High-density Polyethylene Films Research Articles

Plasma Surface Modification of Blown Polyethylene Films for Uniform Atomic Layer Deposition of Al2O3

As polyethylene has unique physical characteristics such as low surface energy, low crystallization temperature, lack of polar groups, complicated lamellar structures, susceptibility to thermal degradation, and so on, most conventional coating techniques are not suitable for it. Atomic layer deposition (ALD) has many benefits over conventional coating techniques, and it can be a good candidate as a coating technique for polyethylene. In this study, a low-temperature ALD technique for depositing layers of Al2O3 on blown, high-density polyethylene (HDPE) films was investigated. The effect of plasma surface modification on the effectiveness of the ALD technique in Al2O3 layer formation was also studied.

Effect of Films on 1,3-Dichloropropene and Chloropicrin Emission, Soil Concentration, and Root-Knot Nematode Control in a Raised Bed

Soil fumigation is an important component of U.S. agriculture, but excessive emissions can be problematic. The objective of this study was to determine the effects of agricultural films (e.g., tarps) on soil fumigant atmospheric emissions and spatiotemporal distributions in soil, soil temperature, and plant pathogen control in the field using plastic films with various permeabilities and thermal properties. A reduced rate of 70% InLine (60.8% 1,3-dichloropropene (1,3-D) and 33.3% chloropicrin (CP)) was applied via drip line to raised soil beds covered with standard high-density polyethylene film (HDPE), thermic film (Thermic), or virtually impermeable film (VIF). 1,3-D and CP emission rates were determined using dynamic flux chambers, and the concentrations in soil were measured using a gas sampler. The pest control efficacy for the three treatments was determined using bioassay muslin bags containing soil infested with citrus nematodes (Tylenchulus semipenetrans). The results show that the Thermic treatment had the highest emission rates, followed by the HDPE and VIF treatments, and the soil concentrations followed the reverse order. In terms of pest control, covering the beds with thermic film led to sufficient and improved efficacy against citrus nematodes compared to standard HDPE film. Under HDPE, >20% of nematodes survived in the soil at 30 cm depth at day 12. The VIF treatment substantially reduced the emission loss from the bed (2% of the Thermic and 6% of the HDPE treatments) and eliminated plant parasitic nematodes because of its superior ability to entrap fumigant and heat within soils. The findings imply that not only the film permeability but also the synergistic ability to entrap heat should be considered in the development of new improved films for fumigation.

Yellow Nutsedge (Cyperus esculentus) Control with Methyl Iodide in Combination with Totally Impermeable Film

Methyl bromide (MBr) has been an industry standard for soil fumigation in a multitude of crops for decades. However, it has been banned by the United Nations Environment Programme, and alternatives to MBr must be implemented to sustain productivity in many vegetable crops that depend on soil fumigation. One alternative that has been implemented in some areas is methyl iodide (MeI). Efficacy of MeI has been demonstrated on many pest species and has been generally similar to MBr. Methyl iodide is a costly material, which has likely limited its adoption. Virtually impermeable film (VIF) and totally impermeable film (TIF) provide greater fumigant retention than low-density and high-density polyethylene film, which can allow for reduced fumigant application rates while maintaining fumigant efficacy. The objectives of this research were to evaluate TIF with reduced rates of shank-applied MeI : chloropicrin (Pic) (50 : 50 w/w) for the control of yellow nutsedge in tomato. Treatments included a standard rate of MeI : Pic (93.3 L ha−1[178 kg ha−1broadcast]) under VIF and TIF, three reduced rates (37.3, 56, 74.6 L ha−1[71.2, 106.8, 142.5 kg ha−1broadcast, respectively]) under TIF, and a nontreated control under TIF. Results indicate fumigant use rates may be reduced from a standard 93.3 L ha−1under VIF to 37.3 L ha−1(60% reduction) under TIF while providing yellow nutsedge control and maintaining tomato yields.

Selection of Thickness of High Density Polyethylene Film for Mulching in Paddy Rice

In water deficit area, judicious use of water is essential for increasing area under crop production with limited water supply. Film Mulching has been advocated as an effective means for conserving soil moisture in rice production. The effects of high density polyethylene (HDPE) film on increasing rice production, controlling weeds and residue amount of plastic were studied under five treatments, including 5, 10, 15 and 20 μm thickness as well as bare cultivation (CK). The results indicated that the HDPE film mulching mode had significant effects on weed control, soil temperature, soil moisture, photosynthetic rate, seedling biomass, yield and residues of plastic film. Combined with economic effect, it showed that the HDPE film of 10 μm is the best option for rice production.

