The influence of 3-glycidyloxypropyl trimethoxysilane on the rheological and in-vitro behavior of injectable composites containing 64S bioactive glass,chitosan, and gelatin

The effect of cross-linker 3-glycidyloxypropyl trimethoxysilane (GPTMS) on the injectability, bioactivity, rheology, washout resistance, and cellular behavior of bio-nano composite pastes containing a sol–gel derived bioactive glass (BG), chitosan (Cn), and gelatin (Gel), were studied. The results indicated that the structural integrity of the samples in the stimulated body fluid (SBF) was improved from 80% to 90% with the increase in the GPTMS content. In addition, the viscosity and injectability of the paste were affected, so that the later changed from 96% to 73% and the former changed from 132 × 10³ to 210 × 10³ Pa.s, with addition of 20 wt% GPTMS. Furthermore, the bioactivity of the pastes was improved with the use of GPTMS. No toxicity was observed in the cellular studies of the GPTMS containing paste after 7 days, and the cells kept their shape and were attached firmly to the paste surface. The results of the present work showed that the use of GPTMS was beneficial in enhancing the properties of injectable paste.     

Synthesis and characterization of a novel freeze‐dried silanated chitosan bone tissue engineering scaffold reinforced with electrospun hydroxyapatite nanofiber

Novel chitosan scaffolds containing different weight ratios of electrospun hydroxyapatite nanofibers (n‐HAs) were fabricated. The fibers possessed diameters in the range 110–170 nm. A fixed concentration of glycidyloxypropyl‐trimethoxysilane (GPTMS) as a crosslinking agent was added to the chitosan solution (CG). The porosity percentage was increased when GPTMS and n‐HAs were added to the chitosan structure. The presence of GPTMS in the chitosan structure caused a decrease in the average pore size. The pores were more irregular in shape than pure chitosan and CG scaffolds when n‐HAs were added. A uniform distribution of n‐HAs was seen for a chitosan‐GPTMS hybrid scaffold containing 25 wt% n‐HAs (CGH25) using energy dispersive X‐ray spectroscopy and mapping. The best values of compressive strength and elastic modulus were achieved for CGH25. The swelling ratio was decreased on adding GPTMS to the chitosan scaffold. Different morphologies of hydroxyapatite deposits on the surface of CG and CGH25 (string‐like versus needle‐like precipitates) were observed after 14 days of soaking in simulated body fluid. For CGH25, the viability of MG‐63 osteoblastic cells improved with respect to CG for up to 72 h of cell culture. These results reveal the potential of the chitosan‐CGH25 scaffold for use in bone tissue engineering. © 2019 Society of Chemical Industry     

The effects on the flexural strength and impact behavior of nanographene ratio of the glass fiber nanocomposite plates

In this study, the flexural strength and the impact behavior of the glass fiber composite plates with the same mesh and layer geometry and the effect of the addition of nanographene (GNP) at various ratios into the matrix were experimentally investigated. The variable examined in the study is the percentage of the nanographene that added in the matrix of glass fiber composite plates. In this study, six types of glass fiber plates were produced; with no nanographene added reference specimen, and with the ratio of 0.15, 0.25, 0.35, 0.45, and 0.70% nanographene added specimens. The effect of nanographene addition to the epoxy matrix on the flexural strength and impact behavior of the specimens was investigated by applying a three‐point bending test and a constant‐energy impact load with the free‐weight test method on the glass fiber plate specimens. The highest flexural strength was observed at the 0.25% nanographene added specimen. Further addition of the nanoparticle caused the flexural strength to decrease. In the free weight drop impact test, the highest acceleration and lowest displacement were found at the 0.25% nanographene added specimen. Adding more nanoparticles adversely affected the impact behavior. The optimum nanographene ratio was determined to be 0.25%. POLYM. ENG. SCI., 59:2082–2091, 2019. © 2019 Society of Plastics Engineers     

Synthesis and performance evaluation of environmentally compliant epoxysilane coatings for aluminum alloy

