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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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.
AUTOCLAVABILITY OF HIGH HEAT POLYCARBONATE RESINS FOR HEALTHCARE APPLICATIONS
Medical applications in healthcare market most often require multiple use or reuse of the instrument. Autoclave sterilization is one of the most common methods to effectively clean the instrument before reuse. To understand the capability of newly developed high heat Lexan* XHT resins in autoclave applications, mechanical property retention including tensile, flexural and practical impact properties were evaluated after multiple autoclave cycles at both 120?øC and 134?øC. These new class of high heat Polycarbonates offer better performance in comparison to conventional polycarbonates at high sterilization temperatures.
COMPARISON OF CARBON NANOTUBES AND CARBON NANOFIBERS BASED NANOCOMPOSITES PREPARED WITH AID OF HIGH POWER ULTRASOUND
The unique morphology and strong inter-tube attraction among CNTs and CNFs makes the dispersion of CNTs and CNFs a big challenge and hence limits their effective use. The comparison of reinforcement efficiency of CNFs and MWNTs in PEI was studied. Ultrasound assisted single and twin screw extruder was used to prepare PEI/CNFs and PEI/MWNTs nanocomposites respectively. The effect of ultrasound on electrical, rheological, morphological and mechanical properties of polyetherimide filled with 1-10wt% of MWNTs and 2-20wt% of CNFs was studied. Ultrasonic treatment caused a reduction in electrical percolation threshold value with a permanent increase of viscosity of treated samples.
FIBER BREAKAGE CALCULATION FOR INJECTION MOLDED LONG FIBER COMPOSITES
The Phelps-Tucker fiber breakage model has been implemented along with fiber orientation models in Autodesk Moldflow Insight to predict fiber length attrition during injection-molding process. The fiber length breakage model is based on the buckling criterion for hydrodynamic force determined by Dinh-Armstrong model, and probability distribution of the length breakage which parameters can be adjusted to match fiber length measurement. A set of measurement data has been used to validate the fiber breakage model implementation, and it has been extended to 3D simulation for more complicated geometries to predict the fiber length distribution in practical applications.
INTERRELATION BETWEEN MELT PROCESSING CONDITIONS, FORMULATION AND PROPERTIES OF POLYPROPYLENE / SHORT FLAX AND HEMP FIBER COMPOSITES
This work investigates the effect of extrusion parameters and formulation on the properties of polypropylene / short flax fiber composites. The parameters that were varied during the twin-screw extrusion process were screw configuration, screw rate, extrusion temperature and flow rate. The effect of the location of the feeding zone of flax fibers is also considered. Concerning the composite formulation, the effect of flax content, presence of coupling agent and of a reactive additive on composite properties are analyzed. The materials were characterized in terms of morphological characteristics, rheological, thermal and mechanical properties.
MELT EXTRUSION FOR THE ENABLEMENT OF PHARMACEUTICAL PRODUCTS - CASE STUDY USING GRISEOFULVIN
Melt extrusion has been gaining interest in the pharmaceutical industry due to the continuous nature and ability to provide unique dosage form characteristics. Enhancement of oral bioavailability to enable drug products has been exploited extensively using melt extrusion. In this study melt extrusion was used for the preparation of griseofulvin extrudates. Using this technology amorphous formulations using non-ionic polymers were prepared. Compositions were evaluated for physical characteristics, chemical performance and dissolution rate. Results showed that all formulations could be prepared below the melting temperature of the drug substance and the resulting formulations provided significant levels of supersaturation during dissolution testing.
BEAD FOAMING IN THE AUTOCLAVE-BASED EPP PROCESS
This paper presents the design of a lab-scale bead foaming system for investigating the mechanism of the formation of cellular morphology and evolution of the crystal melting peaks of the expanded beads. A propeller-guided-cylinder design was incorporated to enhance the circulation during the heating, saturation and downward force during the depressurization of the polymer pellets/water/blowing agent mixture. EPP beads of an average 16-time expansion ratio were fabricated and an extensive study will be conducted to examine the effects of processing parameters on the foaming and crystallization behavior of the beads.
EPOXY/CARBON NANOTUBE COMPOSITES FOR WIND TURBINE BLADES
Epoxy based composites containing multi-walled carbon nanotubes (MWCNTs) have been successfully prepared. The effects of the addition of eight different block copolymers on the dispersion stability of MWCNTs have been systematically analyzed. The suspension of CNTs in different components of the epoxy, i.e epoxy resin and hardener, have been evaluated by preparing suspensions using a tip sonicator and different amounts of block copolymers relative to the concentration of CNTs. The stability of MWCNTs in various media was investigated by using a centrifugation technique. Dispersing agents suitable for the acquisition of long-term stable dispersions of MWCNTs have been identified.
FOAMING BEHAVIORS OF POLYPROPYLENE BLOWN WITH CARBON DIOXIDE UNDER EXTENSIONAL STRESS BELOW TM
Previously, it had been demonstrated that extensional stresses has strong effects in cell nucleation and growth within plastic foaming processes. In particular, our previous work investigated the foaming behavior of polystyrene, an amorphous polymer, under extensional stress via in situ observation of the foaming processes. On the other hand, the effects of extensional stress on semi-crystalline polymers are still not well-understood. This study aims to fill this gap by investigating the foaming behaviors of three different types of polypropylene (PP): linear PP, branched PP, and a PP-PE copolymer, via in situ observation.
UNDERSTANDING EFFECTS OF INTERFACIAL CONTACT AND AGGLOMERATION OF FILLERS ON TENSILE MODULUS OF POLYMER NANOCOMPOSITES
Analytical methods have been widely used to predict mechanical properties of polymer composites. The theories assume perfect filler-matrix interfacial contact and homogenous dispersion of individual fillers into the matrix, which however is not what is observed experimentally especially in nanocomposites. The reason is that in nano-size reinforced polymers the dominant effects of interfacial interaction and presence of fillersƒ?? agglomeration have to be considered. This study investigates the effects of these two factors on the tensile modulus of nanocomposites by combining experimental observations and micromechanical models.
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