Barrier Properties and Structural Study of Nanocomposite of HDPE/Montmorillonite Modified with Polyvinylalcohol

In this work was studied the permeation of CO2 in films of high‐density polyethylene (HDPE) and organoclay modified with polyvinylalcohol (MMTHDTMA/PVA) obtained from melt blending. Permeation study showed that the incorporation of the modified organoclay generates a significant effect on the barrier properties of HDPE. When a load of 2 wt% of MMTHDTMA/PVA was incorporated in the polymer matrix, the flow of CO2 decreased 43.7% compared to pure polyethylene. The results of TEM showed that clay layers were dispersed in the polymeric matrix, obtaining an exfoliated‐structure nanocomposite. The thermal stability of nanocomposite was significantly enhanced with respect to the pristine HDPE. DSC results showed that the crystallinity was maintained as the pure polymeric matrix. Consequently, the decrease of permeability was attributable only to the effect of tortuosity generated by the dispersion of MMTHDTMA/PVA. Notably the mechanical properties remain equal to those of pure polyethylene, but with an increase in barrier properties to CO2. This procedure allows obtaining nanocomposites of HDPE with a good barrier property to CO2 which would make it competitive in the use of packaging.

Indentation device for in situ Raman spectroscopic and optical studies

Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.

Free volume change of elongated polyethylene films studied using a positron probe microanalyzer

Free volume change of low density polyethylene (LDPE) and high density polyethylene (HDPE) films upon mechanical deformation was microscopically investigated by positron probe microanalysis (PPMA). The ortho-positronium (o-Ps) lifetimes were gradually shortened by uniaxial deformation, indicative of shrinkage of the free volume. The o-Ps intensity for HDPE increased by deformation, whereas that for LDPE varied little. It suggests that destruction of crystallites plays an important role in the deformation of HDPE. PPMA is demonstrated to be a promising, powerful probe investigating free volume changes, at different local points subjected to different degrees of deformation, in elongated polymers.

Preparation and Characterization of Antibacterial Zn-Coated High Density Polyethylene Films by Vacuum Evaporation Technology

Zn-coated HDPE films with different amount of zinc deposition were prepared via vacuum evaporation technology. AFM images showed that the size of Zn particles was decreasing evidently with the increase of the amount of Zn deposition on HDPE substrate. The Zn-coated HDPE films exhibited excellent antibacterial activity, especially for S. aureus. Compared with the HDPE film, the improvement of the barrier properties of the Zn-coated HDPE films was observed. Moreover, the barrier properties of the Zn-coated HDPE films were increasing with the elevation of the Zn content on HDPE films. The as-prepared Zn-coated HDPE films have a promising foreground applied in food packaging.

Features of the delocalized crazing of high-density polyethylene in poly(ethylene oxide) solutions

It is shown that the deformation of high-density polyethylene films in poly(ethylene oxide) solutions occurs via the delocalized-crazing mechanism and leads to the formation of polymer blends. With an increase in the draw ratio, the concentration of poly(ethylene oxide) in the blend increases and significantly exceeds the theoretical values calculated from the polyethylene porosity and the poly(ethylene oxide) concentration in the solution. It is suggested that the high concentration of poly(ethylene oxide) in the blends is due to its adsorption on a highly developed surface of polyethylene deformed via the crazing mechanism. The composition of the resulting blends is independent of the strain rate.

Active Modified Atmosphere Packaging of Fresh-cut Bell Peppers: Effect on Quality Indices

<p>Fresh-cut green bell peppers (<em>Capsicum annuum L.</em>) were stored in modified atmosphere packaging (MAP) made of impermeable high-density polyethylene film. Two in-packaging atmospheres and storage temperatures (0 <sup>o</sup>C and 5 <sup>o</sup>C) were tested. The respiration rate of the unpackaged produce and the in-package gas concentration, mass loss, firmness, skin colour, ascorbic acid and visual quality of the packaged produce were estimated. Cutting, increased respiration rate of the unpackaged produce by 24% compared to the intact produce for the same storage temperature. After 5 days of storage at 5 °C, significant O<sub>2</sub> depletion of the active modified atmosphere was found. Limited mass loss (0.4-0.5% of the initial mass) and firmness degradation were estimated in both storage temperatures due to the beneficial effect of packaging. The hue angle (h*) reduction was limited in all cases and the initial green colour was preserved. Initial ascorbic acid content was preserved at 0 °C, but significantly increased at 5 °C. The visual quality of the packaged produce was assessed by six trained panelists and found that was not significantly changed at 0 °C storage. In conclusion, the tested active MAP maintained the initial quality indices of fresh-cut peppers (<em>cv.</em> <em>Twingo F1</em>) for up to 10 days at 0 °C but not at 5 °C.</p>

