Preparation and Characterization of Polypropylene Nanocomposites Filled with Nano Calcium Phosphate

The synthesized nano calcium phosphate by matrix mediated growth and controlled technique was used as nanofiller in the preparation of polypropylene nanocomposites. Nanocomposites with different filler concentrations were prepared. The content of nano calcium phosphate was varied from 1 to 3 wt% in the preparation of PP nanocomposites. During preparation of nanocomposites shear rate was varied by means of increase in rpm, i.e., 60, 70, 80 and 90 with the help of Brabender Plastograph and the effect of shear rate was studied with respective to mechanical and thermal properties of composites. The comprehensive evaluation of the PP nanocomposites filled with nano calcium phosphate was done to observe the substantial improvement in the performance properties. The mechanical and thermal properties were determined by Universal Testing Machine (UTM) and Thermogravimetric Analyzer (TGA), respectively. The morphology of the fracture surfaces of the prepared PP nanocomposites filled with nano calcium phosphate was studied by Scanning Electron Microscopy (SEM).     

Preparation of Mesoporous Zirconium Phosphate-Pyrophosphate with a Large Amount of Thermally Stable Acid Groups on the Pore Surface

Mesoporous zirconium phosphate pyrophosphate of composition Zr(P₂O₇)_0.81(O₃POH)_0.38 was obtained by calcination at 600°C of a mesoporous zirconium phosphite diphosphonate, Zr[(O₃P-C₆H₄-PO₃)_0.54 (O₃P-C₆H₄-PO₃H₂)_0.13(O₃PH)_0.79]. The surface area of this completely inorganic material (215 m²/g) was lower than that of its inorgano-organic precursor (350 m²/g); however, both materials exhibited the same pore distribution, with an average pore diameter of 4 nm, and similar values of the mesopore volume (0.21 and 0.28 cm³/g, respectively). These results showed that the thermal treatment at 600°C leaves nearly unaltered the mesoporous structure of the precursor. ³¹P solid state NMR and TEM investigations were also carried out and discussed. The material obtained represents a considerable advancement in the preparation of zirconium phosphates with high surface area. Due to the good thermal stability of its surface acid groups (700–800°C), it is of interest for potential uses as an acid catalyst at high temperature.     

Nanofiber Formation in the Fabrication of Carbon/Silicon Carbide Ceramic Matrix Nanocomposites by Slurry Impregnation and Pulse Chemical Vapor Infiltration

The objectives of this work were to investigate the fabrication of carbon-fiber-reinforced SiC ceramic nanocomposites using the slurry impregnation process and the pulse chemical vapor infiltration (PCVI) process and to study the influences of processing parameters of the PCVI process on the microstructure variation of the nanocomposites. In this work, SiC nanosized powder was added to the matrix precursor (silicon powder mixed with phenolic resin), followed by the impregnation of the slurry into the preform. In the PCVI process, to densify the nanocomposites, tetramethylsilane (TMS) vapor mixed with hydrogen was used as the vapor precursor for matrix deposition. Fabrication parameters, such as reactant concentrations, pulse number, and holding time, were studied. Morphologies obtained from various processes were compared.     

聚乳酸/纳米载银磷酸锆熔纺纤维制备及性能

利用双螺杆挤出机将聚乳酸(PLA)切片和纳米载银磷酸锆颗粒共混制备纳米载银磷酸锆质量分数为20%的PLA母粒。将母粒和纯PLA切片按照不同比例共混熔纺制备PLA/纳米载银磷酸锆共混纤维。研究了共混纤维的制备方法,运用扫描电子显微镜观察了纤维束外部形貌,测试了纤维的力学及抗菌性能。结果表明,纳米载银磷酸锆在纤维中有少量凝聚,总体分散均匀;随着纳米载银磷酸含量提升,纤维断裂强度先增大后降低,同时纤维的抗菌性不断增加。当载银磷酸锆含量达到1.5%时,纤维的断裂强度最大为0.85 c N/dtex,对大肠杆菌和金黄色葡萄球菌抑菌率达99.9%。     

Preparation and Sustained-Release Property of Triblock Copolymer/Calcium Phosphate Nanocomposite as Nanocarrier for Hydrophobic Drug

