PP Films Research Articles

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.

Development of a Shelf‐Stable Omega–3‐Rich Bar

AbstractOmega–3‐rich bar was developed using flax seed and walnut as sources of omega‐3‐fatty acids. Bars packed in polypropylene (PP, 75 μ), paper (42 GSM) aluminum foil (20 μ) polyethylene (PFP, 37.5 μ) and metalized polyester (12 μ) low‐density/linear low‐density (MP 150 μ) (with and without vacuum) films, were stored under ambient conditions and 37C. The bars packed in PP films spoiled with in 1 month, while those packed in PFP and MP films found stable for 3 months, and the one packed under vacuum in MP film remained stable and acceptable up to 5 months under ambient and 37C conditions. Chemical changes like PV, free fatty acid, thiobarbituric acid and browning index were found more in bars packed in PP films both at ambient conditions and 37C. Oleic acid was found to be the major fatty acid followed by linoleic acid having 2.8 g of omega‐3 fatty acid per 100 g bar.Practical ApplicationsOmega–3‐rich bar was prepared using flaxseed and walnut as the main source of omega‐3‐fatty acids to cater to the needs of consumers especially vegetarians. Foods rich in omega‐3‐fatty acids have proven to be beneficial in improving cardiovascular health, cognitive function, inflammatory problems etc. This bar can be described as a healthy, nutritious, calorie rich and a delicious sweet product.

Preparation and Properties Research of Anti-Fogging Polypropylene Packaging Films

The anti-fogging properties of a new anti-fogging agent containing silicon sprayed on polypropylene were discussed. The anti-fogging agent was prepared by using silicone hydride and silica sol, the new anti-fogging agent with different consistency was daubed on the polypropylene film .The contact angle, first dripping time and ten drippings time of the anti-fogging PP films were tested. According to the range analysis, the best mixture ratio, which was just the optimum formula was found. The relationship between the anti-fogging agent consistence and the anti-fogging performance was discussed too. The result showed that the anti-fogging properties of the coated film were better and the mechanical properties of the coated film enhanced in some sort. The mixture ratio of the anti-fogging agent was that the silica sol was 12phr; the span 80 was 15%; the pH was 5.5. After the film was coated, the tensile strength of machine direction raised by 109.14% than the contrast. The elongation at break of transverse direction raised by 32.51MPa and that of machine direction raised by 17.95MPa. This anti-fogging agent containing silicon was preferable to polypropylene.

TSDC Study of Space Charge Influence on PP Film by Steep Front Impulse Injection

Influence of DC and steep front impulse injection on space charge of PP by thermally stimulated discharge current (TSDC) are studied. The experimental results show that space charge of PP is almost irrelative to the rise time of pulse, but space charge has relationship with polarized field intensity and polarized time, which is similar to the theory of TSDC

Effects of Varying Heptylamine and Propionaldehyde Plasma Polymerization Parameters on Mesenchymal Stem Cell Attachment

AbstractThis paper investigated the impacts of two deposition times (30 s, 60 s) and discharge powers (20 W, 50 W) on the resultant chemical and physical properties of plasma polymers (pp) formed using heptylamine (HA) or propionaldehyde (PA) monomers. Pinhole‐free pp films were formed on all surfaces at deposition rates that varied according to both the time and power employed. XPS and ToF‐SIMS analysis showed that power has a more of an effect than time on the chemical properties of the pp, which may be attributed to differences in monomer fragmentation and cross‐linking. Mesenchymal stem cell (MSC) adhesion did not vary on the four different HApp surfaces, whereas a negative correlation between cell attachment and increasing plasma energy was observed on PApp surfaces. This suggests that the presence of oxygenated groups, particularly aldehyde and carboxylic groups, may have a dominant impact on MSC adhesion to these functional polymer substrates. magnified image

Effect of PPG-PEG-PPG on the Tocopherol-Controlled Release from Films Intended for Food-Packaging Applications

