Synthesis and characterization of 2-D and 3-D covalent networks derived from triazine central cores and bridging aromatic diamines

Nucleophilic substitutions of the reactive chlorine atoms in either cyanuric or phosphonitrilic chloride by the bridging 1,4-phenylenediamine and benzidine units lead to the formation of two- (2-D) or three-dimensional (3-D) covalent networks, according to the spatial arrangement of the chlorine atoms in each particular triazine core. The materials are electrochemically active and stable, and exhibit interesting optical properties. The UV-visible spectral absorptions are significantly red-shifted and can been altered upon chemical oxidation. Furthermore, a three-band absorption spectrum typical of polaronic nature is observed in the case of the layered benzidine/cyanuric chloride network. Either spherical (2-D) or cubic (3-D) morphologies were revealed by SEM analysis, while the XRD patterns indicated partial crystallinity. Due to the inherited ion-exchange properties of the 2-D and 3-D ionic networks, the materials can be regarded as the organic analogues of conventional inorganic layered or zeolitic ion-exchangers.     

A new synthetic approach for difficult benzoxazines: Preparation and polymerization of 4,4′-diaminodiphenyl sulfone-based benzoxazine monomer

The first successfully synthesized benzoxazine in high purity from 4,4′-diaminodiphenyl sulfone (DDS), paraformaldehyde and phenol using high boiling point nonpolar solvent is reported. The solution method for benzoxazine synthesis is modified by using a nonpolar solvent of high boiling point. For comparison, the synthesis of such difficult benzoxazine monomer was prepared in high boiling point polar solvent, dimethylsufoxide. ¹H NMR indicates the purity of the monomer prepared by this novel method to be quite high in comparison with that obtained using dimethylsulfoxide (DMSO). The thermally activated polymerization of the monomer affords polybenzoxazine with T_g at ca. 203 °C. The 5% and 10% decomposition temperatures of the polymer are 324 and 368 °C with 58% char yield, reflecting the excellent thermal stability than the typical polybenzoxazine based on bisphenol-A and aniline.     

The production of biodiesel from vegetable oils by ethanolysis: Current state and perspectives

At present, the homogeneous base-catalyzed methanolysis reaction of vegetable oils is a most often used process for the industrial biodiesel production. The toxicity of methanol, the risk of the methanol vapor explosion and the possibility of the ethanol production from biorenewable resources have contributed to the development of a vegetable oil ethanolysis process for the biodiesel production. In the reaction of vegetable oils and ethanol in the presence of a catalyst, completely agricultural fuels consisted of fatty acid ethyl esters (FAEE) are obtained having physico-chemical properties similar to those of the appropriate methyl esters and diesel fuel. The ethanolysis reaction of various oily feedstocks has been widely studied to optimize the reaction conditions and to develop new catalytic systems and processes based on chemical and biological catalysts, as well as the development of non-catalytic processes. Most researches investigate the application of homogeneous base catalysts. This paper studies the review of vegetable oil ethanolysis investigations for the biodiesel production done so far. The goals of the paper are to present the development of FAEE synthesis by catalytic and non-catalytic processes, their advantages and disadvantages, the influence of some operating and reaction conditions on the process rate and ethyl esters yield, the kinetics models describing the ethanolysis process rate, the process optimization and the possibilities for improving the FAEE synthesis process.     

Synthesis of new polyester polyols from epoxidized vegetable oils and biobased acids

Biobased polyols were synthesized from reaction between epoxidized soybean oil and lactic, glycolic, or acetic acids. Polyols were characterized by NMR, alcohol and acid titration, and SEC. These analyses allowed to determine an average hydroxyl functionality between 4 and 5, with an oligomer content close to 50 wt%. Synthesized polyols were formulated with isocyanate to yield polyurethanes (PUs). Thermal and mechanical properties of obtained materials showed that synthesized polyols lead to rigid and brittle material with Young moduli higher than 900 N/mm² at RT and with T_g values around 50°C. Practical application: The products of the chemistry described in this contribution, i.e.: polyol from vegetable oils and lactic, glycolic, or acetic acids, provide biobased building blocks for further PUs syntheses by reaction with diisocyanates. The obtained PUs are partially biobased and may be applied as binders and coatings.     