The P123/ACP nanocomposite with sizes less than 100 nm consisting of triblock copolymer P123 and amorphous calcium phosphate (ACP) has been prepared by using an aqueous solution containing CaCl₂, (NH₄)₃PO₄, and P123 at room temperature. The P123/ACP nanocomposite is used as the nanocarrier for hydrophobic drug ibuprofen, based on the combined advantages of both amphiphilic block copolymer and calcium phosphate delivery system. The P123/ACP nanocomposite has a much higher ibuprofen loading capacity (148 mg/g) than the single-phase calcium phosphate nanostructures. The drug release percentage of the P123/ACP nanocomposite in simulated body fluid reaches about 100% in a period of 156 h, which is much slower than that of single-phase calcium phosphate nanostructures. It is expected that the P123/ACP nanocomposite is promising for the application in the controlled delivery of hydrophobic drugs.     

Effects of Characteristics of Rubber,Mixing and Vulcanization on the Structure and Properties of Rubber/Clay Nanocomposites by Melt Blending

Summary: Three rubber‐based nanocomposites, natural rubber (NR), styrene‐butadiene rubber (SBR), and ethylene‐propylene‐diene rubber (EPDM) matrixes, were prepared with octadecylamine modified fluorohectorite (OC) by melt blending. X‐ray diffraction (XRD) revealed that the SBR/OC and EPDM/OC nanocomposites exhibited a well‐ordered intercalated structure and a disordered intercalated structure, respectively. In the case of the NR/OC nanocomposite, it exhibited an intermediate intercalated and even exfoliated structure. These results were in good agreement with transmission electron microscopy (TEM) observations. Furthermore, in the NR/OC and SBR/OC systems, the mixing process played a predominant role in the formation of nanometer‐scale dispersion structure, whereas the intercalated structure of EPDM/OC formed mainly during the vulcanization process. The tensile strength of SBR/OC and EPDM/OC nanocomposites loading 10 phr OC was 4–5 times higher than the value obtained for the corresponding pure rubber vulcanizate, which could be ascribed to the slippage of the rubber molecules and the orientation of the intercalated OC. For the strain‐induced crystallization NR, the exfoliated OC efficiently improved the modulus of the NR/OC nanocomposite relative to the pure NR. However, its hindrance on NR crystallization during the tensile process may be the main reason for the decrease in tensile strength of NR/OC.

XRD diffraction patterns of three nanocomposites containing 10 phr organoclay.     

四氢呋喃存在下反应挤出苯乙烯/丁二烯共聚物的微观结构和力学性能研究

在有机锂（BuLi）引发体系下,以双螺杆挤出机为反应器,苯乙烯、丁二烯混和物作为单体,THF（四氢呋喃）为极性添加剂,本体法一步合成了丁苯共聚物。通过多种表征手段,研究了THF的用量对共聚物结构和性能的影响。由1H-NMR谱图计算得知,THF的加入使1,2-聚丁二烯和无规苯乙烯含量明显增加,但THF/BuLi之比超过5以后,增加趋势减缓。采用H2O2/OsO4体系对聚合物分子链中的丁二烯双键进行了深度氧化降解,利用配备小角激光光散射仪的GPC对降解前后的样品进行了分析,结果表明随着THF/BuLi的增加,分子链中长嵌段聚苯乙烯的分子量和含量逐渐降低。TEM分析结果表明随着THF/BuLi的增加,两相界面逐渐变得模糊,两相的相容性增强。拉伸性能测试表明随着THF/BuLi的增加,使拉伸强度逐渐降低,当THF/BuLi=30时,屈服点消失。     

Enhanced Weathering Resistance of Radiata Pine Wood by Treatment with an Aqueous Styrene/Acrylic Acid Copolymer Dispersion

Radiata pine (Pinus radiata Don.) sapwood was treated with an aqueous dispersion solution of styrene/acrylic acid (St/AA) copolymer (5, 15, or 25%) and the treatment effect on weathering of wood was determined. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that the St/AA treatment delayed lignin degradation during artificial weathering; the protection effect increased with St/AA concentration. Decrease in water contact angle upon weathering for the treated wood was also slower than for the untreated control. Scanning electron microscopy revealed that the St/AA polymer filled some wood cell lumina, which facilitates to inhibit moisture and light (especially ultraviolet light) penetration into wood. During 12?months of outdoor exposure, the St/AA-treated wood boards had lower moisture content and less detachment of earlywood cells than the untreated controls. Treatments with St/AA stabilized the surface color by inhibiting photo-oxidation of cell wall polymers and propagation of staining fungi. The results suggest that treatment with St/AA can substantially improve wood’s resistance to weathering.     

