Sustained delivery of hydrocortisone acetate by CS/N‐vinyl‐2‐pyrrolidone/CaCO3 microparticle hybrid hydrogels

The goal of this research is to develop a composite hydrogel system for sustained release of therapeutic agents. The hybrid hydrogels were prepared by radiation crosslinking on aqueous solution of Chitosan (CS)/N‐vinyl‐2‐pyrrolidone (NVP) with different loads of CaCO₃ in the presence of hydrocortisone acetate (HCA), an anti‐inflammatory drugs. Physical characteristics of CS/NVP/CaCO₃ were studied using X‐ray diffraction (XRD) and infrared spectrophotometery (IR). The porous structure of resulted hydrogel was confirmed by SEM micrographs. The effect of doses and calcium carbonate amount on the swelling of the hydrogels was investigated. The ability of the prepared CS/NVP/CaCO₃‐based hybrid hydrogels to be used as drug carriers for anti‐inflammatory‐specific drug delivery system was estimated using HCA as a model drug. POLYM. COMPOS., 35:1176–1183, 2014. © 2013 Society of Plastics Engineers     

Effect of in situ deposition of calcium carbonate in cotton fiber on its mechanical properties

In this study, in order to improve mechanical properties of cotton fabrics, nano-micro sized calcium carbonate (CaCO₃) was deposited in situ on cotton fabrics. The mechanical properties, surface morphology, crystalline index, infrared spectrum, thermal property, and wettability of the deposited fabrics were measured and discussed. The results showed that the breaking strength of cotton fabric increased by about 10% after in situ deposition of nano-micro calcium carbonate. After ultrasonic washing, the strength of cotton fabric deposited CaCO₃ was still increased by about 10%. The crystallinity of the cotton fabric deposited with calcium carbonate increased from 76% to 84%. The hydrogen bond between cellulose molecules and calcium carbonate was confirmed by infrared spectroscopy. The hydrophilicity and thermal properties of cotton fabric were not significantly influenced by calcium carbonate deposition. This provides a new idea for improving the mechanical properties of cotton fabric.     

Influence of the incorporation of fine calcium carbonate particles on the impact strength of polypropylene/polystyrene‐block‐poly(ethylene butene)‐block‐polystyrene blends

The Izod impact strength of two kinds of ternary composites was investigated. One consisted of polypropylene (PP), the triblock copolymer polystyrene‐block‐poly(ethylene butene)‐block‐polystyrene (SEBS), and calcium carbonate (CaCO₃) particles, and the other consisted of PP, carboxylated SEBS (C‐SEBS), and CaCO₃ particles. The mean size of the CaCO₃ particles was about 160 nm. According to scanning electron microscopy observations, the composite with SEBS showed a morphology in which SEBS domains and CaCO₃ particles were independently dispersed in the PP matrix. On the other hand, the composite with C‐SEBS showed a morphology in which CaCO₃ particles were encapsulated by C‐SEBS; that is, a core–shell structure was formed. The Izod impact strength of the composite with SEBS was higher than that of the composite with C‐SEBS and the PP/SEBS and PP/C‐SEBS binary blends. According to observations of the fractured surface, the stress‐whitened area was larger in the composite with SEBS than in the composite with C‐SEBS and the PP/SEBS and PP/C‐SEBS binary blends. The toughening mechanism of the composite, using nanometer‐sized CaCO₃ particles in combination with SEBS, was examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Graft copolymerization of nitrogen‐ and phosphorus‐containing monomers onto cellulosics for flame‐retardant finishing of cotton textiles

Phosphoramide containing an active vinyl group (P‐III) was prepared. Its structure was confirmed by elemental analysis and Fourier transform infrared, nuclear magnetic resonance, and mass spectroscopy. P‐III was evaluated as a fire‐retardant finishing agent for cotton fabrics. It was applied to cotton fabrics using a graft process with an Fe²⁺/H₂O₂ redox system. The major factors affecting the reaction were studied. The finished cotton fabrics were examined for flammability, and the effect of washing on treated fabrics was also examined. The results showed that P‐III can be successfully used as a flame retardant for cotton fabrics. Durably flame‐retardant cotton fabrics were obtained at add‐on levels higher than 38%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2573–2578, 2003     

A facile dip‐coating approach to prepare SiO2/fluoropolymer coating for superhydrophobic and superoleophobic fabrics with self‐cleaning property

In this study, a facile, two‐step dip‐coating approach was reported for the fabrication of the superhydrophobic and superoleophobic cotton fabrics. It was confirmed that the superhydrophobic and superoleophobic composite thin film containing modified‐SiO₂ nanoparticles and fluoropolymer had been successfully fabricated on the cotton fabrics surface, the results demonstrated that the treated cotton fabrics showed good performances, such as superhydrophobicity and superoleophobicity, low water and oil absorption ability, self‐cleaning property and good laundering durability, so forth. The above approach can be applied to potentially advance superhydrophobic and superoleophobic fabrics materials for a variety of applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41458.     

