Design and Synthesis of Novel Hematite Core-Shell Polymeric Composites

2012 ◽  
Vol 627 ◽  
pp. 869-872
Author(s):  
Hong Wang ◽  
Xue Fei Li ◽  
Ying Wang ◽  
Jiao Ren
Keyword(s):  
Methyl Methacrylate ◽  
Chemical Interaction ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Emulsion Copolymerization ◽  
Design And Synthesis ◽  
Structure Morphology ◽  
Methacrylate Monomer ◽  
Higher Temperature

A novel synthetic method was developed for the preparation of core-shell composites consisting of α-Fe2O3cores with poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) shells via emulsion copolymerization of styrene and methyl methacrylate monomer with surfactant of PVP. The structure, morphology and thermal properties of the composites were been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The results confirmed that there was no chemical interaction between α-Fe2O3and copolymer, and the onset of thermal decomposition for nanocomposites shifted to a higher temperature than that for neat copolymer.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

Synthesis of Spherical LiFePO4/C Composites as Cathode Material of Lithium-Ion Batteries by a Novel Glucose Assisted Hydrothermal Method

2013 ◽  
Vol 787 ◽  
pp. 58-64 ◽  
Author(s):  
Xiang Feng Li ◽  
Zhao Zhang ◽  
Fang Liu ◽  
Shu Ping Zheng
Keyword(s):  
Hydrothermal Method ◽  
Raw Materials ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
High Discharge ◽  
X Ray ◽  
High Discharge Capacity ◽  
Optimal Sample ◽  
Structure Morphology

The LiFePO4/C composites with different morphology are synthesized by a novel glucose assisted hydrothermal method at various glucose concentrations (from 0 to 0.25mol/L) and the insoluble lithium source Li2CO3, (NH4)2Fe (SO4)2·6H2O and (NH4)2HPO4(n (Li):n (Fe):n (P)=1:1:1) are used as raw materials. The structure, morphology, thermal performance and electrochemical properties of the synthesized composites are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetry/differential scanning calorimetry (TG-DSC), galvanostatic charge/discharge tests and cyclic voltammetry (CV). The results show that the LiFePO4/C synthesized with 0.125mol/L glucose has the relatively small particles size (0.1~0.5μm) and the well spherical morphology. The optimal sample exhibits a high discharge capacity of 160.0mAh/g at the first cycle and exhibits a good reversibility and stability in CV tests.

Multiple dielectric anomalies in xBiLaO3–(1 − x)PbTiO3 piezoelectrics

2008 ◽  
Vol 23 (2) ◽  
pp. 565-569 ◽  
Author(s):  
Runrun Duan ◽  
Michael S. Haluska ◽  
Robert F. Speyer
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Excellent Agreement ◽  
Structural Changes ◽  
Dielectric Anomaly ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermally Induced ◽  
X Ray ◽  
Higher Temperature

Compositions of xBiLaO3–(1 − x) PbTiO3 over the range 0 ≤ x ≤ 0.225 were calcined and sintered. The dielectric constant with temperature and differential scanning calorimetry measurements were in excellent agreement with respect to Curie-like tetragonal to cubic transformations starting at 495 °C for pure PbTiO3, shifting to lower temperatures with increasing x. For compositions of x ≥ 0.05, a second higher-temperature (∼600 °C) endotherm, and matching dielectric anomaly, were consistently observed, for which there were no structural changes indicated by hot-stage x-ray diffraction. This transformation was speculated to be based on a thermally induced desegregation of B-site cations.

scholarly journals Preparation and Characterisation of Nobiletin-Loaded Nanostructured Lipid Carriers

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Huang ◽  
Huating Dou ◽  
Houjiu Wu ◽  
Zhigao Sun ◽  
Hua Wang ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Chemical Interaction ◽  
Amorphous State ◽  
Spherical Shape ◽  
Entrapment Efficiency ◽  
Nanostructured Lipid Carriers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Lipid Mixture ◽  
Food Response

