Solid 13C Nuclear Magnetic Resonance Research Articles

Research on CO2/CH4/N2 competitive adsorption characteristics of anthracite coal from Shanxi Sihe coal mine.

This study aims to solve the problem of unsatisfactory development and utilization of coalbed methane and CO2 storage efficiency. It is focused on the adsorption behavior of CO2, CH4, and N2 in the macromolecular structure model of Shanxi Sihe coal mine anthracite, as well as the competitive adsorption behavior of CO2/CH4 and CH4/N2 binary gas mixtures with different ratios. Experimental analysis such as elemental analysis, solid 13C nuclear magnetic resonance (13C NMR), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were used to construct the Shanxi Sihe coal mine model of the macromolecular structure of anthracite coal. The Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to study the adsorption capacity and heat characteristics of CO2, CH4, and N2 at different temperatures using a molecular model of anthracite coal from Shanxi Sihe coal mine, as well as the competitive adsorption characteristics of CO2/CH4 and CH4/N2 binary mixtures. The mechanism of the influence of temperature and gas properties on the adsorption capacity and heat of adsorption was revealed from a microscopic perspective. The results indicated that the aromatic carbon content of anthracite in the Sihe coal mine, Shanxi is 81.19%, and the ratio Xbp of aromatic bridgehead carbon to surrounding carbon is 0.489. The aromatic structure is mainly composed of pyrene and anthracene. The molecular formula of the macromolecular structure model of anthracite in Shanxi Sihe coal mine is C233H157O13N2. The adsorption capacity and equivalent adsorption heat of the macromolecular model for adsorbing single-component gas CO2/CH4/N2 decrease with the increase in temperature. The temperature has the greatest impact on CO2 adsorption capacity and adsorption heat, followed by CH4 and N2. Under the competitive adsorption conditions of CO2/CH4 and CH4/N2 binary mixtures, the higher the partial pressure of a single-component gas in the mixture, the greater the adsorption capacity of the gas. The difference in the adsorption heat of CH4 and N2 is smaller than that of CH4 and CO2. The conclusions obtained from the study can provide technical and theoretical support for formulating reasonable drainage methods for coalbed methane wells.

Relevance of chemical structure in different wood wastes to pyrolysis behavior: Kinetics and hydrogen release

Relevance of chemical structure to pyrolysis behavior from different wood wastes was elaborated in this study. Chemical structure was analyzed by solid 13C nuclear magnetic resonance (13C-NMR) and Fourier transform infrared spectrometer (FTIR). Pyrolysis kinetics was analyzed according to thermogravimetric (TG) data. Results showed that the highest content of C1, 4 carbons in cellulose and weak functional groups in hemicellulose in poplar are leading to the lowest Tm and highest weight loss to increase CO release and decrease hydrogen generation. Amorphous C6 of cellulose in cedar with 12.00% has a remarkable impact on formation of more degree of polymerization during pyrolysis leading to activation energy (Eα) of 199.39 kJ/mol at conversion of 0.8, which is further to the highest hydrogen release. Hydrogen generation is dominated by contracting volume and diffusional theory during pyrolysis controlled by C–O structure in wood waste. The methoxy of lignin in cedar is abundant to produce CH4 for hydrogen generation by gas reaction. Torrefaction of cedar decreases the C–O structure and methoxy so that hydrogen generation from torrefied cedar is lower than that from raw cedar. Due to the different chemical structure with different pyrolysis behavior, hydrogen release rate from three wood wastes by pyrolysis follows the order: cedar > fir > poplar.

Construction and optimization of macromolecular structure model of Tiebei lignite.

