PP Films Research Articles

Design of Plasma Discharge Structure for Surface Treatment of PP Film

Low temperature plasma, compared to liquid phase treatment, can effectively overcome the environment pollution, high energy loss and high cost as its high activity. The low temperature plasma, which is not only fairly friendly to the environment but also of less resource consumption, also can realize the cleaning, activating and grafting treatment for materials surface. Based on the numerical model of CRFHCP (Capacitive Radio Frequency Hollow Cathode Plasma) hollow cathode plasma discharge, the key point to affect plasma discharge was analyzed and the morphology of PP film before and after hollow cathode plasma discharge was analyzed. The results showed that the structure of plasma hollow cathode discharge can effectively improved the chemical behaviors of PP film.

Preparation of ZnO/MWCNT/PP composite film and its application as multifunctional protective film

ZnO/MWCNT/PP composite films were prepared by melt extrusion. The films were characterized by DSC, TGA, Reflectance, XRD, and SEM. Composite films showed higher crystallization temperature, increased thermal stability and lower reflectance compared to neat PP film. SEM showed ZnO nano particles dispersed in continuous three dimensional network of MWCNT in the composite films. The composite films showed antibacterial and antifungal property, increase in limiting oxygen index and lower combustion toxicity compared to neat PP film. The composite films showed IR radiation absorbing property which is useful in camouflage applications and very good antistatic property as shown by fast discharge of static charge generated on the film surface. The study shows that the composite films can be used as multifunctional protective films where protection from multiple hazards is required. POLYM. COMPOS., 39:157–170, 2018. © 2016 Society of Plastics Engineers

Plasticization and moisture sensitivity of potato peel-based biopolymer films

This study investigated the effects of the addition of glycerol and high-pressure homogenization on the moisture sensitivity of potato peel-based films (PP films). The films were formed by casting a 3% (w/v) PP suspension containing either a 30 or 50% (w/w, dry basis) glycerol, which was high-pressure homogenized at 69, 138, or 207 MPa with 2, 5, or 10 passes. The elastic modulus and viscosity values were high when the suspensions were treated at 207 MPa with 5 and 10 passes. The moisture sorption isotherms, water diffusivity, and water vapor permeability values were higher in films with 50% glycerol. The findings indicate that high pressures and high pass numbers resulted in anti-plasticization in the film matrix, while the high concentration of glycerol in the film formulation plasticized the film. Thus, the moisture sensitivity of the PP film can be modulated by controlling the homogenization parameters and the glycerol concentration.

Modification of Lithium Ion Battery Separators by Electron Beam Radiation Induced Grafting of Glycidyl Methacrylate onto Porous PP Film

Modification of Lithium Ion Battery Separators by Electron Beam Radiation Induced Grafting of Glycidyl Methacrylate onto Porous PP Film

An optical biochemical oxygen demand biosensor chip for environmental monitoring

An optical biochemical oxygen demand (BOD) biosensor chip has been developed by embedding a biofilm onto an oxygen sensing film (OSF) shielded with polyethylene–polypropylene (PE–PP) film for effect free detection of organic pollution in environmental samples. The biofilm was prepared by immobilizing baker's yeasts (Saccharomyces cerevisiae) with polyvinyl alcohol–styrylpyridinium (PVA–SbQ) matrix and the OSF film was developed by coating the oxygen sensing ruthenium complex (dichloro tris (1,10-phenanthroline)–ruthenium(II)) dye solution (solubilized in nafion fluoropolymer matrix) onto a SO3 glass slide. Silicone rubber (SR) sheet was used to control the biofilm thickness and make the sample injection cavity. Fluorescence intensity (FI) of the biosensor was recorded by an inverted microscope which varies with the concentration of dissolved oxygen (DO) in samples. The biosensor responses were drawn as the changing of FI due to microbial respiration with BOD standard solutions, glucose–glutamic acid soluton (GGA). A good linear relationship was observed between the maximum responses, It=3/I0 (It=3=intensity at 3min time and I0=intensity at 0min time) and GGA concentrations (1 to 20mg/L, R2=0.99, n=3) either in phosphate buffer solution (PBS) or in environmental samples such as river water (RW). The effects of environmental samples upon the sensor performance were completely eliminated due to shielding with only oxygen permeable PE–PP film onto the OSF. In addition, the suitable biofilm type, effects of heavy metals ions as well as preservation and stability of the biosensor also have been investigated. Finally, the newly proposed approach offers a promising and prospective tool for frequent monitoring of organic pollution in environmental samples.

