Characterization of recycled styrene butadiene rubber ground tire rubber: Combining X‐ray fluorescence,differential scanning calorimetry,and dynamical thermal analysis for quality control

Appraisal of the main rubber characterization techniques for styrene butadiene rubber (SBR) was performed on standard SBR samples as well as recycled ground tire rubber (GTR) from an industrial tire recycling facility, containing a blend of SBR and natural rubber. The aim of the work was to provide additional information relevant to quality control in the field of rubber recycling. Benchmark characterization of industrial samples by inductively coupled plasma optical emission spectrometry, atomic absorption spectrometry, solid‐state proton nuclear magnetic resonance, and elemental (CHNS) analysis are reported. X‐ray fluorescence spectrometry is shown to be rapid and quantitative for determining the zinc content in an industrial context. Thermogravimetric analysis, already used to determine carbon black and inorganic material content in rubbers and GTR, is recommended for determination of monomer weight ratios of SBR sources not containing other rubbers, but not for GTR. Differential scanning calorimetry (DSC) measurements of the glass‐transition show that changes in monomer ratio affect glass‐transition temperature values, and therefore, DSC can be used to detect changes in rubber composition from batch to batch. These results show that DSC and X‐ray fluorescence spectroscopy characterization techniques can be used for GTR and may lead to more thorough and rapid quality control procedures of these complex samples. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42692.     

Synthesis,characterization, and performance evaluation of the AM/AMPS/DMDAAC/SSS quadripolymer as a fluid loss additive for water‐based drilling fluid

According to the molecular structure design requirements of the fluid loss additive resistant to high temperature, 2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS), acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC) and sodium styrene sulfonate (SSS) are selected as the structure monomers. Using ammonium persulfate as initiator, a new quadripolymer is synthesized through free radical aqueous solution polymerization. According to the minimum filtration loss of the fresh water‐based drilling fluid with 0.5 wt % quadripolymer, The synthesis conditions are optimized by orthogonal test: the mole ratio of AMPS/AM/DMDAAC/SSS is 5/7/2/1, the monomer concentration is 30 wt %, the initiator concentration is 0.8 wt %, the reaction temperature is 75°C and the pH is 10. The structure of the quadripolymer is characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The results show that the quadripolymer contains all the designed functional groups. The thermal stability of the quadripolymer is tested by thermogravimetry, differential thermogravimetry, and differential scanning calorimetry. The results show that the thermal degradation of the quadripolymer is not obvious before 272.3°C. The rheological performance and filtration loss of the quadripolymer are evaluated. The results indicate that the filtration loss decreases with the increasing dosage of the quadripolymer before and after thermal aging test at 180°C for 16 h, and the filtration loss before the thermal aging test is smaller than that after the thermal aging test. The high temperature high pressure filtration loss (FL_(HTHP)) experiment results also show that the quadripolymer fluid loss additive has excellent temperature‐resistant performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41762.     

Effect of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide on liquid oxygen compatibility of bisphenol a epoxy resin

In this study, bisphenol A epoxy resin (DGEBA) was chemically modified by 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and the molecular structure of the modified epoxy resin was characterized by Fourier transform infrared spectra. The effects of DOPO on liquid oxygen compatibility of DGEBA were calculated using mechanical impact method. The results indicated that epoxy resin (EP‐P1)/4,4‐diaminobisphenol sulfone (DDS) was compatible with liquid oxygen. When compared with EP/DDS, differential scanning calorimetry and thermogravimetry analyses showed that EP‐P1/DDS and EP‐P2/DDS had much higher glass transition temperatures and char yield. X‐ray photoelectron spectroscopic analysis suggested that phosphorus atoms on the surface of EP‐P1/DDS and EP‐P2/DDS could act in the solid phase to restrain the incompatible reaction, which was in accordance with the flame‐retardant mechanism of phosphorus‐containing compounds. The compatibility mechanism of EP‐P1/DDS was further proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40848.     