Preparation and properties of polyamide-imides derived from 1,3-bis(4-aminophenoxy)benzene,trimellitic anhydride,and various aromatic diamines

A diamine, 1,3-bis(4-aminophenoxy) benzene (II), was synthesized in two steps; fist from the condensation of resorcinol with p-chloronitrobenzene in the presence of potassium carbonate, producing I ,3-bis(4-nitrophenoxy) benzene (I), followed by hydrazine hydrate/Pd-C reduction. A two imide rings-preformed dicarboxylic acid, 1,3-bis(4-trimellitimidophenoxy)benzene (III), was prepared from the condensation of diamine II and trimellitic anhydride in 1:2 molar ratio. A series of structurally new polyamide-imides (V_a-p) were directly synthesized from the diacid III and various aromatic diamines (IV_a-p). The resultant polyamide-imides had inherent viscosities between 0.56–1.39 dl/g. All polymers, except some derived from diamines with p-phenoxy structure, showed excellent solubility. Some polymer resulted in tough or flexible transparent films. Dynamic TG data indicated that all polymers possess excellent thermal stability with no significant weight loss up to the temperature of approximately 450 °C in nitrogen, and their 10% weight loss temperature was recorded in the range of 489–577 °C. Measurements of wide-angle X-ray diffraction revealed that some polymers derived from p-phenoxy group-containing diamines showed crystalline patterns.     

Preparation and properties of starch thermoplastics modified with waterborne polyurethane from renewable resources

A waterborne polyurethane (PU) aqueous dispersion was synthesized from castor oil, and blended with thermoplastic starch (TPS) to obtain a novel biodegradable plastic with improved physical properties. The effect of PU content on the morphology, miscibility and physical properties of the resulting blends was well investigated by scanning electron microscopy, differential scanning calorimetry, dynamic mechanical thermal analysis and measurements of mechanical properties and water sensitivity. The research results show that the blends exhibit a higher miscibility when PU content is lower than 15 wt% due to the hydrogen bonding interaction between urethane groups and hydroxyl groups on starch, whereas obviously phase separation occurs in the blends with more than 15 wt% PU. Incorporating PU of 4-20 wt% in TPS results in the blends with improved Young's modulus (40-75 MPa), tensile strength (3.4-5.1 MPa), elongation at break (116-176%). Further, PU also plays an important role in improving the surface- and bulk-hydrophobicity and water resistance of the resulting blends.     

A comparison of poly(ether imide)s from diamines with 2-aminophenoxy or 4-aminophenoxy units: Synthesis, characterization and properties

A series of new 3- and 4-ring bis(2-aminophenoxy) aromatic diamines were prepared. These, and corresponding, conventional bis(4-aminophenoxy) diamines were reacted with several aromatic bis(ether anhydride)s to form poly(ether imide)s. The diamines with 4-aminophenoxy groups gave high-molecular-weight polymers that were cast into films with good mechanical properties. In contrast, in almost all cases, diamines with 2-aminophenoxy groups only gave low-molecular-weight powdery products that could not be cast into coherent films. The low-molecular-weight products, prepared from stoichiometrically equal amounts of monomers, were examined by mass spectrometry and shown, in most cases, to consist primarily of cyclic oligomers; traces of linear oligomers were identified in some samples. Apart from a polyimide prepared from pyromellitic dianhydride and 4,4′-bis(2″-aminophenoxy)biphenyl, the only products found to contain significant proportions of linear oligomers were those prepared with a stoichiometric imbalance of monomers. End groups of the various linear oligomers were identified. The 2-aminophenoxy groups predispose the oligomers to cyclize as amic acids, and to remain as cyclics on imidization. In some cases [1+1] cyclic oligomers were observed although the most common species were the [2+2] cyclic dimers.     

