Characterization and Properties of Hydrophilic Cellulose Acetate Propionate Derivative

The chemical modification of Acrylamidomethyl Cellulose Acetate Propionate (AMCAP) was carried out by radical addition of acrylic acid. The structural modification was confirmed with the aid of FTIR, MS and NMR techniques. Thermal properties of hydrophilic cellulose derivative (AMCAP–H₂O₂) such as glass transition (T_g 153 °C) and thermal stability (372.7 °C) were determined by DSC and TGA techniques, respectively. These thermal properties confirmed the introduction of carboxylic groups into AMCAP structure, which causes an impact in their properties. The AMCAP–H₂O₂ shows minor contact angle compared to AMCAP, giving a more hydrophilic characteristic, due to acrylic acid addition into the side chains of AMCAP polymer.     

Functional Properties of Extruded Starch Acetate Blends

Starch acetate, with degree of substitution of 2, was blended with 0, 7.5 and 15% polylactic acid (PLA), Eastar Bio Copolyester 14766 (EBC) or Mater-Bi ZF03U (MBI) and 10%, 13%, or 16% (d.b.) ethanol and twin-screw extruded at 160°C barrel temperature. Physical characteristics of the extrudates, such as radial expansion ratio, unit and bulk densities, and of the mechanical properties, including unit spring index and bulk spring index, were measured. Type of polymer, polymer content, and ethanol content significantly affected the physical characteristics and mechanical properties. The sample extruded with 7.5% PLA and 13% ethanol had the highest expansion ratio and bulk spring index. The sample with 15% MBI and 16% ethanol had the lowest unit density, while the sample with 7.5% PLA and 16% ethanol had lowest bulk denisty. The highest unit spring index was expressed in the sample containing 7.5% PLA and 10% ethanol.     

Nanocomposites of Cellulose Acetate Butyrate Reinforced with Cellulose Nanocrystals

Nanocrystals were prepared by acid hydrolysis of bacterial cellulose microfibrils. These were topochemically trimethylsilylated, in an attempt to reduce their hydrophilicity. Composites were made by dispersing either native or silylated crystals in cellulose acetatebutyrate matrixes and solution casting of the dispersions. Particles were characterized by transmission electron microscopy. The composites were characterized by differential scanning calorimetry and dynamic mechanical analysis. The unmodified cellulose crystals exhibited better reinforcement characteristics than the trimethylsilated crystals.     

Physical,Mechanical, and Morphological Characteristics of Extruded Starch Acetate Foams

Starch acetates with degrees of substitution (DS) of 0.57, 1.11, 1.68, and 2.23 were prepared and extruded with either water or ethanol. The microstructure, physical properties (radial expansion ratio [RER] and unit density), mechanical properties (spring index [SI] and compressibility), and crystalline structure of the foams were investigated. The functional properties were a function of DS and blowing agent type. When water was used as the blowing agent and DS increased, the foams were pale yellow, with rough and uneven surfaces. The cells were dense, with thick cell walls. Lower RER and SI, with higher DS, were associated with high unit density and compressibility. When ethanol was used as the blowing agent, contrary results were observed. The snow-white foams had smooth surfaces, uniform cells, and smooth cell walls. High RER and SI, and low unit density and compressibility were observed. The changes in SI and compressibility with RER also were examined and found to depend on the type of solvent. A crystalline pattern was observed because of the formation of well-ordered structures during extrusion.     

利用醋酸废水制取醋酸钙镁盐

用三辛胺萃取醋酸废水中的醋酸，加入白云石灰乳反萃、可制得环保型除冰剂醋酸钙镁盐（CMA）。研究了萃取剂组成，剂水比，萃取温度，萃取时间，搅拌速度对萃取效率的影响，确定了反萃的操作条件。试验表明：采用该法处理稀醋酸，工艺简单、醋酸利用率高。     

离子液体萃取法回收废水中的醋酸丁酯

利用离子液体1-己基-3-甲基咪唑六氟磷酸盐萃取模拟废水中的醋酸丁酯。萃取液经减压蒸馏回收醋酸丁酯，离子液体也得到再生。实验结果表明:萃取率随废水与离子液体体积之比(相比)的增加而减小，随萃取时间的延长而增大，随萃取温度的升高而增大;在相比为6∶1、萃取时间为40min、萃取温度为50℃的条件下，萃取率达98.98%，醋酸丁酯纯度达99.8%;回收后离子液体可重复使用且萃取率基本不变。     