Microstructure and melting behavior of a solution‐cast polylactide stereocomplex: Effect of annealing

The effect of annealing on the microstructure and melting behavior of a solution‐cast polylactide (PLA) stereocomplex (sc) was systematically investigated by differential scanning calorimetry and small‐angle X‐ray scattering. A preorder state, an intermediate form between the amorphous and crystalline states, was found in the solution‐cast poly(l ‐lactide)–poly(d ‐lactide) blend. When the annealing temperature (T_a) was below 220 °C, a part of the preorder state directly formed thicker sc crystallites; these corresponded to the second melting peak, which appeared around 250 °C during the heating process. Although the rest melted and became the amorphous phase, it formed a thinner lamella under the restriction of the unmelted initial sc crystallites during annealing; the melting process of this lamella was parallel to that of the new melting peak, which appeared around 220 °C. The melting of the initial crystal formed as the solvent volatilized corresponded to the range of the first melting temperature around 230 °C. When T_a was above 220 °C, the preorder state melted completely, and the initial crystal experienced perfection process. Furthermore, the highest melting temperature of PLA sc (254.1 °C, with a fusion enthalpy of 125.5 J/g) was obtained when T_a was 235 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44626.     

Changes in the melting temperature and crystal structure of poly(vinylidene fluoride) by knotting

A significant increase in the melting temperature of knotted fibers of poly(vinylidene fluoride) (PVDF) was detected by differential scanning calorimetry. The melting peak partially returned to the original peak after the fibers were unknotted. Knotted PVDF fibers were observed with an optical microscope at crossed‐nicol conditions. The knotted portions of the fibers showed birefringence even above the melting temperature of the fibers before knotting. The dependence of the physical properties of PVDF under applied stress was estimated in order to investigate the influence of knotting. The fracture temperature of PVDF fibers increased with applied stress below 1 MPa and decreased above 10 MPa because the applied stress increased the melting temperature of PVDF crystals, but strong stress mechanically broke the fibers. The X‐ray diffraction patterns of the PVDF fibers under different stress were divided into the peaks of α‐ and β‐phase crystals and amorphous. The peak area of the β‐phase crystal increased and that of the amorphous decreased with applied stress. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of low molecular weight silk fibroin by high‐temperature and high‐pressure method

A low molecular weight silk fibroin powder (LMSF) was prepared through high temperature (200°C) and high pressure (20 kgf/cm²), without any addition of chemicals. The carbonized adducts produced during this process were then removed by treatment with activated charcoal. The yield of LMSF by this preparation method was over 60% after the removal of carbonized adducts by using activated charcoal. Amino acid analysis showed an observable decrease in contents of serine and tyrosine in LMSF prepared by this method, as compared to those prepared by neutral salt. The molecular weight of this LMSF was also observably decreased with an increase in the reaction time. From the measurements of differential scanning calorimeter (DSC) and thermal gravimetric analyzer (TGA), thermal properties of LMSF through high temperature and high pressure were also decreased as compared to those produced by neutral salts. In addition, wide‐angle X‐ray diffraction (WAXD) patterns showed that the crystallinity of LMSF differed from that of the original silk fibroin. It can be said that the preparation method of LMSF in this study is a simple, economical, and environmentally compatible process with many advantages. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2890–2895, 2002     

Improving collagen extraction through an alternative strategy based on succinic anhydride pretreatment to retain collagen's triple‐helix structure

The improvement of the extraction yield of collagen while retaining its triple‐helix structure continues to represent a significant challenge for the high‐value utilization of collagen. In this study, pigskin was pretreated by succinic anhydride via the chemical linking of additional carboxylic groups to epsilon amino groups with a conversion degree of 90.2% to obtain pretreatment acid‐pepsin‐solubilized collagen (PAPC). The pretreatment by succinic anhydride increased the tropocollagen distance from 1.39 to 1.42 nm. This permitted acid and pepsin to more easily enter into the fiber clearance and, thus, improved the collagen extraction yield by 9.6%. Furthermore, X‐ray diffraction, Fourier transform infrared spectroscopy, circular dichroism, ultrasensitive differential scanning calorimetry, and atomic force microscopy analysis demonstrated that the triple‐helix conformation of PAPC was well‐maintained. The equilibrium surface tension and isoelectric point of PAPC were 57.48 mN/m and 4.01, respectively; this suggested that the PAPC had surface activity and better solubility in a neutral pH solution. The novelty of PAPC lay in its facilitating fibroblast proliferation, and no extra cytotoxicity was introduced into the collagen after pretreatment. According to these results, our study revealed that succinic anhydride pretreatment as an alternative strategy retained the triple‐helix structure of collagen and improved its extraction ratio; this might be a feasible, yet promising paradigm for the high‐value utilization of collagen. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45424.     