Characterization of high-density polyethylene using laser-induced fluorescence (LIF)

Fluorescence intensity decays of high-density polyethylene (HDPE) films have been studied by laser-induced fluorescence (LIF). An internally cavity-dumped dye laser synchronously pumped with a mode-locked argon-ion laser was used to excite the HDPE samples. The decay in the fluorescence intensity of HDPE film is due to the carbonyl present in the film, and was shown to be dependent on the power density of the incident UV light. The fluorescence intensity decay exhibits second-order kinetics. The experimental results obtained here demonstrate that the photostability of HDPE films can be characterized by the rate coefficient of the fluorescence intensity decay.

Effect of maleic anhydride grafted polyethylene on engineering properties and morphology of fumed silica filled polyethylene blown films

Blown films of high-density polyethylene (HDPE)/fumed silica (FS) composites were prepared by melt-mixing in twin-screw extruder. Maleic anhydride grafted polyethylene (PE-g-MA) was introduced to improve the state of filler dispersion during melt processing. The blown films were tested for thermal, mechanical, morphological, barrier, and optical properties. The Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) study indicated that interaction between FS and HDPE was slightly enhanced by PE-g-MA. No change in percent crystallinity was observed but mechanical properties improved after modification. Morphological analyses showed large FS clusters at higher loading which decreased after modification. Both oxygen and water vapor transmission rates of the films increased in composites as compared to HDPE, plausibly due to formation of nanogaps in blown film and/or increased solubility of penetrant molecules at filler–matrix interface.

Epitaxial crystallization of olefin block copolymers (OBCs) on uniaxially oriented isotactic polypropylene and high-density polyethylene films

The epitaxial crystallization behavior of olefin block copolymers (OBCs) on uniaxially oriented isotactic polypropylene (iPP) and high-density polyethylene (HDPE) films has been investigated by transmission electron microscopy (TEM). The crystallizable blocks of the OBCs under investigation were epitaxially nucleated by both iPP and HDPE substrates and epitaxial growth of OBC lamellae was observed. Epitaxial crystallization of the OBCs has been found for slow and fast cooling conditions from the melt which pointed to the strong interaction between the polyolefin substrates and the OBCs. However, the epitaxial morphology of the OBCs strongly depends on their octene concentration difference (Δ C8) between crystallizable and non-crystallizable blocks, which probably is related to the OBC segregation strength in the melt. With high Δ C8 the development of epitaxial crystallization of the OBC was restricted within isolated crystalline domains surrounded by the amorphous phase. In contrast, with low Δ C8 the oriented lamellae of the OBC were distributed homogeneously on iPP but formed separated crystalline domains on HDPE, which has a stronger nucleation capability than iPP on the crystalline OBC blocks because of its similar molecular architecture. Our study points to epitaxy as another reason for the strong interaction between OBC and polyolefins which causes the advanced compatibilization behavior of OBCs when compared with conventional random copolymers.

Development of a stable open-porous structure in the solvent-crazed high-density polyethylene

It is demonstrated that the tensile drawing of high-density polyethylene (HDPE) films in the presence of physically active media via the mechanism of delocalized crazing results in the development of an open-porous structure in the polymer. Depending on tensile strain, overall volume porosity can reach ∼55%. Here, the parameters of the porous structure (pore and fibril diameters) are in the nanometer range. It is also demonstrated that the nanoporous structure with a highly developed surface formed via delocalized crazing is thermodynamically unstable and the related relaxation processes result in the reduction or complete elimination of porosity. Efficient ways of stabilization and preservation of open porosity and parameters of the porous structure of deformed samples of polyethylene are related to complete removal of the liquid medium from the polymer samples and annealing. This approach makes it possible to obtain open-porous materials based on polyolefins with stable characteristics, which is of a significant practical interest.

Effects of surface treatments and application shanks on nematode, pathogen and weed control with 1,3‐dichloropropene

Preplant fumigation with methyl bromide (MeBr) has been used for control of soilborne pests in high-value annual, perennial and nursery crops, but is being phased out. In 2007 and 2008, research trials were conducted to evaluate the effects of surface treatments and two application shanks on pest control with 1,3-dicloropropene (1,3-D) in perennial crop nurseries. All 1,3-D treatments controlled nematodes similarly to MeBr. Application of 1,3-D with virtually impermeable film (VIF) reduced Fusarium oxysporum compared with unfumigated plots, but was not as effective as MeBr. Applications of 1,3-D with VIF or 1,3-D followed by metam sodium reduced Pythium spp., but 1,3-D followed by intermittent water seals was comparable with the untreated plots. When sealed with high-density polyethylene (HDPE) film or VIF, 1,3-D generally was as effective as MeBr for reducing weed density and total weed biomass, but weed control was reduced by intermittent water seals and in unsealed plots subsequently re-treated with additional 1,3-D or metam sodium. Applications of 1,3-D sealed with HDPE or VIF film or with intermittent water seals can control nematodes similarly to MeBr. However, additional management practices may be needed for effective pathogen and weed control if plastic film is not used.