Biodegradation Properties of Poly-ε-caprolactone,Starch and Cellulose Acetate Butyrate Composites

Blending starches with polymers such as poly-ε-caprolactone (PCL) has been used as a route to biodegradable plastics. The addition of starch has a significant effect on all physical properties including toughness, elongation at break. On blending cellulose acetate butyrate (CAB) with starch and PCL, improvements in most physical and mechanical properties were observed. This is may be due to CAB acts as a compatibilizer between PCL and starch due to the presence of both hydroxyl groups (in starch and CAB) and ester carbonyls (in PCL and CAB). The presence of different compounds affects the way in which other components degrade. For example the structure of CAB within a starch and PCL combination might make the degradation rate different to that when starch was only mixed with PCL. To check whether this was the case, three combinations of different blends were used to calculate the rate of degradation of each of them separately. These degradation rate constants were then used to predict the theoretical degradation which was checked against the experimental value for other different combinations.     

All-Cellulose Composite Fibers Obtained by Electrospinning Dispersions of Cellulose Acetate and Cellulose Nanocrystals

All-cellulose composite fibers were produced by electrospinning dispersions containing cellulose acetate (CA) and cellulose nanocrystals (CNCs). Precursor polymer matrices were obtained after dispersion of CA with different degrees of substitution in a binary mixture of organic solvents. The obtained fibers of CA loaded with CNCs had typical widths in the nano- and micro-scale and presented a glass transition temperature of 145?°C. The CA component was converted to cellulose by using alkaline hydrolysis to yield all-cellulose composite fibers that preserved the original morphology of the precursor system. Together with Fourier Transform Infrared Spectroscopy fingerprints the thermal behavior of the all-cellulose composite fibers indicated complete conversion of cellulose acetate to regenerated cellulose. Noticeable changes in the thermal, surface and chemical properties were observed upon deacetylation. Not only the thermal transitions of cellulose acetate disappeared but the initial water contact angle of the web was reduced drastically. Overall, we propose a simple method to produce all-cellulose composite fibers which are expected to display improved thermo-mechanical properties while keeping the unique features of the cellulose polymer.     

Effect of Sequential Mixing and Compounding Conditions on Cellulose Acetate/Layered Silicate Nanocomposites

Injection molded nanocomposites have been successfully fabricated from cellulose acetate (CA), eco-friendly triethyl citrate (TEC) plasticizer, and organically modified clay with and without maleic anhydride grafted cellulose acetate butyrate (CAB-g-MA) as a compatibilizer. The effects of processing conditions such as mixing methods, pre-plasticizing times, extruder retention times (RT) and addition of compatibilizer on the performance of these nanocomposites have been evaluated. The cellulosic plastic with CA/TEC (80/20 wt%) was used as the polymer matrix for nanocomposite fabrication. The morphologies of these nanocomposites were evaluated through X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. The mechanical properties of the nanocomposites were measured and have been correlated with the XRD and TEM observations. From all of the sequential mixing methods used, powder–powder mixing leads to the most transparent nanocomposites. Cellulosic plastic-based nanocomposites obtained using increased pre-plasticizing times and RT showed better exfoliated structures. In the system containing compatibilizer, the minimum retention time required for obtaining almost completely exfoliated hybrid nanocomposites was shorter than in the system without compatibilizer.     

膜萃取和CaO-MgO乳状液反萃取法由醋酸废水生产醋酸钙镁盐

采用磺化聚醚砜中空纤维膜萃取醋酸废水，再用CaO—MgO乳状液反萃取制备醋酸钙镁盐。考察了膜萃取和反萃取的最佳实验条件。单级膜萃取醋酸废水（醋酸质量分数2％）的最佳条件为：水相走管程有机相走壳程（水外油内）逆流、有机相流量与水相流量比1．3、水相流量0．23mL/min，在此条件下萃取率可达74％；采用二级萃取，总萃取率可达95％。反萃取的最佳条件为：采用质量浓度100g／L的CaO—MgO乳状液作反萃取剂，CaO—MgO与醋酸摩尔比1．0：2．0，投料钙与镁摩尔比2．9：7．0，反萃取时间30min，室温，在此条件下反萃取率高于97％。     