Synthesis,characterization, and in vitro drug release study of 3‐arm poly‐β‐alanine

Synthesis of three arms star‐shaped poly‐β‐alanine (3‐b‐ala) based on tri(prop‐2‐yn‐1‐yl) benzene‐1,3,5‐tricarboxylate (TBT) and azido terminated poly‐β‐alanine (N₃‐P‐ala) was performed using click reaction. TBT was synthesized by nucleophilic substitution reaction between propargyl alcohol and 1,3,5‐benzenetricarbonyltrichloride. For the first time, N₃‐P‐ala was synthesized through anionic polymerization of acrylamide using sodium azide as an initiator. TBT was characterized by FT‐IR and ¹HNMR. N₃‐p‐ala was characterized by FT‐IR, GPC, and ¹HNMR and 3‐b‐ala was characterized by FT‐IR, GPC, ¹HNMR, TGA, and XRD. The synthesized 3‐b‐ala was used for drug loading and releasing studies. Polymer loaded drug (3‐b‐ala‐D) hybrid was used in in vitro studies of drug (Diclofenac sodium) release in phosphate buffer solution (PBS) at 37 ± 0.5°C and pH 7.4. The drug loading and releasing studies were analyzed by UV‐visible spectrophotometer. 3‐b‐ala‐D was examined by AFM to analyze the surface morphology and roughness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42124.     

Stimuli-responsive hybrid composites based on CaCO3 microparticles and smart polyelectrolytes for controllable drug delivery

CaCO₃/aliphatic poly(urethane-amine) (PUA)/sodium polystyrene sulfonate (PSS) hybrid composites with dual-responsive controlled drug delivery property had been prepared via electrostatic interaction. Aliphatic PUA and PSS were employed as smart polyelectrolytes. PSS was also served as crystal growth additive to control the morphology of CaCO₃ microparticles. The electrostatic interaction between PSS and aliphatic PUA under weak-acid condition improved the bonding force between PSS-doped CaCO₃ microparticles and polyelectrolytes. pH-/thermo-responsive drug delivery property and the high drug loading capacity (around 90 %) could be achieved from the prepared hybrid composites. More importantly, the relative content of CaCO₃ microparticles and polyelectrolytes had a significant effect on the morphology and controllable release properties of the hybrid composites. The smart drug release mechanism of the hybrid composites was also analyzed by fitting the cumulative release data to Retger–Peppas equation.     

Production of nano‐calcium carbonate from shells of the freshwater channeled applesnail,Pomacea canaliculata,by hydrothermal treatment and its application with polyvinyl chloride

The use of naturally renewable shells of the freshwater channeled applesnail, Pomacea canaliculata, as a filler to replace commercial calcium carbonate (CaCO₃) was investigated in this study. Ground P. canaliculata shell particles were converted to nano‐CaCO₃ particles by the displacement reaction of calcium chloride in sodium carbonate solution followed by hydrothermal treatment at 100°C for 1 h to synthesize nano‐CaCO₃ with particle sizes of 30–100 nm in diameter. The mechanical properties, in terms of the tensile strength, elongation at brake and impact strength, of polyvinyl chloride (PVC) were greatly improved by mixing with nano‐CaCO₃ at 5–10 parts per hundred of resin. Additionally, the presence of nano‐CaCO₃ at the same levels increased the flame resistance and thermal stability of the PVC composite materials. POLYM. COMPOS., 36:1620–1628, 2015. © 2014 Society of Plastics Engineers     

Preparation and properties of nano‐CaCO3/acrylonitrile‐butadiene‐styrene composites

