The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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The Stiffness of Ionomers: How It Is Achieved and its Importance to Flexible Packaging Applications
The packaging industry uses ethylene ionomers for their unique balance of properties, such as high stiffness and low heat seal initiation temperature. These properties result from complex interactions between ionic and crystalline phases. We use studies of ionic strength, crystallization kinetics and thermal analysis to show how these phases form. This new understanding explains how stiffness develops in ionomers and its role in optimizing flexible packaging performance.
Barrier Needs: At the Core of an Innovative Package Development Process
WHY A PACKAGE???CONTAINMENT MARKETING PROTECTION
Computer Simulation of the Film Blowing Process Incorporating Crystallization & Viscoelastic Effects
A detailed two-dimensional simulation of the film blowing process is developed based on a mathematical model that incorporates the Phan-Thien Tanner (PTT) and Neo-Hookean constitutive equation with crystallization effects. The PTT constitutive equation is employed in the hot region, while the Neo-Hookean constitutive equation is used in the cold region to describe the rheological behaviour of the film. The model predicts bubble shape dimensions, temperature distribution, crystallinity, and orientation.
Effect of Polymer Processing Conditions on Shrinkability of LDPE and LLDPE Films, and on Optical Properties of LLDPE Films
The influence of the die gap (DG), the blow up ratio (BUR) and the frost line height (FLH) over shrinkability of LDPE and LLDPE films, and on the optical properties of LLDPE was evaluated using a 23 full factorial plan. For LDPE and LLDPE, shrink decreases in the extrusion direction and increases in the transverse direction when BUR increases. The die gap and the frost line height do not affect the shrinkability of LLDPE. Regarding LLDPE films optical properties, the haze decreases and the gloss increases when both, the FLH and the BUR, decrease.
A Novel Refractometric Study on the Bulk Polymerization of Methyl Methacrylate
On line refractive index measurement for the determination of conversion ratio in the course of PMMA bulk polymerization was developed using He-Ne laser beam with CCD camera. The Snell’s law was applied to interpret the refraction pattern in CCD camera to calculate the refractive index. It is shown that refractive indexes of MMA/PMMA mixtures vary linearly with conversion ratio in bulk polymerization. Mathematical correlation was developed to fit the experimental data.
In-Line Color Monitoring during Polyethylene Extrusion: Reflectance Spectra and Images
Two methods of monitoring the color of pigmented polyethylene during extrusion are being investigated. The first method utilizes a fiber-optic assisted charge-coupled-device (CCD) spectrometer to measure the color of the polymer melt. Highly precise L*a*b* values can be calculated from the reflectance spectra. The second method employs a CCD camera and RGB values are obtained for each pixel in the image of the extrudate. These RGB values track color changes but are sensitive to lighting.
A Dielectric Slit Die for In-Line Monitoring of Polymer Compounding
The dielectric slit die is a new in-line instrument that is designed as a multipurpose sensing device to measure dielectric, rheological, and optical properties during extrusion. The instrument is mounted at the exit of an extruder and consists of a slit with dimensions 2 mm high by 28 mm wide by 15 cm length along which are situated dielectric, pressure and optical sensors. A flexible design permits interchanging of sensor locations and the addition of new sensors.
Monitoring Polymer/Clay Nanocomposites Compounding Using a Dielectric Slit Die
A new in-line process monitoring instrument, a dielectric slit die, was used to examine the compounding of polymer/clay nanocomposites. The instrument is a multipurpose sensing device for measuring dielectric, rheological, and optical properties during extrusion compounding. We report results of compounding nylon 12 and polyethylene ethyl vinyl acetate copolymer with organo modified clays.
In-Line Measurement of Melt Density in Polymer Extrusion Using Shear Ultrasound Waves
Ultrasound shear waves propagating at a frequency of 2.25 MHz is used to measure the density of polymer melt in real-time during extrusion process. The acoustic impedance of the polymer melt is calculated using the measured reflection coefficient of the ultrasound waves off the polymer melt interface. The ultrasound measurement is independent of the attenuation in the polymer melt, which makes this technique highly desirable for heavily loaded polymers and large extrusion dies.
Warpage Index Based on Cooling and Orientational Effects
Sensitivity of different plastic materials to warpage is a common problem for mold designers. Developing a scaled index to allow for better design depending on the material selection would be beneficial to the plastics industry. This study focuses on warpage caused by non-uniform cooling and flow induced stresses on a diverse selection of thermoplastic materials. The effects of fillers and thicknesses will give a broadened range of warpage sensitivity. The index will create a simplified method of material selection and mold design for optimal products.