Experimental modeling of the electric potential decay at the surface of polypropylene films (PP)

Surface potential decay (SPD) measurements have been considered as the most appropriate technique for the investigation of the corona charging of dielectrics. The aim of the present paper is to point out the interactions between three factors namely: grid potential, grid current and sample size (length), by taking advantage of the experimental design methodology. The experiments were performed on 0.08 mm – thick samples of PP films, in ambient air (temperature: 20 °C–22 °C; relative humidity: 56 %–62 %), The domains of variation of the three factors considered in the experiments were as follows: – 8 to – 12 kV, for grid potential – 50 to – 90 μA for grid current and 70–150 mm, for sample length. The relative SPD after 300 s and 900 s were considered as output variables of the process. The models that express these variables as quadratic polynomial functions of the three factors were obtained using the Design of Experiments methodology and the commercial software MODDE 5.0. They point out that the surface potential decay is faster at higher applied voltages, lower grid currents and smaller sample areas. The grid voltage has a stronger effect at lower values of the grid current. Both the grid voltage and the corona current have a stronger effect of the SPD in the case of the samples of smaller areas. These observations suggest the optimal operating conditions of the corona charging devices for this kind of dielectric materials.

Ultraviolet-C Light Inactivation Kinetics of E. coli on Bologna Beef Packaged in Plastic Films

This study investigated the effects of ultraviolet-C (UV-C) light as a postpackaging treatment on Escherichia coli K-12 on bologna meat packaged in polyethylene (PE), oriented polypropylene (OPP), and ClearTite® films. Findings show that PE film had the highest measured UV-C light transparency among the 15 tested films, at 76 %, followed by PP and OPP films, with 59 and 57 %, respectively. Exposure of PE film inoculated with E. coli K-12 with UV-C light resulted in a 4.6 log CFU/ml reduction after a dose of 164 mJ/cm2. Reduction of E. coli K-12 on inoculated bologna packaged in PE film was higher (1.48 log CFU/g) compared to the other films (OPP and ClearTite®) following treatment with 0.406 J/cm2 of UV-C. The surface-free energy of films was used as an indicator for changes to film surface properties. UV-C light exposure of PE, OPP, and ClearTite® films at doses in this study had no significant effect (P ≥ 0.05) on the surface properties of the treated films. This study demonstrated that treating ready-to-eat meat products, such as a bologna with UV-C light after packaging, can reduce E. coli populations by a 1.5 log cycle without negatively impacting the surface properties of plastic films.

Piezoelectric cellular PP films with enhanced performance for low frequency ultrasound

Piezoelectric cellular PP films are a relatively new type of electromechanical transducer material. They have strong application potential in air-borne ultrasonic transducers because of their low acoustic impedance and high piezoelectric activity. Cellular PP transducers with varied structure in the density range between 251 and 606kg/m3 are processed. They show low acoustic impedances between 0.024 and 0.027MRayls and strong piezoelectric activity with coefficients up to 800pm/V. Acoustic measurements revealed a relative bandwidth of 35% at −6dB (resonance frequency around 150kHz) and an acoustic transmit sensitivity of 6mPa/V at 30cm far on principal axis for circular samples of 16mm diameter. The vibratory pattern of the transducer films were determined below, at and above the resonance frequencies. At frequencies below the resonance, the transducer acts like an ideal piston. In addition, we demonstrate that the transducer samples can be operated at frequencies close to either the first or the second resonance. To do this, fabric samples were contactless inspected in through transmission mode at 140kHz and 400kHz.

Shelf-life extension of refrigerated sea bass slices wrapped with fish protein isolate/fish skin gelatin-ZnO nanocomposite film incorporated with basil leaf essential oil.