CaCO₃/acrylonitrile‐butadiene‐styrene (ABS) and CaCO₃/ethylene‐vinyl acetate copolymer (EVA)/ABS nanocomposites were prepared by melting‐blend with a single‐screw extruder. Mechanical properties of the nanocomposites and the dispersion state of CaCO₃ particles in ABS matrix were investigated. The results showed that in CaCO₃/EVA/ABS nanocomposites, CaCO₃ nanoparticles could increase flexural modulus of the composites and maintain or increase their impact strength for a certain nano‐CaCO₃ loading range. The tensile strength of the nanocomposites, however, was appreciably decreased by adding CaCO₃ nanoparticles. The microstructure of neat ABS, CaCO₃/ABS nanocomposites, and CaCO₃/EVA/ABS nanocomposites was observed by scanning electron microscopy. It can be found that CaCO₃ nanoparticles were well‐dispersed in ABS matrix at nanoscale. The morphology of the fracture surfaces of the nanocomposites revealed that when CaCO₃/EVA/ABS nanocomposites were exposed to external force, nano‐CaCO₃ particles initiated and terminated crazing (silver streak), which can absorb more impact energy than neat ABS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of injection‐homo‐polypropylene filled with nano‐CaCO3

Nano‐CaCO₃/homo‐PP composites were prepared by melt‐blending using twin‐screw extruder. The results show that not only the impact property but also the bending modulus of the system have been evidently increased by adding nano‐CaCO₃. The nano‐CaCO₃ particles have been dispersed in the matrix in the nanometer scale which was investigated by means of transmission electron microscopy (TEM). The toughening mechanism of nano‐CaCO₃, investigated by means of dynamical mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM), lies on that the nano‐CaCO₃ particles take an action of initiating and terminating crazing (silver streak), which can absorb more impact energy than the neat PP. At the same time, the nano‐CaCO₃ particles, as the nuclear, decrease the crystal size of PP, the results of which were investigated by means of polarized optical microscope (POM). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Processability,morphology, thermal,and mechanical properties of rigid PVC composites with liquid macromolecular modifier‐coated CaCO3

Rigid poly(vinyl chloride) (PVC)/CaCO₃ and PVC/liquid macromolecular modifier (LMM) coated CaCO₃ (PVC/LCC) composites were both fabricated by melt mixing. The processability, micro‐structure, dynamic mechanical behavior and mechanical properties of PVC/CaCO₃ and PVC/LCC composites were studied by using torque rheometer, scanning electron microscope (SEM), dynamic mechanical analysis (DMA), and universal mechanical testing machine. The results showed that the synergistic effect of LMM and CaCO₃ particles accelerated the plasticization of PVC resins. The processability of PVC/LCC composites was improved. The dispersion of LCC in PVC matrix was improved by the modification of CaCO₃ particles with LMM. The T_gs of PVC/LCC composites were enhanced by filling with LCC. Because of the synergistic toughening of LMM and CaCO₃ particles, the PVC/LCC composites exhibited excellent notched impact properties at the optimum value of LCC particles content. POLYM. COMPOS., 36:1286–1292, 2015. © 2014 Society of Plastics Engineers     

Optimization of lactic acid production from whey by L casei NRRL B‐441 immobilized in chitosan stabilized Ca‐alginate beads

The production of lactic acid from whey by Lactobacillus casei NRRL B‐441 immobilized in chitosan‐stabilized Ca‐alginate beads was investigated. Higher lactic acid production and lower cell leakage were observed with alginate–chitosan beads compared with Ca‐alginate beads. The highest lactic acid concentration (131.2 g dm^?3) was obtained with cells entrapped in 1.3–1.7 mm alginate–chitosan beads prepared from 2% (w/v) Na‐alginate. The gel beads produced lactic acid for five consecutive batch fermentations without marked activity loss and deformation. Response surface methodology was used to investigate the effects of three fermentation parameters (initial sugar, yeast extract and calcium carbonate concentrations) on the concentration of lactic acid. Results of the statistical analysis showed that the fit of the model was good in all cases. Initial sugar, yeast extract and calcium carbonate concentrations had a strong linear effect on lactic acid production. The maximum lactic acid concentration of 136.3 g dm^?3 was obtained at the optimum concentrations of process variables (initial sugar 147.35 g dm^?3, yeast extract 28.81 g dm^?3, CaCO₃ 97.55 g dm^?3). These values were obtained by fitting of the experimental data to the model equation. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in lactic acid production using alginate–chitosan‐immobilized cells. Copyright © 2005 Society of Chemical Industry     

Rheological and isothermal crystallization characteristics of neat and calcium carbonate‐filled syndiotactic polypropylene