The objective of this manuscript was to investigate and optimise the potential of nanostructured lipid carriers (NLCs) as a carrier system for nobiletin (NOB), which was prepared by high-pressure homogenisation method. Additionally, this study was focused on the application of NOB-loaded NLC (NOB-NLC) in functional food. Response surface method with a three-level Box–Behnken design was validated through analysis of variance, and the robustness of the design was confirmed through the correspondence between the values measured in the experiments and the predicted ones. Properties of the prepared NOB-NLC, such as Z-average, polydispersity, entrapment efficiency, zeta potential, morphology, and crystallinity, were investigated. NOB-NLC exhibited a spherical shape with a diameter of 112.27 ± 5.33 nm, zeta potential of −35.1 ± 2.94 mV, a polydispersity index of 0.251 ± 0.058, and an EE of 81.06%  ±  6.02%. Results from X-ray diffraction and differential scanning calorimetry of NOB-NLC reviewed that the NOB crystal might be converted to an amorphous state. Fourier transform infrared spectroscopic analysis demonstrated that chemical interaction was absent between the compound and lipid mixture in NOB-NLC.

Encapsulation of silica nanoparticles by poly(methyl methacrylate-co-styrene) via emulsion polymerization using dimethylaminoethyl methacrylate

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohammad Barari ◽  
Naser Sharifi-Sanjani
Keyword(s):  
Methyl Methacrylate ◽  
Silica Nanoparticles ◽  
Emulsion Polymerization ◽  
Monomer Concentration ◽  
Molar Ratio ◽  
Average Particle ◽  
Scanning Calorimetry ◽  
Potential Measurement ◽  
Emulsion Copolymerization ◽  
Dimethylaminoethyl Methacrylate

AbstractEncapsulation of silica nanoparticles was performed by emulsion copolymerization of methyl methacrylate (MMA) and styrene (St) using dimethylaminoethyl methacrylate (DM) as an auxiliary monomer. The emulsion polymerization was performed in the presence of silica nanoparticles as the seed to obtain encapsulated silica nanoparticles with polymer content and average particle sizes ranged from 35 wt. % to 85 wt. % and 114 to 272 nm respectively. Electrostatic attraction between anionic surface of silica beads and cationic amino groups of DM is the main driving force for the encapsulation of the silica nanoparticles. The influence of MMA, St and DM concentration on the coating of the silica nanoparticles was studied. It was demonstrated that DM has an important role in stabilizing the system. Transmission electron microscopy showed that coreshell structures with silica particles as core were coated with the polymer, of which the amount and morphology were influenced by the total monomer concentration and molar ratio of MMA to St. Zeta potential measurement confirmed the presence of DM on the surface of composite particles. Thermogravimetric analysis showed that the incorporation of silica in polymer matrix results in an enhancement of thermal stability in the encapsulated products. Differential scanning calorimetry studies indicated that the glass transition temperature of encapsulated particles can be either higher or lower than those of the pure terpolymer counterpart, depending on the DM content of the polymer shell. The products were also characterized by FT-IR spectroscopy.

The curing behaviour and thermo-mechanical properties of core–shell rubber-modified epoxy nanocomposites

2018 ◽  
Vol 27 (3) ◽  
pp. 168-175
Author(s):  
Dong Quan ◽  
Alojz Ivankovic
Keyword(s):  
Mechanical Properties ◽  
Abrupt Onset ◽  
Core Shell ◽  
Curing Process ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Reactive Groups ◽  
Higher Temperature ◽  
Physical Changes

This work investigates the effects of core–shell rubber (CSR) nanoparticles on the curing behaviour and thermo-mechanical properties of an epoxy using differential scanning calorimetry and dynamic mechanical thermal analysis approaches. Interaction between CSR nanoparticles and epoxy matrix is detected at a temperature of approximately 97°C in the curing process. This results in an increase in the glass transition temperature ( Tg) of the cured nanocomposites. Given the semi-dynamic curing schedule, the curing process of all the epoxy nanocomposites consists of an abrupt onset stage followed by a slow diffusion-controlled stage. Higher temperature is required to initiate the curing for the epoxy nanocomposites with higher loading of CSR nanoparticles. This is attributed to the physical changes caused by the addition of CSR nanoparticles, such as the increase in the viscosity and the reduction in the density of the reactive groups. The storage modulus of the epoxy decreases in the glassy region but remains constant in the rubbery region due to the incorporation of CSR nanoparticles.

