Tensile Properties Of Films Research Articles

Nicotine Fast Dissolving Films Made of Maltodextrins: A Feasibility Study

This work aimed to develop a fast-dissolving film made of low dextrose equivalent maltodextrins (MDX) containing nicotine hydrogen tartrate salt (NHT). Particular attention was given to the selection of the suitable taste-masking agent (TMA) and the characterisation of the ductility and flexibility under different mechanical stresses. MDX with two different dextrose equivalents (DEs), namely DE 6 and DE 12, were selected in order to evaluate the effect of polymer molecular weight on film tensile properties. The bitterness and astringency intensity of NHT and the suppression effect of several TMA were evaluated by a Taste-Sensing System. The films were characterised in term of NHT content, tensile properties, disintegration time and drug dissolution test. As expected, placebo films made of MDX DE 6 appeared stiffer and less ductile than film prepared using MDX DE 12. The films disintegrated within 10 s. Among the tested TMA, the milk and mint flavours resulted particularly suitable to mask the taste of NHT. The addition of NHT and taste-masking agents affected film tensile properties; however, the effect of the addition of these components can be counterweighted by modulating the glycerine content and/or the MDX molecular weight. The feasibility of NHT loaded fast-dissolving films was demonstrated.

Carbon nanotube reinforced rigid‐rod polyimide

AbstractMultiwalled carbon nanotube/rigid‐rod polyimide composite films have been prepared by casting a solution of precursor polymer (polyamide acid) containing multiwalled carbon nanotubes (MWNTs) into thin films, followed by a thermal imidization treatment. The composite films were characterized by FTIR, TEM, DSC, TGA and TMA, and the film tensile properties were also examined. The presence of 1.0% MWNTs in the polymer matrix led to more than twofold increase in tensile strength of the rigid‐rod polyimide composite films and improved thermal stability, but reduced in thermal deformation. However, the tensile property did not show further increase when the film contained higher composition of MWNTs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of Gamma Radiation on the Physico- and Thermo-Mechanical Properties of Gelatin-Based Films Using 2-Hydroxyethyl Methacrylate (HEMA)

Gelatin films were prepared from gelatin granules in aqueous medium by casting. Tensile strength, tensile modulus, elongation at break and the glass point of the gelatin films were found to be 27 MPa, 100 MPa, 4% and 51.7°C, respectively. After irradiated with gamma radiation tensile properties were increased due to denser network structure. Gelatin films were soaked in five different formulations containing 2-hydroxyethyl methacrylate (HEMA) (10–50%, by wt), methanol and photoinitiator and then irradiated under gamma radiation. Again, a series of gelatin solutions was prepared by blending varying percentages (10–50% by wt) of HEMA and then films were prepared and irradiated under gamma radiation. It was found that tensile and thermal properties of gelatin films improved significantly.

Thermo-mechanical processing of sugar beet pulp. III. Study of extruded films improvement with various plasticizers and cross-linkers

Thermoplastic sugar beet pulp (thermo-mechanical processing was discussed in previous studies) was formed into film strips by extrusion. Film tensile properties are discussed according to the molecular structure of external plasticizer. Sorbitol, fructose and adipic acid have a marked antiplasticizing effect, while urea and xylitol gave higher ultimate tensile stress than glycerol for a comparable strain at break. Xylitol can be considered as the best plasticizer with UTS and EL of, respectively, 4.9 MPa and 11.3% and water absorption (85% RH, 25 °C) was less than 25%. Glycidyl methacrylate was directly used in the extrusion process as cross-linker. In high humidity atmosphere (97% RH, 25 °C), film water absorption was then kept under 40% while tensile strength and strain were improved of 50% and with a 30 min UV post-treatment the mass gain in absorption was even less than 30% after 5 days.

Nanocellulose reinforced PVA composite films: Effects of acid treatment and filler loading

Nanocellulose was prepared by acid hydrolysis of microcrystalline cellulose (MCC) at different hydrobromic acid (HBr) concentrations. Polyvinyl alcohol (PVA) composite films were prepared by the reinforcement of nanocellulose into a PVA matrix at different filler loading levels and subsequent film casting. Chemical characterization of nanocelluloses was performed for the analysis of crystallinity (Xc), degree of polymerization (DP), and molecular weight (Mw). The mechanical and thermal properties of the nanocellulose reinforced PVA films were also measured for tensile strength and thermogravimetric analysis (TGA). The acid hydrolysis decreased steadily the DP and Mw of MCC. The crystallinity of MCC with 1.5 M and 2.5 M HBr showed a significant increase due to the degradation of amorphous domains in cellulose. Higher crystalline cellulose showed the higher thermal stability than MCC. From X-ray diffraction (XRD) analysis, nanocellulose samples showed the higher peak intensity than MCC cases. Reduction of MCC particle by acid hydrolysis was clearly observed from scanning electron microscope (SEM) images. The tensile and thermal properties of PVA composite films were significantly improved with the increase of the nanocellulose loading.