Microbiological, chemical and sensory changes of sea bass slices wrapped with fish protein isolate (FPI)/fish skin gelatin (FSG) films incorporated with 3% ZnO nanoparticles (ZnONP) (w/w, based on protein content) and 100% basil leaf essential oil (BEO) (w/w, based on protein content) during storage of 12days at 4°C were investigated. Sea bass slices wrapped with FPI/FSG-ZnONP-BEO film had the lowest growth of psychrophilic bacteria, lactic acid bacteria and spoilage microorganisms including Pseudomonas, H2S-producing bacteria and Enterobacteriaceae throughout storage of 12days in comparison with those wrapped with FPI/FSG-BEO, FPI/FSG-ZnONP, FPI/FSG film, polypropylene film (PP film) and the control (without wrapping), respectively (P < 0.05). Lowered increases in pH, total volatile base, peroxide value and TBARS value were found in FPI/FSG-ZnO-BEO film wrapped samples, compared with others (P < 0.05). Sensory evaluation revealed that shelf-life of sea bass slices was longest for samples wrapped with FPI/FSG-ZnONP-BEO film (12days), as compared to the control (6days) (P < 0.05).

Molecular Orientation Effect of Heat-Sealed PP Film on Peel Strength and Structure

Heat sealing properties are optimized by controlling temperature, pressure and dwell time, while film strength depends on the drawn ratio and the molecular orientation of the film. However, heat seal strength of polymer films with high drawn ratio shows lower peel strength, because the adhesion of films needs a higher heat sealing energy for molecular orientation relaxation at heat sealing. In the present study, polypropylene films with a drawn ratio of 1.0×, 1.5×, and 2.5× are heat sealed by using the heat sealing technique. The heat sealing condition is set to heat sealing time 1.0 s, sealing pressure 0.2 MPa, and heat sealing temperature 145°C. The effect of drawn ratio and stabilization temperature of PP films for peel strength are investigated using T-Peel test, DSC, FT-IR, and Raman spectroscopy. As a result, it is found that the peel strength is decreased with increasing the drawn ratio and stabilization temperature of PP films. The difference of ?H and melting point from the result of DSC measurement are exhibited for 1.5× drawn ratio film as compared with 2.5× one. In addition, FT-IR imaging and Raman line mapping reveal the influence and variation of high order structure for heat sealed parts of the drawn PP films.

Study on charge storage characteristics of PP film electret charged by interface polarization method

Electret attracts increasing attention nowadays because of its lasting and stable electrostatic field. To achieve the widespread use of electret material, higher density and better stability of the electret charge storage as well as well-distributed electrostatic field must be ensured at the same time. Based on the mechanism of interface polarization on double-layer media, a novel charging technology for electret is reported in this paper; and PP film is successfully charged through an auxiliary layer to form electret by this proposed method. Effect of charging temperature and charging voltage on the charge storage performance of the as-prepared PP film electret is investigated by means of surface potential measurement. Also its charge storage performance at high temperatures is explored by thermally stimulated discharge technique. Furthermore, its electrostatic field distribution in the directions of X and Y is measured. Results show that the interface polarization charging is more excellent than the corona charging. At a certain temperature, the surface potential of PP film electret increases with increasing charging voltage and both are in a good linear relationship. This is in good agreement with the theoretical analysis in terms of the equation of electret charge accumulation during the charging process. It is shown that in the case of constant charging voltage within the range of 0.53.0 kV, the effect of charging temperature is not obvious when the temperature is below 75 ℃; however, when the temperature is higher than 75 ℃, the surface potential of PP film electret increases with increasing temperature. In addition, its surface potential may change a little with time so it has an excellent charge storage stability. The distribution of its surface potential shows that it exhibits an homogeneous electrostatic field due to interface polarization charging.

Morphological and chemical analysis of PP film treated by Dielectric Barrier Discharge

PP films have been activated by DBD, with different gases (air, N2, H2, CO2) and at different energy treatments. Then film surfaces were analysed by AFM, contact-angle technique, ink test measurements and XPS, to explore modifications in surface topography, wettability, and oxidation state. After the treatments, it is possible to observe the formation of water-soluble low-molecular-weight oxidized materials (LMWOMs), which dimensions and spatial density are related to treatment parameters. Using AFM data it is possible to analyse the statistical distribution of the bubbles sizes. The analysis of XPS spectra shows the formation of oxidized polar groups on surface (e.g. C-O, C=O, COH) and allows to evaluate the extent and the nature of film oxidation, and how it influences surfaces properties. The relationship between surface chemical and morphological modifications and treatment parameters is pointed out. Then PP sample have been monitored in the time, to determine the ageing effects.