活性炭纤维对气体中醋酸丁酯吸附性能的研究

通过试验选择活性炭纤维作为吸附剂,吸气气体中醋酸丁酯。对影响其吸附性能的主要因素进行了研究。     

Lyotropic Liquid Crystal Phases in Cellulose Acetate Phthalate/Hydroxypropyl Cellulose Blends

Cellulose and some of its derivatives form liquid crystalline solutions in a variety of solvents. The present work investigates cellulose acetate phthalate/hydroxypropyl cellulose blends in N,N-dimethylacetamide, in function of concentration and composition, by rheology, considering dynamic viscometry and oscillatory shear tests. The effects of composition, concentration, shear rate, and oscillatory deformation on the rheological functions determines the orientation or mobility of the chain segments in the shear field. Atomic force microscopy and polarized light microscopy studies on corresponding films show that specific interactions, such as the hydrogen bonds between cellulose acetate phthalate and the liquid crystalline component—hydroxypropyl cellulose, stabilizes the morphology, leading to the emergence of different formations typical for lyotropic liquid crystal phases. These studies contribute to a better knowledge of the specific interactions that generate and modify the liquid crystalline properties of cellulose derivatives, required by the applications in electronic domains.     

Synthesis and Characterization of a Thin-Film Composite Nanofiltration Membrane Based on Polyamide-Cellulose Acetate: Application for Water Purification

Membrane separation has been widely used for various applications including microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) processes in the fields of biomedicine, food, and water purification. In this work, a facile synthesis of new polyamide thin-film composite nanofiltration membranes (NF-TFC) for water purification was described. The polyamide thin film was deposed over a synthetic cellulose acetate (CA) support by interfacial polymerization method. 1,3 cyclohexane bis (methylamine) (CHMA) and trimesoyl chloride (TMC) were used as monomers. The membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FT-IR), water uptake, porosity, contact angle, water permeability and rejection towards specific salt and dye molecules. The effect of the variation of the CHMA concentration (0.2–2 wt.%) on the morphology, porosity, water permeation and rejection properties of the prepared membranes was studied. SEM results displayed the growth of the membrane thickness when the CHMA concentration increased from 0.2 to 2 wt.%. The strong adhesion between the cellulose acetate substrate and the polyamide layer explained by the formation of the polyamide film in the substrate surface and inside the pores. The water permeability varied from 36.02 to 17.09 L h^?1 m^?2 bar^?1. The salt rejection of Na₂SO₄ and NaCl increased from 9 to 68% and from 38.41% to 89.4%, respectively, when the CHMA concentration was changed from 0.2 to 2 wt.%. The prepared membranes were further applied successfully for the removal of malachite green and congo red. The results indicated that the maximum rejection reached 89% and 85% for malachite green and congo red, respectively.

     

Utilization of Cellulosic Wastes in Textile and Garment Industries: 2. Synthesis and Characterization of Cellulose Acetate from Knitted Rag

Cellulose acetate (CA) was synthesized from knitted rag, a cellulosic waste of Textile and Garment industries, in the glacial acetic acid, and subsequently acetic anhydride (Ac₂O) in presence of concentrated H₂SO₄ reaction medium. A low to high substitution products were obtained from single step up to seven steps acetylation of cellulose. In this way, it was possible to produce low cost and different grades or substituted acetylation derivatives of cellulose. The synthesized CA was characterized and investigation of its physical characteristics was done. Solubility, acetyl content, acetic acid content, degree of substitution, and molecular weight of CA increased gradually with the increase of the number of reaction steps attaining optimum value at the fourth step. The acetyl and acetic acid content of CA were increased from 39.95 % to 44.25 %, and from 55.73 % to 61.73 % respectively. Similarly, degree of substitution and molecular weight of CA were increased from 2.47 to 2.94, and from 74,249 to 121,437 respectively.     

