Hydroxyethyl Cellulose Acetate Research Articles

Revealing the adsorption energy and interface characteristic of cellulose-graphene oxide composites by first-principles calculations

Synthesizing nanocellulose as the matrix with graphene oxide nanosheets as the functional and reinforcing phases can generate high performance biomass based materials. The first-principles calculation has been used to determine the interface structures and interaction mechanisms between cellulose derivatives (cellobiose, cellulose xanthate, hydroxyethyl cellulose and cellulose acetate) and graphene oxide (GO). The results showed that the composite systems are mainly established by hydrogen bonds and van der Waals interactions; The types of cellulose/derivatives and GO both play an important role in the stability of the composite systems through forming various steric effect and hydrogen bond networks; Cellulose derivatives tend to form more hydrogen bonds with GO, producing numerous charge transfer and greater adsorption energy. The steric hindrance is also an important factor affecting the number of hydrogen bonds, the smaller the steric hindrance, the greater the number of hydrogen bonds. This research provides a theoretical guidance for the design and synthesis of high-performance GO@cellulose/derivatives composite systems.

Preparation and anti-leakage properties of hydroxyethyl cellulose-g-poly (butyl acrylate-co-vinyl acetate) emulsion

A hydroxyethyl cellulose-g-poly (butyl acrylate-co-vinyl acetate)(HEC-g-P (BA-co-VAc)) emulsion was synthesized by free radical emulsion polymerization method from hydroxyethyl cellulose (HEC), butyl acrylate (BA) and vinyl acetate (VAc) in the presence of emulsifier sodium dodecyl benzene sulfonate (SDBS). The structure, thermal stability and morphology of the emulsion were characterized by Fourier-transform infrared (FTIR), thermogravimetric analysis (TGA), transmission electron microscope (TEM) and other analytical techniques. The results proved that BA and VAc monomers had grafted with HEC. Its thermal stability was also significantly improved compared to HEC. Moreover, the prepared emulsion was evaluated to study the performance of preventing water leakage in soil. Compared with the published anti-leakage materials prepared by directly doping hydroxyethyl cellulose, the emulsion interacted with attapulgite to form a dense consolidation layer, which had better anti-leakage performance and water retention. Therefore, the material was more favorable for popularization and application in arid and semi-arid areas.

Homogeneous Grafting of New Amido Groups onto Hydroxyethyl Cellulose Acetate Microfibrils: Solubility Study

Attempts to modify the surface of hydroxyethyl cellulose acetate (HECA-DS AC ~1.5) microfibrils were made using amine terminated molecules. First, the amine compounds were reacted with sebacoyl chloride in nonstoichiometry ratio in order to obtain a monoadduct chloride such as ClCO-(CH 2 ) 8 -CONHR. Then the resulted derivatives were coupled with hydrophobic hydroxyethyl cellulose acetate (HECA) by a condensation reaction in homogenous medium using triethyl amine (N(C 2 H 5 ) 3 ) in THF. The products were characterized by FTIR, 1 H NMR, 13 C NMR, and DRX, and thermal proprieties were also determined. The X-ray diffraction showed that the crystallinity of the amido esters obtained depends on both the degree of substitution and the nature of the graft moiety. The solubility study was based on the determination of the Flory–Huggins interaction parameters (χ) using the partial Hansen solubility parameters (HSP) and that were calculated from the Van Krevlen–Hoftyze (VKH) method and the T. Lindvig approximation. Keywords: cellulose; microfibrils; amidation; Hansen solubility; Flory–Huggins parameters.

