İlhan Özen

Antimicrobial and physical properties of chitosan films incorporated with turmeric extract

In this study, the effects of turmeric extract incorporation on the antibacterial and physical properties of the chitosan films were evaluated. Turmeric containing chitosan-based film was produced with casting procedure and cross-linked with sodium sulfate. Mechanical, optical, thermal properties, and water vapor permeability of the films were studied. The addition of turmeric to chitosan film significantly increased the tensile strength of the film and improved the ultraviolet-visible light barrier of the film. Infrared spectroscopy analysis suggested an interaction between the phenolic compounds of the extract and amin group of chitosan. Antimicrobial activity of the chitosan films was studied against Salmonella and Staphylococcus aureus by plate count agar technique and a better antimicrobial activity was observed with turmeric incorporation. Turmeric incorporated chitosan films with enhanced antimicrobial activity and film stiffness can be suggested as a promising application for food packaging.

Modification of surface properties of polypropylene films by blending with poly(ethylene-b-ethylene oxide) and its application

The possibility of improving the interfacial adhesion between polypropylene (PP) and polyamide layers (PA) has been investigated by means of addition of commercially available amphiphilic poly(ethylene-b-ethylene oxide) (P(E-b-EO)) block copolymers. These block copolymers were added to the PP matrix polymer in a twin screw extruder as integral additive. The change in surface properties of PP films upon incorporating P(E-b-EO) was investigated in model studies of blends prepared by casting PP/P(E-b-EO) solutions in 1,2-dichlorobenzene onto glass and Teflon Petri dishes, by melt pressing of PP/P(E-b-EO) blends between Teflon foils and glass substrates, or by melt extrusion of PP/P(E-b-EO) mixtures. The surfaces of the blend films were analyzed by attenuated total reflection Fourier transform infrared spectroscopy and water contact angle measurements. It was shown that an enrichment of the block copolymer at the surface of the blend depends highly on the conditions of film preparation and is driven by reducing the interfacial energy between the blend and the contacting medium. Effects of shear rate and residence time during normal processing conditions were also revealed. Blown film experiments with PP/P(E-b-EO) blends and PA were carried out for evaluating the effect of the integral P(E-b-EO) additive on the interfacial adhesion.

BARRIER PROPERTIES OF POLYPROPYLENE/POLY(M-XYLENE ADIPAMIDE) AND POLYPROPYLENE/POLY(ETHYLENE-CO-VINYL ALCOHOL) BLEND FILMS

The purpose of this study is to generate polypropylene (PP) blend films with improved oxygen gas and water vapor barrier properties, which are intended to be used in packaging applications. PP blend films containing 5 wt% ethylene vinyl alcohol (EVOH) or poly(m-xylene adipamide) (N-MXD6) were prepared, biaxially stretched, and characterized by employing differential scanning calorimeter, scanning electron microscope, oxygen gas and water vapor permeability analyzers. No barrier property improvement was observed, which is caused by the low amount of the dispersed phase used.

Antimicrobial cerium ion-chitosan crosslinked alginate biopolymer films: A novel and potential wound dressing

Wound dressings require good antiseptic properties, mechanical strength and, more trustably, natural material ingredients. Antimicrobial properties of cerium ions and chitosan are known and alginate based wound dressings are commercially available. In this study, the advantages of these materials were combined and alginate films were crosslinked with cerium(III) solution and chitosan added cerium(III) solution. Films were characterized by Fourier transform infrared spectroscopy (FTIR), light transmittance, scanning electron microscopy (SEM), swelling experiments, water vapor transmittance tests, and mechanical stretching tests. The antibacterial and physical properties of the films were compared with those of conventional calcium alginate films. Both cerium ion crosslinked and cerium ion-chitosan crosslinked alginate films gained antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Cerium alginate-chitosan films showed high resistance to being deformed elastically. Results show that cerium alginate-chitosan films can be flexible, ultraviolet-protecting, and antibacterial wound dressings.