Steady‐state and oscillatory shear behavior of three neat syndiotactic polypropylene (s‐PP) resins and a s‐PP resin (s‐PP#8) filled with CaCO₃ particles of varying content, size, and type of surface modification were investigated. All of the neat s‐PP resins investigated exhibited the expected shear‐thinning behavior. Both the storage and loss moduli increased with decreasing temperature. The shift factors used to construct the master curves were fitted well with both the Arrhenius and the Williams–Landel–Ferry (WLF) equations. The inclusion of CaCO₃ particles of varying content, size, and type of surface modification, to a large extent, affected both the steady‐state and oscillatory shear behavior of s‐PP/CaCO₃ compounds, with the property values being found to increase with increasing content, decreasing size, and surface coating of the CaCO₃ particles. Lastly, the effects of melt‐annealing and crystallization temperatures on isothermal crystallization behavior of s‐PP#8 filled with CaCO₃ particles of varying content, size, and type of surface modification were also investigated. The half‐time of crystallization of neat s‐PP#8 exhibited a strong correlation with the choice of the melt‐annealing temperature (T_f) when T_f was less than about 160 °C, while it became independent of T_f when T_f was greater than about 160 °C. On the other hand, the half‐time of crystallization of s‐PP#8/CaCO₃ compounds did not vary much with the T_f. Generally, the observed half‐time of crystallization decreased with increasing CaCO₃ content and increased with increasing CaCO₃ particle size. Finally, coating the surface of CaCO₃ particles with either stearic acid or paraffin reduced the ability of the particles to effectively nucleate s‐PP#8. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4515–4525, 2006     

Electrostatic self‐assembly dyeing of cotton fabrics

A new approach to the dyeing of cotton fabrics using an electrostatic self‐assembly method was evaluated. Cotton fabrics were pretreated with 2,3‐epoxypropyltrimethylammonuium chloride and cationic charges were produced on the fabric surfaces. For the dyeing of cotton fabric, reactive and acid dyes were used. Oppositely charged anionic reactive/acid dyes and cationic poly(diallyldimethylammonium chloride) were alternately deposited on the surface of cationised cotton fabrics. Ten multilayer films of dye/poly(diallyldimethylammonium chloride) were deposited on the cotton fabric surfaces using a padder. The build‐up of the multilayer films and the level of colour strength (K/S) achieved are discussed. Samples of cotton fabrics were also dyed with the same dyes, but using the exhaust method, and both types of dyed samples were compared. The washing, rubbing and light fastness properties were evaluated for the dyed fabrics.     

Effect of particle size and surface modification on mechanical properties of poly(para‐dioxanone)/inorganic particles

Poly(para‐dioxanone) (PPDO)‐based composites have been prepared by blending PPDO with three different types of CaCO₃ particles, CC1 (nano‐CaCO₃), CC2 (CaCO₃ whisker), and CC3 (silane‐coated CaCO₃ whisker). The effects of particles size, interface adhesion, and crystallinity of composites on mechanical properties were discovered through analysis of the morphology of fracture surfaces, thermal characteristics, and crystalline structure. DSC revealed that the CaCO₃ particles acted as a nucleating agent and promoted crystallinity of PPDO. The effect of CaCO₃ particles on crystallization of PPDO was clearly revealed by using the nucleating efficiency. Smaller size particles exhibit greater nucleating efficiency. Adhesion between PPDO and the CaCO₃ particles plays major roles on the mechanical properties of composites. The tensile strength of PPDO was improved over 54%. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation and characterization of pH‐sensitive microparticles based on polyelectrolyte complexes for antibiotic delivery

pH‐sensitive microparticles formed by combination of a synthetic copolymer and sodium alginate in presence of calcium chloride were prepared in mild conditions for specific water‐soluble drug delivery. The copolymers of acryloxyethyl‐trimethylammonium chloride and N‐vinyl‐2‐pyrrolidone were synthesized by radical polymerization in aqueous solution at 60°C using sodium persulfate as initiator. Fourier transform infrared spectroscopic characterization confirmed the structure of the copolymers and their compositions were determined by potentiometric method. Scanning Electron Microscopy study revealed that microparticles have a rough morphology with size ranging from 450 to 800 µm as measured by optical microcopy. Cefotaxime as a model drug was encapsulated in the microparticles to evaluate the in vitro release behavior under different pH conditions. At physiological temperature, the amount of drug released increased with increasing pH. The amount of drug release from microparticles after 24 h (84%) was more extensive in simulated intestinal fluid when compared with acidic pH environment (20%). These preliminary results suggest that the new microparticles can be used as good candidate for oral drug controlled release in the treatment to colon diseases. POLYM. ENG. SCI., 55:981–987, 2015. © 2014 Society of Plastics Engineers     