磷酸铋作为磷酸钙骨水泥的显影剂及其对材料性能的影响

以部分结晶磷酸钙-磷酸氢钙体系骨水泥为研究对象,探讨了添加磷酸铋作为显影剂对磷酸钙骨水泥的显影性能、凝结时间、流变性、可注射性能、抗压强度、相组成和显微结构的影响.结果表明:添加磷酸铋能显著增强磷酸钙骨水泥的显影性能,当添加磷酸铋达到9%以上时,骨水泥获得了明显的显影效果.添加磷酸铋使磷酸钙骨水泥粘度下降,可注射性显著提高,抗压强度增大,凝结时间延长.但磷酸铋加入量大于12%时会使材料强度下降,综合考虑,加人9%左右的磷酸铋较为合适.磷酸铋有望成为一种新的磷酸钙骨水泥显影剂.     

Preparation of Clay/PMMA Nanocomposites with Intercalated or Exfoliated Structure for Bone Cement Synthesis

Summary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter‐lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (T_d) and glass transition temperature (T_g) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35 °C, of the thermal stability (T_d) with respect to pure PMMA were achieved for many of the composite samples. The T_g of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery.

TEM images of an OA‐clay/PMMA composite.     

Preparation and Application of a Novel Functionalized Coconut Coir Pith as a Recyclable Adsorbent for Phosphate Removal

Abstract

This study was to develop a new adsorbent, Iron(III) complex of an amino-functionalized polyacrylamide-grafted coconut coir pith (CP), a lignocellulosic residue, for the removal of phosphate from water and wastewater. The kinetics of adsorption follows a pseudo-second-order model. The equilibrium sorption capacity of 96.31 mg/g was determined at 30°C from the Langmuir isotherm equation. Complete removal of 16.4 mg/L phosphate in 1 L of fertilizer industry wastewater was achieved by 1.5 g/L AM-Fe-PGCP at pH 6.0. The acid treatment (0.1 M HCl) and re-introduction of Fe³⁺ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity.     

Using a Brush Copolymer as Efficient Dispersant for the Preparation of Highly Stabilized Ag Nanoparticles in Aqueous Suspensions

Silver (Ag) nanoparticle has extremely high surface energy and it is difficult to find an efficient dispersant to prevent its agglomeration in suspensions. A new brush copolymer, succinic anhydride modified epoxy-amine poly[(propylene oxide)-co-(ethylene oxide)]-grafted polymer (EPOA), which can efficiently disperse concentrated aqueous suspensions of Ag nanoparticles is revealed. The dispersion efficiency of EPOA for the dispersion of a 60 nm-Ag nanoparticles in aqueous suspension is studied by measuring its sedimentation and rheological behavior, and the results are compared with those of a commercially available dispersant, ammonium poly(acrylic acid) (PAA-NH₄). Interactions between the dispersants and the Ag nanoparticles are characterized by zeta potential and adsorption analyses. Theoretical calculations are conducted to clarify the adsorption and the dominant dispersion stabilization mechanisms of the dispersants. Compared with PAA-NH₄, EPOA obtains a higher stable suspension of Ag nanoparticles with less significant sedimentation over 1 month. The dispersion homogeneity of the suspension remains excellent even at an extremely high solid loading of 30–40 wt%. According to adsorption analysis, it is suggested that both EPOA and PAA-NH₄ adsorb via single-point attachment through the carboxyl group on the Ag surface. Based on theoretical calculations, the Ag nanoparticles are better stabilized by EPOA via an electrosteric dispersion mechanism.     