Thermal behavior of acrylonitrile carboxylic acid copolymers

Polyacrylonitrile (PAN) and copolymer of acrylonitrile–vinyl acids prepared by solution polymerization technique have been characterized by Differential Scanning Calorimetry (DSC) (under dynamic as well as isothermal conditions), themograviemetric analysis (TGA), and on‐line DSC‐FTIR spectroscopy. The DSC of copolymers was carried out at 5°C/min in nitrogen and air. In nitrogen atmosphere the DSC exotherm show a very sharp peak, whereas, in air atmosphere DSC exotherm is broad, and starts at a much lower temperature compared to what is observed in nitrogen atmosphere. The initiation temperature of PAN homopolymer is higher than that for the copolymers. For instance, the initiation temperature of PAN in air is 244°C, whereas, the onset of exothermic reaction is in the range of 172 to 218°C for acrylonitrile–vinyl acid copolymers. As the vinyl acid content increases the ΔH value reduces. The ΔH value of PAN in air was 7025 J/g, whereas, for P(AN‐AA) with 5.51 mol % of acid it was 3798 J/g. As the content of acrylic acid comonomer is increased to 17.51 mol % the value of ΔH decreases further to 1636 J/g. The same trend was observed with MAA and IA as well. DSC‐FTIR studies depict various chemical changes taking place during heat treatment of these copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 685–698, 2003     

Investigation of the crystalline phase morphology of a β‐nucleated impact polypropylene copolymer

This study covers the preparation and the characterization of β‐nucleated impact polypropylene copolymer (NA‐IPC). Calcium stearate (CaSt), as well as pimelic (Pim) and adipic (Adi) acids, were doped into IPC as mono‐ or bicomponent nucleating agents (NAs) at varying mass ratios. Possible chemical interactions between the NAs and with IPC, as well as the effect of the NAs on the crystallization behavior and nonisothermal crystallization kinetics, were investigated. DSC and XRD results revealed that IPC nucleated with Pim and Pim‐CaSt nucleants induced up to 90% β‐crystals, whereas Adi and Adi‐CaSt formed only about 17% β‐crystals. This was associated with the strong nucleation efficiency of Pim. The nonisothermal crystallization kinetics showed that the crystallization of IPC and NA‐IPC followed a three‐dimensional growth with athermal nucleation mechanism. FTIR showed that none of the NAs chemically reacted with IPC, and the chemical structure of the polymer was thus intact during the treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39923.     

Influence of various reaction media on the thermal and rheological properties of poly(acrylamide‐co‐N‐hexadecylacrylamide)

A hydrophobically modified polyacrylamide (PAM) was synthesized by the copolymerization of acrylamide (Am) and N‐hexadecylacrylamide (hAm) through solution copolymerization in a polar organic solvent. Polymer synthesis was performed in three nonaqueous media, including dimethyl sulfoxide (DMSO), a mixture of DMSO and an anionic surfactant such as sodium dodecyl sulfate, and a mixture of DMSO and an acidic surfactant such as dodecyl benzene sulfonic acid. The obtained copolymer, poly(acrylamide‐co‐N‐hexadecylacrylamide) [poly(Am‐co‐hAm)], was characterized by ¹H‐NMR. The physical properties of poly(Am‐co‐hAm)s synthesized in different media were compared with those of PAM and with each other by viscosity measurement, X‐ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. We investigated the ways in which the polymerization medium affected the hydrophobic distribution within the resulting copolymer structure. This aspect, in turn, should have altered the solution properties and the microstructure of the copolymer. For this purpose, we studied the viscometric behavior in diluted solutions, the thermal behavior and thermal stability of the copolymers, and finally, the crystalline structure of the copolymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39939.     

