Gel Permeation Chromatography Method Research Articles

Gamma Irradiation and the Radiation Shielding Characteristics: For the Lead Oxide Doped the Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers and the Polystyrene-b-Polyethyleneglycol-Boron Nitride Nanocomposites.

This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage rates of PbO were used to research gamma-ray shielding characteristics. The synthesis of the copolymer was done by emulsion polymerization methods. The characterization and morphological analyses of irradiated samples were explored handling with the Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) methods. The gamma-rays that were emitted from the source were observed with a High Purity Germanium (HPGe) detector system and examined with a GammaVision computer program. Our samples, including the different percentage rates of the PS-b-PEG (1000, 1500, 10,000), BN, and PbO, were irradiated in various gamma-ray photon energy regions (from 121.78 keV to 1408.01 keV). Then, Linear-Mass Attenuation Coefficients (LACs-MACs), Half-Tenth Value Layer (HVL), Mean Free Path (MFP), and Radiation Protection Efficiency (RPE) values of the samples were calculated. Via crosschecking the acquired data from samples with and without PbO and BN, it was observed that, if the different percentage rates by weight nano-powder of PbO and BN are added in the polymer mixture, it can be used as a convenient shielding material against gamma rays.

Sunflower and Linseed Oils with Decyl Methacrylate Based Copolymers as Green Lubricating Additives

During the last few years, the greener additives prepared from bio-raw materials with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In the present work, copolymers derived from sunflower and linseed oils with decyl methacrylate were synthesized by a thermal method using benzoyl peroxide (BPO) as a radical initiator. Direct polymerization through the double bonds of the fatty acid chain in the presence of a free radical initiator leads to the formation of ecofriendly copolymeric additives (P1 and P2). The copolymers were characterized by Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (1H-NMR). Thermal decomposition of copolymers was determined by thermogravimetric analysis. The average molecular weight was measured by gel permeation chromatography (GPC) method. Different concentrations of prepared copolymer as additives vis 1, 2, 3, and 4 (w/v) were used to examine the rheological behavior and performance evaluation of the formulated base oil. The copolymer acts as an excellent viscosity improver and better pour point depressant.

Gel-permeation chromatography as a method for monitoring transformations of heavy petroleum fractions during secondary oil refining

A rapid and easy to use method for monitoring transformations of heavy oil fractions during secondary processes of oil refining is proposed. The method is based on the study of changes in the molecular weight characteristics by gel-permeation chromatography (GPC) using a refractometric detector. Optimal conditions for registration of the chromatograms (temperature, eluent consumption and its composition) were specified. Heptane, toluene, and toluene added with 1% and 5% of methanol were studied as eluents, the polarity indices being arranged in a series 0.2; 2.4; 2.43; 2.54. The effect of the nature of the solvent on the type of the product chromatogram is determined. It is shown that addition of a polar solvent to a nonpolar one increases the polarity index, reduces both the degree of association of petroleum molecules and adsorption on the gel. The most available toluene which meets the GPC requirements is chosen as an eluent. Addition of 1% CH3OH to the eluent promotes suppression of polyelectrolyte effects and adsorption. The revealed absence of the dependence of the retained volume and the type of chromatograms on the eluent flow rate and temperature indicates that separation is carried out under conditions of exclusion and completely obeys the theory of exclusive liquid chromatography. The transformation of raw materials during a technological process of oil production at the JSC «ANKhK» was studied using the GPC method under above-mentioned chromatographic conditions. We have studied vacuum distillate of the primary oil refining unit ELOU+AVT-6 (VD) and the product of hydrocracking of the vacuum distillate of the 123PM unit (HVD). It is shown that determination of the molecular weight characteristics provides an important information about the behavior of technological processes. The HVD meets the requirements for hydrocracking products. A decrease in the content of aromatic hydrocarbons in comparison with the raw feedstock is proved by the data of thin layer chromatography (TLC).