Organosilane-based waterborne coatings for corrosion protection of aluminum alloy have been developed by sol–gel process. The coating solutions were prepared by hydrolysis and condensation of methyltrimethoxysilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) in the presence of acid catalyst and amino functional organosilanes namely 3-aminopropyltrimethoxysialne (1N), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (2N) as hardeners. Coating materials were characterized using FT-IR, atomic force microscopy (AFM), UV–visible spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The optimum concentration of GPTMS to hardeners (1N and 2N) and the effect of MTMS:GPTMS molar ratios on corrosion resistance of coatings were studied. Corrosion resistance and porosity in coatings were measured by potentiodynamic polarization studies and electrochemical impedance analysis. Furthermore, hydrophobicity of the coatings was evaluated using contact angle measurements. Bend test, impact resistance test and pencil hardness test were carried out to evaluate the hardness and adhesion behavior of coating.

Results show that the coatings are continuous, defect free and well adherent to the substrate. Structural studies confirm the nanometric level of interaction among the coating components. None of the coating materials show the glass transition temperature in the temperature range of 30–700 °C. Coating materials are thermally stable up to 390 °C. EIS and potentiodynamic polarization studies suggest that the optimum concentration of GPTMS:NH are 1:1 and 3:2 (molar ratio) for 1N and 2N harden coatings, respectively. Improvement in corrosion resistance is observed with increasing GPTMS concentration in coatings. The average porosity of coatings is found to be 7.18% and 10.98% for 1N and 2N harden coatings, respectively. Water contact angle of these coatings are found in the range of 59–78 °C.     

Properties of treated calcium copper titanate filled epoxy thin film composites for electronic applications

In this study, calcium copper titanate (CCTO) fillers were treated with 1%, 5%, and 10% of silane‐based coupling agent 3‐glycidoxypropyltrimethoxysilane (GPTMS). The CCTO treated with 10% GPTMS filled epoxy thin film composite exhibits a remarkable improvement (60%) of dielectric constant than untreated CCTO/epoxy thin film composite. Besides that, results treated CCTO/epoxy thin film composite produced using various epoxy resins showed that OP 392 epoxy thin film composite exhibited the highest glass transition temperature and degradation temperature, moderate dielectric constant, slightly lower coefficient of thermal expansion and lowest dielectric loss compared with D.E.R. 332 and Epolam 2015 epoxy thin film composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43313.     

Preparation of chitosan-sodium alginate/bioactive glass composite cartilage scaffolds with high cell activity and bioactivity

Chitosan-sodium alginate/bioactive glass (CSB) composite cartilage scaffold with outstanding in vitro mineralization property and cytocompatibility is synthesized by freeze drying method. The effect of bioactive glass (BG) addition on the microstructure, porosity, swelling/degradation ratio, in vitro mineralization property and cytocompatibility of CSB scaffold is investigated by the characterization techniques of SEM, XRD, FTIR and BET. Results showed that CSB composite cartilage scaffold had a three-dimensional (3D) porous structure, and both porosity and average pore size met the requirements of cartilage tissue repair. Among, the typical CSB-1.0 had the largest overall pore size and lowest compressive modulus (1.083 ± 0.002 MPa). As the amount of BG increased, pore volume and porosity of CSB scaffolds gradually decreased, and the swelling and degradation ratios gradually reduced. After immersing in SBF for 3 d, cauliflower like hydroxyapatite (HA) was formed on CSB surface, indicating that the scaffold had good in vitro mineralization property. Moreover, the introduction of BG into the composite scaffold can improve the relative cell viability of MC3T3-E1 cells, and CSB-1.0 has the strongest ability to promote the proliferation of cells. Therefore, the as-obtained CSB scaffold can be used as a strong candidate for cartilage tissue engineering scaffold to meet clinical needs.     