Influences of processing on the phase transition and crystallization of polypropylene cast films

ABSTRACTPhase transition and changes of properties of isotactic polypropylene (i‐PP) cast films with the processing conditions have been investigated by wide‐angle X‐ray diffraction, two‐dimensional small‐angle X‐ray scattering, and atomic force microscopy. It was found that chill roll temperature was a major factor, which influenced the formation of mesomorphic phase and its transition to spherulitic structure. Only mesomorphic phase was observed in the films produced under a chill roll temperature of below 40°C. When the roll temperature was increased to 60°C, mesomorphic phase coexisted with spherulitic crystal structure, and totally transformed to monoclinic structure at the roll temperature of 80°C. Differential scanning calorimetry, tensile, and optical tests were also performed on the films. The results showed that the observed structure changes were closely related to the thermal behavior, tensile, and optical properties of the PP films. The influence of die temperature on the films was also discussed, but the effect was much less than chill roll temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41100.

Evaluation of two antimicrobial packaging films against Escherichia coli O157:H7 strains in vitro and during storage of a Spanish ripened sheep cheese (Zamorano)

Abstract The antimicrobial activity of two packaging films (polypropylene – PP- and polyethylene terephthalate – PET-) coated with different concentrations (0, 4, 6 and 8%) of essential oil from Origanum vulgare (OR) and Ethyl Lauroyl Arginate HCl (LAE) was tested against two Escherichia coli O157:H7 strains using in vitro systems and a raw milk sheep cheese model (Zamorano). The influence of the antimicrobials on the sensory attributes of cheese was also evaluated. For both strains, the MBC (minimum bactericidal concentration) values were identical to their respective MIC (minimum inhibitory concentration) values and lower for LAE (25 mg/l) than for OR (200–400 mg/l). PP and PET films coated with OR were tested by a vapour phase assay and the Japanese Standard method (JIS Z 2801:2000). Both films coated with LAE were tested by an agar diffusion method. Overall, in vitro tests were effective against both strains. The inhibitory activity depended on the active compound concentration, the target strain and the packaging material, PET being more effective than PP. For inoculated cheese slices, OR and LAE PP films did not effectively decrease E. coli O157:H7 counts after 7-days cold storage. PET films incorporating 6 and 8% of OR and LAE significantly (p 0.05) affect sensorial characteristics of Zamorano cheese. Packaging with PET films coated with ≥6% LAE concentrations might be useful in reducing E. coli O157:H7 numbers in sheep cheese.

Review of Recent Activities on Dielectric Films for Capacitor Applications

AbstractPolypropylene (PP) film has been used in capacitors since 1970s. The high breakdown strength, low dielectric losses, and high availability make PP well suitable for use as capacitor dielectric. At the moment, the typical energy density achieved with PP film at room temperature is about 1.2 J/cm3. Recent research on PP films focus on improving the permittivity, breakdown strength, thermal withstandability, and thermal conductivity, by producing copolymers, blending with other polymers, or adding inorganic particles. Some results claim energy density higher than double that of commercial bi-axially oriented PP capacitor film. Detailed research approaches and dielectric properties improvements are reviewed in this paper. The major focus is often placed on permittivity and breakdown strength. Unfortunately, little research shows positive results for maintaining the low dielectric losses.

Graft Polymerization of Acrylic Acid onto Polypropylene Film: Immobilization of Chitosan Nanoparticles onto Grafted Films

In this paper the aim is to immobilize chitosan nanoparticles on the surface of the polypropylene film, aqueous phase thermal decomposition characteristics of ammonium persulfate is used. The PP film is first hydroxylation pretreated in the protection of the high-purity nitrogen. And then ceric ammonium nitrate acting as an initiator, induce graft polymerization of acrylic acid on the hydroxylated treated PP film. Thus, carboxyl functional groups are grafted on the surface of PP film. Finally chitason namoparticles are fixed on PP film by the reaction of carboxyl group and the amino group of chitosan. Experimental results show that: when the reaction temperature is 60 ° C, the concentration of acrylic acid is 8% (w/w), the reaction time reaches 4h, the concentration of ceric ammonium nitrate is 2mM, the optimum grafting ratio is obtained, which is up to 0.6008×10-7mol/cm2. Total reflection Fourier transform infrared spectroscopy absorption peaks appear at 1712cm-1, indicating that the-COOH has been successfully grafted to the film surface; the SEM scanning the film surface shows that the chitosan nanoparticles were perfectly immobilized on the modified film. Key words: Acrylic acid, Polypropylene film, Chitosan nanoparticles, Graft polymerization