Rapid and Nondestructive Determination of Polyacrylonitrile Molecular Weight by Fourier Transform near-Infrared (NIR) Spectroscopy

The molecular weight of polyacrylonitrile (PAN) precursors plays an important role in specifying the properties of prepared carbon fibers. However, it is challenging to rapidly and conveniently determine the accurate molecular weight of PAN. Herein, a practical and facile molecular weight determination model of PAN based on near-infrared spectroscopy (NIR) combined with partial least squares (PLSs) is reported. Using the spectral modeling range from 4000 to 6000 cm−1 with standard normal variate (SNV) or multiplicative scatter correction (MSC) combined with smoothing and first-order differential, the optimized models with main factors number of nine are achieved. The models were systematically evaluated by root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP), and root mean squares error of cross-validation (RMSECV). In the determination of the molecular weight of the samples based on these optimized models, the value of the relative standard deviation is only 0.9%, and the value of deviation from the established gel permeation chromatography (GPC) method is between −0.037 × 105 and 0.051 × 105. The results show that the reported NIR method has promising potential for the rapid and nondestructive determination of the molecular weight of PAN in production processes.

Copolymers of Castor and Corn Oils with Lauryl Methacrylate as Green Lubricating Additives

During the last few years, the greener additives prepared from bio-raw materials with low-cost and multifunctional applications have attracted considerable attention in the field of lubricant industry. In the present work, copolymers derived from sunflower and linseed oils with decyl methacrylate were synthesized by a thermal method using benzoyl peroxide (BPO) as a radical initiator. Direct polymerization of fatty acid double bonds in the presence of a free radical initiator results in the development of environmentally friendly copolymeric additives (Co-1 and Co-2). Fourier Transform Infrared (FTIR) and Proton Nuclear Magnetic Resonance (1H-NMR) were used to characterize the resulting copolymers. Thermal decomposition of copolymers was determined by thermogravimetric analysis. The average molecular weight was measured by gel permeation chromatography (GPC) method. Different concentrations of prepared copolymer as additives vis 1, 2, 3, and 4 (w/v) were used to examine the rheological behavior and performance evaluation of the formulated base oil. The prepared copolymers show good thermal stability. Both prepared polymeric additives (Co-1 and Co-2) are evaluated as pour point depressant and excellent viscosity improver. The base oil blended with Co-1 has higher viscosity index value than the base oil blended with Co-2. The pour point values for the base oil blended with Co-1 and Co-2 are ranging from (-11 to -15 oC) and (-12 to -15 oC), respectively.

Influence of soaking temperature time on the ability prepared liquefaction of wood from cashew nut shell waste

Liquefied wood is one of the phenolic resin. However, unlike commercial phenolic resins that are normally synthesized by the chemical reaction between phenol and formaldehyde, liquefied wood is usually produced by reacting phenol with wood-derived materials, and catalyst at 120-180◦C. Depending on whether the catalyst is a base or a acid, the formed resin is a thermoset or a thermoplastic. In this study, wood liquefaction was prepared from a cashew nut shell waste (CNSW), phenol, and sulfuric acid catalyst. The cashew nut shell waste is taken from Binh Phuoc province - Vietnam and crushed to a size of less than 500 mm. Phenol and sulfuric acid catalyst are chemical experiments. The powder of cashew nut shell waste, phenol, and sulfuric acid were mixed and reacted at 150oC for different soaking times. An optimal soaking temperature time was determined through a cashew nut shell waste residue content in wood liquefaction products. The wood liquefaction products also were determined by a number average molecular weight (Mn) and a weight average molecular weight (Mw) by Gel permeation chromatography method (GPC); the function groups by Fourier Transform Infrared method (FT-IR). The results showed that the formed resin is thermoplastic and the optimal soaking time to prepared liquefied wood is 180 minutes. This sample has a residual cashew nut shell waste ratio of 9.44%, a number average molecular weight of 7552, and a weight average molecular weight of 10640. The liquefied wood from cashew nut shell waste can be used as a binder in the manufacture of the medium density fiberboard (MDF) or as a material to promote the sintered process in the production of woodceramic materials. In addition, the liquefied wood can also be pyrolyzed to form carbon fiber. Carbon fiber can be applied as reinforcing materials for ceramic products.

Forensic comparison analysis of plastic vehicle headlamp lens by gel permeation chromatography and statistical methods.

