavor substances should not only protect these substances from volatilization during storage but also improve their diffusion during use. This study aimed to investigate the effects of maltodextrin (MD) with different dextrose equivalent (DE) values on retention of flavor substances during storage, and the dynamic release of flavor substances during dissolution. MDs with three different DE values and whey protein isolate were mixed in a ratio of 4:1 as wall materials to encapsulate ethyl acetate, and powdered microcapsules were prepared by spray drying. It was proved that MD could reduce the diffusion of flavor substances under different relative humidity conditions through the interaction between core material and wall material. During dissolution, MD released flavor substances quickly owing to its superior solubility. The reconstituted emulsion formed after the powder dissolved in water recaptured flavor substances and made the system reach equilibrium. This study explored the mechanism of flavor release during the storage and dissolution of powder microcapsules and should help us understand the application of powder microcapsules in food systems.

Microencapsulation of Tangeretin in a Citrus Pectin Mixture Matrix.

The objectives of this research were to microencapsulate tangeretin, and to evaluate the basic characteristics of the microcapsule products. Tangeretin is a polymethoxyflavone (PMF) which has been revealed to possess various health benefits and is abundant in tangerine and other citrus peels. Microencapsulation technology is widely employed in the food and pharmaceutical industries to exploit functional ingredients, cells, and enzymes. Spray drying is a frequently applied microencapsulation method because of its low cost and technical requirements. In this research, tangeretin dissolved at different concentrations in bergamot oil was microencapsulated in a citrus pectin/sodium alginate matrix. The resulting microcapsule powder showed promising physical and structural properties. The retention efficiency of tangeretin was greater at a concentration of 2.0% (98.92%) than at 0.2% (71.05%), probably due to the higher temperature of the emulsion during the homogenizing and spray-drying processes. Encapsulation efficiency was reduced with increased concentration of tangeretin. Our results indicate that tangeretin could be successfully encapsulated within a citrus pectin/sodium alginate matrix using bergamot oil as a carrier.

Effects of spray-drying temperature on the physicochemical properties and polymethoxyflavone loading efficiency of citrus oil microcapsules

A polymethoxyflavone (PMF)-loaded citrus oil emulsion was prepared as microcapsules via spray-drying. The effects of spray-drying temperature ranges from 110 °C to 190 °C on the physical properties of the citrus oil microcapsule powder, encapsulation efficiency of PMF and the alteration of citrus oil aroma were investigated in this study. The microcapsule powder formed at 150 °C spray-drying temperature possessed low moisture content (1.7%, w.b.), high powder yield (51.4%), good particle integrity and the corresponding reconstituted emulsion had a small droplet size. The encapsulation efficiency of PMF in microcapsule powder decreased as the spray-drying temperature increased from 110 °C to 190 °C (75.8%→45.2%). Electronic nose and GC-MS measurements revealed that the spray-dried powder was close to the aroma of the original citrus oil, although partial volatile components were lost when spray-drying. The results from this study are expected to facilitate the development of PMF-loaded citrus oil microcapsule products for functional foods.

Microencapsulation of Eugenol Through Gelatin-Based Emulgel for Preservation of Refrigerated Meat

Preservation of refrigerated meat has always been a concern in food industry. In our study, eugenol (Eu) microcapsules were prepared to solve this problem. Eu was embedded into a gelatin-based emulgel with both low-energy and high-energy methods. The emulgel was further spray dried to obtain the Eu microcapsule. The physicochemical properties, microstructure, and thermodynamic properties of the microcapsules were studied. Results showed that the microcapsule powders prepared from the high-energy emulgel (HEG) contained less water and appeared no caking. But the microcapsule prepared from the low-energy emulgel (LEG) showed more regular shape. After dissolution, the reconstructed emulgel was investigated in terms of texture, microstructure, thermal properties, and preservation effects. Reconstructed emulgel from both LEG and HEG showed significantly higher gel strength but similar thermal properties comparing to the fresh one. In addition, meat covered with reconstructed emulgel showed less weight loss and more stable pH and total volatile basic nitrogen (TVB-N) value, as well as stronger resistance to bacterial reproduction, especially against lactic acid bacteria. The results indicated that the microencapsulation of Eu through gelatin-based emulgel might be a convenient and effective technology for refrigerated meat preservation.