The feasibility of novel controlled release systems for the delivery of active substances from films intended for food packaging was investigated. Because polyolefins are used highly for food-packaging applications, the reported high retention degree of antioxidants has limited their use for active packaging. Thus, in this study, PP films modified with different chain extenders have been developed to favor and control the release rates of the low molecular weight antioxidant tocopherol. The use of different chain extenders as polymer modifiers (PE-PEG M(w), 575; and PPG-PEG-PPG M(w), 2000) has caused significant changes in tocopherol-specific release properties. High-performance liquid chromatography coupled to PDA-FL and PDA-MS was used to test tocopherol and chain extender migration, respectively. The release of tocopherol from the prepared films with two chain extenders into two food simulants was studied. Different temperatures and storage times were also tested. Varying the structural features of the films with the incorporation of different levels of PPG-PEG-PPG, the release of tocopherol (food-packaging additive) into different ethanolic simulants could be clearly controlled. The effect of the temperature and storage time on the release of the antioxidant has been outstanding as their values increased. The migration of the chain extender, also tested, was well below the limits set by European legislation.

Evaluation of EVOH-coated PP films with oregano essential oil and citral to improve the shelf-life of packaged salad

The aim of this study was to improve the present packaging of salad by combining modified atmosphere packaging with a new antimicrobial active bag consisting of PP/EVOH film with oregano essential oil or citral, with the purpose of extending shelf-life and reducing possible microbiological risks. The (O2) and CO2 barrier properties of PP/EVOH, mechanical properties (Young’s modulus, tensile strength and elongation at break) were determined and compared with those of standard PP films. Antimicrobial tests were carried out for enterobacteria, total aerobic counts, yeasts and moulds, and lactic acid bacteria and psychrotrophic bacteria, and the effect of the release of the antimicrobial agent on the sensory characteristics of the salads was also studied. The application of the EVOH coating results in an increase in the tensile resistance of the PP films and a reduction in the elongation at break. The results showed that microorganism counts bacteria decreased especially at the beginning of the storage period. OEO and CITRAL samples had reductions of 1.38 log and 2.13 log respectively against enterobacterias, about 2 log against yeasts and moulds. The total aerobic counts reduced 1.08 log with OEO and 1.23 log with CITRAL and the reduction of lactic acid bacteria and psychrotrophic was about 2 log. Citral-based films appeared to be more effective than materials containing oregano essential oil in reducing spoilage flora during storage time. Sensory studies also showed that the package with citral was the most accepted by customers at the end of the shelf-life.

Mathematical Model for Shelf-life of Chickpea Sprouts under Modified Atmospheric Packaging

Simulation study compared predicted in-pack gaseous composition of O2 and CO2 with the actual experimental data and predicted in-pack water vapour and temperature as well as the appropriate shelf life of chickpea sprouts. The actual and simulated results for in-pack gaseous composition O2/CO2 was 14.46; 8.45 % and 14.99; 7.92 % for PP package (100g) and 14.22; 8.85 % and 14.21; 10.57 % for 100g of LDPE package containing chickpea sprout under MAP. Verification of developed model considered the prediction of in-pack gaseous composition and storage period packed under PP and LDPE polymeric films with the experimental value and showed a near proximity. A model with the selected quality attribute (lightness of hypocotyl) thus could provide a fair insight into the shelf life of chickpea sprout under modified atmospheric packaging.

Effect of Nanoclay Amount and Compatibilizer Presence on Thermal, Morphological and Mechanical Behaviour of Nanoclay Reinforced Composite Polypropylene Cast Film

Abstract Pure PP film without compatibilizer and nanoclay, nanoclay reinforced PP film without compatibilizer and nanoclay reinforced PP films with compatibilizer were produced to study the effect of nanoclay amount and compatibilizer presence on thermal, morphological and mechanical properties of films. Reinforced films were produced with 1% and 3% nanoclay contents with 3 different compatibilizer amounts to examine if nanoclay addition changes properties of the films in the same manner with different compatibilizer amounts. Melting points of the films slightly increase as the nanoclay content increases. Decomposition temperatures increase, as the nanoclay content increases. As the nanoclay content increases, tensile, burst and tear strengths for the reinforced films decrease. It can be observed that the increase in nanoclay content lowers strain and extension values for reinforced films due to nanoclay dispersion.