Biodegradable Blends with Potential Use in Packaging: A Comparison of PLA/Chitosan and PLA/Cellulose Acetate Films

Poly(lactic acid) (PLA) is a biodegradable polymer that exhibits high elastic modulus, high mechanical strength, and feasible processability. However, high cost and fragility hinder the application of PLA in food packaging. Therefore, this study aimed to develop flexible PLA/acetate and PLA/chitosan films with improved thermal and mechanical properties without the addition of a plasticizer and additive to yield extruder compositions with melt temperatures above those of acetate and chitosan. PLA blends with 10, 20, and 30 wt% of chitosan or cellulose acetate were processed in a twin-screw extruder, and grain pellets were then pressed to form films. PLA/acetate films showed an increase of 30 °C in initial degradation temperature and an increase of 3.9 % in elongation at break. On the other hand, PLA/chitosan films showed improvements in mechanical properties as an increase of 4.7 % in elongation at break. PLA/chitosan film which presented the greatest increase in elongation at break proved to be the best candidate for application in packaging.     

Effect of Poly(Vinyl Acetate) on Mechanical Properties and Characteristics of Poly(Lactic Acid)/Natural Rubber Blends

Natural rubber grafted with poly(vinyl acetate) copolymer (NR-g-PVAc) was synthesized by emulsion polymerization. Three graft copolymers were prepared with different PVAc contents: 1 % (G1), 5 % (G5) and 12 % (G12). Poly(lactic acid) (PLA) was melt blended with natural rubber (NR) and/or NR-g-PVAc in a twin screw extruder. The blends contained 10–20 wt% rubber. The notched Izod impact strength and tensile properties were determined from the compression molded specimens. The effect of NR mastication on the mechanical properties of the PLA/NR/NR-g-PVAc blend was evaluated. Characterization by DMTA and DSC showed an enhancement in miscibility of the PLA/NR-g-PVAc blend. The temperature of the maximum tan δ of the PLA decreased with increasing PVAc content in the graft copolymer, i.e., from 71 °C (pure PLA) to 63 °C (the blend containing 10 % G12). The increase in miscibility brought about a reduction in the rubber particle diameter. These changes were attributed to the enhancement of toughness and ductility of PLA after blending with NR-g-PVAc. Therefore, NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. NR mastication was an efficient method for increasing the toughness and ductility of the blends which depended on the blend composition and the number of mastications.     

A Novel Hybrid 2,4-Dichlorophenoxy Acetate Bead from Modified Cassava Starch and Sodium Alginate with Modified Natural Rubber Coating

A novel herbicide bead was developed by phase separation, utilizing modified cassava starch (CSt), sodium alginate (SA) and 2,4-dichlorophenoxy acetate (2,4 DA), and the beads were also coated with natural rubber grafted with cassava starch (NR-graft-CSt) to aid their water resistance. The alginate gel beads with 65% entrapped 2,4 DA showed 90% release within 24 h. The incorporation of CSt in the beads markedly improved their encapsulation efficiency to 98% and sustained the release of the herbicide for 700 h. The water resistance was improved by coating the beads with NR-graft-CSt when compared with the pure CSt/SA bead. The synthesized bead has excellent potential for agricultural applications.     

Modification of Thermo-Mechanical Properties of Recycled PET by Vinyl Acetate (VAc) Monomer Grafting Using Gamma Irradiation

Vinyl acetate (VAc) monomer of different percentage was grafted onto the recycled polyethylene terephthalate (r-PET) films using gamma irradiation. The properties of these modified films were characterized by Fourier transform infrared spectroscopy (FTIR), mechanical properties testing (Tensile strength, Elongation at break), dynamic mechanical analysis (DMA) and thermo-gravimetric analysis (TGA). The Tensile Strength (TS) of the modified PET film increased by 132.25?% to the highest value of 50.12 MPa at 15% VAc monomer concentration at 3 kGy gamma dose, while the elongation at break (EB) decreased by 31.83?%. FTIR was used to investigate the molecular interaction of the modified films. TGA revealed that curve of the modified PET film shifted toward higher temperature region by 95?°C, which is very close to that of PET film made from virgin flakes. The results indicate that modified PET films of better mechanical and thermal properties were successfully prepared using VAc monomer grafting by gamma irradiation technique.     

Preparation and Characterization of Hybrids of Cellulose Acetate Membranes Blended with Polysulfone and Embedded with Silica for Copper(II), Iron(II) and Zinc(II) Removal from Contaminated Solutions

Journal of Polymers and the Environment - With the objective to assess the suitability of cellulose acetate (CA), polysulfone (PSF) and silica (SiO2) for wastewater treatment, this work presents...