Structure–property relationship of all-cellulose composites

Novel all-cellulose composite films were prepared by partly dissolving microcrystalline cellulose (MCC) powder in an 8% LiCl/DMAc solution. Cellulose solutions were precipitated and the resulting gels dried in a vacuum bag to produce films approximately 0.2–0.3 mm thick. X-ray diffraction (XRD) was used to characterise lateral crystal size and transmission electron microscopy (TEM) was employed to assess the morphology of the composites. During dissolution, the fibrous fragments of MCC were split into thinner cellulose fibrils and crystals were progressively broken down into thinner crystals. The composites were tested in tension and fracture surfaces were inspected by scanning electron microscopy (SEM). It was found that the mechanical properties and final morphology of all-cellulose composites was controlled by the rate of precipitation, initial cellulose concentration and dissolution time. The precipitation conditions were found to play a large role in the optimisation of the mechanical properties by limiting the amount of defects that were induced by differential shrinkage. All-cellulose composites were produced with a tensile strength up to 106 MPa and a tensile modulus up to 7.6 GPa.     

Compressive properties of a new metal–polymer hybrid material

Compressive properties of a new hybrid material, fabricated through filling of an aluminum foam with a thermoplastic polymer, are investigated. Static (0.01 s⁻¹) and dynamic (100 s⁻¹) compression testing has been carried out to study the behavior of the hybrid material in comparison with its parent foam and polymer materials. Considering the behavior of metal foams, the point on a compressive stress–strain curve corresponding to the minimum cushion factor is defined as the “densification” point. The analysis of the stress–strain curves provides insight into the load carrying and energy absorption characteristics of the hybrid material. At both strain rates, the hybrid is found to carry higher stresses and absorb more energy at “densification” than the foam or polymer.     

Structure and orientation relationship of new precipitates in a Cu–Cr–Zr alloy

The crystallography and morphology of the nano-sized precipitate particles in a ternary Cu–Cr–Zr alloy were studied by transmission electron microscopy. A new type of face-centred-cubic (f.c.c) Cr-rich precipitate was observed. This precipitate is ordered and solute enriched on alternate {110} f.c.c planes, with an ellipsoid-shaped morphology. The new orientation relationship (OR) between the precipitate and Cu matrix satisfies [211]M//[011]p and [100]M//[111]p, {-111}M//{200}p and {02-2}M//{02-2}p. The difference between this new OR and the Nishiyama–Wasserman OR between body-centred-cubic (b.c.c) Cr and the Cu matrix can be detailed by Δg vectors in the diffraction patterns. Furthermore, the precipitation strengthening effect is increased greatly with the formation of these new precipitate particles when compared to binary Cu–Cr alloys.     

Mechanical property–porosity relationships of layered calcium silicate hydrate phases

Dynamic mechanical analysis measurements were made on the following calcium-silicate- hydrate systems: 1.4 nm tobermorite (T), jennite (J), synthetic C–S–H (C/S = 0.80, 1.20 and 1.50) and cement paste. The age of the cement paste varied from 3 days to 45 years. Plots of storage modulus versus porosity were constructed for all these materials. The non-uniqueness of the curves is discussed with reference to Taylor’s analysis of strength-porosity curves and the influence of particle type, density and crystallinity. Additional insights regarding the practical application of T–J and T–CH nanostructural models for the C–S–H nanostructure in hydrated cements is provided.     

Structure factors of modified liquid Al–Si alloys

The structure factor and the coordination numbers of liquid Al–Si alloys with different Si content have been measured by a high temperature X-ray diffractometer. Radial distribution functions (RDFs), the nearest atomic distance and the coordination numbers of eutectic Al–Si alloys before and after being modified with Sr and Sb were studied. The RDFs of the liquid alloy were decomposed by five Gaussian peaks. The results show that a Si–Si covalent bond exists in the liquid of eutectic and hyper-eutectic alloys. Sr in the liquid Al–Si has a capability to weaken the covalent bonds of Si–Si, suppressing the nucleation of the eutectic silicon phase. On the other hand, Sb in the liquid Al–Si increases the order degree of Si atoms, decreasing the supercooling degree of the nucleation and promoting the nucleation of eutectic silicon.     

