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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Study on the Sorption and Desorption of N-Pentane in Polystyrene and Polypropylene
This paper studied the sorption/desorption of n-pentane in polystyrene and polypropylene using the sheet samples. The solubility of n-pentane in PS and PP was measured. And the concentration-dependent diffusivity of n-pentane in PS and PP was computationally modeled. Results exhibit that the simulated profiles match well with the experimental data while the penetrant concentration is above 30%.
Chemical Resistance at Different Stress Levels of Materials with Active Packaging Additives
Active packaging is widely used in the food and beverage industry to help ensure optimum food preservation. Currently, there are differing theories on the effects of active packaging additives on stressed induced plastic parts. This paper presents the results of a study that tests the chemical resistance of several different plastics under differing levels of stress when made with active packaging additives.
The Relationship between Shear Imbalance and Thickness
The effects of shear induced flow variation on the filling patterns of injection molds has been well documented in the recent past. Further understanding of their effects will allow engineers to use these effects to their advantage as opposed to attempting to eliminate their impact. This paper studies how shear induced flow variation is effected by thickness for several materials in a single cavity mold. The results and theories contained herein can be a valuable tool to both a design engineer laying out a new mold and a processing engineer producing parts using an existing mold.
Measurement of PP Melt Swelling Due to CO2 Dissolution
Understanding the thermophysical and thermodynamic properties of polymer/gas mixtures is critical for controlling cellular morphology. This paper describes measurements of pure polypropylene (PP) density and PP/CO2 volume swelling at elevated temperatures and pressures using a newly developed method. Also, measured volume swelling is compared with the swelling calculated from SL and SS EOS.
Impact of Foaming on Electrical Conductivity and Fiber Orientation of COC/Carbon Fiber Composites in Injection Molding
This paper investigates the impact of foaming on the electrical conductivity and fiber orientation of a carbon filled cyclic olefin copolymer in injection molding. Results show that foaming can lead to significant improvement of electrical conductivity in the out-of-plane direction. Due to the preferred in-plane fiber orientation during mold filling, the growth of a bubble adjacent to a carbon fiber would re-orient the fiber in the out-of-plane direction.
Pressure Drop Threshold for Nucleation of PS/CO2 Foaming
Two methods to predict the pressure drop threshold (?Pthreshold) to initiate bubble nucleation in polymer foaming processes are developed. One method uses the modified nucleation theory developed in our previous work, while the other utilizes computer simulations to model the growth profiles of the first observable bubbles in batch foaming experiments. Both approaches have shown good agreement in their ?Pthreshold predictions. Moreover, the effects of pressure drop rate, gas content, and temperature on ?Pthreshold are demonstrated.
A Six-Sigma Approach for Investment Plans in a Plastics Production Plant
It is possible to demonstrate that QFD (Quality Function Deployment) within a norm space permits to realize gap analysis and investment plans for a complex plastics production plant, using its process capability in the last Quality house.For the use of the same metric: DPMO, it is possible to compare man power, materials, maintenance, machinery, environment and methods. In these terms it is feasible to benchmarking the investment plans.
Failure Analysis of a Refrigerator Component Based on DOE" & Optimization Techniques"
There are many engineering situations where it is not necessary to analyze the whole domain of a physical model.In such instances, we demonstrate that it is possible to obtain an equivalent bilinear form using Lax-Milgram theorem with an orthogonal form applied to electrical appliance and turbomachinery, with a transfer matrix and variation principles.This transfer matrix solves a problem in shorter time than the Traditional DOE-FEA (design of Experiments) (Finite Element Analysis) Methods.
Weathering and Light Stabilization of Select Plastic Materials
In this paper we will examine various aspects of weatherability for several significant polymers. Light stabilization and polymer degradation mechanisms will be compared as well as strategies for imparting weatherability for these materials. Several UV aging studies will be included to illustrate stabilization techniques, and some comparative studies highlighting accelerated weathering vs. outdoor weathering will be discussed.
A Study of Integration of LIGA and MEDM Technology on the Micro Injection Molding of Ink Jet Printers' Nozzle Plates
A new approach is introduced to fabricate nozzle plates in this study. The micro mold was made by integration of LIGA and M-EDM technology to improve the accuracy. Micro injection molding was applied to produce the nozzle plates. There are sixty micro through-holes on each plate. The diameters of molded nozzle plates were 102±1 micro meters. The proposed manufacture procedures are believed to be more accurate and economical.
