Hydroxyethyl Methyl Cellulose Research Articles

Influence of Tylose MH1000 Content on Gypsum Thermal Conductivity

AbstractThe presented work focuses on the influence of a water-soluble derivative of cellulose, hydroxyethyl methyl cellulose (HEMC), on gypsum thermal properties. The polymer is used as an additiv...

Hydration/Dehydration Behavior of Cellulose Ethers in Aqueous Solution

The hydration numbers of cellulose ethers dissolved into aqueous solution were determined using extremely high-frequency dielectric spectroscopic methods, up to 50 GHz, in which the frequency range of the major dielectric dispersion of free water molecules is clearly observable. Methyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethylmethyl cellulose samples at relatively high degrees of substitution by methyl groups ranged from 1.4 to 1.9, which are an essential reason for water solubility, and additional low molar substitution by hydroxypropyl or hydroxyethyl groups from 0 to 0.25 bearing molar masses (Mw) ranging from 20 × 103 to 300 × 103 was examined in this study. All the samples dissolve well into cold water below room temperature, ca. 25 °C; however, their aqueous solutions show distinct cloud points at high temperatures, such as 38–53 °C, depending not so much on the Mw values but on the substitution condition substantially. The determined hydration numbers per glucopyranose unit (nH) fo...

DETERMINATION OF DEGREE OF SUBSTITUTION (DS) AND MOLAR SUBSTITUTION (MS) OF CELLULOSE ETHERS BY SOLID-STATE 13C NMR SPECTROSCOPY

The work is devoted to determining the substitution parameters of some commercial cellulose ethers by solid-state 13C NMR spectroscopy. The substitution parameters are the degree of substitution (DS) and molar substitution (MS). The objects of study are commercial additives based on hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl methyl cellulose (HEMC). In this paper, the degree of substitution (DS) and molar substitution (MS) were determined, and the distribution of the substituents at positions C-2, C-3 and C-6 of the glucopyranose link was established. The calculation of the degree of substitution (DS) and molar substitution (MS) is based on an analysis of relative intensity values of the spectral regions in the solid-state NMR spectra of cellulose ethers and microcrystalline cellulose. Thus the degree of substitution and molar substitution was determined: MSHEC = 1,41 иDSHEC = 1,08; MSHPMC = 0,69 и DSHPMC = 1,78; MSHEMC = 0,74иDSHEMC = 2,19. Comparison of the results with the literature data shows the effectiveness of the method. The proposed method differs from other existing methods in that it is a simple and informative.

Formation of calcium aluminate hydrates in Portland cement modified by organic admixtures

The formation of calcium aluminate hydrates in Portland cement pastes modified with two organic admixtures, hydroxyethyl methyl cellulose (HEMC) and ethylene-vinyl acetate redispersible polymer powder (EVA), was evaluated by using X-ray diffraction analysis. The results show that both the HEMC and the EVA retard the formation of ettringite and postpone the time to reach maximum ettringite content. However, the stability of ettringite is enhanced and the conversion of ettringite to monosulfate (AFm) is delayed by these two organic admixtures to retain a higher ettringite content in cement pastes at later hydration time. With calcite powders contained in EVA as the anti-blocking agents, the formation of two AFm phases, hemicarboaluminate and monocarboaluminate, is promoted by EVA after 3 d of hydration. Accordingly, more types of calcium aluminate hydrates coexist in the cement paste modified with EVA than in the control paste or in cement paste modified with HEMC. Also, having been synchronously mixed in the cement paste, these two organic admixtures have obvious superposition effects on the formation and evolution of calcium aluminate hydrates.

Effects of HEMC Powder and PP Fiber on the Drying Shrinkage of Cement Mortar

Influences of polypropylene (PP) fiber and hydroxyethyl methyl cellulose (M) on the shrinkage rate of cement mortar and its potential mechanism were investigated. Results show that both the addition of trilobal PP fiber and M would reduce the shrinkage rate of cement mortar if well applied. With the increasing of PP content, the shrinkage rate firstly decreases and then increases, and reaches the lowest shrinkage degree with fiber content of 0.20% (volume fraction). While for cement mortar with M, the greater the dosage, the less drying shrinkage rate. An addition of 0.6% M contributes to a decrease of 23.8% for the 180-days drying shrinkage than the control. Additionally, a combination of both PP fibers and M can significantly reduce the drying shrinkage of mortar, resulting in a decrease of 40% for the shrinkage rate.

