Journal of Plastic Film and Sheeting recent issues

From the editor

Wed, 02 Sep 2009 06:29:05 PDT

Industry news

Wed, 02 Sep 2009 06:29:05 PDT

An Overview on the Technology of Cross-Linking of Starch for Nonfood Applications

Ayoub, A. S., Rizvi, S. S. H. — Wed, 02 Sep 2009 06:29:05 PDT

For commercial success, bioplastics have to possess adequate physical properties. But the same properties of biopolymers — such as starch — that make them environmentally attractive feedstocks can affect their performance as materials. Despite the attractive properties of plant-based plastics, there have been few commercial applications due to their property drawbacks (e.g., high cost, brittleness, and lower impact resistance). Many biopolymers, such as starch, are often hydrophilic and some are even soluble in hot water. These properties have to be managed and controlled through the development of adequate formulations and processing. The primary challenge is to develop fast reactions that can be transformed into viable processes and integrated into existing process lines with economically viable formulations that are friendly to the environment. Cross-linking of starches is the most common method used in polysaccharide chemistry. This article briefly reviews some of the most promising chemistries available for the cross-linking of biodegradable starch materials and their applications.

High Water Barrier Nanobiocomposites of Methyl Cellulose and Chitosan for Film and Coating Applications

Lagaron, J.M., Fendler, A. — Wed, 02 Sep 2009 06:29:05 PDT

Polysaccharides and protein biopolymers are of increasing interest for their use as sustainable film and coating materials. However, their main drawback in these applications is their inherent high water permeability and low water resistance at high relative humidity conditions. In this study, two specifically designed commercial fillers of different nature and aspect ratios were successfully incorporated into two polysaccharides: methyl cellulose and chitosan. The morphology study indicated that a good dispersion with intercalation of the fillers was observed in both matrices. The water barrier properties of the nanobiocomposites were found to be enhanced to a significant extent, particularly for the higher aspect ratio filler, as compared to the pure matrix materials, while the biodegradability of the composite materials was maintained.

Influence of Processing Conditions On the Peel Behavior of Polyethylene/ Polybutene-1 Peel Systems

Nase, M., Langer, B., Grellmann, W. — Wed, 02 Sep 2009 06:29:05 PDT

The specific peel system low-density polyethylene/isotactic polybutene-1 (PE-LD/iPB-1), which is often used for protective packages, was investigated in this study. The required peel force to open the package depends on the content of iPB-1 and on the processing conditions of the blowing process. Commercial products have a constant amount of iPB-1. Thus, a defined peel force can be adjusted by varying the processing conditions. The standard peel system PE-LD with 6 wt% iPB-1 was investigated in dependence on the processing conditions. The most important processing parameters of the processing line (extruder, die head, tube forming area) were varied and their influence on the peel properties was examined. For example the temperatures of the melt within the extruder, the size of the die gap within the die head, and the cooling behavior of the film bubble were investigated. Higher melt temperatures within the extruder decreased the peel force. The investigations also revealed a strong dependence of the peel force on the size of the die gap and on the degree of cooling. The new developed parameter time of solidification was used to characterize the cooling behavior.

from the editor

Mon, 09 Feb 2009 02:49:32 PST

industry news

Mon, 09 Feb 2009 02:49:32 PST

Prediction of Polyethylene Molecular Weight and Molecular Weight Distribution Using Capillary Rheometer

Todd, W. G., Olenius, V. L., Merrick-Mack, J. A. — Mon, 09 Feb 2009 02:49:32 PST

Polyethylene is characterized by molecular weight (MW), molecular weight distribution (MWD), and density. Melt index (MI₂) is measured in the quality control (QC) lab and is used as an indication of resin MW. Melt flow ratio (MFR or MI₂₀/MI₂) is a calculated QC lab number, which is used as an indication of MWD. Density is a measure of crystallinity. This article shows that a capillary rheometer can provide a fast and reliable method on a production line to control MW and MWD by predicting MI₂ and MI₂₀ for a resin within specific ranges of density, melt index and equipment/catalysts.