Structure factors of modified liquid Al–Si alloys

The structure factor and the coordination numbers of liquid Al–Si alloys with different Si content have been measured by a high temperature X-ray diffractometer. Radial distribution functions (RDFs), the nearest atomic distance and the coordination numbers of eutectic Al–Si alloys before and after being modified with Sr and Sb were studied. The RDFs of the liquid alloy were decomposed by five Gaussian peaks. The results show that a Si–Si covalent bond exists in the liquid of eutectic and hyper-eutectic alloys. Sr in the liquid Al–Si has a capability to weaken the covalent bonds of Si–Si, suppressing the nucleation of the eutectic silicon phase. On the other hand, Sb in the liquid Al–Si increases the order degree of Si atoms, decreasing the supercooling degree of the nucleation and promoting the nucleation of eutectic silicon.     

Isothermal aging–microstructure–property relationship of SmCo 2:17 magnets

Abstract

The isothermal aging–microstructure–magnetic property relationship of a SmCo 2:17 alloy was investigated in the present study. The alloy also contained Fe, Cu and Zr as major addition. Its magnetic properties, including intrinsic coecivity H _ci, remanence B _r and maximum energy product (BH)_max, were obtained from the measured second quadrant M–H hysteresis curves. The microstructure of the alloy was characterised using X-ray diffraction (XRD) and TEM. It was found that, as the one step aging temperature was increased from 850 to 900°C, the remanence of the SmCo 2:17 alloy magnet was increased while its coercivity was reduced. The maximum energy product (HB)_max of the magnet was significantly improved by applying a two step aging, consisting of aging first at 900°C followed by aging at 850°C. Based on XRD and TEM analyses, effects of the aging condition on the microstructure and magnetic properties were discussed. The microstructural change observed in the current work included cell size of the cellular structure and the degree of Cu segregation at the cell boundaries. Change in the degree of Cu segregation at the cell boundaries might be the major cause for the change in coercivity of the alloy aged in different aging conditions. The effect of aging condition on the remanence could be attributed to the effect of aging condition on cell size of the cellular structure, which affects the volume fraction of SmCo 2:17 phase in the alloy.     

V2O5–polyimide hybrid material: synthesis,characterization, and sulfur removal properties in fuels

We describe the synthesis of a new sorbent material for desulfurization of gasoline, which is composed of polyimide (PI) and vanadium pentoxide via the solution direct-dispersing method. The highly porous PI–V₂O₅ hybrid materials, containing different concentrations of V₂O₅ ranging from 1 to 10 wt%, were prepared from pyromellitic dianhydride, 2,4,6-triaminopyrimidine, and vanadium pentoxide. The produced PI–V₂O₅ composites were investigated by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscope, and thermal analysis techniques. The effect of V₂O₅ on the sulfur removal properties as well as the thermal stability and porous structure of composites were investigated. Then the obtained material was investigated to determine their sorption characteristics for sulfur compounds from fuels. By use of this material, 91 wt% of the sulfur content was removed from sulfur-containing standard oil. An economic sensitive and simple method for the removal and separation of sulfur in fuel samples, using an PI–V₂O₅ packed mini chromatographic column, was established.     

Synthesis and non linear optical properties of new inorganic–organic hybrid material: 4-Benzylpiperidinium sulfate monohydrate

Single crystals of 4-benzyl-piperidine sulfate monohydrate were grown by slow evaporation method at room temperature. The synthesized compound was characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy, UV–visible and photoluminescence studies. The title compound crystallises at room temperature in the non centrosymmetric space group P2₁2₁2₁.The recorded UV–visible spectrum show good transparency in the visible region and indicates a non-zero value of the first Hyperpolarizability. Photoluminescence spectrum shows a broad and intense band at 440 nm and indicates that the crystal emits blue fluorescence. We also report DFT calculations of the electric dipole moments (μ), Polarizability (α), the static first Hyperpolarizability (β) and HOMO–LUMO analysis of the title compound was theoretically investigated by GAUSSIAN 03 package. The calculated static first Hyperpolarizability is equal to 6.4022 × 10⁻³¹ esu. The results show that 4-benzyl-piperidine sulfate monohydrate crystal might have important non linear optical behavior and can be a potential non linear optical material of interest.     