Comparison analysis of vehicle headlamp lens fragments can help establish links between the relevant vehicle with crime scenes or provide useful information to search the related vehicles. Headlamp lenses are mainly made of polycarbonate with very few signature additives, which makes them difficult to be discriminated by commonplace examination methods of infrared spectroscopy and scanning electron microscope coupled with energy dispersive X-ray spectroscopy. In this study, molecular weights (Mw) and the polydispersity index (PDI) value of 50 vehicle headlamp lens fragments from different vehicles were measured by gel permeation chromatography, and Hotelling's T2 statistical method was applied to facilitate interpretation of the data. Among the total pairs of comparisons between 50 samples, 62 pairs cannot be distinguished, resulting in a discrimination rate of 94.94%. It suggested that the method of gel permeation chromatography and Hotelling's T2 statistical analysis were powerful to make further discrimination between plastic vehicle headlamp lens fragments.

Development of a gel permeation chromatography method for analysing cellulose nitrate in museums.

This article describes the development of a suitable Gel Permeation Chromatography method for cellulose nitrate plasticised with camphor (celluloid) found in cultural heritage. Current sample preparation and dissolution methods, apart from focusing on native, nonderivatised cellulose, require long preparation times, and often employ solvents that induce degradation. This study aims to develop a systematic method for sample preparation of cellulose nitrate that uses the least sample amount possible, is nondegrading, and can be applied on differently aged samples. This is investigated through identification of a suitable solvent system and a statistically designed experiment testing the critical variables affecting the analysis, namely sample condition, sample, and salt concentration (lithium chloride) in N,N-dimethylacetamide. The use of 0.1% sample was inadequate for analysis because it did not fully dissolve in any salt concentration, while the 0.3% negatively impacted the analysis with its high molecular weight distributions. The 0.2% cellulose nitrate in a solution of 0.5% lithium chloride in N,N-dimethylacetamide offered the most consistent and repeatable molecular weight data. This method miniaturised the sample as much as possible and is suitable for museum objects in various ageing conditions.

Molecular weight characteristics and sorption properties of pectin extracted from different substrates

The study of natural polymers is one of the most advanced tasks of modern chemistry. One of these polymers is the common polysaccharide pectin. Widespread acid hydrolysis was used to extract pectin from various substrates. Oxalic, citric and hydrochloric acids have been investigated for this purpose. The water-soluble pectin-containing fraction was extracted from the apples, sugar beet, lemon peel, pine needles. The optimal condition is heating the substrate in a boiling water bath for 1 hour with reflux in a solution of hydrochloric acid (pH 2-3). We neutralized the extract after cooling with an ammonia solution to isolate the dry powder of the pectin-containing component and the pectin was precipitated with ethanol. The study of pectin solutions by the method of gel permeation chromatography showed that they most often have three polymer fractions that are close in molecular weights: ~17-20, ~10-12 and ~0.5 kDa. The content of the last fraction in all selected samples is predominant. Solutions of pre-planted powders of the pectin-containing fraction significantly differ from the previously discussed results: the oligomeric fraction is practically absent in them. For a number of samples of pectin powders, the degree of esterification was determined by potentiometric titration. The dependence of the degree of esterification on both the feedstock and the isolation method was revealed. The method of reverse complexometric titration was used to study the sorption capacity of pectin. The analysis results suggest that there is an inversely proportional dependence of the degree of lead sorption of the pectin sample on its degree of esterification.

Simple cubic self-assembly of PbS quantum dots by finely controlled ligand removal through gel permeation chromatography.

The geometry in self-assembled superlattices of colloidal quantum dots (QDs) strongly affects their optoelectronic properties and is thus of critical importance for applications in optoelectronic devices. Here, we achieve the selective control of the geometry of colloidal quasi-spherical PbS QDs in highly-ordered two and three dimensional superlattices: Disordered, simple cubic (sc), and face-centered cubic (fcc). Gel permeation chromatography (GPC), not based on size-exclusion effects, is developed to quantitatively and continuously control the ligand coverage of PbS QDs. The obtained QDs can retain their high stability and photoluminescence on account of the chemically soft removal of the ligands by GPC. With increasing ligand coverage, the geometry of the self-assembled superlattices by solution-casting of the GPC-processed PbS QDs changed from disordered, sc to fcc because of the finely controlled ligand coverage and anisotropy on QD surfaces. Importantly, the highly-ordered sc supercrystal usually displays unique superfluorescence and is expected to show high charge transporting properties, but it has not yet been achieved for colloidal quasi-spherical QDs. It is firstly accessible by fine-tuning the QD ligand density using the GPC method here. This selective formation of different geometric superlattices based on GPC promises applications of such colloidal quasi-spherical QDs in high-performance optoelectronic devices.