Study on microencapsulation of Lactobacillus plantarum LIP‐1 by emulsification method

AbstractWe prepared probiotic microcapsules with lactoprotein as the wall material using an optimized emulsification method. Results of an orthogonal experiment showed that when the water–oil ratio was 1:10, the skim‐milk concentration was 35% (wt/wt), the emulsification time was 10 min, stirring speed was 600 r/min, microencapsulation efficiency was 86.59%, and particle size was 52.56 μm. The evaluation of microcapsules' performance in simulated human digestion confirmed that the microcapsules released the probiotics completely in simulated intestinal fluid within 90 min. The survival rate after exposure to simulated gastric fluid for 90 min was 53.3%, which was significantly higher than that of free cells (16.81%; p < .05). The freeze‐drying survival rate was 63.10%. The viability of the probiotics decreased only by 0.46 log CFU/g during storage at 4°C for 21 days, benefit by microcapsules' denser structure. These results provide a theoretical reference for an industrial application of microencapsulation.Practical applicationsMicrocapsulation technology can be applied to produce functional and healthy food containing probiotic bacteria, such as yoghurt, cheese, ice cream, and other products. Microcapsule powder can be prepared by freeze‐drying as a lactic acid bacterial starter. Microcapsules are a potential drug delivery system, and Lactobacillus plantarum LIP‐1 is a beneficial probiotic that lowers blood cholesterol.

Microencapsulation of flaxseed oil using polyphenol-adducted flaxseed protein isolate-flaxseed gum complex coacervates

This study aimed to evaluate the applicability of polyphenol-adducted flaxseed protein isolate (FPI)-flaxseed gum (FG) complex coacervates to encapsulate flaxseed oil (FO). FPI was covalently adducted with flaxseed polyphenol (FPP) or hydroxytyrosol (HT). β-sheet was major secondary structure of FPI and its covalent conjugation with polyphenols further increased the β-sheet content. The extent of increase of this ordered structure was found to depend on the type of aducted polyphenol. Subsequently, complex coacervation between polyphenol adducted FPI and FG was studied in terms of optimum complex coacervation pH and protein-to-gum ratio. Compared to FPI and FPI-polyphenol adducts, FPI/FG, (FPI-FPP)/FG and (FPI-HT)/FG complex coacervates had significantly higher random coil and significantly lower β-sheet contents suggesting that these complex coacervates had less ordered structure. Finally, the spray-dried microcapsule powders of FO were produced using FPI/FG, (FPI-FPP)/FG and (FPI-HT)/FG as shell materials. Physicochemical properties of these microcapsules, including surface oil, microencapsulation efficiency and stability against oxidation, were determined. The optimum pH for complex coacervation between FPI/FG, (FPI-FPP)/FG and (FPI-HT)/FG was very close (4.6 ± 0.1) and the optimum protein-to-gum ratio of 6.0 was also identical. All these microcapsules had irregular shape with wrinkled surface morphology. The microcapsules produced using (FPI-HT)/FG complex coacervates had lowest surface oil (1%, w/w) and highest microencapsulation efficiency (95.4%). The microcapsules encapsulated using (FPI-FPP)/FG complex coacervates had the highest stability against oxidation as measured by peroxide value and p-anisidine value. Overall the complex coacervates produced using polyphenol adducted FPI and FG were found to be better than FPI/FG complex coacervates as encapsulating shell materials for oxygen-sensitive oil.

Laboratory evaluation of rutting resistance for asphalt binders and mixtures modified with different thermochromic microcapsule powders

Asphalt binder absorbs a lot of solar energies in summer and causes many pavement distresses and environmental problems. Thermochromic microcapsule powder (TMP) has been applied into asphalt binders as pavement materials since it reversibly changes its colors and dynamically adjusts the reflectivity to solar radiation according to temperature variations. In this research, the rutting resistance of TMP modified asphalt binders was evaluated by the physical properties tests, temperature and frequency sweep test, and multi-stress creep recovery test. The effects of base binder types, TMP types, and TMP content were investigated. The repeated load permanent deformation test was performed on TMP modified asphalt mixtures to verify the findings obtained from the binder performance tests. It is found that two types of TMP show the opposite effects. The use of one type of TMP reduces the rutting resistance of asphalt binders while the use of another improves it. The effect becomes more significant with the increase of TMP content. All TMP modified asphalt binders exhibit low stress-dependence. The consistent findings are obtained from both binder and mixture performance tests. Nonrecoverable creep compliance of asphalt binders is a rational indicator to predict the rutting resistance of different types of asphalt mixtures. The potential reasons for the different modification effects of two types of TMP are preliminarily discovered.

Lamb-Wave-Based Method in the Evaluation of Self-Healing Efficiency

The aim of this research is a feasibility study of self-healing process monitoring in composite laminates. A novel nondestructive method based on the full wavefield of Lamb wave processing is proposed. Experimental verification is presented for glass-fiber-reinforced polymer plate with embedded self-healing function in the form of a dry microcapsule powder. After impacting the specimen to create barely visible impact damage, a series of laser vibrometer full wavefield measurements were carried out and processed to assess self-healing efficiency.