Improved barrier and mechanical properties of novel hydroxypropyl methylcellulose edible films with chitosan/tripolyphosphate nanoparticles

Chitosan/tripolyphosphate nanoparticles were prepared and incorporated in hydroxypropyl methylcellulose (HPMC) films. FT-IR and transmission electron microscopy (TEM) analyses of the nanoparticles, mechanical properties, water vapor permeability, thermal stability, scanning electron microscopy (SEM) of the films were analyzed. Incorporation of chitosan nanoparticles in the films improved their mechanical and film barrier properties significantly. The chitosan nanoparticles tend to occupy the empty spaces in the pores of the HPMC matrix, increasing the collapse of the pores and thereby improving film tensile properties and water vapor permeability. The thermal stability of the films increased with addition of nanoparticles. This study is the first to investigate the use of CS-TPP nanoparticles for the purpose of strengthening HPMC films.

Tensile and moisture barrier properties of whey protein–beeswax layered composite films

AbstractBACKGROUND: There is a lack of research on producing layered protein–lipid composite films with improved tensile and barrier properties compared to films from individual components. Several film‐forming parameters were hypothesized to influence the extent to which lipids were either dispersed within or layered upon whey protein films. Film‐forming parameters investigated were ratio of whey protein isolate (WPI) to beeswax (BW), homogenization method, sodium chloride (NaCl) concentration, and BW particle size.RESULTS: Film percent elongation (E) increased, while tensile strength (TS) and elastic modulus (EM) decreased when BW was incorporated into WPI films, demonstrating a lubricant effect of the BW. Mean water vapor permeability values for WPI film decreased by 57% when the film composition was modified by the addition of 40% BW. BW phase separation was observed in all of the tested films. Particle size of BW in the film‐forming emulsions was larger in the presence of NaCl (100 mmol L−1), indicating a neutralization of particle charge. However, the addition of NaCl did not improve the moisture barrier of WPI‐BW film over the range of film‐forming conditions used in the study.CONCLUSION: The results from this study are useful in determining formulations and conditions for the production of composite films from WPI and BW with improved tensile and moisture barrier properties. Copyright © 2008 Society of Chemical Industry

Properties of Novel Hydroxypropyl Methylcellulose Films Containing Chitosan Nanoparticles

In this study, chitosan nanoparticles were prepared and incorporated in hydroxypropyl methylcellulose (HPMC) films under different conditions. Mechanical properties, water vapor and oxygen permeability, water solubility, and scanning and transmission electron microscopy (SEM and TEM) results were analyzed. Incorporation of chitosan nanoparticles in the films improved their mechanical properties significantly, while also improving film barrier properties significantly. The chitosan poly(methacrylic acid) (CS-PMAA) nanoparticles tend to occupy the empty spaces in the pores of the HPMC matrix, inducing the collapse of the pores and thereby improving film tensile and barrier properties. This study is the first to investigate the use of nanoparticles for the purpose of strengthening HPMC films.

Largely Improved Tensile Properties of Chitosan Film via Unique Synergistic Reinforcing Effect of Carbon Nanotube and Clay

In this work, a great synergistic effect of 2D clay platelets and 1D carbon nanotubes (CNTs) on reinforcing chitosan matrix has been observed for the first time. With incorporation of 3 wt % clay and 0.4 wt % CNTs, the tensile strength and Young's modulus of the nanocomposites are significantly improved by about 171 and 124%, respectively, compared with neat chitosan. This could be understood as due to the formation of much jammed fillers network with 1D CNTs and 2D clay platelets combined together, as indicated by rheological measurement. Our work demonstrates a good example for the preparation of high performance polymer nanocomposites by using nanofillers of different dimension together.