Structure–electrical resistivity relationship of N-doped multi-walled carbon nanotubes

Nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) were synthesized by means of catalytic chemical vapor deposition technique using acetonitrile as carbon source material and ferrocene as catalyst. The structure of the synthesized N-MWCNT was characterized by means of microscopic (SEM, HRTEM) as well as spectroscopic (FTIR, Raman) techniques. Furthermore, the specific resistivity and the electrochemical properties of N-MWCNT were investigated and compared with those of pristine MWCNT. The results are discussed in terms of structural differences between pristine MWCNT and N-MWCNT.     

Coagulation property of hyaluronic acid–collagen/chitosan complex film

Biomacromolecule has been widely used as biomedical material. Because different biomacromolecules possess different properties, how to exhibit the respective advantages of different components on one type of biomaterial becomes the hot spot in the field of biomaterial studying. This work reported a type of complex film that consisted of hyaluronic acid (HA), type I collagen (Col-I), and chitosan (CS) (HA–Col-I/CS, HCC). Then, a series of experiments were performed, such as inverted microscopic observation, atomic force microscopic (AFM) imaging, flow cytometry (FCM) measurement, MTT assay, and MIC assay. In the present work, we observed the growing condition of 3T3 fibroblasts on the surface of the HCC complex film, visualized the morphological changes of platelets during the coagulation process, and discovered microparticles on the platelet membrane. Moreover, we confirmed the microparticles are the platelet-derived microparticles (PMPs) using the FCM. In addition, the minimal inhibitory concentration (MIC) of HCC against Escherichia coli (E. coli) 8099 was 0.025 mg/ml, against Staphylococcus aureus (S. aureus) ATCC 6538 was 0.1 mg/ml. The results together indicated that the HCC film possessed promising coagulation property, cell compatibility and anti-bacteria property, and the potential in future clinical application such as wound healing and bandage. Yangzhe Wu and Yi Hu contributed equally to this work.     

In vitro release of cisplatin from sol–gel processed organically modified silica xerogels

SiO₂, SiO₂/PEG and SiO₂/PDMS xerogels were examined as polymeric carriers for the controlled release of cisplatin—an antineoplasmic medicine. Drug/carrier systems were prepared by the sol–gel method. The effect of organic substitution of the silica xerogel matrix and drying conditions on the release of cisplatin was evaluated. Based on the presented results of the study it may be stated that sol–gel method is useful for entrapping a cisplatin in the pores of organically modified silica gels and for releasing cisplatin mainly in the way of diffusion from the pores of the lattice under the in vitro conditions. The use of organic impurities in silica gel increased the release of cisplatin from xerogel (from 62% to 97% within 7 days), and thermal treatment of all xerogels with cisplatin at the temperature of 80 °C resulted in the acceleration of the drug release (2 days) and increase of the released drug (89–98%).     

Bioactivity of sol–gel derived organically modified silicates: Part I: In vitro examination

Bioactivity was investigated for several organically modified silicates (Ormosils) prepared through sol–gel processes. Ca(II)-free samples were biocompatible only, but Ca(II)containing samples were bioactive and deposited apatite during immersion in a simulated body fluid. The ease of silanol (Si–OH) group formation on the ormosils was considered a predominant factor controlling the bioactivity, while the effect of dissolved Ca(II) ions to increase the degree of supersaturation in the simulated body fluid is secondary.     

Structure–morphology–mechanical properties relationship of some polypropylene/lignocellulosic composites

Natural lignocellulosic materials have an outstanding potential as thermoplastic reinforcement. Polypropylene composites were prepared using different types of lignocellulosic materials by melt blending of 70 wt% polypropylene (PP) and 30 wt% biomasses. The specimens were firstly evaluated for structural and morphological properties by infrared spectroscopy, X-ray diffraction, scanning electron and polarized optical microscopy. Depending on the biomass type, there were evidenced some particular shifts of the infrared bands and also crystallinity changes. An increase in crystallinity is explained by nucleating agent role of biomass. The morphological changes are directly related to variation in mechanical and rheological properties, an increase in Young modulus, melt viscosity and storage and loss moduli being recorded.     

