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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Simulation and Experimental Studies of a Non-Return Valve Performance during Injection Molding
This paper presents the results of the simulation of the dynamic behavior of a non-return valve during the recovery and injection stage of the injection molding cycle. A generalized Newtonian fluid model is used to simulate the flow with FLUENT software. The results of the analysis determine pressure drop, time taken for the valve to open during the recovery stage and time taken for the valve to close during the injection stage. The simulation results are compared with experimental data for three different thermoplastics including HDPE, PC and Nylon-66. Experimental data is obtained for several injection molding runs with pressure transducers installed in the barrel. In addition, the forces that occur on the ring during each molding stage and the relative rotational speeds between the valve and ring during the recovery stage were calculated.
A Practical Approach to Polymer Rheology for Quality Control
Rheological data obtained under the conditions of temperature and shear existing in conversion processes are required for the prediction of the performance of polymer resins in those processes. The capillary rheometer simulates the conditions seen in conversion processes and can be used to produce pertinent data. The ± 3 ? variation of the viscosity verses shear rate curves (over the range of shear rates seen in a process) for a resin or compound, can be used as a tool for monitoring consistency and predicting processability. When the measured viscosities for a material fall within the tube" formed by the upper and lower limits of the variation the product is consistent. If not the way the curve moves out of the "tube" will provide information on the root causes of the product variation. This talk discusses the application of the "tube" concept to a range of filled and unfilled resins using an automated capillary rheometer system that makes the "tube" concept practical for application in quality assurance and process control."
A Practical Approach to Polymer Rheology for Quality Control
Rheological data obtained under the conditions of temperature and shear existing in conversion processes are required for the prediction of the performance of polymer resins in those processes. The capillary rheometer simulates the conditions seen in conversion processes and can be used to produce pertinent data. The ± 3 ? variation of the viscosity verses shear rate curves (over the range of shear rates seen in a process) for a resin or compound, can be used as a tool for monitoring consistency and predicting processability. When the measured viscosities for a material fall within the tube" formed by the upper and lower limits of the variation the product is consistent. If not the way the curve moves out of the "tube" will provide information on the root causes of the product variation. This talk discusses the application of the "tube" concept to a range of filled and unfilled resinsusing an automated capillary rheometer system that makes the "tube" concept practical for application in quality assurance and process control."
Blends of Ethylene/Styrene Interpolymers and Other Polymers: Benefits in Applications
Ethylene Styrene Interpolymers (ESI) exhibit compatibility with a wide range of polymers due to their inherent combination of olefinic and styrenic functionality. In particular, blends of ESI with atactic polystyrene, and polyolefins including polypropylene, have been found to offer interesting and unique combinations of performance properties. Fundamental blend morphology, structure/property relationships, and processability of ESI blends are discussed. Examples and benefits of such blends in applications such as molded articles, films, and foams are discussed.
Effect of Kneading Block Tip Clearance on Performance of Co-Rotating Twin-Screw Extruders
Over the years the design of the co-rotating intermeshing twin-screw extruder has evolved to meet the processor's never ending need for improved performance and processing efficiency. The most significant change in recent years has been the introduction of the high speed high torque machines. These high speed extruders, while producing increased throughput and reduced average residence time, also generate significantly higher shear rates and exit melt temperatures. This paper examined the effect of kneading block tip clearance on machine performance as a function of screw speed and specific rate. Machine performance will be defined in terms of power consumption, extrudate melt temperature, residence time distribution, melt index, and mix quality.
Modification of Cement Using Post Industrial Recycled Acrylonitril Butadiene Styrene (ABS) Latex Powder
Polymer latex modification of cement has increased the ductility of the resultant concrete. However, practical application of the concrete is limited since latex is used in a liquid form. In contrast, we have examined use of post industrial Recycled Acrylonitrile Butadiene Styrene powder (r-ABS). Pullout tests indicate an increase in adhesive bond strength between the polymer-modified mortar and steel re-bar. Thermogravimetric analysis is carried out to examine the influence of the latex on the kinetics of degradation. The results indicate a novel approach of using r-ABS in cement modification.
Thermal Aging Effects on Transport Properties of Polymeric Membranes for Fuel Cell Applications
Although solid polymer electrolyte fuel cells have been considered as environmentally attractive power sources, to date little work has been done on the durability of eletrolyte membranes. It is conceivable that time and prolonged exposure of membranes to elevated temperatures will significantly diminish the effectiveness of electrolyte cells. The goal of this study is to investigate and compare thermal aging and morphology effects on transport properties, such as ion diffusion coefficients and permeability parameters of the membranes for hydrogen ion transfer, of commercially available Nafion® and Dias® membranes and experimental phosphorus containing polyimide membranes. The emphasis of this paper is placed on the design and properties of a diffusion cell necessary for hydrogen ion measurements.