Oil absorbency of diatomite-embedded polypropylene meltblown composite structures

In this study, optimized conditions were established for diatomite grinding, which is a natural inorganic mineral with inherently high oil absorption capacity. Diatomite surface was modified with a fluorocarbon chemical and stearic acid via facile methods for enhancing compatibility between polypropylene and diatomite. Polypropylene/diatomite composites were generated in a twin screw extruder with/without using compatibilizer, and nonwoven structures were produced via meltblown technique. Pore size and void content analyses showed that addition of diatomite led to thicker fibers (1–17 µm (the neat polypropylene) vs. 1–32 µm (2 wt.% diatomite containing polypropylene)). Diatomite incorporation into polypropylene resulted in a rigid and brittle structure and a worsened oil absorption property (rust inhibitor oil absorption capacity: 1184% ± 105% (the neat polypropylene) vs. 718% ± 78% and 1089% ± 136% (2 wt.% diatomite containing polypropylene)). Increasing oil viscosity resulted in increased discrepancy among the oil absorption capacities of the neat polypropylene and diatomite containing polypropylene. Analysis of variance tests showed no changes or statistically insignificant differences in oil absorbency.

Effect of stretching temperature on breathability and waterproofness properties of polyethylene films containing different calcium carbonates

In this study, films from polyethylene and coated calcium carbonate blends were generated and the effects of calcium carbonate type, calcium carbonate loading and stretching temperature were investigated for roughness, morphology, crystallinity, pore size distribution, water pressure resistance and water vapor permeability of the films. The results showed that both breathability and waterproofness properties were only achieved with calcium carbonate possessing small particles (CC2 type) at both 25 and 50℃. Stretching at 80℃ led to ruptures in the films independent of calcium carbonate and loading amount employed. Increasing the calcium carbonate level provided better breathability performance without affecting the waterproofness considerably.

Thermal comfort properties of simulated multilayered diaper structures in dry and wet conditions

The objective of this research is to study the thermal comfort of simulated multilayered diaper structures in dry and wet conditions. To that end, a back sheet, breathable films, a superabsorbent core, and top sheets were provided and diaper structures were generated. In order to reveal their possible effects on thermal comfort, five different types of breathable films and two different types of top sheet layers were selected. Relative water vapor permeability, water vapor resistance, thermal conductivity, thermal resistance, and thermal absorptivity characteristics were analyzed and the results were evaluated statistically using analysis of variance tests. The test results indicated that the breathable film type and the top sheet type used showed significant changes on the breathability and thermal comfort of the diaper structures in dry state. Nevertheless, no statistically significant effects were observed in wet state.

Production and Characterization of Polyethylene/Calcium Carbonate Composite Materials by Using Calcium Carbonate Dry and Wet Coated with Different Fatty Acids

In this study, calcium carbonate (CaCO3) was coated by suitable chemicals using aqueous or dry coating methods in the optimum conditions. Uncoated calcium carbonate having a mean particle size (d50) of 1.6 microns and a top cut (d98) of 8 microns was provided commercially and it was dry and wet coated with saturated fatty acids whose carbon numbers vary between 14 and 18. Coating amount was adjusted to 0.5-2%. Particle size and particle size distribution of the calcium carbonates before and after coating were investigated. After characterization of the coated calcium carbonates, they were incorporated into linear low density polyethylene (LLDPE) in changing amounts using a twin screw extruder. The effects of coating chemicals, coating conditions and filler amount on composite materials were studied by evaluating the thermal (DSC and TGA) and appearance (Scanning Electron Microscope (SEM)) analyses.

Determination of thermorheological phase diagram of poly(propylene)/poly(ethylene-b-ethylene oxide) blends

Abstract The phase diagram of the polypropylene (PP)/poly(ethylene-blockethylene oxide) (P(E-b-EO) blends exhibiting upper critical solution temperature (UCST) was experimentally established by using small amplitude oscillatory shear rheology, in which the binodal line was obtained by dynamic temperature ramps and the spinodal temperatures were quantitatively estimated on the basis of the theory developed by Ajji et al. The measurements were carried out in the linear viscoelastic regime in which the material functions are sensitive to phase separation.