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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PVT BEHAVIOR OF POLYSTYRENE IN PRESENCE OF CO2+N2 BLENDS
PVT behavior of polymer/gas mixture is very important for foaming. The PVT behavior of polystyrene (PS) in presence of carbon dioxide (CO2), nitrogen (N2) and their blends were determined using a laboratory developed PVT apparatus at various temperatures and pressures. It was found that in case of CO2, swelling of PS increased with increase in pressure and decreased with decrease in temperature. However, in case of N2, swelling increased linearly with both temperature and pressure. For CO2+N2 blend system, only the overall swelling of blend in polymer was measured and it increased linearly with pressure and decreased with temperature.
INVESTIGATION OF DIFFERING APPROACHES TO DETERMINE AN OPTIMUM INJECTION VELOCITY DURING MOLD FILLING
Injection fill rate may be the most important processing variable in the injection molding of plastic components. A comparative study was conducted to contrast Scientific Molding and computer simulation for determining optimum injection velocity. One method is based on the behavior of pseudo-plastic non-Newtonian fluids and the other on the predicted results of inputs for process settings by simulation software. Once optimum fill rates were determined they were evaluated against each methods standard to determine if one method is more advantageous than the other. Results suggest Scientific methods are more reliable.
DSC-RAMAN FOR POLYMER CHARACTERIZATION
Both Differential Scanning Calorimeter (DSC) and Raman Spectroscopy are well known techniques for the characterization of polymeric materials. DSC is widely used to investigate phase changes of materials as their temperature is changed, or isothermally. Vibrational spectroscopy can provide complementary information, giving insight at molecular level into the changes accompanying thermal events or reactions. Combining both techniques allows a greater depth of understanding of the changes in materials. Here polymer examples are given to illustrate the potential applications of this technology to polymeric material.
FIBER GLASS REINFORCED COMPOUNDS BASED ON HIGH FLOW POLYCARBONATE COPOLYMERS
Short fiber glass-filled LEXAN* resin High Flow Ductile (HFD) polycarbonate copolymer materials are characterized by higher melt flow compared to their equivalent glass-filled standard polycarbonate samples. The glass-filled HFD compounds show 11-18?øC lower HDT compared to the standard polycarbonate products, but have similar impact, mechanical, and dimensional stability properties. The HFD materials allow for longer injection molding flow lengths and thinner wall parts. In addition, the glass-filled HFD copolymer samples show improved surface gloss in injection molded plaques. In general, increasing the melt temperature, mold temperature, and injection speeds during molding results in increased surface gloss and improved aesthetic appearance.
DEVELOPMENT OF POLYETHER BLOCK AMIDE FOAMS
This study investigated the solid-state batch foaming of Polyether block amide (PEBA) using sub-critical CO2 as the blowing agent. Three different kinds of PEBA polymers and their blends were applied here. The viscosities of the resin were gauged as the foundation of the foaming. The results indicated that there existed an optimal temperature window in the batch foaming process and an optimal portfolio of foaming parameters for the different PEBA resins. Certain elastomer blends show a wider foaming temperature window, and have a higher cell nucleation density. Furthermore, it is beneficial to introduce foam structure for the dielectric applications.
NEW POLYPROPYLENE/TRITICALE COMPOSITES: RELATIONSHIP BETWEEN FORMULATION AND PROPERTIES
This paper discusses the relationship between formulation and properties of polypropylene/triticale straw composites. The composites were prepared by twin-screw extrusion process followed by injection molding with different triticale content from 10 to 40 vol% in the PP matrix in the presence of 3.75 vol% of maleic anhydride grafted polypropylene (PP-g-MA) as coupling agent. Composites with CaO as reactive agent were also prepared. The results demonstrate that triticale fibers are a good reinforcement with a great potential in thermoplastic composites field if the processing procedure and formulation are appropriate.
FUNCTIONALIZED POLYETHYLENE AS PI COUPLING AGENT FOR BETTER DISPERSION OF EXFOLIATED GRAPHENE NANOPLATELETS IN HIGH DENSITY POLYETHYLENE MATRIX
Previous work shows exfoliated graphene nanoplatelets (GNP) do not disperse well within high density polyethylene (HDPE) matrix which results in poor enhancement of conductive and mechanical properties. To improve the dispersion of GNP in HDPE, functionalized polyethylene (PE-g-Py) which is capable of electron interaction with the basal plane of GNP has been synthesized as the pi coupling agent. Mechanical, electrical and morphological characterization of HDPE/GNP nanocomposites in the presence of PE-g-Py have demonstrated the efficiency of this pi coupling agent to promote the dispersion of GNP which leads to considerably improved mechanical property and significantly reduced electrical percolation threshold.
