Modulation of barrier properties of monolayer films from blends of polyethylene with ethylene-co-norbornene (original) (raw)
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Journal of Applied Polymer Science, 2012
Several novel random copolymers of ethylene and 1-olefin counits bearing a highly efficient phenolic antioxidant moiety placed at different distances from the polymerizable double bond were prepared in the presence of a metallocene catalyst. These copolymers were meltblended with an antioxidant-free LDPE in an internal batch mixer to obtain innovative materials containing nonreleasing polymeric antioxidants suitable for safer food packaging applications. Blends and films, obtained by compression molding, were tested for their thermal and thermo-oxidative stability by thermogravimetric analysis both in dynamic and isothermal conditions. Films containing the macromolecular antioxidants showed a longer induction time before O 2 uptake starts and, consequently, a higher degradation temperature than neat LDPE or LDPE containing a low molecular weight commercial additive. Aging tests demonstrated that the new polymeric antioxidants also exert a valid protection against photo-oxidation. Eventually, migration tests demonstrated the absence of any trace of products containing the antioxidant moiety when the films were kept in contact with a food simulant. V C 2011
European Polymer Journal, 2015
This paper presents the structure and properties of two multilayered systems where polymers in adjacent layers were either miscible or immiscible. The miscible system consisted of 2, 17, 18, 24 and nominally 288 layers of alternating low-density (LDPE) and lowdensity/linear-low density (mPE) polyethylene layers with observed thicknesses ranging from 150 nm to 20 lm. The immiscible system consisted of 5 and 19 layer films with a combination of poly(ethylene-co-vinyl alcohol) (EVOH) (thickness: 9 and 1 lm, respectively), LDPE (17 and 7 lm) and a polyethylene adhesive (3 and 1 lm). The purpose of the multi-layering was to increase the crack growth resistance and, in the EVOH-based system, to decrease the oxygen transmission rate. Indeed, the crack growth resistance, as measured on tensile-tested notched films, increased with increasing number of layers. The thinnest polyethylene and polyethylene adhesive layers showed a clear ductile failure when fractured even in liquid nitrogen. Simultaneous synchrotron wide-angle/small-angle X-ray scattering and tensile testing indicated no new deformation features with changes in the layer thickness. The oxygen permeability was the same in the 5-and 19-layer EVOHbased films, but the uptake of n-hexane was strongly reduced in the 19-layer films, demonstrating the effective protective role of the EVOH layers. The n-hexane desorption data of the 2-layer LDPE/mPE film was successfully modeled using the diffusivities and solubilities of the single layers. Crystallization was slower and more confined in the films with thinner layers. The interlayer mixing in the melt (measured by isothermal crystallization from melts of initially layered polyethylene-based systems) was, as expected, significantly faster in the 24-and 288-multilayer films than in the 2-layer film.
Journal of agricultural and food chemistry, 2003
Migrational, permeation, and tensile properties of experimental five- and eight-layer coextruded and laminated films containing a middle buried layer of recycled low-density polyethylene (LDPE) comprising 40-50% bw of the multilayer structure were determined. Respective films containing 100% virgin LDPE as the buried layer were taken as controls. Results showed that the percentage of recycled LDPE in the multilayer structure did not affect overall migration values to distilled water, 3% acetic acid, and iso-octane. In all cases, overall migration values were lower than the upper acceptable limit (10 mg/dm(2)) set by the European Union. Transmission rate values to O(2), CO(2), and water vapor were also not affected by the percentage of recycled LDPE in the multilayer structure. On the basis of O(2) transmission rates, low-barrier, barrier, and high-barrier multilayer structures were produced. Likewise, tensile properties (tensile strength, percent elongation at break, and Young's...
Polymers, 2019
Polymer films based on polyethylene (PE) and ionomer ethylene/methacrylic acid (EMAA) copolymer blend were prepared by film blowing, whose surface properties were tuned by varying processing parameters, i.e., take up ratio (TUR). Blends of PE/EMAA copolymer were firstly prepared by the melt-mixing method, before being further blown to films. The wettability of the film was investigated by measuring the contact angle/water-film encounter time, and optical properties, i.e., the haze and transmittance. The wettability was found to be enhanced with the increase of TUR. So too was the haze, while the transmittance was found to be almost independent of TUR. The XPS and AFM results directly show the increasing polar functional groups (–COO−) on the surface and roughness with increasing TUR. Further analysis of the 2D SAXS and WAXS unveiled the origin of the invariant transmittance, which resulted from the minor change of the crystallinity and the monotonic increase of the haze, with TUR re...