Preparation of small particle diameter thermally expandable microspheres under atmospheric pressure for potential utilization in wood

Small particle diameter thermally expandable microspheres (TEMs) were obtained for potential utilization in wood, with special attention on their particle diameters and expansion properties. The revolving speed of homogenization (RS) of 800 ~ 3000 r min⁻¹ was applied in suspension polymerization under atmospheric pressure to prepare TEMs, with n-hexane as core material and the copolymer of acrylonitrile, methyl acrylate, and vinyl acetate as shell. (a) The effect of the RS on the particle diameters of TEMs presented a negative correlation at low RS and remained stable at high RS, (b) When the RS was 1900 ~ 2100 r min⁻¹, the optimized TEMs with average particle diameters of 3.82 ~ 4.06 μm were prepared, possessing expansion ratios of 3.4 ~ 4.3 and an expansion temperature of 112°C, (c)The optimized TEMs had core-shell structure and high encapsulated content of alkane, and (d) The TEMs with small particle diameters could be impregnated into wood and expand successfully in wood cell lumens.     

Investigation on curing reaction of phthalonitrile resin with nanosilica and the properties of their glass fiber-reinforced composites

In this work, Phthalonitrile containing benzoxazine (BA-ph) and Bisphenol A based cyanate ester (CE) were chosen as the matrix resin. Various amount of nano-SiO₂ was incorporated into BA-ph/CE and their glass fiber-reinforced composite laminates were fabricated. Curing reaction and processability of BA-ph/CE/SiO₂ blends were studied by differential scanning calorimetry and dynamic rheological analysis. Results showed that BA-ph and CE exhibited good processability and curing reaction of BA-ph/CE was not obviously affected by SiO₂. Scanning electron microscope images of the composites showed that SiO₂ particles were well dispersed in BA-ph/CE matrix. Moreover, SiO₂ could act as physical crosslinking points and diluent in matrix as well as between the glass fibers to improve the mechanical properties of composite laminates. As the results of dynamic mechanical analysis and thermogravimetry analysis, composite laminates possessed satisfactory T_g and good thermal stability. With incorporation SiO₂ particles into matrix resin, dielectric constant and dielectric loss of BA-ph/CE/SiO₂/GF composites were increased and showed frequency dependence.     

Synthesis and characterization of well‐defined random and block copolymers of ε‐caprolactone with l‐lactide as an additive for toughening polylactide: Influence of the molecular architecture

Well‐defined multiarmed star random and block copolymers of ε‐caprolactone with l ‐lactide with controlled molecular weights, low polydispersities, and precise numbers of arms were synthesized by the ring‐opening polymerization of respective cyclic ester monomers. The polymers were characterized by ¹H‐NMR and ¹³C‐NMR to determine their chemical composition, molecular structure, degree of randomness, and proof of block copolymer formation. Gel permeation chromatography was used to establish the degree of branching. Star‐branched random copolymers exhibited lower glass‐transition temperatures (T_g's) compared to a linear random copolymer. When the star random copolymers were melt‐blended with poly(l ‐lactic acid) (PLA), we observed that the elongation of the blend increased with the number of arms of the copolymer. Six‐armed block copolymers, which exhibited higher T_g's, caused the maximum improvement in elongation. In all cases, improvements in the elongation were achieved with no loss of stiffness in the PLA blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43267.     

Comparison of the pomegranate seed oil organogels of carnauba wax and monoglyceride

The aims of this study were to prepare organogels from pomegranate seed oil (PO) with carnauba wax (CW) and monoglyceride (MG), compare the organogels with a commercial margarine (CM) and evaluate 3 months storage stability. At 3% organogelator addition, no gels were formed, while at 7 and 10% additions, the oil binding capacities increased and were always higher in CW organogels, with crystal formation times of 8.0 to 14.0 min. Solid fat content (SFC) of the CW organogels varied between 2.96 and 8.71% at 20°C, while MG gels had 2.89–9.43%, and CM had 29.73% SFC. The peak melting temperatures of the CW organogels ranged from 74.73 to 75.74°C and MG organogels ranged from 11.09 to 50.63°C, whereas CM product exhibited 45.92°C peak melting temperature. The hardness of CW organogels was higher than that of MG organogels. The organogels showed potential as spreadable products. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41343.     