Control of the Thickness Distribution of Blown Film By Changing the Flow Channel Gap of the Die Over the Circumference

Gross, H. G. — Mon, 09 Feb 2009 02:49:32 PST

The thickness distribution of blown film is conventionally controlled by either changing the temperature or the velocity of the cooling air. This technique cannot be used for the double bubble process, where the film is cooled by water before being reheated and blown up in a second step. A new technique to alter the localized gap of the flow channel at the exit of the die has been developed. It can be used to control the thickness over the circumference of the blown film for both the conventional and double bubble process. The technology is explained and initial test results achieved are presented herein.

Impact of Metallizer Process Controls On Optical and Gas Barrier Uniformity

Mount, E. M. — Mon, 09 Feb 2009 02:49:32 PST

A vacuum metallizer process study was performed and the results in terms of optical density uniformity, metal adhesion, and barrier uniformity were evaluated. Gas barrier was found to be a complex function of the process parameters studied while adhesion was determined to be sensitive to testing materials as well as process parameters. Visual uniformity was found to depend primarily on metallization pressure.

Characterization of Current Environmentally-Friendly Films

Curtzwiler, G., Vorst, K., Palmer, S., Brown, J.W. — Mon, 09 Feb 2009 02:49:32 PST

The purpose of this study was to evaluate the physical and mechanical properties of environmentally-friendly films for fresh-cut lettuce. This objective was achieved by determining the gas transmission rates for oxygen, water vapor, carbon dioxide, and the thermal and mechanical properties of the films following ASTM standards D3985, F1249, F2476-05, D3418-03, and D882-02, respectively. Electromechanical testing and thermal analysis determined that biodegradable polypropylene (BPP) possessed similar mechanical and thermal properties when compared to the industry standard. This study suggests that BPP films may be used in place of traditional petroleum-based films currently used to package fresh-cut produce.

New UV Absorber for PET Packaging: Better Protection With Less Discoloration

Coughlin, G., Schambony, S. — Mon, 09 Feb 2009 02:49:32 PST

``UVA S-Pack'' is a new UV absorber additive designed to protect PET packaging content from the damaging effects of UV radiation. Compared to conventional UV absorbers that have been used for this purpose, this new product offers broader UV protection with less discoloration. The performance of this new UV absorber in content protection was demonstrated in exposure tests with vitamins and colorants. The product is also FDA-cleared for use in PET for food-contact applications. Due to this product's unique absorption and emission profile, it is expected to also offer suitable performance in polyester-based films and sheets.

Novel Polycaprolactone Nanocomposites Containing Thymol of Interest in Antimicrobial Film and Coating Applications

Sanchez-Garcia, M.D., Ocio, M.J., Gimenez, E., Lagaron, J.M. — Mon, 09 Feb 2009 02:49:32 PST

It is well-known that the nanocomposites technology can significantly enhance, among others, the thermal, mechanical, and barrier properties of plastics. It is also known that most bioplastics, including the thermoplastic biopolymers, have lower than desired levels for certain properties which makes their use in certain packaging applications problematic. The combination of active technologies such as antimicrobials and nanotechnologies such as nanocomposites can synergistically lead to bioplastic formulations with balanced properties and functionalities for their implementation in packaging applications. The present work presents the development and characterization of novel nanocomposites of polycaprolactone with enhanced barrier properties and with controlled-release of the biocide natural extract thymol. The antimicrobial nanocomposites of biodegradable materials were prepared in solution by a casting method. The morphology of the biocomposites was visualized by transmission electron microscopy and by atomic force microscopy, the thermal properties were investigated by differential scanning calorimetry and the relative uptake (solubility) and kinetics (diffusion) of the released biocide were determined by Attenuated Total Reflection Fourier Transformed Infrared spectroscopy. Water, oxygen, and limonene barrier properties were also enhanced in the biocomposites.

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Mon, 09 Feb 2009 02:49:32 PST

From the editor

Thu, 21 Aug 2008 07:52:52 PDT

Industry news

Thu, 21 Aug 2008 07:52:52 PDT

Optical and Electrical Properties of Polycarbonate/MnCl2 Composite Films

Ayesh, A. S., Abdel-Rahem, R. A. — Thu, 21 Aug 2008 07:52:52 PDT

The dependence of the absorption coefficient () on photon energy (h) is determined in the spectral range from 200 to 800 nm at room temperature for polycarbonate (PC)/MnCl₂ composite films. The variation of the absorption coefficient (), optical gap (E_opt), dielectric permittivity (^'), dielectric loss (^''), loss tangent (tan ), impedance (Z), AC conductivity (_ac), DC conductivity (_dc), and relaxation time () with salt concentration and frequency are reported. The observed optical energy gap (E_opt) and energy gap tail (E) is calculated from the measured absorption spectra. It is found that optical energy gap decreases with increasing MnCl₂ concentration and the absorption coefficient reduces sharply (with reduction ratio of 79%) in the UV region at concentration of 20 wt% compared with the PC host. All measured electrical parameters of the composite sheets show frequency and content dependence. Both AC conductivity and DC conductivity increase with MnCl₂ concentration while impedance decreases. Correlation between observed energy gap and AC conductivity is presented.