Effect of HEMC on the early hydration of Portland cement highlighted by isothermal calorimetry

The effects of hydroxyethyl methyl cellulose (HEMC) on the early hydration and main hydrates evolutions of Portland cement were quantitatively investigated by the isothermal calorimetry, setting times, X-ray diffraction analysis, and environmental scanning electron microscope analysis. The results show that HEMC definitely affects the early hydration process of cement paste and retards the beginning of the hydration induction period and acceleration period, but increases the length of these two periods. HEMC decreases the hydration heat evolution rate during the initial reaction period and the acceleration period, but increases the hydration heat evolution rate during the deceleration period. HEMC decreases the hydration heat amount and hydration degree of cement paste at the early hydration time, especially in the first thirty-six hours. There are good positive correlations between the setting time, the length of induction period and the dosages of HEMC. HEMC also delays the formation of the hydrates and affects the morphologies of hydrates. Accordingly, HEMC remarkably retards the cement hydration at the early hydration time, and with its dosage increasing, the retardation effect of HEMC enhances.

Examination of thermo-gelation behavior of HPMC and HEMC aqueous solutions using rheology

In this study, the thermo-gelation behavior of hydroxypropyl methylcellulose (HPMC) and hydroxyethyl methylcellulose (HEMC) were examined by rheology. Temperature sweep shear viscosity measurements revealed a significant decrease in the shear viscosity of HPMC and HEMC at the aggregation temperature (Tagr), which depended on the substitution type (HPMC or HEMC) and degree of substitution. In the dynamic test, G′ decreased slightly at Tagr and increased significantly at the gelation temperature (Tgel). The shear viscosity and shear storage modulus (G′) can be utilized complementarily to examine Tagr and Tgel. Tagr could be detected clearly by the shear viscosity measurement but could not be observed in the G′ measurement. On the other hand, Tgel could not be detected in the shear viscosity measurement although it can be clearly recognized in G′ measurement. Conclusively, the two rheological measurements could be utilized complementarily in detection of Tagr and Tgel. In the meanwhile, HPMC with more hydrophobic residues (methoxy and hydroxypropyl residues) showed smaller Tagr and Tgel than HEMC, which has hydroxyethyl and methoxy groups. Tagr and Tgel decreased with increasing number of hydrophobic groups. Molecular weight almost did not affect Tagr and Tgel of HPMC solution.

Investigation of the cellulose ethers effect on the Portland cement hydration by thermal analysis

Cellulose ethers (CE) are introduced in almost all cement-based dry mortars in order to retain water in mortar mass avoiding losing it too quickly by substrate absorption or water evaporation. In this way the workability of the fresh material, the adherence to the substrate and internal-strength characteristics of mortar, render or tile adhesive are improved. One of the side effects of cellulose ethers is the Portland cement hydration delaying. The influence of six commercial cellulose ethers, hydroxyethylmethyl cellulose (HEMC) type, on the hydration of Portland cement CEM I 42.5 R, was followed by thermal analysis (TG and DTA curves). Three of these cellulose ethers are unmodified, and have different viscosities, while three of them have the same viscosity but differ in the degree of modification (unmodified, one with medium modification and one with high modification). The interest of dry mortars producers for the effects of these cellulose ethers, is generated by the wide offer available on the market and by the absence of systematic data on the effect of different viscosities and degrees of modification on dry mortars properties. In order to quantify the effect of the CE on the cement hydration, the surface area of the endothermic effect corresponding to the dehydration of portlandite (Ca(OH)2), formed after 1, 3, and 7 days of hydration, was defined. It was noted that the proportion of Ca(OH)2 in samples containing CE after 1 day was 30–40 % lower than in reference sample. After 3 and 7 days of hydration the proportion of Ca(OH)2 in samples containing CE approaches that of reference sample (10–20 % less). For the same period of hydration, the different viscosity, and different degree of modification of cellulose ethers cause variations in narrow limits of the proportion of Ca(OH)2, and the degree of cement hydration, respectively.

