Eco-friendly preparation and structural characterization of calcium silicates derived from eggshell and silica gel

In this work, the preparation of calcium–silicate-based composites consisting of natural waste from calcium source as eggshell and silica gel from a desiccator as a silicon source both presenting alternative materials for cheap preparation of eco-friendly calcium–silicate bioceramics has been investigated. The effect of the CaO/SiO₂ ratio on microstructural properties has also been studied. The pseudowollastonite formation has been observed in the case of 40 wt.% CaO and 60 wt.% SiO₂ with lowest porosity and highest density 2.6 g/cm³. In the case of 50 wt.% CaO and 50 wt.% SiO₂, the phase transformation from pseudowollastonite to wollastonite was observed. Increasing the calcium content caused higher apparent porosity with 19%. It was shown that the development of novel ceramics from reused waste, eggshell, or silica can be an optimal solution for the low-cost preparation of calcium silicates with potential applications in medicine or cement, food industry.     

Evaluation of locally available amorphous waste materials as a source for alternative alkali activators

The production of alkali-activated materials with excellent mechanical performance requires the use of water glass, which has a significant carbon footprint. Such materials can have a lower carbon footprint if we replace water glass with alternative activators sourced from waste. In this study, we assessed the suitability of locally available amorphous waste materials (stone wool, glass wool, bottle glass and cathode-ray tube glass) as a source for the preparation of alternative alkali activators. We quantified the amount of silicon and aluminium dissolved in the activator solutions via inductively coupled plasma-optical emission spectrometry. The alternative activators were then used to produce alkali-activated fly ash and slag. The compressive strength values of alkali-activated fly ash specimens upon the addition of NaOH, water glass and the most promising alternative activator were 38.98 MPa, 31.34 MPa and 40.37 MPa, respectively. The compressive strength of slag specimens activated with alternative activators with the highest concentration of dissolved silicon (21 g/L) was, however, 70% higher than the compressive strength of slag specimens activated with only 10 M sodium hydroxide. The compressive strength of slag specimens with the addition of the most promising alternative activator was significantly lower (3.5 MPa) than the compressive strength of those that had been activated by commercial water glass (34.3 MPa).     

Rubber composite materials with the effects of electromagnetic shielding

This work deals with the preparation and properties evaluation of magnetic composites with acrylonitrile butadiene rubber matrix, which are able to shield electromagnetic radiation. In addition to the rubber matrix, these materials contained soft magnetic filler (Li or H40) and ingredients necessary for vulcanization process of prepared rubber compounds (sulfur, accelerator N‐cyclohexyl‐2‐benzothiazole sulfenamide, activators ZnO, and stearin). This study was aimed at the preparation of elastomeric composite materials and evaluation of the influence of ferrite weight fraction on curing characteristics, physical–mechanical, and magnetic properties. The results showed that with increasing content of filler, the moduli, and tensile strength decline. Conversely, elongation at break increased with increasing amount of filler. All composites containing 200 and more phr of ferrite showed sufficient absorption shielding properties, whereas lithium ferrite shows better shielding properties compared with manganese–zinc ferrite H40. POLYM. COMPOS., 37:2933–2939, 2016. © 2015 Society of Plastics Engineers     

The microstructure of alumina pillared acid-activated clays

Factors which affect the microstructure of pillared materials derived from acid activated clays have been investigated by varying the conditions used in their preparation and the level of acid treatment of the host clay prior to pillaring. The pillared acid-activated clays prepared are found to exhibit both micro and mesoporosity with a higher proportion of mesoporosity compared to conventional pillared clays. For materials calcined at 500°C, typical values obtained are in the range 0.02–0.1 cc/g and 50–200 m²/g for micropore volume and surface area respectively with corresponding mesopore values ranging between 0.2–0.4 cc/g and 150–250 m²/g. In all cases, the development of microporosity is at the expense of mesoporosity and therefore, high micropore values are accompanied with low mesopore values and vice versa. The microstructure developed by these materials is critically dependent on the amount (and nature) of pillaring species incorporated by the host clay. Consequently, the preparation conditions (i.e., Al/clay ratio and pillaring (exchange) temperature) affect the microstructure in as much as they influence the amount of alumina incorporated as pillar. The development of microporosity is highest for air-dried materials prepared at 80°C at an Al/clay ratio of 6 mmole/g.     