Cornet‐Like Phosphotriazine/Diamine Polymers as Reductant and Matrix for the Synthesis of Silver Nanocomposites with Antimicrobial Activity

The synthesis of silver nanoparticles attached on the surface of a hollow cornet‐like polymer matrix which served as a reductant and host matrix is described. This hybrid organic/inorganic macromolecular matrix is exhibiting anion‐exchange properties, porous structure and hollow morphologies, and absorptions in the visible light region. Due to the anion‐exchange property and the 3D orientation of the macromolecular chains the material is defining a new functional organic/inorganic hybrid. For the synthesis of nanoparticles, no other reducing agents were used and silver nanoparticles with a mean diameter of less than 20 nm were attached on the surface of the polymer, thus inheriting the composite with high antibacterial activity tested in bacterial strains and yeasts.

     

Preparation and Characterization of Polycarbonate/Poly(propylene)/Attapulgite Ternary Nanocomposites with the Morphology of Encapsulation

Summary: Ternary nanocomposites based on polycarbonate (PC), poly(propylene) (PP), and attapulgite (AT) were prepared via the method of two‐step melt blending, by which the AT was blended with PP prior to compound with PC. Structure and properties of the ternary PC/PP/AT nanocomposites were investigated. The degradation of PC triggered by AT during direct blending process can be inhibited effectively by using two‐step melt blending. It was found that the morphology of encapsulation structure like sandbag was formed in PC matrix, where PP encapsulated AT fibrillar single crystals. DSC experiments showed that in PC/PP/AT ternary nanocomposites, AT had a strong heterophase nucleation effect on PP, resulting in the enhancement of crystallization degree and the crystallization temperature of PP. DMA and mechanical property results showed that the ternary nanocomposites exhibited good balanced toughness and stiffness.

TEM photograph of PC/PP/AT ternary nanocomposite.     

Preparation of the Sulfonamide Containing Block Copolymer as Polymeric Sorbent for Removal of Mercury from Aqueous Solutions

A new sulfonamide containing polymeric sorbent for the removal of mercury ions from waste waters was prepared starting from poly(glycidyl methacrylate)-b-poly(ethylene glycol)-b-poly(glycidyl methacrylate) (PGMA- b -PEG- b -PGMA) triblock copolymer prepared by using the ATRP method. Epoxy groups on the block copolymer were functionalized with amino groups. Ammonia-functionalized PGMA- b -PEG- b -PGMA was treated with excess of benzenesulfonyl chloride to obtain a sulfonamide-based polymeric sorbent. The sulfonamide containing the polymeric sorbent with a 3.5 mmol · g^?1 total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 3.12 mmol g^?1 under non-buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe(II) also were extractable in quantities (0–0.45 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4 M HNO₃ without hydrolysis of the sulfonamide groups.     

铁酸铋/石墨烯纳米复合材料的制备及其对高氯酸铵热分解的催化作用

为了提高纳米复合金属氧化物对高氯酸铵(AP)热分解的催化作用,以Bi(NO₃)₃·5H₂O、Fe(NO₃)₃·9H₂O和GO为前驱体,采用水热法制备了铁酸铋/石墨烯(BiFeO₃/rGO)纳米复合材料;利用XRD、FT-IR、XPS、TGA、SEM和TEM等对所制备样品的结构、粒径及形貌进行了表征;采用差热分析研究了不同添加量的BiFeO₃/rGO纳米复合材料对AP热分解过程的影响,分析了BiFeO₃/rGO对AP热分解的催化机理及其对AP热分解动力学的影响。结果表明,rGO的引入有效阻止了纳米BiFeO₃颗粒的团聚,大大增加了比表面积;当BiFeO₃/rGO纳米复合材料的质量分数为4%时,AP的高温分解峰降低最多,达167℃,表观分解热增加了1631J/g,达2518J/g,表观活化能从172.07kJ/mol降低至128.35kJ/mol,表明所制备的BiFeO₃/rGO纳米复合材料能有效催化AP的热分解。     

A Novel Strategy for the Controlled Synthesis of Silver Halide/Polyaniline Nanocomposites with Different Polyaniline Morphologies