Influence of amino functionalised POSS additive on the corrosion properties of (3-glycidoxypropyl)trimethoxysilane coatings on AA 2024 alloy

The influence of the addition of a mixture of POSS compounds substituted equally by 3-aminopropyl and isobutyl groups (AP₄IB₄ POSS) on sol-gel coatings prepared from (3-glycidoxypropyl)trimethoxysilane (GPTMS) was evaluated from the point of view of their anticorrosion properties. AP₄IB₄ POSS belong to a group of polyhedral oligomeric silsesquioxanes and their functionalisation with amino groups enables cross-linking with the epoxy groups of GPTMS. Additionally, GPTMS molecules react among themselves through hydrolysis and condensation processes of trimethoxysilane groups when catalysed by 0.1 M KF. The results of the Raman and IR measurements revealed that a molar ratio of GPTMS:H₂O = 1:3 is more beneficial than a molar ratio of 1:1.5 for the preparation of sol-gel coatings. The anticorrosion properties of the mixed GPTMS/POSS coatings deposited on AA 2024 aluminium alloy were tested using potentiodynamic electrochemical measurements and a salt-spray chamber test. It was found that the mixed GPTMS/POSS coatings showed improved corrosion protective properties vs. either pure GPTMS or POSS coatings.     

Mechanical behavior of electrophoretically modified CFRP composites at elevated temperatures: An assessment of the influence of graphene carboxyl bath concentration

The study aims at investigating the mechanical behavior of carbon fiber reinforced polymer (CFRP) composites modified with graphene carboxyl at elevated temperature (ET-110°C) and understanding the effect of electrophoretic deposition bath concentration (0.5 g/L, 1.0 g/L, and 1.5 g/L) on their mechanical behavior at ET. The 1.5 g/L composite has revealed a maximum improvement in energy absorbed before failure of 33.25% at RT and 22.54% at ET for flexural testing and ∼35% at RT for short beam shear testing, over neat CFRP composite. The modified composites have shown an improved flexural strain to failure at both RT and ET, with 1.5 g/L composite exhibiting maximum enhancement of 12.41% at RT and 26.52% at ET over neat composite. However, at ET, modified composites exhibited lower flexural strength and interlaminar shear strength values in comparison to that of neat. Viscoelastic behavior of all composites was studied to understand bath concentration's effect on thermal behavior via dynamic mechanical thermal analysis. Differential scanning calorimetry was employed for governing the glass transition temperature of composites. Fractography of tested samples (both ET and RT) was performed utilizing a scanning electron microscope to determine the prominent failure mode.     

Influence of tragacanth resin on the thermal and mechanical properties of fly ash-cement composites

This study was aimed to search the possibility of usage of the thermal power plants fly ashes, cement and tragacanth composites in concrete or plaster by investigating their thermal insulation characteristics. The fly ash used in the experiments is supplied from Af?in Elbistan Thermal Power Station. Portland cement (KPC 325) with resin is used as binding and 24 specimens are prepared depending on the percentage of fly ash and tragacanth. In all fly ash, tragacanth and binding mixture, the weight percentages of fly ash are taken as 0, 10, 20, 30, 40 and 50%. The amount of the resin in the mixture is 0.5, 1 and 1.5% of the weight of the total cement and fly ash.

24 samples were prepared and tested to find out the effects of resin on thermal and mechanical properties of fly ash and cement composites. Whereas fly ash percentage increased from 0% to 50%, i) thermal conductivity and compressive strength decreased 19.37–28.62% and 7.66–16.55% respectively as the porosities of the samples increased 18.91–28.62% with the effect of artificial pores generated by 1.5% resin other than the pores generated by fly ash. ii) the new produced samples can be used as partition walls, floorings, ceiling concretes, briquettes or bricks and plaster.     

