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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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.
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.
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.
M.C. Bergeron, M. Iza, S. Woerly, S. Kaliaguine, M. Bousmina, May 1999
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).
Ivan Javni, Zoran S. Petrovic, Andrew Guo, Rachel Fuller, May 1999
A series of polyurethanes from polyols derived from soybean, corn, safflower, sunflower, peanut, olive, canola and castor oil were prepared and their thermal stability in air and nitrogen assessed by thermogravimetric analysis, FTIR and GC/MS. Oil based polyurethanes generally had better initial thermal stability in air than the polypropylene oxide based polyurethane, while the latter was better in nitrogen. If a higher conversion is taken as the criterion of stability then all oil based polyurethanes have better thermals stability both in air and in nitrogen.
Jonathan Lopez, Sang-Yoon Kang, Krishnamurthy Jayaraman, May 1999
The wall slip flow behavior has been determined for different blends of a polypropylene with an EP rubber. This is done by analyzing capillary flow data with several dies of different diameters. Mooney plots drawn from this data are strongly curved. This is attributed to viscous heating effects and to a more complex slip velocity relation for the blends. The relevant mass, momentum, and energy equations for flow of a power-law fluid through a capillary are solved numerically to incorporate the combined effects of slip and viscous heating, for fitting the capillary flow data.
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.
Wern-Shiarng Jou, Yu-Sheng Su, Jen-Taut Yeh, May 1999
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 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
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.
Byung Hak Lee, Shawn Swenson, Carlos Cadavid, May 1999
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.
Yanmei Li, Xiaodong Tang, John Miranda, Hung-Jue Sue, John Whitcomb, Walter Bradley, May 1999
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.
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.
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.
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.
Shamit Hakani, Sanjay Mehta, Philip Canale, Stephen McCarthy, May 1999
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.
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.
A. Hiltner, M. Parsons, E.V. Stepanov, E. Baer, May 1999
The correlation in mechanism and kinetics of slow crack growth between fatigue and creep of high density polyethylene was studied. The step-wise crack propagation mechanism characteristic of long-term failures in polyethylene was observed over all fatigue and creep loading conditions examined. Fatigue fracture kinetics allowed for extrapolation to the case of creep failure, which suggested that short-term fatigue testing can be used to predict long-term creep fracture properties. Under high stresses the presence of shear deformation retarded crack growth.
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.
Wei Huang, Robert T. Young, Donald G. Baird, May 1999
The invention of the phosphate glasses (P-glass) made the development of new polymer-glass composites possible. However, previous attempts to develop polypropylene/P-glass composites were unsuccessful. Only P-glasses with a very low Tg could be used because of the relatively low processing temperature of polypropylene. The applications of these materials were limited due to the poor durability of the glass. In this work, novel stabilizer systems for polypropylene were utilized to elevate the processing temperature so that a much more durable P-glass could be used. Comparison studies between P-glass and E-glass reinforced composite systems were also performed.
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Society of Plastics Engineers
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