Synthesis and characterization of aqueous (polyurethane/aromatic polyamide sulfone) copolymer dispersions from castor oil

Aqueous dispersions of castor oil-based polyurethane (PUCO)/aromatic polyamide sulfone (APAS) block copolymers (PUCO-co-APAS) were successfully synthesized via a copolymerization reaction. PUCO was prepared by an emulsion polymerization process in four steps, namely isocyanate-terminated prepolymer preparation step (PUCO_NCO), neutralization step, chain extension step and dispersion step, using castor oil (CO), toluene diisocyanate (TDI), dimethylol propionic acid (DMPA) and ethylene diamine (EDA) as a chain extender. APAS was prepared by a polycondensation reaction between bis(4-aminophenyl)sulfone (in molar excess) and terephthaloyl chloride to produce amino-terminated APAS. Three PUCO-co-APAS were prepared via a copolymerization reaction between the amino-terminated APAS and isocyanate-terminated PUCO_NCO prepolymer. APAS, PUCO and PUCO-co-APAS copolymers were characterized using FTIR, ¹H NMR, particle size distribution (PSD), zeta potential (ZP), thermal analysis (DSC and TGA) and GPC. The effect of the copolymerization process on the thermal, chemical, physical and mechanical properties of PUCO films was studied. The obtained results revealed that the mean particle size of PUCO decreased from 80 nm to 46–49 nm after the copolymerization process. Additionally, narrower size distribution was obtained by the copolymerization process. However, the molecular weight increased with increasing the amount of APAS in the copolymer chains. The copolymerized samples showed better thermal stability than PUCO as a result of the stronger hydrogen bonds and the rigid aromatic groups introduced by APAS in the copolymeric chains.     

Fully biobased polyester polyols derived from renewable resources toward preparation of polyurethane and their application for coatings

Renewable resources such as isosorbide and dimer acid were used to prepare fully biobased polyester polyols and polyurethane (PU) coatings. The structural features of polyester polyols were studied by end-group analysis and spectroscopic methods. Then polyols were utilized in the preparation of PU coatings by reacting with diisocyanate. The prepared PU coatings were tested for both mechanical and chemical testings, which involved gloss, cross-cut adhesion, pencil hardness, anticorrosion performance by immersion and Tafel plot methods, and chemical resistance against water, solvent, and acid media. The prepared PUs were also tested for their thermal stability using a thermogravimetric analyzer and surface morphology by a scanning electron microscopy. Tested mechanical properties, chemical resistance, and thermal stability results demonstrated that the renewable sources used in the preparation of PU coatings can be good substitutes over petroleum resources. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47558.     

Synthesis and characterization of new polyamides derived from 1,3‐(4‐carboxy phenoxy) propane and aromatic diamines

Six new polyamides 5a‐f containing flexible trimethylene segments in the main chain were synthesized through the direct polycondensation reaction of 1,3‐(4‐carboxy phenoxy) propane 3 with six derivatives of aromatic diamines 4a‐f in a medium consisting of N‐methyl‐2‐pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel polyamides containing flexible trimethylene segments in the main chain in high yield with inherent viscosities between 0.32 and 0.68 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). The glass‐transition temperatures of these polyamides were recorded between 165 and 190°C by differential scanning calorimetry, and the 10% weight loss temperatures were ranging from 360 to 430°C under nitrogen. 1,3‐(4‐Carboxy phenoxy) propane 3 was prepared from the reaction of 4‐hydroxy benzoic acid 1 with 1,3‐dibromo propane 2 in the presence of NaOH solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Jatropha oil and karanja oil as carbon sources for production of sophorolipids

Biosurfactants like sophorolipids (SL) are mild and environmentally friendly surfactants to be used in cosmetics and health care products. In addition to surfactant properties, SL also possess antimicrobial and skin healing properties. SL are produced by microbial fermentation using refined vegetable oils with glucose as a carbon source. This affects the economics of the production of SL. In the present work, non‐traditional oils like jatropha oil, karanja oil, and neem oil were used as newer feedstock for fermentative production of SL using Starmerella bombicola (ATCC 22214). In the fermentation, jatropha oil and karanja oil gave 6.0 and 7.6 g/L of SL (mainly lactonic form), respectively. HPLC, liquid chromatography–mass spectrometer, and ¹H NMR of crude SL obtained from fermentation broth showed lactonic form of two major SL. Oleic acid and linoleic acid were preferentially consumed over other fatty acids by the organism. Neem oil gave lower yield, i.e., 2.63 g/L of SL (mainly acidic form). Practical applications: Jatropha oil and karanja oil are one of the non‐traditional oils grown wildly in India that have large potential that is still to be explored. These oils contain non‐glycerides components that exclude their use as edible oil. These oils can be used as substrate for SL that can find novel applications like in soil remediation, skin care production, antimicrobial agents, low foaming detergents, and food additives. The current study has provided proof of concept work that has indicated the potential of these oils to be used as substrate for SL. It has opened new avenues and there is further scope to improve the yield by validating the process parameters like aeration rate, residual substrate recycle and pH control.     