DEVELOPMENT AND CHARACTERIZATION OF ENVIRONMENTAL FRIENDLY OPEN-CELL ACOUSTIC FOAMS
Although polymeric open-cell foams provide adequate absorption at medium and high frequencies, they are, as the majority of absorbing materials, inefficient in the low frequency range. Through this study, open-cell polymeric foams were fabricated from Polypropylene (PP) and Polylactide (PLA) by a novel fabrication method combining particulate leaching technique and compression molding. Fabricated foams were compared with a sample of Polyurethane (PU) foam. The materials used in this study are either recyclable or biodegradable which is of great importance considering huge amount of foams used as acoustic absorbers in various industries
FABRICATION AND THERMO-MECHANICAL CHARACTERIZATION OF Fe-Ni NANOPARTICLES /NYLON 6 COMPOSITES
The focus of this study was to develop Fe40Ni60/Nylon 6 nanocomposites and investigate their mechanical and thermal characteristics in order to provide a new polymer nanocomposite for engineering applications. Nanocrystalline Fe40Ni60 nanoparticles were chemically synthesized. Chemical composition, crystallite and particle sizes were determined. Fe40Ni60/Nylon 6 nanocomposites were prepared in a two step process: First the nanoparticles were mixed with Nylon 6 pellets either manually or using the solution mixing technique. Then the composites were fabricated through extrusion and injection molding. Results indicated that the manually mixed 3 wt% nanocomposite has higher storage modulus but lower impact strength than pure Nylon.
ACOUSTIC BEHAVIOR OF PERFORATED EXPANDED POLYPROPYLENE FOAM
This study shows the acoustic behavior of perforated closed cell expanded polypropylene (EPP) bead foam structures to develop new application for EPP as an acoustic material. The closed cell EPP foam structure was perforated using mechanical perforation technique by drilling holes to make it open-celled foam. The perforated EPP foam was characterized for sound absorption. It is optimized by the selecting proper perforation ratio, which is governed by pore size and spacing between the adjacent two pores. The results obtained shows that EPP is a potential material for sound absorption application.
IMPROVEMENT OF THE STABILITY OF POLYMER BONDED RARE-EARTH-MAGNETS DURING THE INJECTION MOLDING PROCESS
Polymer Bonded Magnets can be cost effectively produced by injection molding of polymers with magnetic fillers. Rare-Earth-fillers (RE) like NdFeB or SmCo in comparison with other permanent magnetic fillers have remarkably higher magnetic properties. Nevertheless they are very reactive and oxygen susceptible which leads to polymer degradation and filler oxidation during the processing. This paper deals with two different methods of resolution to improve the thermal and thermo-oxidative stability of rare earth filled polymers during processing: powder coating and processing under inert atmosphere.
STRAIN LOCALIZATION AND RATE SENSITIVITY OF GLASSY POLYMERS UNDER SHEAR DEFORMATION
Shear deformation is used to investigate strain localization and rate sensitivity in glassy polymers using novel experimental techniques. The dynamic mechanical analysis of a series of acrylate-based polymers is used to relate molecular architecture to observed deformation trends. Narrow distributions of relaxation times associated with the beta relaxation correlate with higher levels of strain relaxation. The proximity of the test temperature to the temperature of the beta relaxation appears to strongly affect the rate sensitivity in PMMA. Physical aging is also shown to increase localization at low strain rates.
THE EFFECT OF TESTING PARAMETERS ON THE FUNCTIONAL IMPACT RESISTANCE OF UPVC COMMERCIAL PRODUCTS
The testing of plastics has become decidedly different and as technology improves, it is necessary to evaluate the accuracy of results based on testing methods, particularly when functional durability is critical. The research discussed in this paper focuses on the effect of changing test parameters in relation to the falling dart impact test, more commonly referred to as the Gardner impact test (ASTM D5420). The drop weight protocol accommodates real geometries and reflects environmental conditions including temperature and percent relative humidity, as well as end-use impacting speeds but is affected by tup weight, probe diameter, and support ring.
PRELIMINARY RESULTS FOR INJECTION MOLDED SHORT GLASS FIBER THERMOPLASTIC COMPOSITES WITH A CIRCULAR FRONT
A two dimensional axisymmetric simulation for predicting the flow-induced orientation of glass fibers in injection molded composite parts is presented. The mass and momentum balance equations are discretized using Galerkin finite element method and the constitutive equation for fiber orientation is discretized using discontinuous Galerkin finite element method. Material parameters used in the model are determined using rheology and experimental fiber orientation is used for initial conditions. Simulation results are in close agreement with the trend seen in experimental data with still need for improving the simulation to capture the orientation in regions close to frontal flow and the walls.
