Laser Particle Diameter Analyzer Research Articles

Synthesis and Optimization of GO/PMMA/n-Octadecane Phase Change Nanocapsules Using Response Surface Methodology

Nano Encapsulated Phase Change Materials (NEPCMs) are a crucial part of solar energy systems due to their high thermal storage density. The particle size of the NEPCMs is especially of great importance due to its effect on heat transfer and long-term use during applications. In this study, nanocapsules containing Phase Change Material (PCM) n-dodecanol as core and polymethyl methacrylate (PMMA) as shell were synthesized by miniemulsion polymerization with Graphene Oxide (GO) nanosheets as an extra protective screen situated at the interface between the core and the shell. The experiments were designed with the Central Composite Design (CCD) of Response Surface Methodology (RSM). The nanocapsules synthesis experiments were conducted as per the statistical design to determine the optimum process conditions. The effect of initiator/Methyl methacrylate(MMA) mass ratio (BPO/MMA wt.%), n-octadecane/MMA mass ratio (PCM/MMA), stabilizer/MMA mass ratio (triton X-100/MMA wt.%), water/MMA mass ratio (H2O/MMA) and GO/MMA ratio on the nanocapsule properties were investigated. The correlation between nanocapsule properties (melting latent heat and average particle size of nanocapsules) and affecting factors were evaluated and verified. The numerical optimization showed that the optimum nanoparticle size (110 nm) and latent heat (148.5 J/kg) can be obtained at H2O/MMA of 11.3 wt%, PCM/MMA mass ratio of 1.88wt%, X-100/MMA of 10.81wt.%, and BPO/MMA of 2.96 wt.% and GO/MMAof 3.79wt%. The optimized nanocapsules were characterized by Fourier Transform InfraRed (FT-IR) spectroscopy, Transmission Electron Microscope (TEM), Differential Scanning Calorimetry (DSC), ThermoGravimetric Analysis (TGA), and laser particle diameter analyzer. The thermal cycling tests indicate the high thermal resistance of the prepared core-shell system, even after 100 heating/cooling cycles, and have an excellent potential for energy storage and release performance of the system.

Development and thermal performance of nanoencapsulated PCM/ plaster wallboard for thermal energy storage in buildings

The Phase Change Material (PCM) integrated in building envelope can decrease the energy requirement for maintaining thermal comfort by enhancing the thermal energy storage of the wall and the roof. This work deals with experimental study of the thermal behavior of new plaster composite containing a nanoencapsulated PCM. Nanocapsules containing phase change material (NPCM) n-dodecanol as core and polymethyl methacrylate (PMMA) and CuO nanoparticles as shell were synthesized by miniemulsion polymerization and characterized by using FTIR, SEM, TEM, DSC, TGA and laser particle diameter analyzer. The average diameter of PCP was 195 nm, and the latent heat of phase change and encapsulation efficiency were 148.88 J/g and 72.28%, respectively. The Plaster - NPCM composites were produced in this project using compression molding and their effective thermal conductivity, latent heat and apparent specific heat were investigated. The addition of the PCM to the wall can enhance the heat storage in the wall. CuO consisted nanocapsules exhibited better thermal stability and conductivity and reliability determined by thermal cycling analysis. Reduce-scale test cells, (including room 1 without PCM wallboard and room 2 PCM wallboard) were compared to study the thermal performance of the PCM contained wallboard in passive systems. The results indicate that the PCM system can narrow indoor air temperature fluctuations and maintain indoor thermal comfort at most of the time of the year. The results demonstrate the suitability of incorporating nanoencapsulated PCM into plaster.

Gum arabic/maltodextrin microencapsulation confers peroxidation stability and antimicrobial ability to pepper seed oil

In this study, pepper seed oil (PSO) was microencapsulated by spray drying at optimum conditions: oil/total solid material at 20% (w/w), gum Arabic/maltodextrin (GA/MD) at 1/5 (w/w), and air inlet temperature of 184 °C. Particle size distribution and morphology of the PSO powder (PSOP) were determined by a laser particle diameter analyzer and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) were employed to identify the specific chemical groups of PSO, MD, and GA in the PSO-GA/MD complexes. The thermal stability of PSOP was evaluated by thermogravimetric (TGA) and differential thermal analysis (DTA). PSOP displayed inhibitory activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis although PSO had an antimicrobial activity against only Staphylococcus aureus. GA/MD microencapsulation resulted in significant preservation of PSO against oxidation during storage period.