Synthesis and properties of soy hull‐reinforced biocomposites from conjugated soybean oil

The tensile and flexural properties of new thermosetting composites made by the free radical polymerization of a conjugated soybean oil (CSO)‐based resin reinforced with soy hulls have been determined for various resin compositions. The effects of reinforcement particle size and filler/resin ratio have been assessed. The thermal stability of the new materials has been determined by thermogravimetric analysis and the wt % of oil incorporation has been calculated after Soxhlet extraction (the extracts have been identified by ¹H‐NMR spectroscopy). The resin consists initially of 50 wt % CSO and varying amounts of divinylbenzene (DVB; 5–15 wt %), dicyclopentadiene (DCPD; 0–10 wt %), and n‐butyl methacrylate (BMA; 25–35 wt %). Two soy hull particle sizes have been tested (<177 and <425 μm) and two different filler/resin ratios have been compared (50 : 50 and 60 : 40). An appropriate cure sequence has been established by differential scanning calorimetry (DSC) analysis. The results show a decrease in the properties whenever DVB or BMA is substituted by DCPD. Also, larger particle sizes and higher filler/resin ratios are found to have a negative effect on the tensile properties of the new materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Reaction-Activated Sintering of Silicon Nitride Materials

The effect of various factors (purity of the precursor silicon powders, mechanical grinding techniques, type and amount of nitridation and sintering activators used, and heating conditions) on the phase formation, structure, and physicomechanical properties of silicon nitride materials obtained by reaction-activated sintering under normal nitrogen pressure has been studied. Specimens with a bending strength of about 545 MPa were prepared.     

Cow Dung-Based Biochar Materials Prepared via Mixed Base and Its Application in the Removal of Organic Pollutants

Cow dung (CD) is a waste product of livestock production. Improper disposal of a large amount of CD will cause environmental pollution. In this work, three biochar materials based on CD (BMCD) were prepared by using three types of base, including KOH, NaOH, and mixed base (MB, a mixture of equal mass NaOH and KOH) as activators to investigate the different physicochemical properties of BMCDs (BMCD-K, BMCD-Na, and BMCD-MB). The objective was to verify the effectiveness of MB activation in the preparation of biochar materials. The results show that MB has an effect on the structural characteristics of BMCDs. In particular, the surface area and total pore volume, the specific surface area, and the total pore volume of BMCD-MB (4081.1 m² g⁻¹ and 3.0118 cm³ g⁻¹) are significantly larger than those of BMCD-K (1784.6 m² g⁻¹ and 1.1142 cm³ g⁻¹) and BMCD-Na (1446.1 m² g⁻¹ and 1.0788 cm³ g⁻¹). While synthetic dye rhodamine B (RhB) and antibiotic tetracycline hydrochloride (TH) were selected as organic pollutant models to explore the adsorption performances, the maximum adsorption capacities of BMCD-K, BMCD-NA and BMCD-MB were 951, 770, and 1241 mg g⁻¹ for RhB, 975, 1051, and 1105 mg g⁻¹ for TH, respectively, which were higher than those of most adsorbents. This study demonstrated that MB can be used as an effective activator for the preparation of biochar materials with enhanced performance.     

Chemical,biological, and antibacterial characterization of silica glass containing silver and gold nanoparticles

The aim of this study has been the preparation of sol‐gel glasses with potential antibacterial properties. Bioactive glasses containing different percentages of silver and gold nanoparticles have been synthesized via the sol‐gel method. The obtained glasses have 0.5, 1, 1.5, and 2 wt% silver as well as a constant amount of gold nanoparticles (AuNP) added as colloidal solution (15 wt%). Fourier Transform Infrared (FTIR) spectroscopy was used to characterize the materials. Scanning electron microscopy (SEM) has been used to investigate the surface of each sample. Moreover, the materials have been characterized in order to verify their antibacterial activities as well as their bioactivity and cytocompatibility as a function of Ag and Au content. SEM/EDX analysis has shown that the samples are bioactive because they are able to stimulate hydroxyapatite nucleation on their surface when soaked in a simulated body fluid (SBF). WST‐8 assay of 3T3 cells, placed in contact with the material extracts, has showed that the glass does not induce cytotoxicity. Staphylococcus epidermidis and Pseudomonas aeruginosa strains have been used for the evaluation of the antibacterial properties of each sample. The experimental data have shown that all synthesized materials have antibacterial activity. However, the two bacterial strains respond differently to the materials. The data show that the presence of AuNP causes a decrease in the antibacterial activity of Ag⁺ ions.     