Tragacanth gum-graft-polyacrylonitrile: synthesis,characterization and hydrolysis

A large number of cyanide functional groups were introduced onto the carbohydrate biopolymer tragacanth gum to yield hydrophobic graft copolymer, tragacanth gum-g-polyacrylonitrile. Thus, graft copolymerization of monomer acrylonitrile (AN) was carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. The highest percentage of grafting (543%) and the lowest homopolymer content (10%) were achieved through a systematic optimization of the polymerization variables, including reaction time, temperature, and concentration of CAN, AN and the gum. Evidence of grafting was examined by comparing FTIR spectra. The optimally prepared tragacanth gum-g-polyacrylonitrile copolymer was also characterized thermally and morphologically. It was hydrolyzed in alkaline medium to achieve an in-situ crosslinked hybrid network with ultra high water absorption capacity (swelling in water, 30700%; swelling in saline, 6550%). The swelling characteristic of the semi-synthetic super-absorbent hydrogel was preliminarily investigated. The chemical structure, thermal characteristics and morphology of the hydrogel hybrid product were briefly studied.     

Sugar palm fiber/polyester nanocomposites: Influence of adding nanoclay fillers on thermal,dynamic mechanical,and physical properties

In this research, nanoclay used as filler in sugar palm‐reinforced composites was investigated by the physical, thermal, and dynamic mechanical properties. Various concentrations of nanoclay were used to fabricate composites by using hand lay‐up technique, followed by hot compression molding with naturally woven sugar palm fiber‐reinforced in polyester matrix. Among various weight concentrations such as 1–5% of nanoclay, it was found that 2% nanoclay‐filled composite (NC) demonstrated the best balance of thermomechanical properties and significantly enhanced the composite. DMA demonstrated that 2% nanoclay content resulted in improved viscoelastic behavior and higher glass transition temperature (T_g) of the composites. TGA also showed improvement in properties, whereas 3% nanoclay‐filled composite showed superior onset temperature, and 5% nanoclay‐filled composite exhibited highest remaining residue. The nanoclay filler was very effective to fill the porous structure and maintain the thickness stability. The thickness swelling was reduced with increasing amount of nanoclay in composites. Overall, the addition of nano clay improved thermal and physical properties of sugar palm‐reinforced polyester composite. J. VINYL ADDIT. TECHNOL., 26:236–243, 2020. © 2019 Society of Plastics Engineers     

Porous organosilicone modified gelatin hybrids with controllable and homogeneous in vitro degradation behaviors for potential application as skin regeneration scaffold

This work aims at investigating intensively the effects of organosilicone species and their dosage on the physicochemical and particularly the in vitro degradation properties of gelatin hybrids. We prepared various porous organosilicone modified gelatin hybrids with epoxy‐polydimethylsiloxane (PDMS) and/or glycidoxypropyltrimethoxysilane (GPTMS) and further systematically investigated their degradation behaviors in simulated physiological environments. It was found that the chemical composition, thermal stability, crosslinking degree, mechanical properties and porous structure of the gelatin hybrids could be tuned by adjusting the amount of PDMS and GPTMS. More importantly, degradation rates of the gelatin hybrids were reduced with increasing content of GPTMS, implying that the degradation behaviors could be controlled by tailoring the chemical interaction between the gelatin and organosilicone moieties. In addition, gelatin hybrids modified with both PDMS and GPTMS (PGs‐GE) were demonstrated as a homogeneous hybridization, and their maximum weight losses met the typical healing period of a normal skin wound. Noticeably, the P1G1‐GE hybrid with PDMS to GPTMS molar ratio 1:1 exhibited appropriate weight loss, integrity of pore structure and synchronous dissolution of silicon and protein during the degradation process, indicating a homogeneous degradation behavior. Furthermore, both the original and degraded P1G1‐GE hybrid exhibited favorable cytocompatibility in vitro. The findings will be helpful for further insight into the in vivo degradation of gelatin hybrids, suggesting their potential application as skin regeneration scaffolds. © 2019 Society of Chemical Industry     

Effect of filler treatments on rheological behavior of calcium carbonate and talc‐filled polypropylene hybrid composites