Ultra High Shear Rates and Their Effect on the Physical and Melt Properties of an Injection Molded Parts
The purpose of this experiment is to determine how ultrahigh shear rates affect the physical and melt properties of polystyrene and polypropylene injection molded parts. Three different runner inserts will be utilized to accomplish this. These three inserts vary the duration and overall shear rate undergone by plastic during the injection process. Data will be collected from tensile and melt flow tests to determine the effects of ultra high shear rates and shear times on the injection molded parts.
Design and Material Issues Affecting Jetting during Injection Molding
This paper presents a study that evaluates the effect of gate and runner designs on jetting, which develops during injection molding. Additionally, the study looks at the sensitivity of various materials to jetting and the material characteristics that affect their tendency to jet. This data is compiled in a table where the materials are ranked on a scale of jettability that will allow mold designers and CAE analysts to use as a frame of reference. Jettability will be more predictable, and many processing problems will be avoided through this research.
A Proplyene Glycol Alternative for Mold Cooling
Cooling of an extrusion blow molded part is important in production of blow-molded parts. The ability to cool faster and more uniformly will create faster cycle times and better overall part quality. This experiment is intended to establish the benefits of using an aqueous solution of organic salt combined with a special corrosion inhibitor instead of propylene glycol. Using a modified mold of a 0,943 liter bottle, temperature readings were taken from the mold. The data collected from the mold was compared to the water and propylene glycol.
Copolymerizations of Water and Oil Soluble Monomers in Lyotropic Liquid Crystals
Homopolymer and copolymer hydrogels have been synthesized via the photopolymerization of water-soluble and oilsoluble monomers in Pluronic Lyotropic Liquid Crystals. In particular, the polymerization kinetics, and physical properties have been examined. Results show that higher polymerization rates occur in the inverse phases for the water-soluble monomer and in normal phases for the oil-soluble monomer. Polymer nanostructure and copolymer content play a vital role in the compressive modulus of the polymer hydrogels.
The Effect of Dose Rate on the Morphology of Gamma Irradiated Ultra High Molecular Weight Polyethylene (UHMWPE)
The wear properties of the UHMWPE are known to improve with increasing gamma irradiation integral dose, but very few studies have been done on the effect of dose rates. This study uses a dose of 75 kGy at 0.25 kGy hr-1 and 2.9 kGy hr-1. The degree of crystallinity and modulus are larger for the low dose rate. Cross-link appears to be associated with low dose rates and chain-scission at high dose rates.
Soak and Dope: Diffusion of Dyes into Polymers via Organic Solvents
Polymer swelling and disentanglement created using organic solvents can be used to diffuse fluorescent organic dyes into a polymer matrix. We report on our characterization of this process of submerging polymer plates and films into a bath of solvent with dissolved dye, aptly named: soak and dope. Optical clarity, penetrationlayer thickness, and dye concentration were measured versus soak time. Dye concentrations of up to 9x10-5 mol/cm3 were obtained with penetration-layer thickness ranging between 5 ?m to 800 ?m.
Effects of Fiber Orientation on Dielectric Strength
This paper explores the role fiber orientation of a reinforced plastic material plays in relation to a material’s dielectric properties. This study focuses on dielectric strength of glass-reinforced Polypropylene. This information will allow designers to realize the relative effect the orientation of fibers has on the dielectric properties of their choice material. The results will also aid in design of more robust electrical components.
Development of Monitoring Software for an Extrusion Process
This paper discusses the development of monitoring software to be used in a data acquisition system for a Killion KTS-100 extruder. Central to this computer-based system is LabVIEW software that is particularly good for data acquisition, analysis and data visualisation. Using LabVIEW, a graphical user interface was designed to facilitate the various operational requirements of the process. From here, the operator can set and observe the states of the many inputs and outputs of the system. The potential for such software to be developed to encompass additional functions will also be described.
Numerical Simulation of Two-Layer Film Coextrusion of Polymer Melts
Numerical simulation of fluid flow is a faster and efficient way to improve process design. Polyflow, a commercially available simulation package, was used to simulate two-layer film coextrusion of polymer melts through a slit die. Simulation results for isothermal and non-isothermal flow of generalized Newtonian fluids are discussed, especially the interface predictions, extrudate shapes, and temperature profiles.
Quo Vadis Injection Molding?
At the moment there exist more than 100 procedures for making products from plastics, rubbers, ceramics, metals, or from the combinations of these matters or materials which can be denoted as injection molding (die casting). Where is going the development of this most important cyclic procedure of making parts with defined three-dimensions? The answer to this question is based on the analysis of the functions of this procedure and systematization of injection molding by different criteria as well as the fractal history of general technology and is, only by innovative means.
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