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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THE INTERDIFFUSION OF POLYMERIC GRADIENT REFRACTIVE INDEX (GRIN) LENS MATERIALS
The interdiffusion of two miscible polymers used to fabricate GRIN lenses, polymethylmethacrylate (PMMA) and poly(styrene-co-acrylonitrile) (SAN17) with 17% AN content, was studied as a function of contact time during a multilayer coextrusion process. Oxygen permeability increased from following the series model to following a miscible blend model as the number of layers increased from 17 to 1025. A model relating permeability and the interdiffusion state within the layers successfully predicted the observed permeability trends, and was used to determine the mutual diffusion coefficient of PMMA and SAN17.
STRUCTURE AND PROPERTIES OF PENTABLOCK AND TRIBLOCK COPOLYMER BLENDS
Styrene-ethylene/butylene styrene (SEBS) block copolymers are used in a wide range of film and molded applications, particularly where good weatherability (i.e. UV resistance) is needed. These block copolymers also have poor moisture transport characteristics. NexarTM is a family of pentablock copolymers recently developed by Kraton Polymers LLC, whose properties include (a) high water vapor transport, (b) good mechanical integrity, both dry and wet, (c) thermal and chemical resistance, and (d) ion selectivity. The purpose of this work was to create elastomeric films that have moisture transport properties and, to investigate the structure and properties of SEBS / Nexar's blends
ULTRASONICALLY ASSISTED EXTRUSION OF CARBON BLACK, CARBON NANOFIBER AND CARBON NANOTUBE FILLED STYRENE-BUTADIENE RUBBER COMPOUNDS AND PROPERTIES OF THEIR VULCANIZATES
Ultrasonically assisted extrusion of styrene-butadiene rubber (SBR) compounds filled with carbon black (CB), carbon nanotube (CNT) and carbon nanofiber (CNF) was carried out. The effects of ultrasonic amplitude on extractable amount, swelling behavior, mechanical properties, abrasion, electrical resistivity and morphology were investigated. Ultrasonic treatment at certain amplitudes led to an increase of the crosslink density, modulus and tensile strength. Also, it caused a reduction in the electrical percolation threshold. A better dispersion of ZnO and creation of unique nanofiller agglomerates were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy.
NEW DEVOLATILIZATION PROCESS FOR THERMOSENSITIVE AND HIGHLY VISCOUS POLYMERS IN HIGH VOLUME KNEADER REACTORS
The achievable final volatile content within kneader devolatilization processes is highly dependent on the final melt temperature. For thermosensitive polymers the state of the art process performs poorly. The amount of dissipated energy leads to a heat up of the polymer, limiting the maximal kneader shaft speed and therefore volatile removal rate. This new process uses a suitable additional volatile compound to cool off the dissipated energy by evaporation using the off gas to strip and boost the mass transfer coefficient. A complex multi-parameter study is presented, to predict performance of industrial equipment from pilot scale data.
EFFECTS OF GLASS FIBERS ON THE PROPERTIES OF MICRO MOLDED PLASTIC PARTS
Glass fibers are used to reinforce plastics and to improve their mechanical properties. But plastics filled with glass fibers are concern for molding of micro parts. The aim of this paper is to investigate the effects of glass fiber on the replication quality and mechanical properties of polymeric thin ribs. It investigates the effect of feature size and gate location on distribution of glass fibers inside the molded parts. The results from this work indicate that glass filled plastic materials have poor replication quality and non-homogeneous mechanical properties due to the non-uniform distribution and orientation of glass fibers.
VISCOELASTICITY OF POLYMERS; FUNDAMENTALS, APPLICATIONS, AND CASE STUDIES
In this review paper the fundamentals of polymer viscoelasticity will be explained and its applications to different polymers will be discussed. Firstly, the viscous-state properties like viscosity, shear thinning, Newtonian flow, and molecular structure will be explained. Secondly, the solid-state properties like the storage modulus, loss modulus, thermal stability, and molecular mobility will be clarified. The relation of these properties to the thermo-mechanical properties of different polymers and nano-composites will be reviewed as well. Finally, a successful story of using viscoelasticity as a failure analysis tool will be summarized.
STRUCTURAL RELAXATION AND PHYSICAL AGING OF POLYSTYRENE IN NANOLAYER CONFINEMENT
Layer-multiplying coextrusion technology was used to produce multilayered films of polystyrene (PS) and polycarbonate (PC). The multilayered films with PS layer thickness down to 20nm were extruded. The structural relaxation of polystyrene under PC confinement was investigated using two approaches. In the first method, the PS layers were cooled from the melt at different rates. The subsequent heating thermograms revealed that the relaxation of the PS was similar to the bulk sample. Another experiment included physical aging of PS layers below the Tg at 80?øC. The subsequent heating thermograms showed that the aging rate of PS remained unchanged under confinement.
