Water-carrying Agent Research Articles

The shape memory effect of crosslinked ultra-high-molecular-weight polyethylene prepared by silane-induced crosslinking method

Crosslinked ultra-high-molecular-weight polyethylene (UHMWPE) with excellent shape memory properties was prepared from the silane-grafted UHMWPE mixed with water-carrying agent by compression molding. The alkoxysilane hydrolyzation and condensation reaction of the silane-grafted UHMWPE allowed for the generation of Si–O–Si chemical crosslinking points between the polymeric chains. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results confirmed that silane has been grafted on UHMWPE chains successfully. The resulting crosslinked products were characterized using dynamic mechanical analysis, gel measurement, impact test, tensile test, thermogravimetric analysis and shape memory bending test to obtain insight into the relationship between the structure and the properties. By controlling the content of water-carrying agent, the average molecular weights between crosslinking points (M c) reduced from 29,530 to 9540 g/mol. The decomposition temperature (T d) value increases from 467.7 for virgin resin to 491.5 °C for the crosslinked product with 91.64% gel ratio. The crosslinked materials showed much better shape memory effect than pure UHMWPE; the shape recovery ratio (R ν ) value of silane-induced crosslinked UHMWPE with 1.0 phr water-carrying agent reaches above 98.0% under multiple deformation recovery cycle. Therefore, the silane-induced crosslinking UHMWPE has a great potential in the shape memory material applications.

The biomimetic catalytic synthesis of acetal compounds using β-cyclodextrin as catalyst

Based on the principle of biomimetic catalysis, β-cyclodextrin was applied to the acetalation reaction as a facile and efficient catalyst, and the synthesis was environmentally friendly with atomic economy. The influencing factors of the acetalation reactione.g.the reaction time, the volume of water-carrying agent, the molar ratio of catalyst to benzaldehyde and the molar ratio of glycol to benzaldehyde had been studied. The yield of benzaldehyde glycol acetal would reach a maximum of 81.3% under the conditions approached. Six of other acetals were also synthesized. Moreover, a plausible reaction mechanism for the formation of acetal had been proposed.

Synthesis, Characterization and Performance of Superplasticizer with a Multi-Arm Structure

A novel superplasticizer with a multi-arm structure, i.e., a “core” connected with multiple copolymer “arms”, was synthesized through two steps including an esterification reaction between polyhydric alcohols and acrylic acid and a copolymerization reaction in an aqueous solution among the esterification product, isobutenyl polyethylene glycol and acrylic acid. The reaction conditions were determined, and the results showed that the esterification rate can reach above 95% with a water-carrying agent of 70g, a catalyst/alcohol molar ratio of 0.07, an inhibitor/monomer molar ratio of 0.03, and a reaction time of 7 hrs. The reaction products were characterized by 1H Nuclear Magnetic Resonance (1H NMR) and Fourier Transform infrared spectroscopy (FTIR). It is confirmed to be the multi-arm structure, and the self-synthesized superplasticizer with a multi-arm structure exhibited higher energy efficiency, which was in accordance with its excellent paste fluidity performances and adsorption behavior in cement paste

Optimization of Process Variables in the Synthesis of Isoamyl Isovalerate Using Sulfonated Organic Heteropolyacid Salts as Catalysts

Based on single factor experiments, a three level, four variable central composite designs were carried out to establish a quadratic regression model for the catalytic synthesis of isoamyl isovalerate over sulfonated organic heteropolyacid salts as a function of molar ratio of alcohol to acid, reaction time, the amount of water-carrying agent and the amount of catalyst. The optimum conditions were obtained as follows: n (isoamyl alcohol): n (isovaleric acid) = 1.1:1, amount of catalyst was 6.4% of acid, reaction time 2 h and water-carrying agent 10 mL. Under these conditions, the yield of isoamyl isovalerate reached 97.5%. The ionic liquid could be reused six times without noticeable drop in activity. Under optimum conditions, catalysts showed a superior catalytic efficiency and reusability due to better superacidity, lower molecular transport resistance and self-separation characteristics.