The study of oxazolidone formation from 9,10-epoxyoctadecane and phenylisocyanate

The formation of oxazolidone from 9,10-epoxyoctadecane and phenylisocyanate was studied. One branch of epoxidized vegetable oil with one epoxy group per chain corresponds to 9,10-epoxyoctadecane. This model could explain the probability of oxazolidone formation from natural oil-derived epoxides. Epoxidized natural oils are TG consisting of glycerin and three FA with or without one to three epoxy groups in the middle of the chain. To study oxazolidone formation from an internal epoxy group without possible interference from the side reactions on the ester group, 9,10-epoxyoctadecane was selected as the most appropriate model compound. Epoxy groups in the middle of allong aliphatic chain are of low reactivity toward isocyanates, and preparation of oxazolidones requires fairly harsh conditions such as high temperatures and catalysts, which also promote side reactions. The dominant side reaction is rearrangement of the epoxy groups. We found that the direction and magnitude of the rearrangement and the yield of any particular product depended on the catalyst used. Lithium chloride, aluminum trichloride, and zinc iodide catalyzed oxazolidone formation, along with the catalysis of side reactions such as ketone and carbonate formation. Aluminum trichloride showed the highest conversion of 9,10-epoxyoctadecane to oxazolidone. Aluminum triisopropoxide, triphenylantimony iodide, and imidazole did not catalyze the formation of oxazolidone. They were effective as catalysts of epoxy group rearrangement and promoted the formation of hydroxyl, ketone, and carbonate compounds. Hydroxyl groups reacted with isocyanate to produce urethane.     

Oxygen barrier materials from renewable sources: Material properties of softwood hemicellulose‐based films

The aim of this study was to investigate the film‐forming ability of the hemicellulose O‐acetyl‐galactoglucomannan (AcGGM) and to evaluate its potential as a barrier material. The polymer film was evaluated by measurement of its oxygen permeability (Ox‐Tran® Mocon), thermal properties (differential scanning calorimetry), and dynamic mechanical properties under a humidity scan (humidity‐scan DMA). The AcGGM was isolated from industrial process water obtained from mechanical wood pulping. The self‐supporting films were formed by solution‐casting from water. As expected, a plasticizer was needed to avoid brittleness, and glycerol, sorbitol, and xylitol were compared. However, these additives resulted in higher sensitivity to moisture, which might be less beneficial for some applications. Interesting oxygen barrier and mechanical strength properties were achieved in a film obtained from a physical blend of AcGGM and either alginate or carboxymethylcellulose, both having a substantially higher molecular weight than AcGGM. No phase separation was observed, since all the components used were rich in hydroxyl functionalities. When a plasticizer was also added to the binary mixture, a compromise between (1) low O₂ permeability, (2) high mechanical toughness, and (3) flexibility of an AcGGM‐based film was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2985–2991, 2006     

Synthesis of core-shell polyurethane-polydimethylsiloxane particles in cyclohexane and in supercritical carbon dioxide used as dispersant media: a comparative investigation

Polyurethane-polydimethylsiloxane particles of tuneable diameter in the range 0.5-5 μm, have been synthesized by step-growth polymerization, both in cyclohexane and in supercritical carbon dioxide (scCO₂) used as dispersant media. The feasibility of the polyaddition between ethylene glycol and tolylene-2,4-diisocyanate, selected as monomers, was first demonstrated in cyclohexane, in the presence of hydroxy- or isocyanate-terminated polydimethylsiloxane used as a surfmer. The polymerizations were then carried out in scCO₂ at 60 °C and above 200 bar, after the solubility of each reactant has been determined in scCO₂, at various pressures and temperatures. Both in cyclohexane and in scCO₂, the reaction extent was determined by means of FTIR spectroscopy. The structure and the morphology of the resulting powdery polyurethane-polydimethylsiloxane ‘core-shell’ material were confirmed by NMR, SEC, TEM and SEM techniques.     