CONSIDERATION OF MULTIAXIAL LOAD CONDITIONS IN MECHANICAL FEA SIMULATIONS OF RUBBER PARTS
An important basis for a development of technical elastomer parts is the numerical structure analysis for the mechanical dimensioning i.e. Finite-Element-Analysis (FEA). The mechanical properties of carbon-black filled elastomers are highly dependent on the load-condition (uniaxial, pure shear and equibiaxial). Standard material models do not take the load condition into account and describe the material behavior rather poorly. In order to describe the load condition-dependent mechanical material behaviour accurately, subroutines are developed for the FEA. The usage of these hyperelastic material models furthermore leads to a more accurate description of the mechanical behaviour for the examined carbon black filled rubber.
IMPROVING THE MECHANICAL PROPERTIES OF POLYETHYLENE AND POLYPROPYLENE RECYCLED STREAMS USING POLYOLEFIN ELASTOMERS AND FUNCTIONALIZED POLYOLEFINS.
The ability to be recycled is an important attribute for many plastics. By melting and reprocessing thermoplastics for re-use the carbon footprint can typically be reduced compared to the use of virgin materials. The benefits of incorporating recycle content into new and existing applications, however, must be tempered by the reality that recycled plastics may not have the same performance as virgin materials due to either 1) degradation by weathering/aging, 2) contamination, or 3) thermo-mechanical degradation from re-processing. To minimize these effects, it is important to understand the benefits of utilizing impact modifiers and compatibilizers.
A SCIENTIFIC APPROACH TO SPECIFYING AND MODELING PLASTICS FOR LIGHTING
There are many ways to characterize and communicate essential information about plastic materials destined for use in lighting applications. Most lack the specificity required by the lighting systems designer in order to predict system performance. There are ways to model and specify materials that provide easier intuitive understanding and techniques that allow predictive CAD tools to be used. Lighting materials description Conventional methods of characterization Improved methods of characterization and description Influence on solid state light sources Comparisons of methods for use in subsequent modeling
GASOLINE ABSORPTION AND MECHANICAL CHARACTERISTICS OF BIODEGRADABLE POLYMER IN AUTOMOTIVE APPLICATION
This paper evaluates the potential use of biodegradable polymer for fuel system components by considering operating conditions. Organic liquid diffusion into biodegradable polymer was observed by fuel immersion at various temperatures ranging from 5 to 50§C until the equilibrium condition was achieved. During the immersion time, mass uptake and length swelling were recorded periodically. The data were plotted for diffusion coefficient calculation at each temperature. Changes in mechanical properties were also investigated through tensile, flexural and impact testing. The results resemble the impact of gasoline absorption on biodegradable polymers when used for the under-hood components of a vehicle.
THE EFFECT OF MATERIAL COMPOSITION ON THERMAL EXPANSION AND MECHANICAL STRENGTH OF POLYMER CONCRETE USED FOR MANUFACTURING A BASE OF CNC GRINDING MACHINE
This paper examine thermal expansion coefficient (CTE), flexural strength (FS) of polymer concrete (PC) containing different resin volume fraction (RVF) and figuring out the influence of the CET on the precision of the CNC grinding machine. Different samples of PC have been prepared adopting variety RVF as follows 17%, 15% and 13%. Aggregates were Basalt, Sand, and Fly Ash. CET was tested using custom built device. FS was tested according to Australian standard AS 1012.11. Results illustrates that RVF in PC has significant effect on CET, FS. ANSYS 12.1 visualize the CET influence on effective components of CNC grinding machine.
AUTOMATION AND ASSEMBLY SOLUTIONS OF MICRO INJECTION MOLDING PROCESSES
Because of the difficult contact with miniaturised components the following treatment steps must already considered with the micro injection molding production . Micro injection molding parts have connected a low weight with a surface relatively big to the mass. The electric-static forces lead to the liability of the parts in the tool surfaces, what prevents dropping into the container.A manual use of the parts is, because of the low dimensions no more possible. With the micro injection molding process, the application of using automation devices are necessary already with unusually low numbers of micro parts.