퀵 브레드 쌀 머핀 제조용 첨가물로써의 바이오폴리머(Hydroxyethyl Methylcellulose, HEMC) 활용성 검정

We examined the quality characteristics and conducted a sensory evaluation of muffins made with rice flour and the biopolymer hydroxyethyl methylcellulose (HEMC) to identify a new health functional food additive. First, overrun and foam stability of HEMC-HV (high viscosity) was better than HEMC-LV (low viscosity) to prepare muffins. Also the quality of rice muffins(volume, specific cake volume, and baking loss) was analyzed. There was no significant difference in the sensory evaluation of rice flour muffins containing foam mixture(egg white:HEMC-HV, 3:1, v/v) and muffin made from flour. The results showed that HEMC-HV was suitable for quick bread muffin-making using 100% rice flour.

Antihyperglycemic and antioxidative effects of Hydroxyethyl Methylcellulose (HEMC) and Hydroxypropyl Methylcellulose (HPMC) in mice fed with a high fat diet.

The effect of dietary feeding of hydroxyethyl methylcellulose (HEMC) and hydroxypropyl methylcellulose (HPMC) on the glucose metabolism and antioxidative status in mice under high fat diet conditions was investigated. The mice were randomly divided and given experimental diets for six weeks: normal control (NC group), high fat (HF group), and high fat supplemented with either HEMC (HF+HEMC group) or HPMC (HF+HPMC group). At the end of the experimental period, the HF group exhibited markedly higher blood glucose and insulin levels as well as a higher erythrocyte lipid peroxidation rate relative to the control group. However, diet supplementation of HEMC and HPMC was found to counteract the high fat-induced hyperglycemia and oxidative stress via regulation of antioxidant and hepatic glucose-regulating enzyme activities. These findings illustrate that HEMC and HPMC were similarly effective in improving the glucose metabolism and antioxidant defense system in high fat-fed mice and they may be beneficial as functional biomaterials in the development of therapeutic agents against high fat dietinduced hyperglycemia and oxidative stress.

Hypoglycemic and antioxidative effects of hydroxyethyl methylcellulose in mice fed with high fat diet

The effect of hydroxyethyl methylcellulose (HEMC) with different viscosities on the glucose metabolism and antioxidative defense system in high fat-fed mice was investigated. The mice were randomly divided into five dietary groups: normal control diet (NC), high fat diet (HF), and high fat diet supplemented with high viscosity (HF-HV), moderate viscosity (HF-MV), and low viscosity (HF-LV) HEMC fibers. After 6weeks, the HF group showed a marked increase in body weight gain, body fat, blood glucose concentration, insulin level, and erythrocyte lipid peroxidation rate relative to the NC group. However, supplementation of HEMC in the diet suppressed these high fat-induced hyperglycemia and oxidative stress through enhancement of the activities of hepatic glucokinase and antioxidant enzymes. The hypoglycemic and antioxidative effects increased with increased viscosity of the HEMC consumed. These results illustrate that HEMC with high viscosity may be useful in the management of high fat diet-induced hyperglycemia and oxidative stress.

Antihyperlipidemic effects of hydroxyethyl methylcellulose with varying viscosity in mice fed with high fat diet

The effect of dietary feeding of hydroxyethyl methylcellulose (HEMC) with different viscosities on the body weight and lipid metabolism in high fat-fed mice was investigated. The animals were given normal control diet (NC group), high fat diet (HF group), and high fat diet supplemented with HEMC with high (HF–HV), moderate (HF–MV), or low (HF–LV) viscosity for 6weeks. At the end of the experimental period, the HF groups showed a marked increase in body weight and fat, plasma triglyceride and total cholesterol concentrations, and free fatty acid levels and a significant decrease in HDL-cholesterol concentration relative to the control group. However, addition of HEMC in the diet counteracted this high fat-induced hyperlipidemia via inhibition of lipogenesis and regulation of adipokine production. The antihyperlipidemic effect increased with increased viscosity of the HEMC consumed. This study illustrate that HEMC with high viscosity may be effective in lowering the risk of hyperlipidemia and obesity under high fat diet condition.