MODELING ELASTOMERIC AND THERMOSET FOAMS: KINETICS, HEAT AND NUCLEATION
The curing reaction of an aliphatic epoxy resin and EPDM rubber is modeled from differential scanning calorimetry, generalizing a methodology proposed by Hernandez-Ortiz and Osswald. The kinetics is represented by Kamal-Sourour model with and without diffusion reaction control and was extracted using a non-linear regression method coupled with the heat and mass balance equations. The kinetic fitting methodology uses dynamic and isothermal differential scanning calorimetries allowing the differentiation of high and small peaks during the curing and diffusion reaction control regimens.
APPLICATION OF THE METHOD OF ELLIPSES FOR DETERMINING FIBER ORIENTATION IN LONG FIBER COMPOSITES
Fiber orientation within long glass fiber polypropylene composites in center-gated injection molded discs was determined at various percentages of flow. The results were compared directly to short fiber results for the same geometry. In addition, end-gated plaques were molded using the same short and long fiber materials for additional comparison. Results suggest that an area of high radial flow occurs for long fibers at low fill percentages during the filling process for end-gated plaques. Due to the increased length, long fibers have a large increase in flexibility and curvature within the injection molded system, complicating flow and prediction of orientation.
pH AND TIME DEPENDENT HYDROLYTIC DEGRADATION OF BIOPLASTICS FROM RENEWABLE MONOMERS
Two renewable copolymers, poly(trimethylene malonate) (PTM) and poly(trimethylene itaconate) (PTI), have been produced with ester bonds incorporated into the polymer backbone to facilitate hydrolytic and/or enzymatic degradation. A hydrolytic degradation study of these renewable polymers in aqueous solutions adjusted to pH values is described. Final weight loss varied from 20 to 37 wt% for PTM and from 7 to 21 wt% for PTI as a function of aging time and initial solution pH. Degraded samples were characterized by FTIR, GPC, DSC, and TGA. PTI showed a slower degradation rate than PTM.
COMBINATIONAL EFFECTS OF MECHANICAL VIBRATION AND SHEAR ON THE CELL MORPHOLOGY OF MICROCELLULAR POLYMETHYL METHACRYLATE
In this paper, a novel electromagnetic dynamic foaming simulator was designed to investigate the combinational effects of shear and vibration on the morphology of microcellular polymethyl metacrylate (PMMA) samples by using supercritical carbon dioxide (ScCO2) as a blowing agent. Mechanical vibration induced by electromagnetic field was introduced into the foam process. Furthermore, in order to strengthen the shear effect, the rotor of the special designed simulator was machined to be whorled. It was shown that at a certain amplitude and frequency of vibration, the cell diameter of samples decreased and cell density increased.
DYNAMIC MECHANICAL PROPERTIES OF NOVEL POLYIMIDE/SUBTITUTED POLYANILINE-COPOLYMER-CLAY NANOCOMPOSITE FILMS
Novel polyimide/poly(N-ethyl-aniline-co-aniline-2-sulfonic acid-clay(SPNEAC-PI) nanocomposite films containing water soluble poly(N-ethyl-aniline-co-aniline-2-sulfonic acid-modified-clay (SPNEAC) have been successfully synthesized. The Dynamic Mechanical Spectrometry (DMS) results show decreasing Tg of the nanocomposite films with increasing SPNEAC loading. The area under the ñ-transition curve which is correlated with damping and impact energy increases with increasing SPNEAC loading. A 5wt% addition of SPNEAC improved damping of neat-PI films by 137%. SEM micrographs of the nanocomposite films showed an open cross-sectional morphology.
INFLUENCE OF SCREW CONFIGURATION AND MIXING CONDITIONS IN TWIN-SCREW EXTRUSION ON DISPERSION OF MWNT IN PCL COMPOSITES
To produce electrically conductive or electrostatic dissipative polymer composites containing carbon nanotubes (CNT) melt processing is the favored route. As electrical properties are desired at low filler fractions, a high degree of dispersion is required in order to benefit from the intrinsic CNT properties. This study discusses the influence of screw configuration, rotation speed, and throughput on the residence time and specific mechanical energy (SME) and the resulting macroscopic CNT dispersion in polycaprolactone (PCL) based masterbatches containing 7.5 wt.% multi-walled carbon nanotubes (MWNT) using an intermeshing co-rotating twin-screw extruder Berstorff ZE25. From the best masterbatch a dilution set was performed.
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