A New Technological Study on Synthesis of Bis(2-chloroethoxy)Methane

bis(2-chloroethoxy)methane was synthesized by the reaction of ethylene chlorohydrin and Oligopolyformaldehyde under sulfuric acid catalysis. optimum reaction conditions obtained were as follows: the molar ratio of Oligopolyformaldehyde and ethylene chlorohydrin of 1.2:2, catalyst dosage was 5‰mass fraction of ethylene chlorohydrin, toluene were chose as water-carrying agent, All reactant were refluxed on temperature of 110°C until no water generated. Under the optimum conditions the yield of bis(2-chloroethoxy)methane was 97.7%. The structure of bis(2-chloroethoxy)methane were conformed by ATR IR. The purity of bis(2-chloroethoxy)methane were 99% by gas chromatographic detection.

Heteropolyacid-based ionic liquids as effective catalysts for the synthesis of benzaldehyde glycol acetal

A series of environmental benign ionic liquid (IL) catalysts, synthesized by incorporating varied amounts of tungstophosphoric acid (TPA) and pyridinium propyl sulfobetaine (PPS) zwitterionic precursor, were exploited for homogeneous conversion of biomass. In particular, these water-soluble PPS-TPA IL ([PPSH]xH3−xPW12O40; x=1.0–3.0) catalysts were evaluated for acetalization of benzaldehyde with glycol. The catalyst system revealed self-separation characteristics, which resulted in the formation of biphasic product/catalyst layers to render facile product separation and catalyst recycling. Among various PPS-TPA ILs examined, the [PPSH]2HPW12O40 catalyst exhibited excellent durability and an optimal acetal yield over 85%, in good agreement with that predicted by factorial design of experiments and response surface methodology (RSM). The effects and correlations of different experimental variables such as reaction time, relative reactant concentration, amount of water-carrying agent, and amount of catalyst were addressed by the Box–Behnken design (BBD). The deduced optimal conditions lead to an acetal yield of 85.2%, which is consistent with experimental results and that predicted by the BBD model. The superior acetalization activities observed for the novel PPS-TPA IL catalysts are attributed to their highly acidic nature and weak mass transport resistance.

Conversion of platform chemical glycerol to cyclic acetals promoted by acidic ionic liquids

The condensation of glycerol, a platform chemical from renewable materials, with benzaldehyde to generate cyclic acetals was investigated using acidic ionic liquid as catalyst. Evidence was presented that the product mixture of 4-hydroxymethyl-2-phenyl-1,3-dioxolane and 5-hydroxyl-2-phenyl-1,3-dioxane, with cis and trans two stereo-isomers for each one identified by 1H NMR were obtained. Further modification of reaction conditions promoted by N-butyl-pyridinium bisulfate ([BPy]HSO4) led to the totally cyclic acetals with 99.8% yield at room temperature. A micro water-removal reactor constituted by ionic liquids was proposed, which favourably shifted the condensation equilibrium to the product side by transferring the produced water out of the organic phase in time, so that the water-carrying agent or reactive distillation was avoided. Moreover, the product separation made this methodology more accessible to sustainable green biomass chemistry.

Research on Esterification Technology of Polycarboxylate Superplasticizer and its Cement Paste Fluidities

The synthesis process of esterification products used for the preparation of polycarboxylate superplasticizier (PCE) was systematically investigated, and the influences of water dosage, the catalyst dosage, reaction time and inhibitor dosage on the esterification rate and cement paste fluidities were determined. The results showed that the esterification rate can reach more than 95% as the water-carrying agent of 70 g, catalyst-alcohol ratio of 0.07, reaction time of 7 hours, inhibitor-acrylic acid ratio of 0.03, respectively. The obtained esterification products subsequently copolymerized with macromonomer to prepare PCE, and then the application performances were tested by adding PCE to cement pastes. From the fluidity results, the cement paste fluidity and fluidity retention capacity of PCE were better than those of commercial PCE, and this was in accordance with the high esterification rate of its esterification rate.