Mastering the molecular structure of coal is important for the effective utilization of coal. For a detailed study of the microstructural characteristics of Tiebei lignite, its molecular structure was characterized by elemental analysis, solid 13C nuclear magnetic resonance (13C NMR), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results showed that the aromatic carbon content of Tiebei lignite was 51.98%, the aromatic carbon structure was mainly composed of benzene and naphthalene, and the ratio of aromatic bridgehead carbon to surrounding carbon Xbp was 0.14. Oxygen existed in phenol, ether, carbonyl, and carboxyl; nitrogen-containing structures mainly existed in the form of pyrrole and pyridine; sulfur mainly existed in thiophene sulfur; and aromatic substitution was mainly in the form of trisubstitution. The molecular formula of the macromolecular structure model of Tiebei lignite was C190H161O57N2, and the 13C NMR spectrum of the model was in good agreement with the experimental results, which fully verified the accuracy of the macromolecular structure model of Tiebei lignite. The construction of a macromolecular structure model of Tiebei lignite is essential to intuitively understand the molecular structure characteristics of Tiebei lignite and to provide theoretical support and guidance for the micromechanism research and prevention of lignite spontaneous combustion and other disasters.

Model construction and optimization of coal molecular structure

Understanding the structural characteristics of coal molecular at the molecular level is of paramount importance for the effective utilization of coal. In this work, the molecular structure of coal sample, from Liuzhuang(LZ) Coal Mine in Anhui Province, China, is investigated using modern analytical techniques, such as elemental analysis, X-ray photoelectron spectroscopy (XPS),Fourier Transform Infrared Spectroscopy(FT-IR) and Solid 13C nuclear magnetic resonance spectroscopy (13C NMR). It is found that the aromatic compounds of LZ coal are mainly in the form of 2 and 3 rings, with an aromaticity of 40.99% and the ratio of aromatic bridge carbon to aromatic peripheral carbon is 0.232. sulfur element is too low to considered in the model. Based on the above analysis, the molecular formula of LZ coal is inferred as C158H143O35N7. The experimental 13C NMR is consistent with the simulated spectrum, which indicates the accuracy of LZ molecular structure model. The molecular structure model is constructed and optimized by using classical molecular dynamics and the density functional based tight-binding method to obtain the lowest energy and most stable conformation, respectively. The optimized model has a more prominent steric configuration, but the lamellar structure of the aromatic layer is arranged in a more disordered manner. The experimental FT-IR spectra of the model are in preferably good agreement with the simulated results, which proves the correctness of LZ molecular structure. The molecular structure of LZ mine coal established in this paper can provide basic scientific data for further investigation of gas adsorption and resolution in coal seams at the atomic and molecular scales. Overall, Compared to contemporary technologies, these results show a good comparability among the different techniques and therefore provide comprehensive, accurate analytical technique to analyze the molecular structure of coal.

Evaluation of natural ageing responses on Burmese amber durability by FTIR spectroscopy with PLSR and ANN models

Amber ageing is an inevitable process, which is very important in precious organic gemstone relics protection. In order to explore the mechanism of amber ageing and estimate the durability of Burmese amber, this research investigates the changing spectral features of Burmese ageing amber via Fourier Transform Infrared Spectroscopy (FTIR) and solid 13C Nuclear Magnetic Resonance spectroscopy (NMR) and develops the regression models for its micro-hardness by micro-FTIR spectra. The Partial Least Squares Regression (PLSR) and Artificial Neural Networks (ANN) methods as well as Competitive Adaptive Reweighted Sampling (CARS) algorithm for wavelength variables selection have been applied to predict and assess the Vickers hardness of amber samples with different ageing degrees. As a result, the FTIR and the solid 13C NMR spectra reveal that the contents of CO groups (of esters) increase substantially, and which of the other oxygenic groups (CO (of acids), COC, COCC) increase modestly in amber ageing. When comparing with the results of four different models (PLSR, ANN, CARS-PLSR and CARS-ANN), the CARS-PLSR model obtained the optimal results as follows: the squared correlation coefficient of calibration(R2cal) is 0.9230 and the root mean square error of calibration (RMSEC) is 1.2977 HV; the squared correlation coefficient of prediction (R2pre) is 0.7762 and the root mean square error of prediction (RMSEP) is 2.2208 HV. The overall results sufficiently demonstrate that FTIR spectroscopy technique coupled with appropriate chemometrics methods are very promising tools to estimate and predict the hardness property of Burmese ageing amber.