Plasticizing Effects of Beeswax and Carnauba Wax on Tensile and Water Vapor Permeability Properties of Whey Protein Films

ABSTRACT: The possible plasticizing effect of beeswax (viscoelastic wax) and carnauba wax (elastic wax) on tensile and water vapor permeability properties of whey protein isolate (WPI) films was studied. For the experiments, 3 groups of films with different WPI:glycerol ratios (1:1; 1.5:1; 2:1, 2.5:1, and 3:1) were prepared. The 1st group was made without the addition of wax, and the latter 2 groups were made with the addition of beeswax and carnauba wax, respectively, mixing 1 part of wax to 1 part of WPI. Lipid particle size, water vapor permeability, tensile properties, and thickness of films were analyzed and measured. The results show that the incorporation of beeswax produced a plasticizing effect in WPI:glycerol films, whereas carnauba wax produced an anti-plasticizing effect. The moisture barrier properties of WPI:glycerol films benefit from the addition of beeswax, by both increase of the hydrophobic character and decrease of the amount of hydrophilic plasticizer required in the film.

Preparation and characterization of low‐density polyethylene/banana starch films containing compatibilizer and photosensitizer

AbstractComposite films containing various percentages of banana starch and low‐density polyethylene (LDPE) were prepared. The effects of the compatibilizer, banana starch content, and photosensitizer content on the thermal and tensile properties of these films were investigated. The banana starch content was varied from 5 to 20 wt % of LDPE, whereas benzophenone was added as a photosensitizer in three different amounts (0.25, 0.5, and 1 wt %) based on LDPE. In these films PE‐graft‐maleic anhydride (PE‐g‐MA) was used as a compatibilizer at 10 wt % banana starch. It was found that the thermal stability of the composite films remained unchanged with respect to the amount of banana starch and benzophenone content. The addition of banana starch had no effect on the melting temperature and degree of crystallinity of the films. Similarly, PE‐g‐MA had no effect on the melting temperature but decreased the degree of crystallinity of the LDPE phase. Benzophenone caused an increase in the melting temperature but decreased the degree of crystallinity of LDPE in the films. Increasing the amount of banana starch decreased the tensile properties of the composite films. The addition of PE‐g‐MA as a compatibilizer increased the tensile properties compared with the uncompatibilized films. However, benzophenone had no effect on the tensile properties of the blend films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2717–2724, 2006

Influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification

This study investigated the influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification. Tensile properties of films were determined while the yield, size, drug contents and release characteristics of the microspheres were examined. Tensile properties of calcium alginate matrix were significantly affected by the orientation and arrangement of the polymer chains. High viscosity alginates gave rise to higher yields and bigger microspheres. Generally, microspheres with high drug content and slower rate of drug release had high Ca2+ contents and were produced from alginates of higher viscosity. Within an alginate microsphere batch, small sized microsphere fractions had higher drug contents but showed faster drug release rates. Microspheres having a defined size range revealed great dependence of encapsulation efficiency and drug release rates on viscosity and extent of Ca2+-alginate interaction. Viscosity appeared to exert a predominant influence on the microsphere properties.

Effect of spatial architecture on cellular colonization

The spatial cell-material interaction remains vital issue in forming biodegradable scaffolds in Tissue Engineering. In this study, to understand the influence of spatial architecture on cellular behavior, 2D and 3D chitosan scaffolds of 50-190 kD and >310 kD MW were synthesized through air drying and controlled rate freezing/lypohilization technique, respectively. In addition, chitosan was emulsified with 19, 76, and 160 kD 50:50 poly lactide-co-glycolide (PLGA) using 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) as stabilizer. 2D and 3D scaffolds were formed by air drying and lyophilization as before. Tensile and compressive properties of films and scaffolds were analyzed in wet conditions at 37 degrees C. Alterations in the cell spreading, proliferation, and cytoskeletal organization of human umbilical vein endothelial cells (HUVECs) and mouse embryonic fibroblasts (MEFs) were studied. These results showed that the formed 3D chitosan scaffolds had interconnected open pore architecture (50-200 microm size). HUVECs and MEFs had reduced spreading areas and circular morphology on 2D chitosan membranes compared with 3D chitosan scaffolds. The fluorescence photomicrographs for actin (using Alexa Fluor 488 phalloidin) and cytoplasm staining (using carboxyfluorescein diacetate-succinimidyl ester) demonstrated that the cells spread within 3D chitosan matrix. 2D and 3D emulsified chitosan and chitosan/PLGA scaffolds reduced the spreading of HUVECs and MEFs even further. Proliferation results, analyzed via MTT-Formazan assay and BrdU uptake assay, correlated with the spreading characteristics. The reductions in cell spreading area on emulsified surfaces were not detrimental to the viability and endocytic activity but to proliferation. The observed alterations in cellular colonization are in part due to the substrate stiffness and surface topography. In summary, these results suggest a significant influence of spatial architecture on cellular colonization.