Analysis of Injection Molding to Fabricate Patterned Media with Nano Pillars
We examined a low cost technology for perpendicular magnetic patterned media that uses a metallic nanostamper and injection molding process. In this paper, we focused on the analysis of injection molding with passive heating, where the replication of 50 nm nanopillar arrays was successful. The effect of the thermal insulation layer on the replication quality was examined by analytical and experimental methods. Finally, the properties of magnetic layer deposited on the injection molded nanopillar array were analyzed.
Viscoelastic Behavior of Sulfonated Polystyrene Ionomers
Sulfonated polystyrene ionomers (alkali metal salts) with molecular weight below the entanglement molecular weight of polystyrene were prepared. The rheological behavior of the ionomers was characterized by dynamic and steady-state shear experiments. In general, the viscosity of the ionomers increased with sulfonation level and as the size of the cation decreased. Whereas, the starting polystyrenes were Newtonian fluids, the ionomers were non-Newtonian and viscoelastic.
Visco-Elastic Polyurethane Foams Creep Behavior and Recoverability Analysis
The creep behavior and mechanism of several visco-elastic foams were analyzed in this paper to understand the structure property relationship. The creep behavior and recoverability of these foams were characterized by the compression set, short time creep test, as well as hysteresis with an optical extensometer. The creep mechanism was analyzed and explained based on foam cell structure (cell orientation and uniformity) and material property. Material parameters and cell structure that possibly control the creep and recoverability of visco-elastic foams are also discussed.
On Formulation and Processing of Rigid Polyurethanes via Controlled Cure
A range of polyurethanes (PU) based on methylene diphenyl diisocyanate and polyether polyols varying in molecular mass, backbone structure and functionality are studied. Examination of the kinetic parameters of the PU reactions shows that the curing behavior and the hardness of such complex PU systems do not follow simple mixing rules. Scaling relationships to describe these complex dependencies and basic guidelines for formulation and processing are developed. Limitations of using the OHindex to predict the polyol reactivity are also discussed.
Validation of Injection Molding Simulation Results to Actual Molded Product
The flow patterns and injection pressures predicted using injection molding simulation software and actual flow patterns and injection pressures of the molded parts using a short study were compared and quantified. A method of validation was developed to compare the simulation results with actual molded parts and indicated that by using the correct combination of mesh type and certain process settings in the simulation software, an accurate prediction can be achieved with the simulation.
Flexural Creep Testing of Thermoplastic Composites
Flexural creep behavior of nylon 6/6 based long fiber thermoplastics (LFT) was determined using transient and dynamic testing methods. While the effect of increasing fiber volume fraction reduced creep, there was only a negligible effect of flow orientation effect. The creep data generated by dynamic mechanical analysis (DMA) tests was consistent with the transient tests.
PVC / Layered Silicate Nanocomposites: Preparation, Characterization, and Properties
Optically transparent nanocomposites were prepared via twin-screw extrusion of a medical-grade flexible PVC resin and an organically modified montmorillonite. Intercalation and orientation of the montmorillonite layers were observed via x-ray diffraction. A positive influence on barrier properties was noted, including a five-fold increase in oxygen barrier at minimal clay loading. Consistent with the literature, no significant changes in thermal stability in air were observed.
Preparation and Characterization of Polyester Thermoset Xerogels for Tissue Engineering Scaffolds
Porous polyester thermoset xerogels have been produced via sol-gel chemistry. The pore structure of these materials is tunable and can be altered independent of or in tandem with alterations in composition by adjusting solvent quality, solids content, and processing methodology. Cytocompatibility studies on selected xerogels imply effects of both pore size and materials chemistry, with fully aliphatic polyesters with large pore structures allowing for the growth of mammalian cells.
Modeling of Expansion of Extruded Filamentary Foam
This paper undertook a numerical study to characterize expansion of extruded polystyrene foam blown with CO2. The effects of processing parameters on foam expansion outside filamentary extrusion dies were examined. Efforts were made to optimize the processing parameters for the achievement of highly expanded foams.
Rigid PVC-Based Nanocomposites Produced through a Novel Melt-Blending Approach
Based on the fusion behaviors of PVC, the influence of compounding route of PVC/Montmorillonite nanocomposites, on their properties, including flexural, tensile, dispersion, and morphology was studied. The experimental results indicate that both the extent of property improvement and dispersion of nanaoparticles in PVC/Montmorillonite nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing.
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