Preliminary design for establishing compost maturity by using the spectral characteristics of five organic fertilizers

The maturity of compost is involved in the availability of nutrients to crops and improvement of soil properties after fertilization. In the past, the determination of composts maturity mostly required analysis in the laboratory previously and it must consume a lot of time and cost. This study was conducted to use Fourier Transform Infrared (FTIR) spectroscopy and solid 13C Nuclear Magnetic Resonance (13C NMR) spectroscopy to understand the mature characteristics of five type of common composts. The FTIR analysis showed that all composts contained aromatic groups. In addition, the surface of five composts contained the functional groups including hydroxyl group, carboxyl group, amino group etc. However, these functional groups changed along with maturity degree. It is recognized that the aliphatic group located at 2930 cm−1 and 2850 cm−1 showed a decreasing peak, and amino acid at 1385 cm−1 was disappearing gradually due to the decomposition of organic matter by bacteria. There may be used to identify the maturity degree of composts. Increase of aromatic group at 1650 cm−1, carboxy (–COOH) and phenolic OH group at 1385 cm−1 may prove the full maturity of composts. 13C NMR analysis showed that five type of matured composts are mainly consisted with aliphatic groups and aromatic groups. The surfaces of the composts contained C–O bonds (ester, ethers, carbohydrate and other functional groups), COO− (carboxyl and ester carbons) and C=O bond (aldehydes and ketones). The strength of different absorptive characteristics of FTIR and 13C NMR may be a clue to identify the maturity of composts for the design of detective instruments in the future.

Study on the mechanism of graft polymerization and sulfonation of proton exchange membranes for fuel cell

Poly (styrenesulfonic acid)-grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membrane (ETFE-PEM) applied for fuel cells was prepared by radiation induced-grafting using gamma-ray from 60Co source based on three steps (i) irradiation, (ii) polystyrene-graftedpoly(ethylene-alt-tetrafluoroethylene) (PS-g-ETFE), and (iii) sulfonation (ETFE-PEM). Mechanism of grafting and sulfonation of ETFE-PEM with grafting degree of 22% and sulfonation degree of 93% was revealed by solid 13C nuclear magnetic resonance (solid 13C NMR), Fourier transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM). The obtained results indicated that the styrene was grafted on the matrix of ETFE polymer by the π bond-breaking reaction which could be attributed to free radicals and formed the polystyrene chain at the surfaces of crystalline phases. The styrene migrated deep into the membrane due to the concentration gradient. The grafting reactions occurred at sites of C-H and C-F in the ETFE backbone but dominantly at the C-F sites while the sulfonation took place at the para position of polystyrene. The signatures related to side (secondary) reactions and by-products were not observed in the spectra indicating that the graft polymerization and sulfonation are well-controlled.

Modeling of Antioxidant Activity, Polyphenols and Macronutrients Content of Bee Pollen Applying Solid-State 13C NMR Spectra.

An application of solid 13C nuclear magnetic resonance (NMR) spectroscopy for the determination of macronutrients, total polyphenols content, antioxidant activity, N C S elements, and pH in commercially available bee pollens is reported herein. Solid-state 13C NMR spectra were recorded for homogenized pollen granules without chemical treatment or dissolution of samples. By combining spectral data with the results of reference analyses, partial least squares models were constructed and validated separately for each of the studied parameters. To characterize and compare the models’ quality, the relative standard errors of prediction (RSEP) were calculated for calibration and validation sets. In the case of the analysis of protein, fat and reducing sugars, these errors were in the 1.8–2.5% range. Modeling the elemental composition of bee pollen on the basis of 13C NMR spectra resulted in RSEPcal/RSEPval values of 0.3/0.6% for the sum of NHCS elements, 0.3/0.4% for C, 1.8/1.9% for N, and 4.2/6.1% for S quantification. Analyses of total phenolics and ABTS antioxidant activity resulted in RSEP values in the 2.7–3.5% and 2.8–3.8% ranges, respectively, whereas they were 1.4–2.1% for pH. The obtained results demonstrate the usefulness of 13C solid-state NMR spectroscopy for direct determination of various important physiochemical parameters of bee pollen.