Effect of Microwave Heating of Kafirin on the Functional Properties of Kafirin Films

ABSTRACTTo improve the functional properties of cast kafirin films, dry kafirin, extracted with an aqueous ethanol‐based solvent at 70°C, was microwave‐heated. No effect on film tensile properties was found. Two strategies were employed to improve the effect of microwaving: extraction of kafirin using an aqueous tert‐butanol‐based solvent at ambient temperature to minimize temperature‐induced denaturation and wetting the kafirin to increase its dielectric properties. Microwave heating this kafirin to 90 or 96°C and holding for 1–2 min more than doubled maximum tensile strength and Young's modulus, and decreased strain by about one‐third compared with films made from nonmicrowaved kafirin. Film water vapor permeability was reduced by at least one‐third. Digestibility of microwaved kafirin and films was also substantially decreased, and film biodegradability was slowed slightly. Microwave heating gave a film microstructure with fewer and smaller size pores. SDS‐PAGE showed microwave‐induced intermolecular cross‐linking of the kafirin monomers, which was possibly responsible for the modification of film properties. Microwave heating of kafirin can be used to modify kafirin film properties, but the kafirin must be microwaved wet and be as close as possible to its native state.

In vitro characterization of chitosan–gelatin scaffolds for tissue engineering

Recently, chitosan–gelatin scaffolds have gained much attention in various tissue engineering applications. However, the underlying cell–matrix interactions remain unclear in addition to the scaffold degradation and mechanical characteristics. In this study, we evaluated (i) the degradation kinetics of chitosan and chitosan–gelatin scaffolds in the presence of 10 mg/L of lysozyme for dimensional stability, weight loss, and pH changes for a period of 2 months, (ii) tensile and compressive properties of films and scaffolds in wet state at 37 °C, (iii) viability of fibroblasts and human umbilical vein endothelial cells (HUVECs) on scaffolds, and (iv) the alteration in cell spreading characteristics, cytoskeletal actin distribution, focal adhesion kinase (FAK) distribution and PECAM-1 expression of HUVECs under static and 4.5, 8.5, 13 and 18 dyn/cm 2 shear stress conditions. Degradation results showed that gelatin-containing chitosan scaffolds had faster degradation rate and significant loss of material than chitosan. Mechanical properties of chitosan are affected by the addition of gelatin although there was no clear trend. Three-dimensional chitosan and chitosan–gelatin scaffolds supported fibroblast viability equally. However, chitosan membranes decreased cell-spreading area, disrupted F-actin and localized FAK in the nucleus of HUVECs. Importantly, the lowest shear stress tested (4.5 dyn/cm 2) for 3 h washed away cells on chitosan suggesting weak cell adhesion. In the blends, effect of gelatin was dominant; actin and FAK distribution were comparable to gelatin in static culture. However, at higher shear stresses, presence of chitosan inhibited shear-induced increase in cell spreading and weakened cell adhesive strength. No significant differences were observed in PECAM-1 expression. In summary, these results showed significant influence of blending gelatin with chitosan on scaffold properties and cellular behavior.

Physical properties of edible films made from mixtures of sodium caseinate and WPI

Abstract The physical properties of thin films (25–30 μm) made from mixtures of sodium caseinate (NaCas) and whey protein isolate (WPI) were investigated. Films were formed by mixing solutions of NaCas (2.5% w/w protein), plasticised with glycerol (NaCas–gly) at a glycerol:protein ratio of 0.32, with WPI solutions (2.3% w/w protein), plasticised (WPI-gly) at a glycerol:protein ratio 0.37. Tensile and water barrier properties of films formed from mixtures of NaCas–gly and WPI-gly were similar to films containing NaCas–gly only. Films containing only WPI-gly had higher maximum load and elastic modulus values than the mixed films. Increasing the NaCas–gly content of the films from 25 to 100% greatly increased solubility. This increased film solubility may increase the number of food applications for protein-based films.

Characterization of Chitosan Films for Tissue Engineering Applications

Chitosan (β-(l,4)-2-amino-2-deoxy-D-glucose) is a naturally occurring, abundant biopolymer with desirable biomedical material properties of biodegradability, low toxicity, and good biocompatibility. These properties indicate that chitosan may be suitable as a surface for mammalian cell growth and tissue engineering. The attachment and growth of NIH-3T3 fibroblasts on chitosan films and controls was measured. Chitosan films of 0.5, 1.5, and 3.0% (w/v) support the attachment and proliferation of NIH-3T3 fibroblasts at rates slightly lower than polystyrene controls. The film tensile properties, surface roughness, and surface free energies indicate that the film-formation technique gives films with reproducible physical and chemical properties. Our results indicate that UV–IR treatment of chitosan films can change the water in air (WIA) contact angle and surface free energy (SFE) of the films, and can potentially be used to optimize the attachment and spreading of fibroblasts on these films. The ability of these chitosan films to support cell attachment and growth indicates their potential use as biomedical surfaces. This research may result in the development of biodegradable tissue-engineering matrices.