Effect of thermal treatment on the mechanical and viscoelastic response of polypropylenes incorporating a β nucleating agent

2018 ◽  
Vol 51 (6) ◽  
pp. 562-579 ◽  
Author(s):  
K Belkouicem ◽  
A Benarab ◽  
R Krache ◽  
R Benavente ◽  
E Pérez ◽  
...  
Keyword(s):  
Young Modulus ◽  
Nucleating Agent ◽  
Thermal Treatments ◽  
Mechanical Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Good Balance ◽  
X Ray ◽  
Structure Morphology ◽  
Ultimate Properties

The influence of two thermal treatments on the structure, morphology, and ultimate properties exhibited by isotactic polypropylene (iPP), synthesized by conventional Ziegler–Natta iPP (Z-iPP) or metallocene iPP (m-iPP) catalysts, has been investigated in the present work. Novelty of this research consisted in the incorporation of a β nucleating agent in two different contents to the m-iPP. Results attained are compared with those found in the Z-iPP and important differences are observed. Differential scanning calorimetry and X-ray diffraction experiments revealed that coexistence of different crystalline lattices took place depending on the type of iPP: β and α forms were found in the β nucleated Z-iPP specimens, whereas α, β, and γ polymorphs could be developed in the m-iPP with nucleating agent. On the other hand, the iPP glass transition temperature ( Tg) did not exhibit a significant change because of the addition of β nucleant, as deduced from Dynamic Mechanical Thermal Analysis (DMTA) analysis. Moreover, the size and shape of the iPP spherulites was totally changed by the presence of the β agent. This nucleant promoted the formation of smaller spherulites in a greater amount, as demonstrated by optical microscopy. Concerning the mechanical parameters, microhardness, MH, and Young modulus, E, values were in the fast crystallized samples lower than those presented by their slowly cooled counterparts. A good balance in properties was seen for the slowly crystallized m-iPP that incorporated a 5 wt% content in β nucleating agent, this fact being ascribed to the coexistence of the three α, β, and γ polymorphs.

Characterization of Core-Shell Structure Palygorskite Modified by Nano-CaCO3 (PnC) Composite Particles

2013 ◽  
Vol 750-752 ◽  
pp. 348-351
Author(s):  
Di Fang Zhao ◽  
Ming Hua Li ◽  
Jin Song Xie
Keyword(s):  
Thermal Stability ◽  
Shell Structure ◽  
Composite Particles ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Stability Properties ◽  
Structure Morphology ◽  
Palygorskite Clay ◽  
Core Shell Structure

In this work, Core-shell structure palygorskite/nanoCaCO3(PnC) composite particles have been synthesized chemically, employing solution precipitation methods. Crystal structure, morphology and thermal stability properties are investigated by means of X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Thermogravimetric (TG) analysis. The results showed that the PnC particles were almost monodispersed microsphere aspect with the size was about 1-3 μm diameter. The nanocomposite particles exhibit the marked thermal stability properties than the palygorskite clay mineral.

scholarly journals Glass Transition Temperature and Microhardness of Compatible and Incompatible Elastomer/Plastomer Blends

1970 ◽  
Vol 33 (1) ◽  
pp. 15-24 ◽  
Author(s):  
MF Mina ◽  
GH Michler ◽  
FJ Balta Calleja
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Core Shell ◽  
Scanning Calorimetry ◽  
Rubber Toughened ◽  
Shell Particles

Glass transition temperature (Tg) of core-shell particles-toughened poly(methyl- methacrylate) (CSPTPMMA) and natural rubber-toughened PMMA (NRTPMMA), which are basically the PMMA/elastomer blends with different concentrations of elastomer heterogeneously distributed in the samples, was investigated by means of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and microindentation technique (MT). Microhardness (H) of the samples was measured using MT. Core-shell particles (CSP) with a rubbery shell and natural rubber (NR) were used as reinforcing materials for the production of compatible and incompatible blends, respectively. Results reveal a good correlation of the glass transition temperature (Tg) obtained from DSC and DMA, and that deduced from MT.  The H-value of each sample is compared with its Tg-value. Increase of Tg with the increase of H, which is a general behavior of polymers, is not maintained in the both blends investigated. Contrary to expectation, H is shown to decrease with increasing glass transition temperature in case of CSP-toughened compatible blends while it decreases with the decrease of Tg-value only in case of NR-modified incompatible blends for lower NR concentration (<1 wt%) and does not depend on Tg for rubber content higher than 1 wt%.  Keywords: Glass transition temperature, microhardness, rubber-toughened poly(methyl -methacrylate), core-shell particle, differential scanning calorimetry DOI: 10.3329/jbas.v33i1.2946 Journal of Bangladesh Academy of Sciences, Vol. 33, No. 1, 15-24, 2009

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