Effect of hydrothermal treatment on the carbon structure of Inner Mongolia lignite

Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis, liquefaction, and gasification processes. Here, hydrothermal treatment of Inner Mongolia lignite (IM) was carried out in a lab autoclave. The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy, and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy. The curve-fitting method was used to calculate the content of the functional groups quantitatively. The results show that hydrothermal treatment is an effective method for upgrading the lignite. The side chains of the aromatic ring in lignite are altered, while the main macromolecular structure remains nearly the same. The hydrothermal treatment of IM could be divided into three temperature-dependent stages. The first stage (< 493 K) is the decomposition reaction of oxygen functional groups, where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K. In the second stage (493–533 K), hydrolysis of functional groups and hydrogen transfer between water and lignite occur. Here, the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533, and the content of quinone generates from the condensation of free phenol increased. The third stage (> 533 K) involves breakage of the covalent bond, and the content of CH4 and CO in the emission gas clearly increase.

Synthesis of carboxyl functionalized microporous organic network for solid phase extraction coupled with high-performance liquid chromatography for the determination of phenols in water samples

In this work, the carboxyl functionalized microporous organic network (MON-COOH) was synthesized as an efficient adsorbent to fabricate solid phase extraction (SPE) column for the extraction of p-nitrophenol, p-chlorophenol, 2,6-dichlorophenol and 2,3-dichlorophenol from water samples, followed by their analysis with high performance liquid chromatography (HPLC). The obtained MON-COOH was characterized with solid 13C nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, thermogravimetric analysis, N2 adsorption-desorption isotherms, scanning electron microscope and water contact angle experiments. The integrating of carboxyl groups into aromatic MON's networks led to their good enrichment for the studied phenols. The hydrogen binding, π-π and hydrophobic interactions played key roles during the extraction. Effects of adsorbents type, desorption solvent and volume, pH and ionic strength were studied. Under the optimal extraction conditions, the MON-COOH column for SPE coupled with HPLC for the determination of the selected four phenols gave the linear range of 0.5–1000 μg L−1, the limit of detections (LODs, S/N = 3) of 0.13–0.62 μg L−1, the limit of quantifications (LOQs, S/N = 10) of 0.43–2.06 μg L−1, the enhancement factors of 113–216, and the intra-day, inter-day and column-to-column precisions (relative standard deviations, RSDs) of 2.8–6.1, 4.1–8.7 and 6.7–10.3%, respectively. The developed method was successfully applied to the analysis of phenols in wastewater samples with the recoveries of 80.3–99.5%. These results revealed the potential of functional MONs as efficient adsorbents in sample pretreatment.

Chemical structure evolution of kerogen during oil generation

Abstract Kerogen was isolated from the source rock of Well L69, Zhanhua depression, Bohai Bay Basin and an artificial pyrolysis experiment was carried out in a closed gold tube system with a heating rate of 2 °C/h. Products were collected at eleven temperature points every ten degrees from 350 °C to 450 °C. The soluble organic matter and residual kerogens from the experiment were quantified by weighing. Furthermore, the residual kerogens were analysed by element analysis, X-ray photoelectron spectroscopy (XPS) and solid 13C nuclear magnetic resonance (13C NMR) spectroscopy to determine the chemical structural of kerogen during oil generation. Combining the data from the analyses, information on the elemental compositions as well as on how functional groups were connected in residues was obtained. Seven molecular models of initial and residual kerogens were established to trace the structure changes in kerogen with maturity. The results suggest that as the temperature increases, aliphatic chains and small clusters of aromatic groups break down from kerogens, generating soluble hydrocarbons at temperatures of less than 390 °C (Easy% Ro1.15). At higher thermal maturity, a few short aliphatic carbons remain in the structure of residues. The number of aromatic groups increases and their size grows with increasing maturity, with condensation occurring at aromatic groups at high temperature, while these residues have little potential for oil generation.