Structure and properties of hydroxyapatite/hydroxyethyl cellulose acetate composite films

The main aim of this research work was to develop a new inorganic–organic film. Hydroxyapaptite (HAp) particles that represent the inorganic phase was mixed well with hydroxyethyl cellulose acetate (HECA), which representing the organic phase and then the inorganic–organic films were fabricated by evaporating of the solvent. The structure as well as the properties of the formed films were characterized using different analytical tools such as field emission scanning electron microscopy (FEG-SEM), thermo-gravimetric analysis (TGA), Fourier transform infra-red (FT-IR) spectroscopy. The obtained results revealed that, the HAp nanoparticles was well dispersed and well immobilized throughout the formed films. This can be attributed to the role of the nano- and micropores in the HECA substrate. In addition, a strong interaction occurred between HAp and HECA matrix. The results showed also good thermal stability and miscibility as well.

Synthesis and characterization of the new cellulose derivative films based on the hydroxyethyl cellulose prepared from esparto “stipa tenacissima” cellulose of Eastern Morocco. II. Esterification with acyl chlorides in a homogeneous medium

AbstractEsparto “Stipa tenacissima” cellulose esters derivatives: HECA‐COOC4H8COOC2H5, HECA‐COOC8H16COOC2H5, and HECA‐COOC6H4COOC2H5 were successfully prepared in Tetrahydrofuran (THF)/triethylamine system with a degree of substitution (DS), respectively, DSAD‐Et=0.32, DSSB‐Et=0.22, and DSTRP‐Et=0.50 using hydroxyethyl cellulose acetate (HECA; DSAC=0.50) as intermediate product, and we avoided the drawbacks of cellulose solubility. The structural modifications were investigated using Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance (1H‐NMR), Carbon‐13 nuclear magnetic resonance (13C‐NMR), and Distortionless Enhancement by Polarization Transfer 135° (DEPT‐135). The results from these analyses revealed the presence of the characteristic groups indicating that the grafting reaction was successful. The crystallinity and the structure order changes during the esterification reactions were recorded by X‐ray diffraction (XRD), it is found that the crystallinity degree decrease from 63.1% for Esparto “Stipa tenacissima” cellulose to 27.74% for HECA. The thermal stability of the esterified and unmodified cellulose samples was studied by thermogravimetric analysis (TGA)‐differential thermal analysis (DTA); the modified HECA exhibits a decrease in thermal stability relatively to the unmodified HECA, and this may be related to the groups grafted. The resulted cellulose esters HECA‐Px (x = 1, 2, or 3) were soluble in THF and present an amorphous structure justified by XRD spectra. It was noted by TGA‐DTA analysis that the cellulose esters with low melting range were proved as thermoplastic polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Ring-banded spherulites in poly(?-caprolactone) blended with hydroxyethyl cellulose acetate as an indication for partial miscibility

The morphologies of poly(ϵ-caprolactone) (PCL) blends with hydroxyethyl cellulose acetate (HECA), a thermotropic liquid crystalline polymer (TLCP), were investigated by optical microscopy. It is demonstrated that when the pure PCL is crystallized from the melt, a spherulitic morphology arises with distinct Maltese crosses. With the addition of the HECA, the spherulites of the PCL/HECA blends show not only the Maltese crosses but also distinct extinction rings (i.e., a ring-banded spherulitic morphology). The average periodic distance of the extinction rings decreases drastically with the increase of the HECA content from 0.5 to 5 wt % in the mixture, whereas it decreases only slightly with the further increase of HECA. The periodicity of extinction rings is also influenced by the crystallization temperature. The formation of the ring-banded spherulites of PCL in PCL/HECA blends is explained in terms of stress-induced twisted lamellar crystallization and used as an indication of the molecular solubility of the HECA in the PCL. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1681–1686, 2001

Toughening of epoxy resin blended with thermotropic hydroxyethyl cellulose acetate