Physical Properties of Whey Protein-Hydroxypropylmethylcellulose Blend Edible Films
Journal of Food Science, 2008
The formations of glycerol (Gly)-plasticized whey protein isolate (WPI)-hydroxypropylmethylcellulose (HPMC) films, blended using different combinations and at different conditions, were investigated. The resulting WPI: Gly-HPMC films were analyzed for mechanical properties, oxygen permeability (OP), and water solubility. Differences due to HPMC quantity and blend method were determined via SAS software. While WPI: Gly and HPMC films were transparent, blend films were translucent, indicating some degree of immiscibility and/or WPI-HPMC aggregated domains in the blend films. WPI: Gly-HPMC films were stronger than WPI: Gly films and more flexible and stretchable than HPMC films, with films becoming stiffer, stronger, and less stretchable as the concentration of HPMC increased. However, WPI: Gly-HPMC blended films maintained the same low OP of WPI: Gly films, significantly lower than the OP of HPMC films. Comparison of mechanical properties and OP of films made by heat-denaturing WPI before and after blending with HPMC did not indicate any difference in degree of cross-linking between the methods, while solubility data indicated otherwise. Overall, while adding HPMC to WPI: Gly films had a large effect on the flexibility, strength, stretchability, and water solubility of the film polymeric network, results indicated that HPMC had no effect on OP through the polymer network. WPI-HPMC blend films had a desirable combination of mechanical and oxygen barrier properties, reflecting the combination of hydrogen-bonding, hydrophobic interactions, and disulfide bond cross-linking in the blended polymer network.
Journal of Applied Polymer Science, 2003
Linear low-density polyethylene (LLDPE) with different fillers such as silica, mica, and soy protein isolate were compounded using a single screw extruder and blown into films by a Konark blow-film machine. The filled LLDPE films were characterized for physicomechanical and optical properties. Barrier properties such as water vapor transmission rate and oxygen transmission rate of the filled LLDPE films were also reported. Microcrystalline parameters such as crystal size (〈N〉) and lattice distortion (g in %) of the filled LLDPE films were estimated from the wide-angle X-ray scattering method using Hosemann's paracrystalline model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2938–2944, 2003
Mono- and bilayer biopolymer films: Synthesis and characterisation
Journal on Processing and Energy in Agriculture
The purpose of this paper is to improve the properties of biopolymer protein monofilms and produce a novel bilayer biopolymer film on the basis of the monofilms analyzed. Biopolymer monolayer films, based on pumpkin oil cake (PuOC) and zein, and a bilayer film, based on PuOC and zein (PuOC/Zein), were produced as a result of the study. The visual, mechanical, physicochemical and structural properties of the films were evaluated. The results obtained showed that the PuOC film exhibited the highest elongation at break, followed by the bilayer film, whereas the zein film showed the lowest elongation at break. However, the zein film showed the highest tensile strength, followed by the PuOC film. The tensile strength of the bilayer PuOC/Zein film was almost 3 times lower than that of the PuOC film, and almost 4 times lower than that of the zein film. The physicochemical properties recorded indicate that the hydrophobic zein film is the least sensitive to moisture, affecting the moisture sensitivity of PuOC film by reducing the moisture content, swelling and total soluble mater of the bilayer PuOC/Zein film. Based on the FTIR spectra, it could be concluded that there are no significant differences between the two sides of the bilayer PuOC/Zein film. Both sides of the bilayer film examined indicated characteristic peaks for protein biopolymer films in the FTIR spectrum.
Oligobetapinene as barrier improver to CO2 of HDPE in thin films of binary blends
Polimeros-ciencia E Tecnologia, 2004
Quenched thin films (about 100 microns thick) of high-density polyethylene (HDPE) / oligobetapinene (OBP) blends were prepared by melt mixing with the amount of OBP varying from 0 to 40%. The results of CO2 permeation, thermal behavior and morphology are reported. From -130 to -100 °C we observed two peaks in DSC measurements, the lower one being ascribed to g-transition of HDPE. The upper one attributed to Tg which was shift at high contents of OBP. The OPB molecules also displayed another transition at higher temperatures. The normalized degree of crystallinity of HDPE remained constant while the overall crystallinity of the blends was reduced in all blends. We have hypothesized that three distinct phases coexist, viz. a HDPE-amorphous phase with some amount of OBP molecules, OBP-amorphous phase with polyolefin and HDPE-crystalline phases. The permeation test revealed a decrease in permeability to CO2 independent of the amount of OBP in the blends. The reduction of gas permeation could be explained mainly by the rigidity of the OBP rich phase that has counterbalanced the decrease of overall crystallinity of the film blends.
2012
Packaging of foods in high barrier and strong materials is essential to attain food safety, and nanocomposite technology leads in search of the above kind of packaging material. The effect of compatibilizer, nanoclay and thickness of film on morphology, oxygen transmission rate (OTR), water vapor transmission rate (WVTR), tensile strength and percent elongation of linear low density polyethylene (LLDPE)-based nanocomposite films are studied using response surface methodology. The maximum reduction in OTR and WVTR over the control (0% compatibilizaer, 0% nanoclay and 100 µm film thickness) is 24.7% and 64.9%, respectively in the treatment having 5% compatibilizer, 2% nanoclay and 100 µm thickness. The regression models are developed for the prediction of OTR and WVTR. The maximum increase in the tensile strength and percent elongation over the control (0% compatibilizaer, 0% nanoclay and 100 µm film thickness) is 54% and 7.64%, respectively. Treatment having 5% compatibilizer, 2% nanoclay and 100 µm thickness of nanocomposite films showed better morphological, barrier and strength characteristics than other treatments. This paper helps to design the packaging films according to the requirement of foods to be stored using the developed regression models.