Sorption mechanism of enrofloxacin on humic acids extracted from Brazilian soils

Veterinary antimicrobials are emerging environmental contaminants of concern. In this study, the sorption of enrofloxacin (ENR) onto humic acids (HAs) extracted from three Brazilian soils was evaluated. HAs were characterized by elemental analysis and solid 13C nuclear magnetic resonance spectroscopy. The sorption of ENR onto HAs was at least 20-fold higher than onto the soils from which they were separated. Ionic and cation bridging are the primary interactions involved. The interactions driven by cation exchange are predominant on HAs, which appear to have abundant carboxylic groups and a relatively high proportion of H-bond donor moieties with carbohydrate-like structures. Interactions explained by cation bridging and/or surface complexation on HAs are facilitated by moieties containing conjugated ligands, significant content of oxygen-containing functional groups, such as phenolic-OH or lignin-like structures. HAs containing electron-donating phenolic moieties and carboxylic acid ligand groups exhibit a sorption mechanism that is primarily driven by strong metal binding, favoring the formation of ternary complexes between functional groups of the organic matter and drugs.

Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China.

Forms and labilities of plant-derived organic matters (OMs) including carbon (C) and phosphorus (P) were fundamental for understanding their release, degradation and environmental behaviour in lake ecosystems. Thus, solid 13C and solution 31P nuclear magnetic resonance (NMR) spectroscopy were used to characterize biomass of six aquatic plants in Tai Lake, China. The results showed that carbohydrates (61.2% of the total C) were predominant C functional group in the solid 13C NMR spectra of plant biomass, which may indicate high lability and bioavailability of aquatic plants-derived organic matter in lakes. There was 72.6-103.7% of the total P in aquatic plant biomass extracted by NaOH-EDTA extracts. Solution 31P NMR analysis of these NaOH-EDTA extracts further identified several molecular species of P including orthophosphate (50.1%), orthophosphate monoesters (46.8%), DNA (1.6%) and pyrophosphate (1.4%). Orthophosphate monoesters included β-glycerophosphate (17.7%), hydrolysis products of RNA (11.7%), α-glycerophosphate (9.2%) and other unknown monoesters (2.1%). Additionally, phytate, the major form of organic P in many lake sediments, was detected in floating plant water poppy. These inorganic P (e.g. orthophosphate and pyrophosphate) and organic P (e.g. diester and its degradation products) identified in plant biomass were all labile and bioavailable P, which would play an important role in recycling of P in lakes. These results increased knowledge of chemical composition and bioavailability of OMs derived from aquatic plants in lakes.

The structure and pyrolysis product distribution of lignite from different sedimentary environment

Low-temperature pyrolysis is an economically efficient method for lignite to obtain coal tar and improve its combustion calorific value. The research on the distribution of pyrolysis product (especially coal tar yield) plays an important role in energy application and economic development in the now and future. Pyrolysis test was carried out in a tube reactor at 873K for 15min. The structure of the lignite was measured by solid 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The thermal analysis was analyzed by thermo-gravimetric (TG) analyzer. The results show that the pyrolysis product distribution is related to the breakage of branch structures of aromatic ring in lignites from different sedimentary environment. The gas yield and composition are related to the decomposition of carbonyl group and the breakage of aliphatic carbon. The tar yield derived from lignite pyrolysis follows the order: Xianfeng lignite (XF, 13.67wt.%)>Xiaolongtan lignite (XLT, 7.97wt.%)>Inner Mongolia lignite (IM, 6.30wt.%), which is mainly influenced by the aliphatic carbon contents, the CH2/CH3 ratio and the oxygen functional groups in lignite. The pyrolysis water yield depends on the decomposition of oxygen functional groups. IM has the highest content of oxygen-linked carbon so that the pyrolysis water yield derived from IM is the highest (9.20wt.%), and is far more than that from the other two lignites.