Synthesis and characterisation of poly(arylene sulphides): Part 11. Preparation of poly(1,4-phenylene sulphide) directly from bis(4-bromophenyl) disulphide

Reaction conditions for the preparation of poly(1,4-phenylene sulphide) (PPS) directly from bis(4-bromophenyl) disulphide (BBD) have been established. Reactions were performed in a boiling quinoline/pyridine solvent mixture (91% by vol. quinoline) in the presence and absence of copper powder. Reaction products were fractionated and the fractions characterised using elemental analysis, IR and NMR spectroscopy, viscometry, hot-stage microscopy, differential scanning calorimetry, thermogravimetry and curing studies. The yields and properties of the polymeric fractions are compared to those of similar fractions obtained from preparation of PPS by solution polymerisation of copper(I) 4-bromobenzenethiolate under conditions which correspond to those employed in this work. PPS was not produced, and BBD was almost quantitatively recovered when copper was absent from the reactants. Reactions performed using an equimolar ratio of copper to BBD produced PPS of molar mass approximately 2–4 × 10³ gmol^?1 in 76% yield after 8h reaction. However, this PPS was contaminated with an insoluble infusible material which had a deleterious effect on the physical properties of derived cured PPS materials. The yield of PPS decreased and the quantity of contaminant increased as reaction time increased. PPS of molar mass approximately 10⁴g mol^?1 was obtained in 50–60% yield, free from insoluble infusible material, when the molar ratio of copper: BBD was increased to 2:1; it exhibited normal properties on curing.     

Multifunctional Cu2+‐montmorillonite/epoxy resin nanocomposites with antibacterial activity

Multifunctional nanocomposites can be achieved by addition of modified layered nanoclays to impart to the final materials a designed set of properties. The easy reproducible preparation of copper modified montmorillonite has been reported here together with its spectroscopic characterization, including ²⁹Si NMR in the solid state. Epoxy‐nanocomposites and glass fiber reinforced laminates containing 1% wt and 3% wt of Cu²⁺‐MMT have been prepared and characterized. Thermal and mechanical properties have been evaluated. The experiments carried out to evaluate the antibacterial activity showed that the epoxy‐resin nanocomposites with 3% wt of Cu²⁺‐MMT exhibited an inhibition action higher than 96% against Escherichia coli and Staphylococcus aureus. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44733.     

Insulating rigid polyurethane foams from laurel tree pruning based polyol

The present work deals with the production of a natural polyol from laurel tree pruning waste, aiming the preparation of polyurethane foams. The obtained bio-polyol was characterized and applied into foams studying the influence of the isocyanate used and the addition of the physical blowing agent. The incorporation of the polyol allowed 40% polyol substitution for those foams in which TDI was used, and up to 60% using MDI. Apparent density, cell morphology, mechanical, and thermal properties were evaluated. Mechanical and thermal properties of the foams improve to a greater amount of polyol in the matrix. Specifically, the best thermal and mechanical properties (274.99 and 7275.91 kPa for compressive strength and Young Modulus, respectively) were obtained with 50% polyol substitution (0.63 R_NCO/OH). Foams showed small, well-defined cell morphology. Laurel derived polyol can be used for the preparation of foams using MDI, since the mechanical, and thermal properties are promising for obtaining insulation materials in the construction industry.     