Comparative evaluation of the hypolipidemic effects of hydroxyethyl methylcellulose (HEMC) and hydroxypropyl methylcellulose (HPMC) in high fat-fed mice

The effect of hydroxyethyl methylcellulose (HEMC), in comparison with hydroxypropyl methylcellulose (HPMC), on the body weight and lipid metabolism in mice fed with high fat diet was investigated. The animals were given normal control diet (NC group), high fat diet (HF group), or high fat diet supplemented with either HEMC (HF+HEMC group) or HPMC (HF+HPMC group) for 6weeks. At the end of the experimental period, both HF+HEMC and HF+HPMC groups showed reduced body weight, body fat, plasma triglyceride and total cholesterol contents, atherogenic index and free fatty acid level, and increased HDL-cholesterol concentration relative to the HF group. The hypolipidemic effect was partly due to the inhibition of lipogenesis and regulation of adipokine production. These findings demonstrate that compared with HPMC, HEMC was similarly effective in improving the lipid metabolism under high fat diet condition and may be useful in the prevention and treatment of high fat diet-induced hyperlipidemia.

HEC influence on cement hydration measured by conductometry

Cellulose ethers are of universal use in factory-made mortars, though their influences on mortar properties at a molecular scale are poorly understood. Recent studies dealt with the influence of hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) molecular parameters on cement hydration. It was concluded that the degree of substitution is the most relevant factor on cement hydration kinetics, contrary to the molecular weight. Nevertheless, the major role played by the substitution degree has not been verified for other types of cellulose ethers such as hydroxyethyl cellulose (HEC), which generally possesses a higher hydration retarding capacity compared to HPMC and HEMC. In this frame, a study of the impact of HEC molecular parameters on cement hydration was performed. A negligible influence of the molecular weight was observed. Moreover, the results emphasize that the hydroxyethyl group content mainly determines the delay of cement hydration.

Analysis of the substituent distribution in the glucosyl units and along the polymer chain of hydroxypropylmethyl celluloses and statistical evaluation

Three hydroxypropylmethyl celluloses (HPMC 1, 2, 3; DSMe=2.06, 1.99, 2.04; MSHP=0.21, 0.19, 0.21) have been analyzed with respect to their methyl and hydroxypropyl pattern in the glucosyl units and along the polymer chain. The determination of the methyl pattern in the glycosyl unit was performed by GLC/MS after hydrolysis, reduction, and acetylation, while the distribution of hydroxypropyl residues in the monomers could be analyzed with higher sensitivity including a permethylation step prior to hydrolysis. To determine the distribution of the substituents along the polymer chain, a method developed for hydroxyethylmethyl cellulose (HEMC) was applied. This method comprises random partial acid hydrolysis after perdeuteromethylation and reductive amination with propylamine, followed by N- and O-alkylation, yielding completely alkylated and permanently charged oligosaccharide derivatives. These compounds could be quantitatively analyzed by means of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), since all discrimination effects related to the hydroxyalkyl groups are leveled off by the sample preparation procedure in combination with the choice of a MALDI-TOF instrument. Methyl data deviate to some extent from the random distribution calculated from the monomer composition, but in contrast to methyl cellulose (MC) or HEMC, it is not heterogeneous, but more regular. The distribution of HP groups is random within experimental error as has been found for HEMC as well.

HPMC and HEMC influence on cement hydration

Cellulose ethers such as hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) are common admixtures in factory made mortars. Nevertheless, their use principally remains empirical, and no cement–admixture interaction mechanism has ever been rigorously demonstrated. The main issue of this publication deals with the control of secondary effects generated by these admixtures such as the retardation of cement hydration. In this frame, a study of the impact of HEMC and HPMC molecule parameters on the modification of cement hydration was carried out. Minor influence of the molecular weight and of the hydroxypropyl or the hydroxyethyl group content was observed. On the contrary, the results emphasize that the methoxyl group content appears as the key parameter of the hydration delay mechanism.