염증세포주를 이용한 생체재료 용출물의 체외 생체적합성 평가

Various biometerials have been researched and have been developed for treatment of some disease through transplantation to body. They have been evaluated by in vitro cytotoxicity test using some skin-derived cell lines for prediction of their biocompatibility in vivo. However, the results of experiments using mesenchymal or epithelial cells could not be considered in vivo immune reaction. In this study, we evaluated the biomaterial-elution (elute from high density polyethylene film) using some cell lines (L929, Jurkat, U937) in vitro, and then that results were compared with in vivo results from guinea pig sensitization test. In sensitization test, saline and elution of syringe could not induce erythema, but only DNCB (hypersensitive chemical) induce erythema at guinea pig sensitization test. In cell experiment, the cytotoxicity results of inflammatory cells (Jurkat; T lymphocyte, U937; monocyte) was no difference with L929 (fibroblast) in the overall trend. However, inflammatory cell lines were only secreted inflammatory cytokine (TNF-<TEX>${\alpha}$</TEX>, INF-<TEX>${\gamma}$</TEX>) in some materials (biomateriallution, FAC, DNCB). And the biomaterial-elution did not have toxicity to the cells, but it induced the inflammatory cytokines in inflammatory cell lines only. So, we were predicted inflammatory reaction through the cytokine resultes of inflammatory cell lines, and it was more correlated with in vivo results than cytotoxicity test. Therefore, we suggested that the inflammatory cytokine assay using inflammatory cell lines are more effective method in vitro for evaluation of biocompatibility of biomaterials or chemicals.

電子線グラフト重合法による製塩用新規イオン交換膜の開発 （第3報）高密度ポリエチレン製フィルムへのグリシジルメタクリレートおよびジビニルベンゼンの共グラフト重合

電子線グラフト重合法による製塩用新規イオン交換膜の開発 （第3報）高密度ポリエチレン製フィルムへのグリシジルメタクリレートおよびジビニルベンゼンの共グラフト重合

Derivatographic studies of polyethylene containing a dispersed semiconductor

The tendencies of the changes in the physical-chemical characteristics of high-density polyethylene films and polyethylene composites with a volumetric content of TlInS2 ferroelectric-semiconductor of up to 10% are investigated with the help of the DTA method. The changes in the thermophysical characteristics of the analyzed composites are shown to be related to the structural changes of the polymer under the effect of the additive particles with different degrees of dispersion. At 5 vol % of TlInS2, the additive particles act as artificial nuclei of structure formation.

Fabrication of a polymer with three-dimensional structure by the ion beam graft polymerization method

The graft polymerization method is one of the most effective techniques to produce a new polymer with unique function. To produce the polymer, we conducted experiments on radiation graft polymerization using ion beams of several hundred keV energy. A high density polyethylene (PE) film was irradiated with H + beams, then, graft polymerization with monomer solution such as acrylic acid or acrylonitrile was conducted. Radicals generated by the interaction between the beam ions and the PE molecules become the starting point of the graft polymerization. Since the range in PE depends on ion energy, the density distribution of the graft chain can be controlled by the ion energy. Using a mask which restricts the ion beam incidence, PE sheets containing graft chains only in the unmasked area were obtained. Multiple ion beam graft polymerization can produce a polymer which has some functional bases at specified position. We have demonstrated the production of a polymer film with a three-dimensional structure.

Electron-Beam-Induced Modifications in High-Density Polyethylene

Post-irradiation studies have been carried out to elucidate the effects of electron beam irradiation on the structural, optical, dielectric, and thermal properties of high-density polyethylene (HDPE) films. The experimental results showed that both the optical band gap and activation energy of HDPE films decreases with an increase in the doses of electron radiation. The electrical measurements showed that dielectric constant and the ac conductivity of HDPE increases with an increase in the dose of electron radiation. The thermal analysis carried out using DSC and TGA revealed that the melting temperature, degree of crystallinity, and thermal stability of the HDPE films increased, obviously, due to the predominant cross-linking reaction following high doses of electron irradiation.