Relaxation Behavior of Polyethylene Oriented by Various Techniques

Abstract

Stress relaxation of high-density polyethylene extrudates and those crystallized from highly deformed melt (PE-1) have been investigated in a wide range of temperatures (?50 to +120°C) and draw ratios from 5.5 up to 12.2 at the different constant tensile strains from 1 up to 20%. The experimental data obtained have been summarized by the time-temperature superposition principle. Relative intensity of stress relaxation (the stress drop in 10³ s divided by the initial stress) has been observed to increase together with the growth of draw ratio despite the enhancement of the short-term properties. The radiation cross-linking of the PE-1 samples may only decrease the stress relaxation intensity by 30%. The relaxation properties of a number of oriented polyethylene samples produced by various techniques were compared. It has been established that all the investigated materials are characterized by similar values and high relative drops in stress, whereas the short-term properties are essentially different. It points out to the relaxation processes being intensive both in the oriented and unoriented PE.     

Preparation Process Orthogonal Optimization and Mechanical Properties of Microcellular Foam Polypropylene

Melt strength, pressure and the amount of gas have significant effects on the foaming of polypropylene (PP). It is convenient to study the influence of these factors on foaming effect by orthogonal test. The experiment result shows that within the set factors and levels, the improvement of melt and the concentration of foaming masterbatch has the greatest influence on the cell size and density of foamed PP, respectively. When the concentration of azodicarbonamide (ADC) is 15 %, PP/ethylene-propylene terpolymer (EPDM) = 90:10, and SiO₂ content is 3%, the foaming effect is the best. At this time, the cell diameter decreases by 42.7%, cell density increases by more than 7.5 times compared with that without optimization. Material density decreases from 0.92 to 0.56 g cm⁻³. It is also found that good closed-cell structure can improve the bending and impact properties of PP in varying degrees, especially the impact strength is 55.7% higher than that of neat PP. Finally, the promoting mechanism of cell structure on mechanical properties of materials is discussed, which is of great significance for the preparation of microfoamed PP materials and the deep research of its cell structure.     

Hybrid MCM-41 grafted by a general microwave-assisted procedure: a characterization study

Hybrid materials obtained through a Microwave-assisted grafting of organic functional groups on mesoporous silica (MCM-41 type) have been characterized by X-ray powder diffraction, TG-DSC, N₂ adsorption, solid state ¹³C- and ²⁹Si-NMR, TEM and SEM. The studied grafting procedure is effective in the preparation of hybrid organosilicas under solvent-free conditions. Microwaves allows an ultra-fast and clean functionalization of the mesoporous materials and the method has been applied to produce a wide series of functional materials. The hybrid materials maintain the original mesoporous structure when the loading of linked organic groups does not exceed 10 %. In this cases, the slight pore volume reduction is linearly correlated to the organic amount in the product. If functional groups able to interact among them through hydrogen bond are used, hybrid materials exhibit high Organic/SiO₂ ratios and low pore volumes due to the formation of a network occluding the pores, where functional groups of free organosilane molecules interacts with the functional groups of molecules linked to the matrix. NMR data confirm that the network is composed by organosilane molecules linked or not to the framework. Acid washing is able to labilize hydrogen bond and open the network. In the case of bulky but chemically inert functionalising agents the network is not produced.     

Preparation and characteristics of composite films with functionalized graphene/polyimide

Polyimide (PI) has the inherent defect of poor intrinsic thermal conductivity and cannot meet the increasing demand for rapid heat dissipation in the thermal management introduction. To improve the thermal conductivity of PI, in this study, thick sheet graphene-ionic liquid (TSG-IL) functionalized graphene has been prepared by a one-step ultrasonic-chemical method. Under the action of mechanical force, IL is successfully modified on the surface of TSG, and TSG is peeled to some extent. TSG-IL/PI has been prepared the typical method of solution casting followed by thermal imidization. The structure, morphology, thermal conductivity, and mechanical properties of the composites are evaluated by Fourier-transform infrared spectroscopy, x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, and Hot Disk thermal conductivity tests. When the amount of TSG-IL is 0.3 wt%, the thermal conductivity of TSG-IL/PI (0.18 W·m⁻¹·k⁻¹) than pure PI and TSG (ultrasonication)/PI increased by 50.0% and 28.6%, respectively. Moreover, it can maintain good mechanical properties, and its tensile strength (121.5 MPa) is 6.5% and 3.5% higher than that of pure PI and TSG (ultrasonication)/PI, respectively. The potential for application in the preparation of composites with high-thermal conductivity is promising.     