Microencapsulation of sour cherry oil by spray drying: Evaluation of physical morphology, thermal properties, storage stability, and antimicrobial activity

In this study, sour cherry seed oil (SCSO) loaded gum Arabic (GA)-Maltodextrin (MD) microcapsules were developed by using spray-drying technique. The optimum processing conditions determined using the response surface methodology (RSM) were as follows: a weight ratio of GA to MD (GA:MD composition) of 1:11, a weight ratio of oil to total solid (core-wall ratio) of 20%, and inlet temperature of 195 °C. SCSO powder (SCSOP) was characterized in terms of morphology and size using scanning electron microscopy (SEM), and a laser particle diameter analyzer. The presence of SCSO in GA/MD matrix was confirmed by using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The thermal stability of the SCSOP was assessed using thermogravimetric (TGA) and differential thermal analysis (DTA). Microencapsulation provided a remarkable oxidative stability to SCSOP compared to free sour cherry oil. The antimicrobial potential of the microcapsules were assessed against pathogenic bacteria, yeast and mold.

The influence of emulsifiers on preparation and properties of microencapsules of melamine–urea–formaldehyde resins with n‐dodecanol as phase‐change material

AbstractMelamine–urea–formaldehyde resins/n‐dodecanol microencapsulated phase‐change materials (microPCMs) were prepared by in situ polymerization method in this work. In the microPCMs, the n‐dodecanol was used as phase‐change material (PCM) for thermal energy storage, and the melamine–urea–formaldehyde resins (MUF) acted as shell materials. The Fourier‐transform infrared spectroscopy (FT‐IR) indicated that the PCM n‐dodecanol is encapsulated in the MUF shell controlling pH of n‐dodecanol emulsion at 4.5, and there is no chemical reaction between them. The thermal properties of the microcapsules were measured by differential scanning calorimeter (DSC). The morphology and particle size of the microPCMs were surveyed by scanning electron microscopy (SEM) and laser particle diameter analyzer. The results showed that styrene‐maleic anhydride copolymer (SMA) anionic emulsifier is suitable for the preparation of MUF microPCMs. The cooling and melting phase‐change enthalpy were 130.5 and 135.2 J/g, and the cooling and melting phase‐change temperature were 20.9 and 19.11°C when core–shell ratio reached 3:1. In addition, increasing amount of SMA can enhance the phase‐change enthalpy.

Physicochemical changes of maize starch treated by ball milling with limited water content

A granular maize starch with limited amounts of water was ball milled, and the structural changes were investigated. The chemical changes were analyzed in terms of amylose content, hydroxyl and carbonyl contents, and intrinsic viscosity. The granule or aggregation structures were characterized by X‐ray diffraction, differential scanning calorimetry, laser particle diameter analyzer, and scanning electron microscope. The gelatinization and paste property were measured with a Rapid Visco‐Analyzer. Under the ball‐milling conditions of 25 wt% water content based on the starch, a ball diameter of 15 mm, a weight ratio of ball to starch at 4:1, and milling time of 3 h, the ball‐milled starch granules did not have apparent gelatinization or agglomeration. After the ball milling, the system temperature increased by 25.5°C. The resultant starch granules displayed a flat‐ or oval‐shaped pattern without edges, and their particle size slightly increased with a narrower size distribution. The ball‐milled starch was mildly oxidized, and the intrinsic viscosity and the amylopectin content decreased a little. The crystallinity of granules decreased greatly from 31.1 to 13.0%, concurrent with a decrease in the thermal transition enthalpy. The pasting temperature increased, while the peak viscosity, breakdown, and setback greatly decreased. Our results indicated that the limited additional water in the ball‐milling process helps expand the amorphous region in starch granules and could reduce damage level of starch molecules and granules.