Synthesis of Butanone 1,2 - Propanediol Ketal by Sulfamic Acid as Catalyzed

Butanone 1,2-propanediol ketal was synthesized by butanone and 1,2-propanediol as raw materials and sulfamic acid as catalyst. The effects of the mole ratio of raw materials agent, the dosage of the water-carrying agent and catalyst, reaction time on the product yield were discussed separately. Experimental results showed that sulfamic acid was a suitable catalyst for synthesizing of butanone 1,2-propanediol ketal. And the optimal reaction conditions are as follows: the mole ratio of butanone to 1,2-propanediol is 1:1.5, the amount of the catalyst is 2.2%, the water-carrying agent is 25ml, the reaction temperature is 358-378K and reaction time 3h. In this condition, the yield of production could reach 93.8%.

Catalytic Synthesis of Isoamyl Acetate by Ion Exchange Resin-Supported (NH<sub>4</sub>)<sub>6</sub>[MnMo<sub>9</sub>O<sub>32</sub>] • 8H<sub>2</sub>O with Waugh Structure

Ion exchange resin-supported (NH4)6[MnMo9O32]8H2O with Waugh structure is used to prepare supported solid catalyst. Performance of this catalyst is researched by means of synthesis of isoamyl acetate. Optimal reaction conditions determined by orthogonal experiment are as follows: acid-alcohol molar ratio is 2.5:1, reaction time is 120 min, catalyst dosage is 0.8 g, dosage of water-carrying agent is 2.5 ml, esterification yield reaches 95.1%. This catalyst is characterized by high catalytic efficiency, easy separation and recovery, absence of environmental pollution and being reusable, etc.

Synthesis and Characterization of Triethanolamine Borate

Starting with boric acid and triethanolamine , the effect of the different types of the water-carrying agent on the yield was invested, and influences of dosage of water-carrying agent ,the mole ratio of reactants, reaction time on yield were discussed, the optimized reaction conditions were confirmed. The structure of the product was described by Fourier transform-infrared (FT-IR) spectroscopy, NMR Spectroscopy analysis, mass spectrometry (MS) and thermodynamic properties was analyzed by differential scanning calorimetry (DSC) and thermogravimetry (TG).

Effect of Hot Water and Water-carrying Agent on the Properties of Silane-water Crosslinked Linear Low Density Polyethylene

Abstract The influence of hot water and the water-carrying agent aluminum potassium sulfate dodecahydrate (alum) on the mechanical and thermal properties of the silane-water crosslinked linear low density polyethylene (LLDPE) was investigated. LLDPE was melt-grafted with various content of vinyl trimethoxysilane (VTMS) using dicumyl peroxide (DCP) as initiator. The results show that the contribution of hot water to gel content is poor, about 2 to 16%, compared with that of the silane grafted LLDPE. Is feasible to achieve silane-water crosslinking reaction with alum for self-crosslinked LLDPE; furthermore, the self-crosslinked LLDPE has lower crosslink density (ν). It was found that alum could not only conduct silane-water crosslinking reaction effectively, but also improve the mechanical properties, especially the elongation behavior. The heat of fusion (ΔHm), the melting temperature (Tm), and the degree of crystallinity (Xc) of the hot water crosslinked LLDPE decreased with the advancement of VTMS. The Avrami exponent n of self-crosslinked sample was larger than that of hot water crosslinked sample. This means that the alum could contribute to the growth of crystallization.

An efficient method for preparation of propyl gallate using Brønsted acidic ionic liquid N-methyl pyrrolidonium hydrosulfate [Hnmp]HSO4

The synthesis of propyl gallate using Brønsted acidic ionic liquid N-methyl pyrrolidonium hydrosulfate [Hnmp]HSO4 as an efficient catalyst with gallic acid and n-propanol as materials was studied. The influence factors, such as the selection of water-carrying agent, reaction temperature, molar ratio of reactants, the dosage of catalyst, and the reaction time were also investigated. The results showed the optimum reaction conditions were as follows: the molar ratio of n-propanol and gallic acid and catalyst was 5:1:0.3, reaction time was 5h and the yield of propyl gallate was up to 89.8% without water-carrying agent at 95–105°C.