Thermoporometric Characterization of PHPMA Hydrogels
Differential Scanning Calorimetry (DSC) has been used to determine the pore size and pore size distribution of a surgical poly(N-2-hydroxypropyl) methacrylamide (PHPMA) hydrogel. The dry PHPMA (xerogel) was swollen in H2O and the pores size of the gel was determined from the solidification thermogram of H2O obtained at very slow cooling rate. The shift in the solidification equilibrium temperature of a known condensate held inside a porous material is pore size-dependent and enables the deduction of pore radii distribution of the material. The results obtained from this technique were compared with those obtained by B.E.T (Brunauer, Emmett and Teller).
Benefits of High Speed Machining Technology to Plastic Injection Mold Builders
This paper will show significant time and cost savings to plastic injection mold builders by using high speed machining (HSM) technologies. It addresses overall productivity and production process improvement in the manufacture of sophisticated three dimensional core and cavity mold components using hardened steel machining processes compared to conventional mold production processes. A case study will compare the HSM process to conventional processes in the production of a complex mold cavity. The case study results will demonstrate real benefits of HSM to reduce overall manufacturing operations, man hours, capital resources and delivery time.
The Effects of PE/PA/PVA Blends' Compositions upon the Barrier Properties of Blow-Molded Containers
This research investigates how compositions of PE/PA/PVA (Polyethylene/Polyamide/ Polyvinylalcohol) blends influence the barrier properties of blow-molded containers for methanol/gasoline fuel. The objectives of this research is to improve the barrier properties of PE/MPAPVA blend for methanol /gasoline fuel. We found that the content of PVA and CP (Compatibilizer Precusor) affect methanol/gasoline fuel permeation rate. Furthermore, the compositions of MPAPVA exhibit a significant influence on the barrier properties of blow-molded PE/MPAPVA containers. The composition of PE/MPAPVA blends for the best permeation resistance is 20% of CP blended with MPAPVA. This formula exhibits the best barrier properties for methanol/Gasoline fuel with weight lost less than 1g/24Hr.
The Kinetics of Shear-Induced Crystallizatio in Poly(Ethylene Terephthalate)
The kinetics of shear-induced crystallization in PET was studied. The shear-treated samples were obtained from controlled shear rate apparatus (CSR, Fig. 1) and the capillary viscometer. The samples of use were observed the differences of crystallization behavior by DSC. The kinetic model suggested by Hoffman-Lauritzen, Nakamura were used to analyze experimental results. The crystallization behavior of shear-treated samples depended also on temperature and shear stress. On the lower shear rate region, the rate of crystallization depended on shear stress. And the growth rate induced by fluid flow reached the critical point on the region of a certain high shear rate. The empirical data were simulated by the suggested model
Processing Characteristics of PSU/PC Blend Associated with Degradation in Injection Molding
This study investigates the effect of degradation of the PSU/PC blend on quality characteristics of the molded parts. Experiments were conducted at two sets of melt temperatures - 'normal' temperature, where no severe degradation is expected (T-zone 1); and 'elevated' temperature, where significant degradation should occur (T-zone 2). ASTM D638 tensile bars were used for molding and measured for quality parameters of part weight, warpage, and tensile strength. Small fluctuations in the process variables were purposely introduced for T-zone 1 and T-zone 2. As the results, T-zone 1 provided more consistent shot-to-shot part properties and less process disturbances for all the parameters than T-zone 2. The subsequent baking of the molded parts rendered most of the parts excessively warped for T-zone 2. Back pressure was an important variable regarding shot-to-shot variations in all the parameters.
Correlation Study for Minimizing Shrinkage of PFA Molded Parts
This study deals with investigating the relationship between part weight and shrinkage of PFA molded parts against process variations. The extensive experiments were conducted using DOE techniques in the ranges of process variables. Resulting part weight is also compared to the predictions. This study extends further to determine the influences of varying hold time and back pressure, respectively, on part weight and shrinkage. An optimum hold time is obtained comparatively from the results of the experiment, prediction, and theoretical formula. As the results, there existed good correlation between part weight and shrinkage, and between actual part weight and predictions against process variations. As the hold time varied, both the experiment and the predictions of the part weight matched well in trend, and indicated a distinctive gate freezing time.