Investigation of the properties of conductive hydrogel composite containing Zn particles

In this work, the conductive hydrogel composites containing Zn particle synthesized and their electrical and thermal properties were investigated. Polyacrylamide/Zn composites were synthesized by free radical polymerization in aqueous solution. The effect of preparation conditions such as the influence of crosslinker amount, initiator amount, Zn amount, and water absorbency on electrical conductivity of hydrogel was investigated. The effect of preparation conditions on thermal properties has been characterized using thermogravimetric analysis (TGA) method. The structures of metal‐composites were evaluated by FTIR and scanning electron microscopy (SEM) methods. SEM revealed a more uniform pore size when Zn particles were used when compared with pure polyacrylamide. TGA curves showed that both hydrogels were stable upto 600°C. The Zn/polyacrylamide hydrogels have a good conductivity of 4.30 mS cm^?1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanically strong waterborne poly(urethane-urea) films and nanocomposite films

A series of transparent waterborne poly(urethane-urea) (PUU) films and nanocomposite films were prepared using isocyanate excess (5–50 mol% excess relative to the hydroxyl groups) and omitting the common chain-extension step in the acetone method of the preparation. The surplus isocyanate groups were converted into urea and eventually biuret linkages via the reaction with water during the last phase inversion step. Nanocomposites were prepared by the direct mixing of the PUU nanoparticles in water with aqueous nanosilica or montmorillonite powder followed by slow water evaporation. Variable urea/biuret content is responsible for substantially different tensile properties; the neat organic films show elongation-at-break values of 100%–1120%, tensile strength values of 0.07–22.1 MPa, and energy-to-break of 0.1–85 mJ × mm⁻³. All of the materials can be potentially used as soft-to-hard topcoats, depending on the specific demands. The most promising materials are films prepared at 30 and particularly 40 mol% isocyanate excess.     

High-performance dispersant of coal–water slurry synthesized from wheat straw alkali lignin

Environmental concerns have stimulated interest in utilizing plant-derived materials in various industrial fields. The main objective of the present study was to synthesize a new type of high-performance lignin series dispersant of coal–water slurry (CWS) from wheat straw alkali lignin (WAL), and determine the affecting factors in the reaction and the application performance for CWS preparation. The experimental results showed that the inherent viscosity and the sulfonic group content of the modified wheat straw alkali lignin (MSL) are the key factors affecting its dispersing effect for CWS. In the reaction, the reactant mass concentration and the sulfonating agent amount were changed to obtain the MSL with different inherent viscosities and sulfonic group contents, and the MSL with intermediate inherent viscosity (6.0 ml/g) and higher sulfonic group content (1.80 mmol g^− 1) was found to have excellent dispersing effect for CWS. The MSL obtained from optimized process was used as dispersant for CWS preparation, the studies of the properties of CWS showed that MSL has similar dispersing effect with naphtalenesulfonate–formaldehyde condensate, and far better dispersing effect than lignosulphonate. Recently this kind of new dispersant has been applied in several power plants in China.     

高分子碳系自由基引发剂及其应用

介绍了碳系自由基引发剂的结构，热分解性能和作用机理，以及它们在功能性工程塑料的制备，高分子改性，粘合剂和阻燃材料方面的应用。     

Synthesis and characterization of hybrid organic–inorganic materials based on sulphonated polyamideimide and silica

The preparation of hybrid organic–inorganic membrane materials based on a sulphonated polyamideimide resin and silica filler has been studied. The method allows the sol–gel process to proceed in the presence of a high molecular weight polyamideimide, resulting in well dispersed silica nanoparticles (<50 nm) within the polymer matrix with chemical bonding between the organic and inorganic phases. Tetraethoxysilane (TEOS) was used as the silica precursor and the organosilicate networks were bonded to the polymer matrix via a coupling agent aminopropyltriethoxysilane (APTrEOS). The structure and properties of these hybrid materials were characterized via a range of techniques including FTIR, TGA, DSC, SEM and contact angle analysis. It was found that the compatibility between organic and inorganic phases has been greatly enhanced by the incorporation of APTrEOS. The thermal stability and hydrophilic properties of hybrid materials have also been significantly improved.