Thermotropic hydroxyethyl cellulose acetate (HECA) was totally miscible with uncured epoxy resin, and the miscibility was not influenced by the degree of substitution (DS) of HECA. When the epoxy resin was cured with diamine (DDA), HECA became immiscible with the epoxy resin matrix, and a heterogeneous system was formed. Epoxy resin existed as a constant phase, and HECA-rich domains were dispersed in the matrix with dimensions of about 0.2–0.5 μm. Epoxy resin could be toughened by HECA, and the impact strength of the epoxy resin blends with 10 wt % HECA was the maximum. HECA exhibited the highest toughening ability when the epoxy resin was cured at the temperature at which the HECA existed as a liquid crystalline state. The toughening ability was also influenced by the degree of substitution for acetyl of HECA, and the impact strength of the epoxy resin blends decreased with increasing the DS for acetyl of HECA. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1159–1163, 1998

Influence of thermal history on the formation of liquid crystalline phase of hydroxyethyl cellulose acetate

The influence of thermal history on the formation of HECA liquid crystalline phase was studied by DSC. It was found that the degree of ordering in the liquid crystalline phase was heterogeneous, and the multiphase transformation appears when the liquid crystalline phase transformed to the isotropic one. When HECA was annealed in the liquid crystalline state, the parts with the lower degree of ordering could transform to ones with the higher degree of ordering, and the temperature and the enthalpy of the phase transformation from the liquid crystalline phase to the isotropic phase increased. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1137–1142, 1998

Toughening of epoxy resin blended with thermotropic hydroxyethyl cellulose acetate

Toughening of epoxy resin blended with thermotropic hydroxyethyl cellulose acetate

Influence of thermal history on the formation of liquid crystalline phase of hydroxyethyl cellulose acetate

The influence of thermal history on the formation of HECA liquid crystalline phase was studied by DSC. It was found that the degree of ordering in the liquid crystalline phase was heterogeneous, and the multiphase transformation appears when the liquid crystalline phase transformed to the isotropic one. When HECA was annealed in the liquid crystalline state, the parts with the lower degree of ordering could transform to ones with the higher degree of ordering, and the temperature and the enthalpy of the phase transformation from the liquid crystalline phase to the isotropic phase increased. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1137–1142, 1998

Morphology of polyethylene blended with thermotropic hydroxyethyl cellulose acetate

Morphology of low-density polyethylene (PE)/thermotropic hydroxyethyl cellulose acetate (HECA) blends, and the melting and crystallization behavior of PE in the blends were studied. The “sea island” morphology was observed in PE/HECA blends. The process of melting and crystallization of PE in blends was independent of the HECA fraction when the PE fraction was larger than 50 wt %. When the PE fraction is smaller than 20 wt %, however, multiple crystallization was observed in the low temperature region. HECA was incompatible with PE crystals in the blends, but partially compatible with the amorphous part of PE. HECA could exist between the PE lamellae in PE spherulites, and concentric ring morphology was observed in spherulites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1285–1291, 1998

Biodegradable polymer blends of poly(3-hydroxybutyrate) and hydroxyethyl cellulose acetate

The melting and crystallization behaviour and phase morphology of poly(3-hydroxybutyrate) (PHB) and hydroxyethyl cellulose acetate (HECA) blends prepared by casting films have been studied by differential scanning calorimetry (d.s.c.), Fourier transform infra-red ( FTi.r.), scanning electron microscopy and polarizing optical microscopy. The melting temperatures of PHB in the blends were independent of the blend composition with PHB contents above 20%. The melting enthalpy of the blends decreased with increase in the HECA component and was close to the additive value of the enthalpy of the two components. The glass transition temperatures of PHB in the blend were constant at about 8°C. No specific interaction between the two components was found by FTi.r. The crystallization of PHB in the blend was affected by the HECA component, especially in the PHB/HECA (20/80) blend. During the d.s.c. cooling run at a lower cooling rate, two separate transitions were found for PHB/HECA (80/20), (60/40) and (40/60) blends, which corresponded to the crystallization of PHB and the phase transition of HECA from an isotropic phase to a mesophase in the blends, respectively. The phase transformation of HECA from an isotropic phase to a mesophase was almost independent of the PHB component.