Commercial stearic acid treated calcium carbonate (CaCO₃) was used to make a comparative study on rheological behavior of the CaCO₃ and talc‐filled polypropylene (PP) hybrid composites with nontreated filler. Apparent shear viscosity and extrudate swell were investigated with variation of filler ratio and temperature with 30% by weight total of filler was used in PP composite. The Shimadzu capillary rheometer was used to evaluate shear viscosity and shear rate of the composite. It was found that the shear viscosities decrease with increasing shear rate. The apparent shear viscosity of the composite containing the stearic acid treated is slightly lower than untreated filler. Shear thickening behavior at higher shear rate has also shown by 15/15 treated composites at higher temperature about 220°C and investigation by SEM has proved that filler being densely packed at that condition. Treated composites also exhibit lower swelling ratio value than untreated composite, and swelling ratio also decreases linearly with increasing temperature and the die length–diameter ratio. It is believed that dispersion of filler play an important role not only on shear viscosity but also on swelling ratio of PP composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5421–5426, 2006     

Effect of swelling on the cholesteric structure of ethyl‐cyanoethyl cellulose/crosslinked poly(acrylic acid) composite films

The swelling behavior of ethyl‐cyanoethyl cellulose [(E‐CE)C]/crosslinked poly(acrylic acid) [PAA] cholesteric liquid crystalline composite films and the structural variation of the cholesteric phase during the swelling and the drying process were studied. It was found that the wavelength of the selective reflection of the composite films was shifted to the long wavelength direction during swelling. Both the pitch of the cholesteric phase and the distance between neighboring molecular layers were increased, and the helix axis was inclined after swelling. Moreover, the swelling behavior of the composite films in water was reversible, which means that the optical properties and structural characters of the films could be changed back to their original states after the films were dried from the equilibrium swelling state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3574–3578, 2004     

Preparation of composite‐crosslinked poly(N‐isopropylacrylamide) gel layer and characteristics of reverse hydrophilic–hydrophobic surface

The composite‐crosslinked poly(N‐isopropylacrylamide) (PNIPAAm) gels were prepared by grafting N‐isopropylacrylamide on the surface of glass plates modified by organosilanes. The glass plates as the substrate increase the mechanical strength of composite PNIPAAm gel layers. We investigated the effects of a series of organosilanes and the reaction time of organosilanes on surface characteristics, such as the static contact angle and the layer thickness. We discuss the equilibrium swelling ratio and the water release behavior of the gel layers in terms of the crosslinking density of the composite gels. The composite gels exhibit not only the characteristics of remarkable water release but also the reversed hydrophilic–hydrophobic surface properties. The gel layers are hydrophilic under 25°C and change to hydrophobic above 40°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1–11, 1999     

Hybrid films synthesised from epoxidised castor oil, γ-glycidoxypropyltrimethoxysilane and tetraethoxysilane

Novel organic–inorganic hybrid films were synthesised through the reaction of epoxidised castor oil (ECO) with γ-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethoxysilane (TEOS). The amounts of GPTMS employed were sufficient to react with 25, 50 or 75% of the epoxy groups present in the ECO, whilst the mass proportions of ECO to TEOS varied from 90:10 to 70:30. Films were pre-cured at room temperature under an inert atmosphere, and subsequently submitted to thermal curing. Macro and microscopic properties of the films, including adhesion, hardness, swelling in toluene, microstructure (scanning electron microscopy) and thermal properties were determined as a function of the proportion of organic to inorganic precursor. Morphologic studies showed that the hybrid films were microscopically homogeneous when lower proportions of inorganic precursors were employed. Hardness and tensile strength increased, and swelling in toluene decreased, with the increase in the concentration of inorganic precursors. Good adhesion of the films to an aluminium surface was observed throughout the hybrid series.     