Effect of Relative Humidity During Tabletting on Matrix Formation of Hydrocolloids: Densification Behavior of Cellulose Ethers

ABSTRACTThe aim of this research was to investigate the elastic-plastic deformation behavior of the cellulose ethers hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), and sodium carboxymethylcellulose (NaCMC) at relative humidities (RH) of 38, 57, and 75% and assess how the release of drugs embedded in such matrices is affected by the inner structure of the tablets formed during tabletting. Sorption and desorption isotherms and glass transition temperature were determined between 32 and 75% RH. The materials were equilibrated at 38, 57, and 75% RH and tabletted to a range of graded maximum relative densities. Pressure-time and displacement-time curves were analyzed by use of the Heckel Junction and a modified Weibull function (pressure-time only). After equilibration at the different RHs, all materials were in the glassy state. The respective degrees of polymerization had negligible effect on the absolute content of water, the sorption isotherms, and finally the densification behavior. At 38% RH, NaCMC contains the same amount of water as HPMC and HEMC, but deforms less plastically than the latter. This is attributed to tight binding of the water of hydration in the former. With increasing RH, NaCMC becomes only a little more plastic than both HPMC and HEMC, although it contains more than twice the amount of water. The binding strength of water and its molecular mobility, not the amount, seems to determine the readiness for volume reduction under load.

Rapid Identification of Angiotensin-Converting Enzyme Genotypes by Capillary Electrophoresis

The traditional method for DNA separation is slab gel electrophoresis. Because slab gel electrophoresis, which involves the casting, loading, running, and staining of the gel is labor-intensive and time-consuming, high-resolution capillary electrophoresis (CE) has become an attractive alternative. CE, by contrast to conventional electrophoretic techniques, is capable of rapid, automated, reproducible, and high-resolution separation of minute amounts of DNA samples. To separate DNA fragments by CE, polyacrylamide gels or liquid buffers containing soluble polymers are used. Soluble polymers, such as hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and methyl cellulose act as effective molecular sieves and allow for separation of DNA according to size (1). CE has recently shown promising results for the analysis of double-stranded DNA such as restriction fragment length polymorphisms and polymerase chain reaction (PCR) products (2)(3). The insertion (I)/deletion (D) of a 287-bp sequence polymorphism within intron 16 of the gene for angiotensin-converting enzyme (ACE) is strongly associated with serum ACE concentrations (4). The D allele has been identified as a risk factor for the development of coronary heart disease and myocardial infarction (5). In addition, the deletion polymorphism has been associated with either microalbuminuria or overt nephropathy in diabetic patients (6)(7). Here we report a sensitive, simple, rapid, and nonisotopic procedure for identification of …

The concentration dependence of the ‘zero-shear’ specific viscosity for a commercial hydroxyethylmethylcellulose (HEMC) in water at several temperatures

This short paper presents preliminary results on the ‘zero-shear’ specific viscosity η sp 0 of a commercial hydroxyethylmethylcellulose (Tylose MH-4000) in water, at the temperatures 10, 25 and 40·5°C, over a wide range of concentrations. At the two higher temperatures, two regions are found in the plot of log C[ η] 0 against log η sp 0 with a C ∗[η] 0 value of about 2·5. This is consistent with the behaviour of other random-coil polymers. At 10°C however, there is an interesting ‘upward shift’ in this plot in the dilute region. It is suggested that this is related to the different degree of hydration of the oligo(ethyleneoxide) side chains at this temperature.

Drug release from non-disintegrating hydrophilic matrices: sodium salicylate as a model drug

Tablets containing different concentrations of sodium salicylate in a (hydroxyethyl)methylcellulose matrix swelled without disintegration or attrition. The release rate of the drug from the whole tablet was shown to conform with a model diffusional equation for two-sided release from a slab maintaining a constant surface-volume ratio on swelling, and the rate constant was linearly dependent on the drug dosage, as predicted by this equation, when the polymer concentration was kept constant. With varying polymer concentration, correction of the rate constants for their dependence on drug content of the matrix yielded constants dependent on the polymer concentration only. Such rate constants observed a semi-logarithmic relation to polymer content and extrapolated to give reasonable diffusion coefficient values for hypothetical low and high polymer content matrices. The temperature coefficient yielded a high value (9.15 kcal . mol−1) for the activation energy of the diffusion process, consistent with the energy barrie in a polymer matrix. Such treatment of rate constants and component concentration variables offers a valuable method of correlating formulation and release parameters in non-disintegrating hydrophilic matrices.