Characterization of biodegradable polymers by inverse gas chromatography. II. Blends of amylopectin and poly(ε‐caprolactone)

Amylopectin (AP), a potato‐starch‐based polymer with a molecular weight of 6,000,000 g/mol, was blended with poly(ε‐caprolactone) (PCL) and characterized with inverse gas chromatography (IGC), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). Five different compositions of AP–PCL blends ranging from 0 to 100% AP were studied over a wide range of temperatures (80–260°C). Nineteen solutes (solvents) were injected onto five chromatographic columns containing the AP–PCL blends. These solutes probed the dispersive, dipole–dipole, and hydrogen‐bonding interactions, acid–base characteristics, wettability, and water uptake of the AP–PCL blends. Retention diagrams of these solutes in a temperature range of 80–260°C revealed two zones: crystalline and amorphous. The glass‐transition temperature (T_g) and melting temperature (T_m) of the blends were measured with these zones. The two zones were used to calculate the degree of crystallinity of pure AP and its blends below T_m, which ranged from 85% at 104°C to 0% at T_m. IGC complemented the DSC method for obtaining the T_g and T_m values of the pure AP and AP–PCL blends. These values were unexpectedly elevated for the blends over that of pure AP and ranged from 105 to 152°C for T_g and from 166 to 210°C for T_m. The T_m values agreed well with the XRD analysis data. This elevation in the T_g and T_m values may have been due to the change in the heat capacity at T_g and the dependence of T_g on various variables, including the molecular weight and the blend composition. Polymer blend/solvent interaction parameters were measured with a variety of solutes over a wide range of temperatures and determined the solubility of the blends in the solutes. We were also able to determine the blend compatibility over a wide range of temperatures and weight fractions. The polymer–polymer interaction coefficient and interaction energy parameter agreed well on the partial miscibility of the two polymers. The dispersive component of the surface energy of the AP–PCL blends was measured with alkanes and ranged from 16.09 mJ/m² for pure AP to 38.26 mJ/m² when AP was mixed with PCL in a 50/50% ratio. This revealed an increase in the surface energy of AP when PCL was added. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3076–3089, 2006     

Structural properties of CrF3‐ and MnCl2‐filled poly(vinyl alcohol) films

Poly(vinyl alcohol) (PVA) films filled with different amounts of CrF₃ and MnCl₂ were prepared by the casting method. Differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) analysis were used to study the changes in the structure properties that occurred because of filling. The changes occurring in the measured parameters with increasing filler contents were interpreted in terms of the structural modification of the PVA matrix. All the studied samples had a main melting temperature due to the main crystalline phase of PVA. The intensity and position of this peak depended on the filling level. However, the samples of CrF₃‐filled PVA films with a filling level greater than or equal to 10 wt % revealed another melting temperature, which indicated the presence of a new crystalline phase in addition to the main crystalline phase. The changes that occurred in the degree of crystallinity of the studied samples were examined. The calculated degree of crystallinity was formulated numerically to be an exponential function of the filling level. The XRD patterns of the studied samples confirmed the DSC results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1115–1120, 2003     

Preparation and characterization of thermoresponsive poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) hydrogel materials for smart windows

In this study, a series of thermoresponsive cross-linked copolymer poly [N-isopropylacrylamide(NIPAm)-co-N-isopropylmethacrylamide(NIPMAm)] (P-M series samples: P-M-0, 10, 20, 30, 40, where numbers are co-monomer contents) hydrogels were prepared by free radical polymerization using the main monomer N-isopropylacrylamide (NIPAm), co-monomer N-isopropylmethacrylamide (NIPMAm), cross-linking agent N, N-methylenebisacrylamide, initiator (ammonium persulfate)/catalyst, and solvent water. In addition, a series of samples [P-G series samples: P-G-0, 10, 20, 30, 40, where numbers are co-solvent glycerol content) were prepared using P-M-40 as components and water/co-solvent glycerol as a mixed solvent. The effects of co-monomer NIPMAm and co-solvent glycerol contents on the lower critical solution temperature (LCST)/freezing temperature and light transmittance as function of temperature of the prepared copolymer gels were investigated. The resulting thermoresponsive polymer gels had LCSTs in the range of 17.9 to 38.7°C and freezing points in the range of 6.3 to −38.5°C. These gels are suitable materials for smart windows that are responsive to various environmental conditions.     