Silver halide/polyaniline nanocomposites with different polyaniline morphologies, i.e., nanotubes and nanofibers, were successfully synthesized simply based on the general chemical oxidation polymerization process of aniline in halide acid aqueous solution (i.e., HCl or HBr) with the presence of dodecylbenzenesulfonic acid (DBSA)‐stabilized silver nanoparticles (NPs) as the precursors of silver halide NPs (i.e., AgCl or AgBr). X‐ray diffraction (XRD) and FT‐IR results confirmed the structures of resultant silver halide/polyaniline nanocomposites. TEM and SEM images demonstrated that AgCl or AgBr NPs were well‐dispersed and embedded in the polyaniline matrix. The reasons for the new strategy for the preparation of silver halide/polyaniline nanocomposites were based on two key points: the first was the high reactivity of silver NPs with HCl or HBr to generate AgCl/AgBr NPs. Second, with the assistance of DBSA, polyaniline could be synthesized with various nanostructures, i.e., nanotubes and nanofibers.

     

Preparation of polypropylene/montmorillonite nanocomposites with an exfoliated structure by a designed route

Nanocomposites of polypropylene (PP) and montmorillonites (MMT) were prepared by solid‐phase grafting reactive organomontmorillonite (ROMT) and polar monomers onto powdered PP and melt‐blending granule PP with the master batches as PP/MMT grafting copolymers (PPMG). The structure and properties of the PP/MMT nanocomposites (PPMN) were investigated by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. GPC showed that the numerical molecular weight and polydispersity of the graft copolymers of PPMG were approximately 4793 and 2.197, respectively. FTIR confirmed the solid‐phase graft copolymerization. XRD and TEM indicated the formation of the exfoliated, layered silicates (tactoids). The mole ratio of compound alkylammoniums and the exothermic enthalpy from solid‐phase graft copolymerization played key roles in the formation of tactoids. The optimum mole ratio of organophilic alkylammonium to reactive alkylammonium was 3 : 1. The mechanical and thermal properties increased with the contents of PPMG, and a preferable state was achieved at approximately 8 phr PPMG (parts of reagent per 100 parts of PP) because of the plastification of the exfoliated silicates and the graft copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3889–3899, 2006     

Pyridine‐Modified Polymer as a Non‐Covalent Compatibilizer for Multi‐Walled CNT/Poly[ethylene‐co‐(methacrylic acid)] Composites Fabricated by Direct Melt Mixing

Multi‐wall CNT/poly[ethylene‐co‐(methacrylic acid)] composites were prepared by melt mixing. To improve dispersion and promote polymer/nanotube interactions, a novel non‐covalent compatibilizer is synthesized by reacting the polymer with 4‐(aminomethyl)pyridine. The composite based on the pristine polymer shows electrical and rheological percolation thresholds at nanotube loadings of 1.85 and 1.4 wt%, respectively. When 5 wt% of the pyridine‐modified compatibilizer is added, the corresponding values are reduced to 1.44 and 0.8 wt%, respectively. The electrical resistivity decreases even further as 10 wt% of the novel dispersing agent is used. Microscopy and Raman spectroscopy confirm the improved dispersion and π‐interactions established during melt mixing.

     

Preparation and characterization of carbon-coated LiFePO4 cathode materials for lithium-ion batteries with resorcinol-formaldehyde polymer as carbon precursor

LiFePO₄/C composites were synthesized by two methods using home-made amorphous nano-FePO₄ as the iron precursor and soluble starch, sucrose, citric acid, and resorcinol-formaldehyde (RF) polymer as four carbon precursors, respectively. The crystalline structures, morphologies, compositions, electrochemical performances of the prepared powders were investigated with XRD, TEM, Raman, and cyclic voltammogram method. The results showed that employing soluble starch and sucrose as the carbon precursors resulted in a deficient carbon coating on the surface of LiFePO₄ particle, but employing citric acid and RF polymer as the carbon precursors realized a uniform carbon coating on the surface of LiFePO₄ particle, and the corresponding thicknesses of the uniform carbon films are 2.5 nm and 4.5 nm, respectively. When RF polymer was used as the carbon precursor, the material showed the highest initial discharge capacity (138.4 mAh g^− 1 at 0.2 C at room temperature) and the best rate performance among the four materials.