Mathematical model to describe the release of an antimicrobial agent from an active package constituted by carvacrol in a hydrophilic EVOH coating on a PP film

Antimicrobial active packaging is a novel technology in which a chemical compound (or mixture) is purposely incorporated into a packaging material to be released into the food to protect it from deterioration. The effectiveness of an antimicrobial package is strongly related to the balance between the controlled release of the active compound and microbial growth kinetics. This work characterizes and models the release of carvacrol from an EVOH coating on a PP film which can be employed as an active packaging system. The kinetics and extent of carvacrol mass transport within the packaging components were fully characterized as a function of relative humidity. As expected, water uptake by the EVOH coating acts as a triggering mechanism for activity. The partition equilibrium for carvacrol in the complex film largely favors (10,000-fold) the EVOH layer in dry conditions, although in humid conditions the solubility in both polymers is very close (4-fold). Kinetically, the presence of humidity increases the value of D for carvacrol in EVOH from 3 · 10 −19 m 2/s in dry conditions to 3 · 10 −15 m 2/s in a wet environment. After the experimental characterization of carvacrol transport, the efficiency of the release of carvacrol was estimated with a novel mathematical model based on the finite element method and successfully compared with the evolution of carvacrol concentration in a real packaging system. The model developed can be employed in the optimization of package design in order to ensure the maintenance of a specific concentration of the active agent in the headspace, high enough to prevent potential growth of a particular foodborne spoiling or pathogenic microorganism on the preserved foodstuffs. This model could easily be extended to similar packaging systems as long as an inventory of experimental data for all the parameters and coefficients involved is available, sufficiently complete to fulfill all the mathematical requirements demanded by the model.

Micropower Generators and Sensors Based on Piezoelectric Polypropylene PP and Polyvinylidene Fluoride PVDF Films - Energy Harvesting from Walking

This paper presents investigation of piezoelectric proprieties of polypropylene PP and polyvinylidene fluoride PVDF films at an angle of their application as micropower generators and foot pressure sensors in walking process. Obtaind micropower from single layer is about 1.7W and 5.3W for polypropylene film and about 1.7W and 3.3W for polyvinylidene fluoride film. Obtained voltage from single film layer is 8.9V to 14V for PP film and 2 to 3.4V for PVDF film. Obtained micropower from piezoelectric film and course character of voltage in function of time during walking process, depends from used film and shoe insole construction, where active element was sandwich. Recived data record of voltage, power and foot movement images from measuring system, can be use in dynamic investigations of posture defects.

Effect of montmorillonite on orientation of drawn polypropylene films

AbstractFilms of polypropylene/organically modified montmorillonite (PP/OMMT) nanocomposites were drawn at two different temperatures with various draw ratios. The effect of OMMT on the orientations of the crystalline and amorphous phases was studied using polarized infrared spectroscopy. It is found that OMMT layers always retard the orientation of the crystalline phase. The higher the OMMT loading, the stronger the retardance effect. In contrast, the effect of OMMT layers on the orientation of the amorphous phase depends on draw temperature and OMMT loading. A favorable effect on the orientation of the amorphous phase is observed at low OMMT loading and high draw temperature, but the retardance prevails at high OMMT loading and low draw temperature. The favorable effect on orientation at high draw temperature is attributed to the stabilization effect of OMMT layers on the conformation of amorphous PP chains. Such an effect was further verified by comparing the crystallization behavior and the morphologies of drawn PP and PP/OMMT films crystallized from 180°C. Memory effect is observed for crystallization of drawn PP/OMMT film, but it is not obvious for the drawn film of neat PP. Spherulites are formed for orientated neat PP films cooled from 180°C, but cylindrites are still formed after the drawn PP/OMMT films undergo melting at 180°C and recrystallization. The stabilization effect disappears at higher temperature (230°C). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Atmosfera modificada e refrigeração para conservação pós-colheita da nêspera 'Fukuhara'