Effect of torrefaction on structure and fast pyrolysis behavior of corncobs

Pretreatment of corncobs using torrefaction was conducted in an auger reactor at 250–300°C and residence times of 10–60min. The torrefied corncobs were fast pyrolyzed in a bubbling fluidized bed reactor at 470°C to obtain high-quality bio-oil. The heating value and pH of the bio-oil improved when the torrefaction as pretreatment was applied; however, increasing bio-oil yield penalties were observed with increasing torrefaction severity. Fourier transform infrared Spectroscopy (FTIR) and quantitative solid 13C nuclear magnetic resonance spectrometry (NMR) analysis of torrefied corncobs showed that the devolatilization, crosslinking and charring of corncobs during torrefaction could be responsible for the bio-oil yield penalties. Gas chromatography-mass spectrometry (GC–MS) analysis showed that the acetic acid and furfural contents of the bio-oil decreased with torrefaction temperature or residence time. The results showed that torrefaction is an effective method of pretreatment for improving bio-oil quality if the crosslinking and charring of biomass can be restricted.

Characterization of Acacia mangium polyflavonoid tannins by MALDI-TOF mass spectrometry and CP-MAS 13C NMR

The MALDI-TOF mass spectrometry (MS) and solid state CP-MAS 13C Nuclear Magnetic Resonance (NMR) spectroscopic technique were introduced to characterize Acacia mangium tannin (condensed tannins). The MALDI-TOF MS illustrated a series of peaks corresponding to oligomers of condensed tannins of up to 11 flavonoid units (3200 Da). A. mangium condensed tannins were found to consist predominantly of prorobinetinidin combined with profisetinidin and prodelphinidin. Both the MALDI-TOF mass spectra and the solid state CP-MAS 13C NMR indicated that the A. mangium tannins obtained from Kudat, had an almost completely linear structure; In addition, Lembah Beringin, consist of “angular” polymer structure; and Tawau, has included “twice-angular” polymer structures present in oligomers type of up to 7 flavonoid units. The high degree of polymerization of linear, angular type, twice-angular structures and longer oligomer (3200 Da) chains have not been observed in previous studies of condensed tannins. The spectra also indicated that A. mangium tannins are more heavily branched and have higher degree of polymerization (>7.0) compared to commercial mimosa (A. mearnsii) tannin (4.9). Because tannins are phenolic, it was expected that they can be used to replace phenol–formaldehyde (PF) adhesives.

Explaining the Flocculation of Hassi Messaoud Asphaltenes in Terms of Structural Characteristics of Monomers and Aggregates

X-ray diffraction, liquid 1H and solid 13C nuclear magnetic resonance (NMR), Raman, Fourier transform infrared (FTIR), laser desorption/ionization-time of flight (LDI-TOF) mass and fluorescence spectroscopy have been used to determine structural properties of asphaltenes obtained from Hassi Messaoud crude oil. While liquid 1H- and 13C-NMR, IR, and LDI-TOF mass and fluorescence spectroscopy allow the determination of the chemical composition and structure of single asphaltene molecules, X-ray diffraction and Raman spectroscopy make it possible to asses parameters characterizing small asphaltene clusters. The proposed characterization of petroleum asphaltenes affords information that leads to better understanding of asphaltene flocculation conditions.