壳聚糖/碳酸钙杂化膜的研究

通过壳聚糖/钙盐复合膜浸泡在Na2CO3水溶液的方法制备出了壳聚糖/碳酸钙杂化膜。用X射线衍射仪和扫描电子显微镜表征了杂化膜内碳酸钙的晶体结构和形貌。研究了杂化膜的力学性能、溶胀率、吸光度及热稳定性。结果表明:杂化膜内碳酸钙为长3.0μm,宽1.0μm的棒状晶体,以及直径为1.0~5.0μm的多层球形晶体。随着碳酸钙的质量分数从2.69%增加到4.20%,杂化膜的溶胀率从231.6%下降到149.5%,膜的吸光度也逐渐增加。当w(CaCO3)=3.12%时,杂化膜的拉伸强度达到最大值52.12 MPa。杂化膜的分解温度为315℃,高于壳聚糖膜的分解温度290℃。这种生物相容性好的杂化膜有望用作骨细胞培养的支架材料。     

Structure‐property and swelling behavior of electron beam irradiated poly(vinyl alcohol)/acrylamide/sodium montmorillonite clay composites

Composites based on poly(vinyl alcohol) (PVA), acrylamide monomer (AM) and sodium montmorillonite clay (MMT) were prepared, in the form of thin films, by solution casting. The PVA/AM/MMT composites films were then exposed to electron beam irradiation to form crosslinked network structure. The structure‐property behavior of PVA/AM/MMT hybrids was demonstrated by x‐ray diffraction (XRD), scanning electron microscopy, gel content, color intensity, thermogravimetric analysis (TGA) and swelling behavior in aqueous solutions. The results indicated that the introduction of MMT clay ratio up to 5% decreased the gel content of PVA/AM hydrogels. The color measurements indicated that the introduction of MMT clay ratio up to 5% was shown to affect the color intensity of composite films. It was found that both PVA/AM hydrogels and PVA/AM/MMT composites reached the equilibrium swelling state in water after four hours; however PVA/AM/MMT composites displayed higher swelling than PVA/AM hydrogels. However, the swelling of PVA/AM hydrogels or their composites at the equilibrium state increased with increasing temperature up to 60°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of fiber concentration on mechanical and thermal properties of fiber‐reinforced polypropylene composites

A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene‐co‐ethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP–PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) with reference to the fiber concentration. Although, by increasing PP fiber concentration in PPE, no significant difference was found in melting and crystallization temperatures of the PPE, the storage, and the tensile and flexural modulus of the composites increased linearly with fiber concentrations up to 50%, 1.5, 1.0, 1.3 GPa, respectively, which was approximately four times higher than that for the pure PPE. There is a shift in glass transition temperature of the composite with increasing fiber concentration in the composite and the damping peak became flatter, which indicates the effectiveness of fiber–matrix interaction. A higher concentration of long fibers (>50% w/w) resulted in fiber packing problems, difficulty in dispersion, and an increase in void content, which led to a reduction in modulus. Cox–Krenchel and Haplin–Tsai equations were used to predict tensile modulus of random fiber‐reinforced composites. A Cole–Cole analysis was performed to understand the phase behavior of the composites. A master curve was constructed based on time–temperature superposition (TTS) by using data over the temperature range from −50 to 90°C, which allowed for the prediction of very long and short time behavior of the composite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2260–2272, 2005     

碳化过程中大水灰比水泥浆体孔结构的变化(英文)

使用特殊的增黏剂与聚羧酸减水剂,制备了掺加石灰石粉、高炉矿渣、硅灰等混合材的普通波特兰水泥浆体和和低热硅酸盐水泥浆体(水粉比为1.0)。这些水泥浆体在20℃的水中养护4年后基本完全水化。这些硬化水泥浆体在5%(质量分数)CO2、相对湿度66%和温度20℃条件下进行碳化,对比研究碳化前后水泥浆体孔结构的变化。结果显示:碳化浆体内孔直径大于10nm的孔体积明显减少;碳化浆体的孔径分布向大孔径范围偏移;掺加混合材的硬化水泥浆体结构明显趋于松散;与不掺加任何混合材的水泥浆体相比,掺加混合材的水泥浆体的孔径更大。