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.
Joining and adhesive properties of polymeric composites are of critical importance for emerging applications in the aeronautical, aerospace and marine industries. Traditional macroscopic adhesion testing techniques evaluate macroscopic properties of materials, with limited information on the molecular level processes that control actual performance. Nanomechanical and nanotack evaluations utilizing advanced nanoprobe techniques of polymer/fiber composites reveal differences in performance at the molecular level.
Highly filled polymeric materials exhibit complex rheological properties. In this study the rheological characteristics of highly filled suspension based on ethylene octane copolymer binder and Dechlorane filler were studied. Steady shear and thixotropic behaviors are discussed.
Thermal residual stresses, internal fuel pressure and acceleration stresses during launch stage were evaluated and quantified for cryogenic composite fuel tank design. Fuel leakage induced temperature variation through laminate thickness after initial cracking was applied to a progressive failure analysis. Comparison of the results with conventional failure analyses was performed. Critical temperature and pressure conditions for failure initiation and whole laminate cracking were found based on the failure analysis.
The luminance of an injection molded V-groove light-guide plate (LGP) was found to be affected by the depth of melt filling of the grooves. Imperfections in filling are influenced by local pressure and temperature histories. The measurements of the depth of melt filling were carried out at different locations using two optical grade polycarbonate (PC) moldings obtained at various processing conditions.
The outermost surfaces of plants are covered by a cuticular membrane which modulates the interactions of the plant with its environment and provides a protective barrier to pathogens. As this interface is a composed primarily of a biopolymer, physical methodologies for their study of polymer mechanical behavior and chemical make-up can provide molecular level details of these systems. In this paper we will briefly describe so important questions in plant biology and the methodologies needed to address these problems which can be found in polymer and physical chemistry.
Sulfonated poly (arylene ether sulfone) copolymer has been shown to be a promising material for proton exchange membranes for fuel cell via a lab-scale batch solution casting followed by a mild radiation drying. The effects of the conditions of intense forced convection air on the morphology and performance of this copolymer film have been investigated for industrial production.
A mathematical model and computer simulation describing the constant heat sealing process for linear, semi-crystalline polymer films has been applied to heat sealing process optimization. Among the applications explored are the identification of a sealant resin melt index range that ensures maximum heat strength achievement for a prescribed dwell time, the development of sealing conditions for controlled frangibility seals, and heat sealing equipment specification and selection.
A continuous solution film casting process was studied for manufacturing novel polymer membranes for PEM fuel cells. A lab reverse roll casting machine was built and used to cast membranes with typical thickness of 25 micron to 50 micron. Investigation was made to establish the casting and drying conditions to produce voids-free, uniform membranes with desired thickness. The proton conductivity, mechanical properties and morphology of the membranes were evaluated.
Direct numerical simulations are conducted in two dimensions to compute the permeability of membranes filled with aligned flakes. The effects of flake aspect ratio, volume fraction, spatial distribution and size dispersion are examined. Lots of simulations have been carried out using a fast multipole-accelerated boundary element method, and the results are compared to some of the existing models.
Aluminum and thermoplastic elastomer (TPE) hybrids are prepared by insert injection molding. No pre-heating or macroscopical mechanical bonding are needed. The key step is an appropriate etching of the aluminum surface giving a porous surface for melt penetration. In this work, the effect of injection molding parameters on bond strength is studied using Taguchi optimization. Mechanical strength is determined by peel test. Also, the effect of insert/TPE thickness ratio is studied.
Pulse cooling is a method where mold temperatures are monitored, and cold water is introduced to control the steel temperature. A variation of this technique delivers water immediately after mold closing for variable pulse times. Using this approach, better distribution of surface temperature on injection molded parts may be achieved compared to traditional cooling with a thermolator. Thermocouples and a thermal camera were used to evaluate mold and part surface temperatures respectively.
A process study of vacuum metallizer was performed and the results in terms of optical density uniformity, metal adhesion and barrier uniformity were studied. 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.
This paper investigates the foaming behavior of wood fiber/HDPE composites with small amounts of nano-clay. The nano-clay dispersion was characterized by XRD and TEM. An extrusion foaming experiment blown with N2 was conducted. The cell nucleation and growth of composite foams were studied with varying processing parameters, such as temperature, pressure and clay content. The effect of nano-clay on the final cell morphologies and foam density of wood fiber/clay/HDPE nanocomposite foams were identified.
Using dynamic mechanical analyzers the relaxation behavior of a loosely cross-linked model epoxy resin was investigated before and after room temperature aging. Preliminary results indicate a stiffening of the storage moduli occurs below –50 °C, the ? relaxation temperature of the epoxy network, with a subsequent softening of the network above room temperature and a drop in the apparent glass transition temperature (Tg ). of the material with aging.
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%.
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 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.
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.
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.
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.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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