国内外MBS树脂的生产和最新研究进展

概述了国内外PVC抗冲改性剂MBS的生产现状,不同牌号MBS产品的主要性能、用途,以及MBS树脂的新塑合成技术和发展趋势。     

Integrated chemo- and biocatalytic processes: a new fashion toward renewable chemicals production from lignocellulosic biomass

Concerns over climate change and environmental pollution resulting from petroleum refining has spurred the exploitation of green replacements for producing chemicals and fuels. Valorization of lignocellulosic biomass into chemicals represents a promising alternative to petroleum refining. Biological and chemical catalysis are two leading routes for lignocellulose variolization, but strategies relying simply on biological or chemical conversion have shown limitations. Integrating biocatalysts with chemocatalysts could leverage the inherent strengths of both while circumventing their respective disadvantages, benefiting product yield and selectivity, and reducing cost and waste generation. This review focuses on the coupled chemocatalytic and biocatalytic synthesis of renewable chemicals from polysaccharides and their derived platform chemicals. In addition, strategies for producing value-added products from lignin via integrated chemical depolymerization and biological conversion are highlighted. The techno-economics of integrating chemocatalysts and biocatalysts in producing chemicals in the context of biorefinery are also discussed. Finally, perspectives on designing integrated chemical and biological catalysis for renewable chemicals production are provided. © 2022 Society of Chemical Industry (SCI).     

Synthesis and characterisation of new polymaleamides from N,N′-ethanedianilinebisisomaleimide with some aromatic diamines

Five polymaleamides have been synthesised by the ring-opening polyaddition of N,N′-ethanedianilinebisisomaleimide (EBIMI) with aromatic diamines (having methyl or methoxy ring substituents) at room temperature; EBIMI was synthesised from N,N′-ethanedianilinebismaleamic acid. Infrared, ¹³C NMR, and UV–visible spectroscopies, inherent viscosity measurements, thermogravimetry, differential scanning calorimetry and mass spectrometry have been used to characterise these polymers.     

Additive manufacturing of silicon nitride ceramics: A review of advances and perspectives

Silicon nitride (Si₃N₄) ceramic has been widely applied in various engineering fields. The emergence of additive manufacturing (AM) technologies provides an innovative approach for the fabrication of complex-shaped Si₃N₄ ceramic components. This article systematically reviews the advances of the AM of Si₃N₄ ceramic in recent years and forecasts the potential perspectives in this field. This review aims to motivate future research and development for the AM of Si₃N₄ ceramic.     

中国煤基活性炭生产设备现状及发展趋势

阐述了原煤直接破碎活性炭、柱状成型活性炭与压块破碎活性炭3种煤基活性炭的生产工艺,说明压块破碎活性炭是未来发展的主流产品。重点介绍了活性炭生产过程中主要生产设备的应用现状,包括捏合设备、柱状成型设备、压块成型设备、炭化设备以及活化设备等,并从易用性、处理能力、环保、造价、自动化水平、设备成熟度等方面对比分析了不同生产设备的特点。最后对中国活性炭生产设备发展趋势进行了展望,提出活性炭设备正朝着设备大型化、节能减排化、专业设备制造标准化以及生产设备自动化等方向发展。     

Synthesis of nanostructured SiC by magnesiothermal reduction of silica from zeolite ZSM-5 and carbon: The effect of carbons from different sources

Nanostructured SiC was synthesized by magnesiothermal reduction of silica derived from zeolite ZSM-5 with a Si/Al ratio of about 80 and four carbons from different sources. The carbons were carbon black and three carbons synthesized by impregnating furfuryl alcohol or sucrose into three porous templates (ZSM-5, clinoptilolite and MCM-48). Magnesiothermal reduction was carried out by reacting mixtures of silica, carbon and magnesium powder at 600–800 °C in a flowing argon atmosphere. The starting materials and final products were characterized by X-Ray diffraction, thermogravimetric analysis, scanning electron microscopy and BET analysis. The results indicated that the synthesis of nanostructured SiC is influenced by the chemical nature of the carbon and its surface area.