Study of Moisture Diffusion Behavior in Hybrid IM7/BMI Composites
Moisture diffusion behavior in IM7 carbon fiber-reinforced bismaleimide composites (IM7/BMI) is investigated under two different temperatures at 100% relative humidity. Three-ply uni-weave, crossply-weave and hybrid of uni-weave and crossply-weave composites are utilized for the present study. Diffusion behaviors in those IM7/BMI composites are found to be significantly influenced by laminate architecture. A finite element model based on Fick's second law is used to predict the moisture diffusion behavior in hybrid composites. It is found that both the neat resin and composites follow the Fickian diffusion behavior only at short times. At longer times, moisture diffusion begins to deviate from Fickian behavior and suggests that addition moisture absorption mechanisms take place.
A Study on the Cure of the Siloxane-Modified Epoxy Resins
Siloxane-modified epoxy resins were studied in this research. The modified epoxy resins were cured with 3 mol% of 2-ethyl-4-methyl imidazole (EMI-24). The curing kinetics and the physical properties of the network were characterized using DSC and FTIR methods. The thermal stabilities of epoxy resins were obtained through TGA measurement. The fracture toughness was measured through double torsion tests. The fracture analysis shows that the siloxane-modified epoxy resin has a higher fracture toughness (by 140%) and rougher fracture surface than the unmodified epoxy. The modified resins also show better thermal stabilities and longer pot lifes than unmodified resins. The cure of siloxane-modified epoxy resin followed the first-order reaction kinetics. The glass transition temperatures of modified epoxy resins were obtained.
Phase Structure Characterization and Processing-Structure-Property Relationships in Linear Low-Density Polyethylene Blown Films
Linear low-density polyethylene (LLDPE) blown films fabricated under two different processing conditions were investigated. Morphological characterization was performed using solid-state nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and infra-red (IR) dichroism. It is found that the stalk height of the film blowing process has a strong effect on the mechanical properties of LLDPE blown films. Good correlation between mechanical properties and morphological features is found.
Mechanical Properties and Dispersion Behavior of Composite Materials Compounded with Surface Treated Titanium Dioxides
The mechanical properties of polycarbonate compounded with titanium dioxide are investigated. Titanium dioxide treated with methyl polysiloxane on alumina silica coating is compounded in the matrix polymer using twin screw extruder. Izod impact strength of this composite material is higher than that of the composite material compounded with untreated titanium dioxide. The dispersibility of this treated filler are evaluated by fracture surface and turbidity of the solution of the composite materials. The results suggest that the composite material compounded with titanium dioxide which is treated with methyl polysiloxane and alumina silica at the same time has higher dispersibility. And the melt viscosity of composite material shows same behavior with neat polycarbonate. This suggest that the melt viscosity is affected by the dispersibility of particles.
Evaluation of Oxidative Stability of Flexible Polyolefins by Oxidative Induction Testing with ?-Oryzanol and ?-Tocopherol Antioxidants
Polyolefins are used in food and medical applications, among many reasons, because of their history of biocompatibility. However, these materials are prone to oxidative degradation in the presence of heat, light or other energy sources and molecular oxygen (autoxidation). Thus antioxidants are added to stabilize polyolefins. Flexible polyolefins (FPO) were compounded with the biological antioxidants ?-oryzanol and ?-tocopherol for this study. The antioxidants were then tested by Oxidative Induction Test (OIT) for effectiveness to stabilize FPO. The results showed a marked increase in oxidative stability of FPO with ?-tocopherol, while ?-oryzanol showed results that merit further research.
Applications of DSC in Conjection with FTIR in Plastic Identification
Accurate material information can help with failure analysis, reengineering, competitive analysis, and quality control. One of the most common and quick techniques used in plastic analysis is Fourier Transform Infrared (FTIR) microspectroscopy. However, FTIR has difficulties in accurately identifying filled polymers, blends, and polymer families such as polyamides and polyesters. This paper will present a few cases when the FTIR technique alone was very difficult to identify an unknown plastic, an alternative simple technique Differential Scanning Calorimetry (DSC) was used to assist in determining the unknown by obtaining information on physical properties such as melting and/or glass transition temperatures.
Optical Studies of Sheared Polymer Droplets
The use of shear flow to emulsify immiscible polymers is ubiquitous in the processing of polymer blends. Although the pioneering work of Taylor [1-4] on isolated Newtonian droplets remains at the foundation of our understanding, emulsions of viscoelastic fluids can display a variety of interesting and novel phenomena under shear [5-9]. Here, video microscopy is used to measure the shear response of dilute polymeric emulsions. At low shear rates, the behavior is in agreement with the Taylor picture. In the limit of strong shear, we observe a transition in which the droplets elongate along the vorticity axis. A simple model is offered that relates this behavior to the viscoelastic nature of the melt components.
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