Synthesis of Methylacryloypropyl-POSS/Poly(fluorine-acrylate) Core-Shell Nanocomposites and Effect on Thermal Properties of Materials

Core-shell nanocomposites were prepared from acrylates, fluorine- containing methacrylate monomers and methylacryloypropyl polyhedral oligomeric silsesquioxanes (MAP-POSS) by emulsion polymerization. The properties of latex and nanocomposites were characterized by FTIR, NMR, TEM, laser particle diameter analyzer, DMA and TGA. The results showed that the particle diameter of composite latexes was about 33.5 nm, dynamic mechanical loss peak temperature Tp of the nanocomposites had the best high value at 99.6°C when 7 wt.% MAP-POSS was added, which is 7.8°C higher than the pure polyacrylates. MAP-POSS could increase the thermal stability of materials, the initial thermal decomposition temperature increases about 34°C.

Synthesis and Characterization of Emulsion Coating of Fluorinated Polymethacrylate Modified by POSS

The core-shell nanocomposite particles were prepared from acrylate monomers and octavinyl polyhedral oligomeric silsesquioxane (V-POSS) by emulsion polymerization. The structure and properties of emulsion and latex film were characterized by FT-IR, dynamic mechanical analysis (DMA) and TEM and laser particle diameter analyzer (LPDA). The results showed that the V-POSS/polyacrylated (V-POSS/PMA) composite latexes was prepared and the diameter is about 36.1 nm when added 5wt% V-POSS. DMA results showed that the mechanical loss (tanδ) peak temperature (Tp) of the film enhance with increasing V-POSS content and had the best high Tp at 88.4°C for added 7 wt% V-POSS, which increased 7.8 °C than had not V-POSS. Thermogravimetric analysis (TGA) showed that the addition of V-POSS can increase the thermal decomposition temperature and improved the thermal stability of polyacrylate.

Synthesis of polymerizable quaternary ammonium emulsifier and properties of its fiber crosslining emulsion

A polymerizable emulsifier with quaternary ammonium groups as polar heads, epoxy groups as functional moieties were synthesized and investigated in pre-emulsified seed copolymerization of styrene and butyl acrylate. The chemical structure and composition of polymerizable quaternary ammonium emulsifier were confirmed by 1H nuclear magnetic resonance spectrum(1H NMR) and Fourier transforms infrared (FTIR). Latexes were characterized by using FTIR, differential scanning calorimetry and laser particle diameter analyzer. Properties of latexes alongside with their sizing properties have been characterized. Results showed that the polymerizable quaternary ammonium was a potential candidate for emulsion polymerization. Its critical micelle concentration was approximately 1.512g/L; a large part of emulsifiers was joined polymerization with monomers, only small part anchored on the surface of the emulsion particles; surface tension and particle size of latexes, water absorptions of latexes films were affected greatly by the polymerizable emulsifier; latex-treated paper showed better water resistance (lower Cobb value) and higher surface strength.

Fabrication and characterization of nanocapsules containing n-dodecanol by miniemulsion polymerization using interfacial redox initiation

Phase change material nanocapsules with n-dodecanol as the core and styrene-butyl acrylate copolymer as the shell were prepared by miniemulsion polymerization using interfacial redox initiation. The morphology, particle size, polydispersity index, thermal properties, and structure of the nanocapsules were characterized by TEM, laser particle diameter analyzer, DSC, TGA, and FT-IR. When the monomers/n-dodecanol mass ratio of 1:1 was used, the phase change enthalpy and encapsulation efficiency of the nanocapsules reached to 109.2 J/g and 98.4%, respectively. The thermal decomposition temperature of the nanocapsules was about 195 °C. Spherical nanocapsules with a mean diameter of 100 nm and a phase change temperature of 18.4 °C were obtained, which have good energy storage potential.

Preparation, characterization and thermal properties of nanocapsules containing phase change material n-dodecanol by miniemulsion polymerization with polymerizable emulsifier

Nanocapsules containing phase change material (PCM) n-dodecanol as core and polymethyl methacrylate (PMMA) as shell were synthesized by miniemulsion polymerization with polymerizable emulsifier DNS-86 and co-emulsifier hexadecane (HD). The nanocapsules were characterized by using Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and laser particle diameter analyzer. The effects of polymerizable emulsifier and co-emulsifier on the properties of nanocapsules were studied. The results show that thermal properties of nanocapsules are affected greatly by the addition methods of HD and the amounts of DNS-86 and HD. Adding HD into water phase is helpful for the encapsulation of n-dodecanol. When the mass ratios of DNS-86 to n-dodecanol and the mass ratios of HD to n-dodecanol were 3% and 2%, the phase change latent heat and the encapsulation efficiency of nanocapsules reached to the maximum value of 98.8 J/g and 82.2%, respectively. Spherical nanocapsules with mean diameter of 150 nm and phase change temperature of 18.2 °C are obtained, which are sure to have a good potential for energy storage.