Influence of Transitional Metal Ions on Lyotropic Liquid Crystals of Hydroxyethyl Cellulose Acetate inN,N-Dimethylformamide

The influence of inorganic salts on the formation of lyotropic liquid crystals of hydroxyethyl cellulose acetate (HECA) in N,N′dimethylformamide (DMF) was studied. In the presence of CaCl2, an inorganic salt of a principal group metal, the solution of HECA/DMF/CaCl2 was a biphasic system. The temperature of the transformation from the liquid crystalline phase to the isotropic one increased with adding CaCl2 because local HECA concentration increases in the HECA/DMF phase. When CuCl2 or CoCl2, inorganic salts of transitional metals, was added, the solutions were monophasic systems and the complexes of HECA with Cu2+ or Co2+ were formed in solutions, which results in the increase of the temperature of the transfomation from the liquid crystalline phase to the isotropic one.

Kinetics of Nonisothermal Transformations of Thermotropic Hydroxyethyl Cellulose Acetate

Abstract The kinetics of non-isothermal transformation from isotropic to anisotropic phases of hydroxyethyl cellulose acetate (HECA) was studied by DSC at different cooling rates. It was found that the modified Avrami equation could be used in study and the exponent n was closed to 1. The rate of transformation increased with decreasing temperature and the apparent activation energy E was about 2.641 KJ/mol. The half-time of transformation t ½ was smaller than that of polymer crystallization and increased with temperature. The rate of transformation appears the maximum with temperature and the temperature at the largest rate of transformation shifted towards the low temperature with increasing cooling rate and the kinetic ability of transformation was also enlarged.

Light‐scattering and size‐exclusion chromatographic characterization of hydroxyethyl cellulose acetate

AbstractA recently developed analytical method of combining off‐line laser light scattering (LLS) and size exclusion chromatography (SEC) was used to investigate a set of moderately distributed hydroxyethyl cellulose acetate (HECA) samples in tetrahydrofuran (THF) at room temperature. Our results have shown that this new LLS + SEC method is suitable for the characterization of molecular weight distribution of HECA. By using this method, we have simultaneously determined two calibrations of V (cm3) = 45.3 − 1.89 log (M) and D (cm2/s) = 2.45 × 10−4 M−0.60, where M is the molecular weight of HECA; V, the elution volume in SEC; and D, the translational diffusion coefficient in dynamic LLS. In addition, our results have also indicated that the chain conformation of HECA in THF at room temperature is a slightly extended linear coil. © 1995 John Wiley & Sons, Inc.

Molecular interactions and formation of lyotropic liquid crystals of hydroxyethyl cellulose acetate

The relationship between the hydrogen bond (H-bond) interactions and the formation of the cholesteric liquid crystalline phase was studied by Fourier transform infrared spectroscopy (FTIR), refractometry and polarizing microscopy. It was quite evident that the H-bonding played an important role in the early stage of the formation of cholesteric liquid crystalline phase in hydroxyethyl cellulose acetate (HECA)/dimethyl sulfoxide (DMSO) solutions and the rigidity of the HECA chains was more important to form liquid crystalline phase than molecular interactions when the concentration is very high.

Thermotropic behavior of hydroxyethyl cellulose acetate

AbstractThermotropic behavior of hydroxyethyl celloulose acetate (HECA) was studied by polarizing microscopy, DSC, and X‐ray diffraction. It was found that HECA was an anisotropic liquid between the temperature from 130 to 185°C on heating, and when the temperature was over 185°C, it became isotropic. In cooling, however, mesophase began to form at about 165°C. The transformation temperature decreased with decreasing molecular weight and the temperature region of transformation decreased with decreasing the distribution of the molecular weight for HECA. The kinetic ability of tranformation appeared the maximum with molecular weight. The HECA liquid crystal is cholesteric and the distance between layers of ordered molecular chains was enlarged when HECA was transformed from liquid crystalline glass to the liquid crystalline state. © 1994 John Wiley & Sons, Inc.