Evolution of Poly(propylene) Morphology in the Rubbery State under Uniaxial Strain

The evolution of the crystalline morphology of two poly(propylene) films deformed in the rubbery state using wide‐ and small‐angle X‐ray scattering and extensional rheology experiments is presented. The mechanical behavior can be either isotropic or anisotropic depending on the manufacturing process. The microstructure change of the polymer is linked to the thermomechanical behavior of PP films below and close to the melting temperature. The reorientation of the crystalline phase during the deformation is shown to occur quickly when the deformation temperature is largely lower than the melting temperature and for low strain rates. The formation of a fibrillar structure oriented along the stretching direction following the fragmentation of initial crystals is highlighted.

Crystalline and Lamellar Structure of Polypropylene Fibrillated Fibres

The effects of processing conditions on the structure of polypropylene fibrillated fibres were studied using a combination of wide- and small-angle X-ray scattering methods. In particular the impact of selected stages of processing on the crystalline and lamellar structure of PP were analyzed. It was stated that crystalline phase is built from α crystals. The crystallinity index as well as the Herman orientation factor of the crystalline phase is found to have a correlation only with the draw ratio of the PP film. The lamellar structure also changes with the draw ratio.

Comparison of biodegradability of various polypropylene films containing pro-oxidant additives based on Mn, Mn/Fe or Co

The biodegradability of two polypropylene films with low content of ethylene (a statistical copolymer (PPs) and a block copolymer (PPb) with balanced additions of phenolic antioxidant and pro-oxidants based on Mn, Mn/Fe or Co was studied. Abiotic pre-treatments by accelerated artificial photooxidation and thermooxidation representing about 3–4 years of outdoor weathering, including 3–4 months of exposure to daylight and 3 years in soil were followed by FTIR and SEC measurements. When a controlled oxidation was reached in the films, they were inoculated, in a second step, with the strain Rhodococcus rhodochrous in mineral medium and incubated up to 180 days. The metabolic activity of bacteria was evaluated by measuring ATP content, ADP/ATP ratio and cell viability. Complementary 1H NMR experiments were conducted on the incubation media, with and without cells, in order to monitor the consumption of soluble compounds excreted from the oxidized polymers by R. rhodochrous cells. The main conclusions are that the Co derivatives (with Co content ≥ 150 ppm) must be considered toxic for R. rhodochrous. PP films containing pro-oxidants based on Mn and Mn + Fe give positive results for the biotest (low ADP/ATP ratio, post-development in Petri dishes). However the biodegradability of oxidized PP films is less efficient in comparison to oxidized PE films (see paper published in this journal). This observation may be correlated with the accumulation in the incubation media of oxidized oligomers that cannot be metabolized rapidly by the bacterial cells and/or by the residual crystallinity of PP derivatives.

Development and Evaluation of Shelf Stability of Flaxoat Nutty Bar in Different Packaging Materials

Flaxoat nutty bar, a granola cereal bar was developed using oat and wheat as major cereal ingredients and their shelf life was assessed in polypropylene (PP 75 μ), paper (42 GSM) aluminium foil (20 μ) polyethylene (PFP, 37.5 μ) and metallised polyester (MP, 12 μ) low density/linear low density (150 μ) (with and without vacuum) films and stored under ambient temperature conditions and 37℃. Chemical changes in bar under different packaging materials during storage revealed that, the bar remained stable and acceptable for 12 months at ambient conditions irrespective of the packaging materials used, while at 37℃, the bar packed in PP films remained stable for 6 months only and rest of the bars packed in PFP, MP and MP (vacuum) films found stable and acceptable for the entire storage period of 12 months. The effect of aw on lipid peroxidation established the maximum stability of the bar at 0.33 aw. Fourteen fatty acids were identified in which oleic (50.91%), linoleic (22.50%) and palmitic (12.63%) acids were found to be the major fatty acids. Fortification of a bar with vitamin C, B1 and B2 contents to meet 50% RDA enhanced vitamin contents and the maximum retention was observed in bars packed under vacuum in MP films.