Effect of neutron irradiation on the structural,mechanical, and thermal properties of jute fiber

This article describes the effect of neutron irradiation on jute fiber (Corchorus olitorius). The jute fibers (4.0 tex) were irradiated by fast neutrons with an energy of 4.44 MeV at different fluences ranging from 2 × 10⁹ to 2 × 10¹³ n/cm². An important aspect of neutron irradiation is that the fast neutrons can produce dense ionization at deep levels in the materials. Structural analysis of the raw and irradiated fibers were studied by small‐angle X‐ray scattering (SAXS), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. Thermal analysis carried out on the raw and irradiated fibers showed that the thermal stability of the fibers decreased after irradiation. The mechanical properties of the jute fibers were found to decrease after irradiation. The SAXS study showed that the average periodicity transverse to the layer decreased after irradiation, which may have been due to the shrinkage of cellulosic particles constituting the fiber. The residual compressive stress developed in the fiber after irradiation resulted in a decrease in crystallite size as supported by our XRD analysis. Observation with SEM did not indicate any change produced in the surface morphology of the fiber due to irradiation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Studies of thermal,mechanical properties,and kinetic cure reaction of carboxyl-terminated polybutadiene acrylonitrile liquid rubber with diepoxy octane

Epoxy resins, despite their unique properties, have limitations in many applications due to their low fracture toughness. One of the most effective methods to overcome this limitation is to use toughening agents, such as carboxyl terminated poly butadiene-acrylonitrile (CTBN) in the epoxy matrix. CTBN can react with various compounds, such as epoxies. In this study, we investigated the severity of CTBN sedimentation with di epoxy octane (DEO) in the presence basis catalysts. The studied of the physical properties of the synthesized copolymer in the presence of pyridine compared to other catalysts increases mechanical properties (248.43% elongation, 0.63 MPa strength, and 32 hardness with Shore A) and decreases the glass transition temperature (−45.1) of the copolymer. Investigated the cure kinetics of the CTBN-DEO reaction was in the presence of pyridine using a nonisothermal technique of differential scanning calorimetry, and the curing kinetic parameters, such as activation energy (E_a), pre-exponential factor (A), and rate constant (k), were calculated by different kinetic methods. The obtained curing kinetic values with different kinetic methods are well-matched, the E_a values are in the range of 91.3–97.1 kJ.mol⁻¹ and the A values are in the range of 0.48 × 10¹¹–1.51 × 10¹¹ S⁻¹.     

Synthesis and characterization of microencapsulated sodium phosphate dodecahydrate

Microcapsules loaded with sodium phosphate dodecahydrate (DSP) were prepared according to the solvent evaporation method. The microencapsulated phase‐change materials (MEPCMs) possessed methyl methacrylate crosslinked with ethyl acrylate generated poly(methyl methacrylate) (PMMA) as the coating polymer. The influences of the polymerization time, polymerization temperature, and organic solvent types on the performances of the MEPCMs were studied in this report. The results indicate that the polymerization time and temperature had barely any effect on the size but a significant effect on the surface morphology of the microphase‐change materials. The solubility of the shell material varied in different organic solvents, and this to different phase‐transition enthalpies. In addition, DSP could be encapsulated well by PMMA, and the as‐prepared MEPCMs were equipped with a good morphology and a small particle size. When toluene and acetone were used as organic solvents, the MEPCMs had an interesting energy storage capacity of 142.9 J/g at 51.51°C, and this made them suitable for different applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1516–1523, 2013