Study on mechanical and flow properties of acrylonitrile‐butadiene‐styrene/poly(methyl methacrylate)/nano‐calcium carbonate composites

Acrylonitrile‐butadiene‐styrene (ABS)/poly(methyl meth‐acrylate) (PMMA)/nano‐calcium carbonate (nano‐CaCO₃) composites were prepared in a corotating twin screw extruder. Four kinds of nano‐CaCO₃ particles with different diameters and surface treatment were used in this study. The properties of the composites were analyzed by tensile tests, Izod impact tests, melt flow index (MFI) tests, and field emission scanning electron microscopy (FESEM). This article is focused on the effect of nano‐CaCO₃ particles' size and surface treatment on various properties of ABS/PMMA/nano‐CaCO₃ composites. The results show that the MFI of all the composites reaches a maximum value when the content of nano‐CaCO₃ is 4 wt%. In comparison with untreated nano‐CaCO₃ composites, the MFI of stearic acid treated nano‐CaCO₃ composites is higher and more sensitive to temperature. The tensile yield strength decreases slightly with the increase of nano‐CaCO₃ content. However, the size and surface treatment of nano‐CaCO₃ particles have little influence on the tensile yield strength of composites. In contrast, all of nano‐CaCO₃ particles decrease Izod impact strength significantly. Stearic acid treated nano‐CaCO₃ composites have superior Izod impact strength to untreated nano‐CaCO₃ composites with the same nano‐CaCO₃ content. Furthermore, the Izod impact strength of 100 nm nano‐CaCO₃ composites is higher than that of 25 nm nano‐CaCO₃ composites. POLYM. COMPOS., 31:1593–1602, 2010. © 2009 Society of Plastics Engineers     

Mechanical properties,thermal stability,and crystallization kinetics of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/calcium carbonate composites

Bacterial polyester poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB) containing 5 mol% 4HB was composited with different calcium carbonate (CaCO₃) fillers. The effect of CaCO₃ contents on thermal properties, mechanical property, and crystallization kinetics was evaluated. The thermal stability of P3/4HB was reduced by mixing with CaCO₃ particles. With increasing CaCO₃ content, the elongation at break, tensile strength, and impact strength decrease; however, elastic modulus increases. When P3/4HB with 20 mol% 4HB was added into the P3/4HB/CaCO₃ composite, the impact strength were enhanced significantly; however, the elongation at break and tensile strength were only slight to moderate improvements. However, when compared with nano‐ and light‐CaCO₃, heavy CaCO₃ had the best mechanical properties. The nonisothermal and isothermal crystallization results demonstrated that the crystallization rate of P3/4HB was reduced and the highest crystallinity was obtained for all kinds of CaCO₃ fillers at 40 phr content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO₃ composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO₃, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO₃ particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO₃ particles. The crystallization and mechanical properties of PP/nano‐CaCO₃ composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO₃ particles, favored the nucleation effect of nano‐CaCO₃, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO₃ composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO₃, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polyaniline–TiO2 hybrid‐coated cotton fabric for durable electrical conductivity

A polyaniline–TiO₂ hybrid was coated on cotton fabric to make it electrically conductive. A One‐pot method of synthesis with acetic acid medium was used, in which TiCl₄ was used as precursor. The oxidative polymerization of aniline adsorbed on TiO₂ (anatase form) was performed in the presence of cotton fabric. Fabric crystallinity was least affected by the coatings, as confirmed by XRD analysis. FTIR studies revealed interactions between fiber and hybrid. The morphological study through SEM showed the uniform coating of hybrid over the fibers of the cotton fabric and AFM analysis revealed the rod‐like structure of the hybrid. The strength of the coated fabrics was assessed using abrasion tests. The electrical conductivity was determined using electrochemical impedance spectroscopy (EIS).The conductivity value varied with respect toTiO₂ content and ranged in the order 10^?4 to 10²S/cm. The effect of atmospheric aging was assessed. A more durable conductivity was observed in hybrid‐coated fabric than pristine polyaniline‐coated fabric. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013