Transport and Tensile Properties of Compression-Molded Wheat Gluten Films

Mechanical and transport properties were assessed on wheat gluten films with a glycerol content of 25-40%, prepared by compression molding for 5-15 min at temperatures between 90 and 130 degrees C. Effects of storing the films up to 24 days, in 0 and 50% relative humidity (RH), were assessed by tensile measurements. The films were analyzed with respect to methanol zero-concentration diffusivity, oxygen permeability (OP), water vapor permeability (WVP), Cobb60 and sodium dodecyl sulfate (SDS) solubility coupled with sonication. The SDS solubility and methanol diffusivity were lower at the higher molding temperature. Higher glycerol content resulted in higher OP (90-95% RH), WVP, and Cobb60 values, due to the plasticizing and hygroscopic effects. Higher glycerol contents gave a lower fracture stress, lower Young's modulus, lower fracture strain, and less strain hardening. The mold time had less effect on the mechanical properties than mold temperature and glycerol content. The fracture stress and Young's modulus increased and the fracture strain decreased with decreasing moisture content.

Effect of Various Additives on Tensile Properties of Polyethylene Films Irradiated in Air, Water, N2, and Vacuum

Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) films of different thickness (0.06 mm, 0.2 mm, and 0.35 mm) were irradiated in vacuum, water, nitrogen, and air atmospheres for various doses from 40 kGy to 200 kGy. Radiation cross-linking occurred at lower doses and chain scission dominated at higher doses. The extent of radiation cross-linking and, consequently, tensile strength (TS) were found to be dependent on the oxidation layer as well as the thickness of the polyethylene (PE) films. The oxidation layer of the PE film was related to the amount of oxygen present in the media of irradiation When different additives from hindered amine light stabilizer (HALS) and ultraviolet light absorber (UVA) were incorporated into these PE films, the extent of radiation cross-linking as well as TS improved. Irradiation in water medium was found to improve radiation cross-linking and TS compared to irradiation in nitrogen and air atmospheres. Irradiation in a vacuum system did not produce any virtual improvement over water system irradiation. Irradiation in water medium is cost-effective compared to that in vacuum and nitrogen atmosphere.

Sodium dodecyl sulfate treatment improves properties of cast films from soy protein isolate

The manufacture of edible/biodegradable films or coatings can potentially add value to soy protein. This study was conducted to determine the effect of sodium dodecyl sulfate (SDS) on selected physical properties of glycerin-plasticized soy protein isolate (SPI) films. Films were cast from heated (70 °C for 20 min), alkaline (pH 10) aqueous solutions of SPI (5 g/100 ml water), glycerin (50% w/w of SPI), and SDS (0, 5, 10, 20, 30, or 40% w/w of SPI). Tensile strength (TS), elongation at break (E), moisture content (MC), total soluble matter (TSM), water vapor permeability (WVP), and color values ( L, a, and b) were determined after conditioning film specimens at 25 °C and 50% relative humidity (RH) for 2 days. SDS reduced ( P<0.05) film TS by as much as 43% for films with 40% SDS (6.2 vs. 10.9 MPa for control SPI films). In contrast, film E increased ( P<0.05) notably with addition of SDS even at 5%. Films with SDS had smaller ( P<0.05) MC and larger ( P<0.05) TSM values than control SPI films. Films containing 10% or more SDS had lower WVP values than control SPI films by as much as 50%. Increased yellowness, evidenced by greater ( P<0.05) + b color values, was noted for films with high amounts (20, 30, or 40%) of SDS. Changes in tensile, solubility, and water vapor barrier properties of SPI films due to the addition of SDS were largely attributed to disruption of hydrophobic associations among neighboring protein molecules as the non-polar portions of the SDS molecules attached onto hydrophobic amino acid residues within the film structure. It was demonstrated that adding anionic surfactant SDS to film-forming solutions prior to casting could greatly modify the properties of SPI films. In particular, SDS improved the water vapor barrier ability and the extendibility of SPI films, both desirable attributes when assessing the potential of such films for packaging applications.