Study on Upgrading and Further Usage of Glycerol from Waste Water

Waste water from enzymatic biodiesel technology (contained glycerol 5%) is treated as following: Firstly, waste water is filtered with a gauze, add KOH to PH=7~8, and filter to remove salt soap. Secondly, the processed liquid distil at 50°C in Rotary Evaporator vacuum to remove most of water and methanol, then concentrated solution use plinthic flocculants (mass ratio of 100:1), stirring at 70°C to eliminate colloid. Finally, at 180°C, 0.8 kPa to vacuum distil to collect glycerol of purity up to 90.43％.The glycerol react with acetic acid to get glycerol triacetate with phosphotungstic acid catalyst, toluene as water-carrying agent. Thus comes out the yield of more than 90％ glycerol triacetate in 6 hours.

Esterification process to synthesize isopropyl chloroacetate catalyzed by lanthanum dodecyl sulfate

Isopropyl chloroacetate has been synthesized by esterification of chloroacetic acid and isopropanol, using lanthanum dodecyl sulfate (LDDS) as the catalyst. Various factors that affected the esterification have been investigated, such as reaction time, different water-carrying agent and the amount of catalyst. Under the condition of 1.2/1 molar ratio of isopropanol to chloroacetic acid, 1.0% catalyst (molar percent of chloroacetic acid), 2.5 h reaction time, 5 mL cyclohexane as water-carrying agent and reflux temperature, the esterification conversion of isopropyl chloroacetate reaches 98.3%. The catalytic activity of LDDS is almost equal to that of a BrA˜nsted acid. LDDS, as one kind of water-tolerant Lewis acid, is an excellent catalyst compared to the traditional Lewis acid.

SDS-Catalyzed Esterification Process to Synthesize Ethyl Chloroacetate

Using sodium dodecyl sulfate (SDS) as the catalyst, ethyl chloroacetate has been synthesized by esterification of chloroacetic acid and ethanol. Various factors that affected the esterification have been investigated, such as reaction time, different water-carrying agents, and amount of catalyst. The esterification yield of ethyl chloroacetate reached 97.1% with 1.2/1 molar ratio of ethanol to chloroacetic acid, 1.0% catalyst (molar percentage of chloroacetic acid), 2.5 hr reaction time, 5 mL cyclohexane as water-carrying agent, and reflux temperature. The catalytic activity of SDS is almost equal with Br⊘nsted acids, such as sodium hydrosulfate or p-toluene sulfonic acid. Its catalytic activity is greater than that of most Lewis acids. SDS can easily hydrolyze into sodium hydrosulfate, which plays an essential role during the esterification process. The advantage of this catalytic process is that it is environmentally friendly, with high esterification yield, which may meet the standards of green chemistry.

Esterification of Chloroacetic Acid with Alcohols Catalyzed by Zinc Methanesulfonate

Zinc methanesulfonate is prepared and used as a catalyst in many esterification reactions of chloroacetic acid with nearly equimolar amounts of alcohols. The catalytic activity, reusability, and handling of the catalyst are found to be good. Some factors that affect the esterification reaction of chloroacetic acid with isopropanol are investigated. Under the conditions of 1.1:1 molar ratio of isopropanol to chloroacetic acid, 0.5 mol% of the catalyst (molar percent of chloroacetic acid), 2.5 h of reaction time, ca. 14 mol% of cyclohexane (molar percent of chloroacetic acid) as water-carrying agent, and the temperature 85-90°C, the yield of isopropyl chloroacetate is 96.2%. In most cases, the catalyst is reused six times without obvious loss of catalytic activity.