A rápida perda de qualidade pós-colheita limita a comercialização da nêspera no mercado de frutas frescas. Neste sentido, este trabalho teve por objetivo avaliar os efeitos da utilização de atmosfera modificada na conservação pós-colheita da nêspera 'Fukuhara' armazenada sob refrigeração (1 °C / 90% UR). Para tanto, os frutos (≈450 g) foram acondicionados em bandejas de poliestireno e embalados em dois tipos de filme: polietileno de baixa densidade (PEBD, 50 µm) e polipropileno (PP, 30 µm), sendo, em seguida, armazenados a 1 °C / 90% UR. Os frutos foram comparados a um controle que não envolveu a aplicação de filmes. As análises físico-químicas (perda de massa, firmeza, sólidos solúveis, pH e acidez titulável) foram realizadas aos 15, 30 e 45 dias sob refrigeração, seguido por período de três dias sob condição ambiente (25 °C / 80% UR). A composição gasosa (O2/CO2) no espaço livre das embalagens, a incidência de podridões e de manchas escuras na epiderme dos frutos também foram avaliadas. Os resultados mostraram que a utilização de filme PEBD e PP para a conservação pós-colheita da nêspera, apesar de ser eficaz na redução da perda de massa e não alterar a cidez titulável, o pH e a firmeza dos frutos, não é indicada para o aumento do período de conservação, pois deprecia sua qualidade devido a condições de anaerobiose e elevada incidência de podridões.

Investigation on Flame Retardancy and Antidripping of New Intumescent Flame Retardant Polypropylene Film

A novel intumescent flame retardant (IFR) system consisting of a novel char forming agent (CFA), modified ammonium polyphosphate (MAPP), a synergistic agent (4A zeolite) and an antidripping agent (SN3300) was used in an intumescent flame retardant polypropylene film (IFR-PP film). The original ammonium polyphosphate (OAPP) was modified by octadecylamine to enhance its compatibility with the PP matrix. According to the results obtained from the flame retardancy tests, MAPP had a higher efficiency than OAPP, and the IFR-PP film without the antidripping agent reached a high limiting oxygen index (LOI) value, but it failed to pass UL-94 VTM-0 rating (0.2 mm). The reasonable loading of SN3300 was 0.10~0.15 wt.% (26 wt.% loading of IFR). Greater or smaller loadings did not help the samples to pass VTM-0 rating, and even deteriorated the flame-retardancy of the film. Based on thermogravimetric analytical data, the IFR enhanced the thermal stability of composites at high temperature and effectively increased the char residue. The cone results demonstrated that the IFR could reduce the flammability of PP films based on reduced heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP); also IFR containing MAPP became more effective in reducing smoke release than one containing OAPP The mechanical properties test results showed that films containing MAPP had better tensile strength and tear strength. The morphological structures observed by scanning electron microscopy (SEM) showed that MAPP had much better compatibility with a PP matrix than OAPP, and it made the char layer become more homogeneous and dense.

Structural properties and superhydrophobicity of electrospun polypropylene fibers from solution and melt

Isotactic polypropylene (iPP) has successfully been electrospun from both solution and melt using an elevated temperature setup. First, PP nanofibers with two different average diameters (0.8 μm and 9.6 μm) were obtained via electrospinning of iPP in decalin, and the effect of deformation and solidification on the morphological and structural features of the resulting fibers was studied. Secondly, melt electrospun PP fibers with two different average diameters were also fabricated to compare the structures with those of solution electrospun PP fibers. DSC and XRD results show that β form crystals which can increase the impact strength and toughness of electrospun fibers are present in sub-micron scale PP fibers from solution, while fibers from melt mostly show α form crystals. The annealed fibers have changed their morphological forms into α and γ crystal forms. Finally, it is observed that electrospun PP fiber webs both from solution and melt exhibit superhydrophobicity with a water contact angle about 151° which is substantially higher than those of a commercial PP non-woven web and a compression molded PP film, 104° and 112°, respectively. Such superior hydrophobicity was observed for all PP electrospun fibers and it was not altered by the processing scheme (solution or melt) or fiber diameter (sub-micron or micron). Enhanced hydrophobicity of electrospun PP fiber webs contribute to excellent barrier performance without losing permeability when they are applied to protective clothing.

Effect of Low Pressure Nitrogen–Oxygen (N2/O2) Plasma Treatment on Surface Properties of Polypropylene Films

In this paper the effect of plasma treatment by using mixed gas (N2/O2) on surface properties of a Polypropylene PP films were investigated as a function of O2 content and treatment time. Results obtained by using Fourier Transform infrared spectrometer (FTIR), contact angle measurement and scanning electron microscopy (SEM). It is found that plasma treatment can change chemical structure of polymer surfaces partially. SEM images revealed distinct changes in topography of PP due to O2/N2 plasma treatment. Finally wettability and surface energy before and after treatment investigated in different conditions.