Castor oil based eco-friendly lubricating oil additives

The application of vegetable oil based additive for lubricating oil has attracted considerable interest due to their biocompatibility and multifunctional performances compared to conventional additives. In the present work, we have synthesized homopolymer of castor oil and copolymer of castor oil with styrene by thermal method without any solvent at different percentage composition by using BZP (benzoyl peroxide) as initiator. Characterization of the additives was completed by spectral technique (FT-IR and NMR spectroscopy). The molecular weight of the prepared additives was determined by gel permeation chromatography method (GPC method). Thermo gravimetric analysis (TGA) method was used to study the thermal stability of the prepared polymers. Standard ASTM methods were used to investigate the performance of all the prepared polymers in SN150 mineral oil as viscosity index improver (VII), pour point depressant (PPD) and antiwear. Biodegradability of all the polymers was determined disk diffusion method. From the experimental results, it was found that copolymers are more effective as VII, PPD and antiwear than homopolymer. Moreover, average molecular weight, thermal stability and performances as VII and antiwear increase with increasing the percentage of styrene in copolymers.

Temperature Stability of DC Conductivity and Breakdown of Crosslinked LLDPE

In this paper, a way to improve the temperature stability of DC conductivity and breakdown characteristics of polyethylene (PE) is proposed using a crosslinked linear low density polyethylene (LLDPE). The ratio of DC conductivity, as well as breakdown strength values under 90 to 30°C is used to determine the temperature stability of DC properties. The closer it is to 1, the better the performance of temperature stability. The results show that when using crosslinked-LLDPE material, the ratio of DC conductivity under 90 to 30°C is 10.5, while it is 461.6 for crosslinked-LDPE samples with the same DCP content. And the ratio of DC breakdown strength is 0.97 for crosslinked-LLDPE, while it is 0.32 for crosslinked-LDPE. The gel permeation chromatography (GPC) method, hot-set test, differential scanning calorimetry (DSC) analysis and scanning electron microscopy (SEM) images show that the fine arrangement and smaller molecular weight between crosslinks of molecular and morphology structure that LLDPE owns contribute to the improvement in comparison with LDPE. The findings may contribute a solution to the development of HVDC power cable insulation materials.

Adsorption Characteristics of Synthesized Polyelectrolytes onto Alumina Nanoparticles and their Application in Antibiotic Removal.

The present study aims to investigate the adsorption of synthesized poly(2-acrylamide-2-methylpropane sulfonic acid) (PAMPs) onto alumina nanoparticles and their application in the removal of ciprofloxacin (CFX) antibiotic from a water environment. The PAMPs were successfully synthesized and characterized by nuclear magnetic resonance and gel-permeation chromatography methods. The number- and weight-average molecular weights of PAMPs were 6.76 × 105 and 7.28 × 106 g/mol, respectively. The charge reversal of nanoalumina after PAMPs modification from positive to -37.5 mV was determined by ζ-potential measurement, while the appearance of C ═ O and N-H functional groups in PAMPs observed by Fourier-transform infrared spectroscopy confirmed them as the main indicators for adsorption of PAMPs onto a nanoalumina surface. The maximum adsorption capacity of PAMPs onto nanoalumina in 100 mg/L KCl was about 10 mg/g. The adsorption isotherms were fitted well by a two-step adsorption model. Application of PAMPs-modified nanoalumina (PAMNA) in CFX removal was also thoroughly studied. The optimum conditions for CFX removal using PAMNA were found to be pH 6, 10 mM NaCl, contact time 90 min, and adsorption dosage 5 mg/mL. The CFX adsorption isotherms and kinetics were in accordance with the two-step and pseudo-second-order models, respectively. The application for CFX removal in actual hospital wastewater was greater than 80%. The results of this study demonstrate that PAMNA is a new and promising material for antibiotic removal from wastewater.

Lastingly Colored Polylactide Synthesized by Dye-Initiated Polymerization.