Oil cracking: An important way for highly efficient generation of gas from marine source rock kitchen

The potentials of gas generation by kerogen in the late period and by crude oil cracking are closely related to the origin of natural gas in the high-to over mature marine area and their exploration perspectives. The carbon structure of kerogens, with different types and at different evolution stages, have been experimentally studied using the high magnetic field solid13C nuclear magnetic resonance technique in order to determine the oil and gas potential of kerogens. Results show that the contents of gas potential carbon(GPC) of types I, II, III kerogens at the high-to over mature stage are very low, indicating their weak gas-generating capacity and limited gas production; however, the content of oil potential carbon(OPC) of the low mature type I kerogen is much higher, implying that a large amount of crude oil generated during the oil-generating period will be the material for later gas generation by oil cracking. The kinetic experiment of gas generation by crude oil cracking shows that, when the temperature is about 160°C (Ro=l.6%), the crude oil will start to produce large amounts of gas; the temperature range for major gas generation of crude oil is higher than that of the kerogens, and the gas production is 2 to 4 times higher than that of kerogens. The natural gas derived from oil cracking (called oil-cracked gas) is much abundant in methyl hexamethylene, which is quite different from the natural gas produced by thermal degradation of kerogens (named kerogen degradation gas) at high-to over mature stage.

Blends of poly(hydroxyether of bisphenol A) and polycarbonate: in situ polymerization preparation, miscibility, and transreaction

In the presence of polycarbonate (PC), the polymerization of diglycidyl ether of bisphenol A (DGEBA) and bisphenol A in the melt was initiated to prepare blends of poly(hydroxyether of bisphenol A) (phenoxy) and PC. The polymerization reaction started from the initially homogeneous ternary mixture consisting of DGEBA, bisphenol A, and PC; phenoxy/PC blends with PC content up to 20 wt % were obtained. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to characterize the miscibility of the as-polymerized blends. All the blends displayed separate glass transition temperatures (Tg's), that is, the blends were phase-separated. The formation of a two-phase structure is considered to result from phase separation induced by polymerization. This result is consistent with the immiscibility established through solution- and melt-blending approaches. The insolubility of the as-polymerized blends showed that crosslinking between the components occurred. Both Fourier-transform infrared (FTIR) and solid 13C-nuclear magnetic resonance (13C-NMR) spectroscopic studies demonstrated a transreaction between the components and in situ polymerization of DGEBA and bisphenol A in the presence of PC, which yielded a phase-separated, transreacted material. The results of this work provide a contrast to those of the transreacted phenoxy/PC blends based on conventional blending methods; however, the transreaction in the present case occurred at a much lower temperature (180oC), at which polymerization blending was carried out. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1181–1190, 1999

Blends of poly(hydroxyether of bisphenol A) and polycarbonate:in situpolymerization preparation, miscibility, and transreaction

In the presence of polycarbonate (PC), the polymerization of diglycidyl ether of bisphenol A (DGEBA) and bisphenol A in the melt was initiated to prepare blends of poly(hydroxyether of bisphenol A) (phenoxy) and PC. The polymerization reaction started from the initially homogeneous ternary mixture consisting of DGEBA, bisphenol A, and PC; phenoxy/PC blends with PC content up to 20 wt % were obtained. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to characterize the miscibility of the as-polymerized blends. All the blends displayed separate glass transition temperatures (Tg's), that is, the blends were phase-separated. The formation of a two-phase structure is considered to result from phase separation induced by polymerization. This result is consistent with the immiscibility established through solution- and melt-blending approaches. The insolubility of the as-polymerized blends showed that crosslinking between the components occurred. Both Fourier-transform infrared (FTIR) and solid 13C-nuclear magnetic resonance (13C-NMR) spectroscopic studies demonstrated a transreaction between the components and insitu polymerization of DGEBA and bisphenol A in the presence of PC, which yielded a phase-separated, transreacted material. The results of this work provide a contrast to those of the transreacted phenoxy/PC blends based on conventional blending methods; however, the transreaction in the present case occurred at a much lower temperature (180oC), at which polymerization blending was carried out. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1181–1190, 1999