Phase assemblage study and cytocompatibility property of heat treated potassium magnesium phosphate–silicate ceramics

This article reports the study on a new generation bioactive ceramic, based on MgKPO₄ (Magnesium Potassium Phosphate, abbreviated as MKP) for biomedical applications. A series of heat treatment experiments on the slip cast silica (SiO₂) containing MKP ceramics were carried out at 900, 1,000 and 1,100°C for 4 h in air. The density of the slip cast ceramic increases to 2.5 gm/cm³ upon heat treatment at 900°C. However, no significant change in density is measured upon heat treatment to higher temperature of 1,000 and 1,100°C. On the basis of XRD results, the presence of K₂MgSi₅O₁₂ and dehydrated MgKPO₄ were confirmed and complementary information has also been obtained using FT-IR and Raman spectroscopy. In order to confirm the in vitro cytocompatibility property, the cell culture tests were carried out on selected samples and the results reveal good cell adhesion and spreading of L929 mouse fibroblast cells. MTT assay analysis with L929 cells confirmed non-cytotoxic behavior of MKP containing ceramics and the results are comparable with sintered HAp ceramics. It is expected that the newly developed MKP based materials could be a good substitute for hydroxyapatite (HAp or HA) based bioceramics.     

Synthesis of soluble polyimide/silica–titania core–shell nanoparticle hybrid thin films for anti-reflective coatings

In this study, researchers prepared polyimide/silica–titania core–shell nanoparticle hybrid thin films (PI/SiO₂–TiO₂) from soluble fluorine-containing polyimide, colloidal silica, and titanium butoxide. The soluble polyimide with carboxylic acid end groups (6FDA–6FpDA–4ABA–COOH) could condense with titanium butoxide to provide organic–inorganic bonding, and thus prevent macrophase separation. TGA and DSC analysis showed that the decomposition temperature of hybrid materials increased with an increase in the content of silica–titania nanoparticles within the hybrid films. FTIR spectra indicated that the imidization was complete and the cross-linking Ti–O–Ti network formed. HRTEM and HRSEM images showed that the size of the core–shell nanoparticles were 18–20 nm. The thickness of titania shell on the silica is about 2.5 nm. The n&k and UV–Vis analysis showed that the prepared hybrid films had good optical properties and a high refractive index of 1.735. Researchers applied the prepared PI/SiO₂–TiO₂ hybrid thin films to develop a three layer antireflective (AR) coating on the glass and PMMA substrate. Results showed that the reflectance of the AR coating on the glass and PMMA substrate at 550 nm was 0.356 and 0.495%, respectively. The transparency was greater than 90% for both AR coatings on the glass and PMMA substrates.     

Synthesis of a bi-structured hybrid in a CaO–SiO2-PTMO system and in vitro evaluation on its potential of bone-bonding property

Organically modified silicates incorporated with calcium salts produce novel, bioactive materials, which bond directly to living bone, because after exposure to a physical environment, calcium silicates have a high hydroxyapatite-deposit potential. In this study, transparent, monolithic, bi-structured hybrids were prepared using a sol–gel process for the CaO–SiO₂-PTMO system. To establish the bi-structure, two types of sols were prepared: a polymer-rich sol that had a starting composition of PTMO/TEOS in an 80/20 mass ratio and a ceramic-rich sol that had a starting composition of TEOS/Ca(NO₃)₂ in a 1/0.3 molar ratio. The bi-structured hybrid was synthesized using a gelation process, where the ceramic-rich sol was placed on the polymer-rich wet gel. An interfacial structure with tight binding was established between the two gels that had the potential to form calcium phosphate within a period of 6 h on the bi-structured hybrid. This process led to the successful synthesis of a bi-structured hybrid with a high potential for bone-bonding property, which was also flexible.