Flow Stability and Thickness Uniformity in Continuous Extrusion

Derezinski, S. J. — Thu, 21 Aug 2008 07:52:52 PDT

For continuously extruded products, such as sheet and profile extrusions, thickness uniformity is a key quality factor, and it is directly linked to flow oscillations or flow disturbances at the die. Many sources of flow oscillations in the extrusion system are identified, and methods are shown on how to configure the melt delivery system to minimize their transmission to the die. These methods are illustrated with a model based on the theory of hydraulic transients.

Data Analysis of an Extrusion Experiment

Wagner, J. R., Spalding, M. A., Crabtree, S. L. — Thu, 21 Aug 2008 07:52:52 PDT

The objective of this work is to demonstrate the usefulness of high-speed data acquisition in characterizing the extrusion process. This article analyzes the barrel pressures and motor current data acquired using a high-speed data acquisition system. Graphical analysis shows the relationship between screw design and screw speed.

from the editor

Fri, 28 Mar 2008 02:52:46 PDT

industry news

Fri, 28 Mar 2008 02:52:46 PDT

Selecting Equipment To Minimize Production Costs and Maximize Profitability

Smith, D., Spalding, M. A., Gould, R. J. — Fri, 28 Mar 2008 02:52:46 PDT

Specifying and installing the proper equipment for a process is the key to minimizing the long-term cost of producing products. But often the objective to purchasing equipment is to minimize the initial capital cost. Minimizing this initial purchase cost, however, may require the purchaser to add costly modifications to the line after installation, creating higher operating costs, lengthy troubleshooting, and a delay to market entry. Principles and strategies are presented here that show how to avoid this mistake, and case studies are provided as learning tools.

Heat Seal Strength of Barrier Films Used in Vacuum Insulation Panels At Room Temperature and At -130{degrees}C

van Malsen, J., Tenpierik, M.J., Looman, R.H.J., Cauberg, J.J.M. — Fri, 28 Mar 2008 02:52:46 PDT

This paper describes experiments conducted in the framework of a research project aimed at finding suitable barrier films for vacuum insulation panels (VIPs), which are used for applications in the cooling industry (especially for ducts in liquified natural gas [LNG] installations) and in the building industry. It explores the heat seal strength of four makes of film used for this purpose. A secondary purpose was to investigate the influence of the heat seal parameters on the heat seal strength of the tested films. The heat seals were tested at room temperature and at -130°C, from which it readily became clear that the heat seal parameters can be chosen freely within certain limits.

Understanding Why Adhesion in Extrusion Coating Decreases With Diminishing Coating Thickness

Morris, B. A. — Fri, 28 Mar 2008 02:52:46 PDT

It is well known that in extrusion coating, the coating adhesion to the substrate decreases with decreasing thickness. The study on this phenomenon is divided into three parts. Part I explores the reduction in adhesion of LDPE to paper and other porous substrates. Several hypotheses are proposed for the origin of this decrease, including a reduction in oxidation time, faster cooling in the air gap, and more rapid quenching in the nip. A model of the molten polymer penetration into the substrate shows that the greatest effect is cooling in the nip; thinner coatings have less time to flow into the substrate interstices once the chill roll contact is made. The model results agree well with experimental adhesion data from the literature.

In Part II, adhesion to aluminum foil and other nonporous substrates is studied. Several hypotheses are proposed for why peel strength decreases in these structures, including a reduction in the air gap time, faster air gap cooling, more rapid nip quenching, and stress imposed during drawing. Modeling and experimental results show that cooling in the nip and imposed stress have the greatest impact.

In Part III, the peel test is analyzed to understand why the peel strength of better adhering adhesives are more sensitive to changes in coating thickness. The analysis shows that changes in the critical dimension of the deformation region at the peel front may be responsible.