Effects of wet ball milling on lead stabilization and particle size variation in municipal solid waste incinerator fly ash

Water-extracted municipal solid waste incinerator (MSWI) fly ash was treated by a process of wet ball milling, using desalinated water as the milling solution. We investigated the influence of the milling process on the partitioning and leaching characteristics of lead (Pb) and the particle size distribution. The results show that 93.11% of the Pb was partitioned into the milled ash, 2.60% to the milling balls, and 0.17% to the inner surface of the milling jar, while amounts lower than the detection limit remained in the milled solution. As tested by the toxicity characteristic leaching procedure (TCLP), the leaching of Pb was inhibited after short-term grinding (from 5.2 to 1.2 mg/L after 1 h of milling), and further reduced by about 96% after 96 h of ball milling. The mobility of the heavy metal was analyzed after a sequential extraction procedure. The results also show that Pb tended to become more stable after milling. The size distribution of particles was analyzed by a laser particle diameter analyzer and their morphology during grinding was observed using scanning electron microscopy. The median size of the fly ash decreased significantly from 36 to 5 μm after 0.5 h of milling, but then only slightly, from 5 to 2 μm, with further milling from 0.5 to 96 h, due to the concurrent actions of fragmentation and/or agglomeration. The reason for the stabilization of Pb by ball milling was probably that Pb was sealed in the milled fly ash during the fragmentation and agglomeration of particles.

Preparation, characterization, and thermal properties of microPCMs containing n-dodecanol by using different types of styrene-maleic anhydride as emulsifier

Microcapsules containing polar phase change material (PCM) n-dodecanol were synthesized by in situ polymerization using melamine-formaldehyde resin as shell and styrene-maleic anhydride copolymer (SMA) as emulsifier. The effects of polarity of PCM and types and amounts of SMA emulsifier on the properties of microencapsulated PCMs (microPCMs) were studied and characterized by using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and laser particle diameter analyzer. The results show that thermal properties of microPCMs are affected greatly by the types and amounts of SMA. Anionic SMA emulsifier is suitable for the encapsulation of n-dodecanol. The polarity of PCM leads to the higher adding amount of SMA emulsifier. When mass ratio of emulsifier to n-dodecanol is 4.8%, the phase change latent heat and encapsulation efficiency reach to the maximum value of 187.5 J/g and 93.1%, respectively. Irregular spherical microPCMs with mean diameter of 30.6 μm and phase change temperature of 21.5 °C are obtained and can be used for energy storage.

Preparation of CuInSe 2 thin films by paste coating

Precursor pastes were obtained by milling Cu-In alloys and Se powders. CuInSe 2 thin films were successfully prepared by precursor layers, which were coated using these pastes, and were annealed in a H 2 atmosphere. The pastes were tested by laser particle diameter analyzer, simultaneous thermogravimetric and differential thermal analysis instruments (TG-DTA), and X-ray diffractometry (XRD). Selenized films were characterized by XRD, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results indicate that chalcopyrite CuInSe 2 is formed at 180°C and the crystallinity of this phase is improved as the temperature rises. All the CuInSe 2 thin films, which were annealed at various temperatures, exhibit the preferred orientation along the (112) plane. The compression of precursor layers before selenization step is one of the most essential factors for the preparation of perfect CuInSe 2 thin films.

The Effect of Water Droplet Size of Water Spray on Liquid Pool and Fire Suppression

The fine water droplet size spray is recognized as a perfect, fire suppression media for most fire accidents. Due to the undissolvable property with water for common use petrochemical substances, such as methanol, diesel and heptane, the water droplet size may severely influence the liquid fire extinguished effect with water spray. Therefore, an appropriate water droplet size range shall be understood for better fire extinguished effect design. An. experimental, program was investigated using laser particle diameter analyzer (PDA) to examine the test water droplet size under six different water supply pressures. A single water spray head was installed under the ceiling at a constant distance. The experimental results show that a water droplet size less than 700 micro-m may provide a better liquid pool fire extinguished effect for one liter liquid under a constant water flow rate test condition. However, it should be noted that the results are limited to the experimental, conditions.