Formation of Poly(propylene)‐Based Biocomposite Films and Their Use in the Attachment of Methylene Blue

AbstractBiocomposite PP‐g‐PAAc‐CS films based on PP were generated and utilized as support of methylene blue, a thiazidic dye. Using a photograft polymerization of acrylic acid, the PP film was functionalized with carboxyl groups (PP‐g‐PAAc), which attached chitosan by electrostatic bond. A longer poly(acrylic acid) chain or a higher CS immobilization temperature led to a higher chain interpenetration and crosslinking reaction. Immobilized MB confirmed to possess redox activity from its reaction with ascorbic acid, where the dye decomposition rate ($R'_{\rm d} $) increases together with the chain interpenetration, then decreasing with the increase in the crosslinking degree.magnified image

Fluorine Plasma Treatments of Poly(propylene) Films, 2 – Modeling Reaction Mechanisms and Scaling

AbstractThe surface properties of commodity hydrocarbon polymers such as poly(propylene) (PP) can be modified by functionalization with plasma‐generated radicals and ions. For example, affixing fluorine to a hydrocarbon surface lowers surface energy and increases hydrophobicity. One such process is treatment of PP films in low‐pressure, capacitively coupled plasmas (CCPs) sustained in F2‐containing gas mixtures. F atoms produced in the plasma abstract H atoms from the hydrocarbon and passivate the resulting alkyl sites producing CFn sites. Energetic ion and photon fluxes sputter and initiate crosslinking. In this paper, the plasma fluorination of PP in a CCP sustained in Ar/F2 is discussed with results from a two‐dimensional plasma hydrodynamics model. The surface reaction mechanism includes a hierarchy of H abstraction and F/F2 passivation reactions, as well as crosslinking, and ion and photon‐activated processes. Predictions for surface composition were compared to experiments. We found that the lack of total fluorination with long plasma exposure is likely caused by crosslinking, which creates CC bonds that might otherwise be passivated by F atoms. Increasing steric hindrances as fluorination proceeds also contribute to lower F/C ratios.magnified image

Thermo- and Photo-Degradation of LDPE and PP Films Using Metal Oxides as Catalysts

Degradation of LDPE and PP films using the photo sensitive metal oxides or pro-oxidants (e.g. Fe2O3, CuxO, ZnO, and TiO2 at various particle sizes) as the catalysts in both thermo- and photo-oxidation of plastic films with oxygen followed by photolytic process to give free radicals has been studied. Our preliminary study in hexane solution found that the carbonyl index (CI) increased under the shortwave ultraviolet (254nm) significantly greater than under the longer wave (366nm) due to its greater energy and highly absorbed by the pro-oxidants generating more free radical concentration which could then be photolysed into carbonyl compounds. The pro-oxidant blended PE and PP films under ultraviolet (254nm) irradiation showed the carbonyl index elevation at the beginning and then reducing to a constant level similarly in most cases. This probably suggested that the carbonyl primarily formed and degraded into other free radicals. Under shortwave ultraviolet irradiation for 72 hours, the LDPE films containing nano-sized rutile-TiO2 and nano-sized anatase-TiO2 (1%w/w) were able to reduce the film tensile strength by 32% and 55%, respectively. The film containing micron-sized commercial TiO2 lower the film tensile strength only by 7-10%. However, the tensile strength of the TiO2 blended PP films tends to increase possibly because the rate of cross linkage exceeds the rate of scission.

Acetophenone and Benzophenone Derivatives as Catalysts in Photodegradation of PE and PP Films

Due to their versatile functionalization, acetophenone and benzophenone derivatives as plastic additives were synthesized and blended into PE and PP to study rate of degradation under ultraviolet irradiation by monitoring carbonyl index, tensile strength and weight loss. The photolytic reactions of these ketones in benzene solution showed that acetophenone derivatives, especially 3-nitroacetopheone, underwent rapid degradation under the short-wave ultraviolet (254 nm) rather than in the black light (366 nm) while benzophenone derivatives showed small carbonyl index reduction. However, both groups of ketones, in hexane solution or in PE and PP films, primarily lowered the carbonyl index and rised up again except for the bromo derivatives. At 96 hrs of UV irradiation, the tensile strength of the acetophenone-blended PE film reduced only 20% while the tensile strength of the acetophenone-blended PP film decreased dramatically upto 90% and 95% for the benzophenone-blended PP.