USE OF SURFACE LAYER ON PRE-HARDENED TOOL STEEL CAN IMPROVE MOULD LIFE LENGTH AND SIMPLIFIES MOULD MANUFACTURING
The last decades have seen rapid development in hard-machining, enabling faster tool-manufacturing when using pre-hardened tool steels. Such steels are usually delivered in hardness up to Approx. 40 HRC. However, pre-hardened tool steel having 45 HRC is today available on the market. Such hardness is suitable in many molding applications, but when molding reinforced plastics, such as glass-fiber reinforced ones, higher mold surface hardness is required to achieve desired mold life length. Application of surface engineering (Nitriding, PVD-coating etc.) on pre-hardened tool steel enables the tool designer/tool maker to tailor-make the desired mold surface properties
PHYSICAL PROPERTY RETENTION OF EXTERIOR AUTOMOTIVE MOLD-IN-COLOR PLASTICS AFTER UV EXPOSURE
To reduce manufacturing costs and address environmental issues, coatings free Mold-In-Color plastics are now replacing coated plastics. This paper will explore the physical property retention / weathering performance of various Mold-In-Color plastics used for exterior trim. Exposed specimens are analyzed for their change in physical properties then analyzed for change in surface chemistry via infrared spectroscopy and surface topography. It is concluded that some plastics containing styrene experience a change in physical properties and surface chemistry upon UV expose while other materials like PMMA acrylic retain their original performance.
STUDY ON CONTINUOUS EXTRUSION FOAMING OF PP/PS/NANO-CLAY WITH SUPERCRITICAL CO2
The PP/PS/Nano-clay blends were foamed in this paper using a single-screw extruder foaming system and cell structure of foamed samples was characterized using SEM. By comparing cell morphology, foam expansion ratio, cell density etc, the effect of blend ratio for R-PP/PS/Nano-clay blends on cell morphology of foamed samples was studied. The results showed foaming behavior of PP could be improved when it was blended with PS, and the addition of Nano-clay further improved the foaming property of the blends. Microcellular foamed plastics with cell-population density as high as 2.16 108cells/cm3 were obtained when 5wt% Nano-clay was included in the formulation.
MEASUREMENT AND ANALYSIS OF EXTRUSION FOAMING BEHAVIOR OF PP/PDMS BLENDS
Foaming behavior of PP/PDMS blends was investigated using a single extruder foaming system, with CO2 as the foaming agent. Influences of die temperature and foaming agent conten on foam expansion ratio, cell density and die pressure were analyzed. Our research showed that gas loss and crystallization stiffening of the melt at low temperature were the two governing factors of foam expansion ratio, and the addition of PDMS improved the expansion ratio of PP foamed samples at higher loadings (5wt% and 7wt%) of foaming agent. Foamed samples with expansion ratio as high as 23 were obtained as 5wt% CO2 was used.
CAUSE OF OCCATIONAL FAILURE OF CPVC PIPES AND FITTINGS IN HYDRONIC HEATING SYSTEMS
CPVC pipes and fittings are commonly used in hydronic heating systems. However, there are occasional failures of CPVC pipes and fittings used in these systems due to chemical contamination by the lubricant oil used in the heat exchanger refrigerant. Although leaks in the heat exchanger are rare, when a leak does occur, it can lead to almost immediate failure of the CPVC piping system. This paper discusses the results of our forensic failure analyses on CPVC hydronic piping. Also we present the results of our studies on the chemical compatibility of refrigerant lubricant oils.
EFFECT OF ULTRA-HIGH THERMAL TREATMENT OF CARBON NANOFIBERS ON EMI SE OF LLDPE NANOCOMPOSITES
The electromagnetic interference shielding effectiveness (EMI SE) and the electrical properties of linear low density polyethylene modified by heat treated carbon nanofibers (Pyrograf III PR-19) and mesophase pitch-based carbon fibers were investigated. After thermal treatment of the nanofibers to 2500C, 20 wt% PR-19 thermal treated nanocomposites displayed a resistivity of ~1e5 cm, and EMI SE values as high as 15 dB for most of the VHF-UHF frequency range. These nanocomposites retained half of the flexibility and strength as well as one-third of the ductility, relative to the LLDPE. EMI SE analysis indicates that absorption is the primary shielding mechanism.
THE PREPARATION OF NANO-CLAY/POLYPROPYLENE COMPOSITE MATERIALS WITH IMPROVED PROPERTIES USING SUPERCRITICAL CARBON DIOXIDE
Supercritical carbon dioxide (scCO2) was used as a processing aid to improve the level of exfoliation and, in some cases, the dispersion of nano-clay in polypropylene (PP). The anisotropic properties of injection molded nano-clay/PP composites were studied. The use of scCO2 with modified processing methods lead to materials which showed improvements in the mechanical properties of 78.4% compared to the pure PP matrix for a 18wt % clay loading. A further improvement in properties is expected with higher levels of nano-clay, improvements in the processing method, and the use of a highly crystalline PP matrix.
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