An efficient synthesis strategy of a well-defined polylactide–dye conjugate in a controlled fashion is presented. The introduction of coloring species as end groups of polylactide (PLA) has been performed by using new homoleptic aminophenolate magnesium or zinc coordination compounds. The molecular structure of metal complexes has been determined in solution by NMR spectroscopy, and in the solid state by X-ray analysis. Lastingly colored polymers were obtained with 2-[4-(Nitrophenylazo)-N-ethylphenylamino]ethanol (Disperse Red 1) and 2-[4-(2-Chloro-4-nitrophenylazo)-N-ethylphenylamino]ethanol (Disperse Red 13) at very high lactide conversions, based on MALDI-ToF measurement, and the macromolecules were nearly fully chain end dye-functionalized. Based on 1H NMR, the DPn of conjugates was in the range of 10–300, which was consistent with the reaction setup. Various methods of gel-permeation chromatography (GPC) analysis were applied, and they demonstrated that the number-average molar mass (Mn) values (polystyrene (PS) standards) were a bit higher than calculated, the molar mass distribution index (ƉM) values were moderate to high, the TDA (triple detection array) system was inappropriate for analysis, measurements with PDA (photo diode array) detection at 470 nm gave nearly the same molar mass distributions such as the refractometer, and the relative absorbance of conjugates at 470 nm increased linearly versus (DPn)−1. The presented approach connects the gap between the current strategy of obtaining colored polymer fibers and the design of tailor-made initiators with eco polyesters designed for the targeted applications.

Polymeric nanomaterialsbased on iron (III) tris-acetylacetonate: synthesis, structure and properties

The formation of iron (III) polychelates under different conditions has been investigated: at mechanochemical activation of iron (III) tris-acety lacetonate with subsequent condensation in boiling toluene (method 1) and through chelate heating in air at 100, 150, and 200°C (method 2).The obtained compounds have been studied by the methods of gel permeation chromatography, diffractometry and infrared spectrometry, scanning electron microscopy, and gamma resonance spectroscopy.Based on the obtained data, the maximal particle size has been calculated. The fractal structure of spherical particles was presented.

Salinomycin-loaded PLA nanoparticles: drug quantification by GPC and wave voltammetry and biological studies on osteosarcoma cancer stem cells.

A new straightforward gel permeation chromatography (GPC) method was developed to calculate the drug encapsulation efficiency and loading content of Poly(lactic acid) nanoparticles (PLA NPs) loaded with Salinomycin (Sal), exploiting the capability of this technique to separate a macromolecular/molecular mixture on the basis of the molecular weight of each component. The proposed GPC method allowed Sal detection until 1% of Sal content in PLA NPs, avoiding sample pre-treatments. The method was validated by wave voltammetry (SW) technique, using a slightly modified literature procedure, useful to detect Sal in the concentration range 0.4 ≤ C/μmol/L ≤ 12 (linear concentration range). PLA-based NPs were prepared by nanoprecipitation with either native and functionalized PLA. Specifically, folate-decorated PLA NPs (PLA-FA NPs) were obtained by CuAAC click functionalization of alkyne-grafted PLA with azide-folate. Sal-loaded NPs were characterized physicochemically and morphologically. They exhibited adequate physicochemical properties, good drug encapsulation efficiency (98 ± 0.5% and 99 ± 0.5%), and loading content (8.8 ± 0.1% and 8.9 ± 0.1% for PLA/Sal and PLA-FA/Sal NPs, respectively). The size of empty PLA NPs resulted smaller (90 ± 3.2nm and 680 ± 15.3nm, for PLA NPs and PLA-FA NPs respectively) than the correspondent drug-loaded NPs (110 ± 3.8nm and 875 ± 20.5nm, respectively). Their biological activity was assessed on osteosarcoma bulk cells MG63, healthy osteoblast cell line (hFOB1.19), and enriched osteosarcoma cancer stem cells (CSCs), showing cell-depending effect. Entrapped Sal maintained its cytotoxic effect on CSCs and MG63 cells, with a potency comparable to the free drug and no evident benefit was detected for folate-decorated PLA NPs respect to native PLA NPs. Graphical abstract.

Universal calibration of gel permeation chromatography using evaporative light scattering detector coupled with viscometer

The linearized evaporative light scattering detector (ELSD) allows the evaluation of molecular weight distributions (MWD) of a range of polymers using conventional gel permeation chromatography (GPC), and is a suitable replacement for the differential refractive index (DRI) detector in applications which will benefit from fast equilibration, solvent gradients or when working with low polymer concentrations. Further, when DRI is coupled with a viscometer, the Universal Calibration GPC method also allows the evaluation of Mark–Houwink–Sakurada parameters K and alpha, which provides valuable information on the chemical structure of polymer chains. Therefore, for a wider acceptance of ELSD in GPC, we investigated the possibility of coupling the ELSD with the viscometer. Recommendations are provided for successfully coupling the ELSD and viscometer, as well as on software adjustments to calculate K and alpha parameters. For linear polyethylene, a good correlation was found between the measured and the expected K and alpha values.

Intelligent Poly(N-Isopropylmethacrylamide) Hydrogels: Synthesis, Structure Characterization, Stimuli-Responsive Swelling Properties, and Their Radiation Decomposition.

Poly(N-isopropylmethacrylamide) (p(NiPMAm)) is one of the lesser known homopolymers that has significant potential for designing new “intelligent” materials. The aims of this work were the synthesis a series of cross-linked p(NiPMAm) hydrogels by the free radical polymerization method and the application of gamma-ray radiation for additional cross-linking. The synthesized p(NiPMAm) hydrogels were structurally characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of unreacted monomers was analyzed using high pressure liquid chromatography (HPLC) to evaluate conversion of monomers into polymers. The swelling behavior was monitored in dependence of pH and temperature changes. The previous aim of gamma-ray radiation was the further the cross-linkage of the obtained hydrogel sample in the gelatinous, paste-like state, but the gamma-ray radiation caused decomposition. After absorbing irradiation doses, they transformed into the liquid phase. The results obtained by the gel permeation chromatography (GPC) method indicated that only oligomers and monomers were present in the irradiated liquid material, without molecules with a higher average molar mass, i.e., that the decomposition of the hydrogels occurred. Additionally, the irradiated liquid material was analyzed using the static headspace gas chromatography mass spectrometry (HSS-GC/MS) and gas chromatography/flame ionization detection (HSS-GC/FID) methods. The presence of unchanged initiator molecule and a dominant amount of four new molecules that were different from homopolymers and the reactant (monomer and cross-linker) were determined.

A simple fractionation method and GPC analysis of organosolv extracts obtained from lignocellulosic materials

The elucidation of lignin structural features is necessary for the efficient application of this polymer. Fractionation is an effective technique to achieve homogeneous lignin fractions, helping to better understand its composition and structure, and improving its use as source of phenolic compounds. This work develops a new and simple fractionation method of organosolv extracts obtained from lignocellulosic materials that enables the selective separation of lignin (from complex macromolecules to low molecular weight aromatic compounds originated from their degradation) from saccharides derived from hemicelluloses and cellulose. For this purpose, the non-catalytic organosolv extraction of lignin from almond shells was performed with dioxane/water mixtures and then the successful fractionation of the organosolv extracts with anhydrous tetrahydrofuran was achieved, resulting in the selective separation of lignin (lignin fraction) from saccharides (saccharide fraction). Gel permeation chromatography (GPC), thioacidolysis, and GC-MS were used as analytical methods to qualitatively determine the purity of both fractions. In addition, GPC was also used to quantify the content of lignin monomers and furfural in the organosolv extracts, thus allowing valuable information on the state of degradation of the lignin and hemicelluloses extracted to be obtained, respectively. The application of the GPC method also enabled the determination of the molecular weight distribution of the extracted lignin in the same analysis.

Research on synthesis and properties of early strength polycarboxylate superplasticizers with different lengths of side chain

A series of early-strength polycarboxylate superplasticizers with different lengths of side chain were synthesized by methyl allyl polyoxyethylene ether (HPEG) as macromonomers with different molecular weights. The structural parameters of polycarboxylate superplasticizers were calculated by gel permeation chromatography method. The performance of the synthesized samples were characterized by hydration heat, X-ray powder diffraction and concrete test. The results show that the longer the side chain be, the better the early strength effect be, when the side chain length is greater than 67.64, the early strength of the synthesized polycarboxylate superplasticizers are better than that of a foreign multinational enterprise.