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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PROPERTY RETENTION OF HIGH-FLOW MEDICAL-RESINS AFTER GAMMA-IRRADIATION
In this work, newly-introduced polycarbonate resins targeted for medical device applications, Makrolon Rx2435 and Makrolon 2258 were studied after sterilization with 30 kGy and 60 kGy gamma-irradiation. Despite characteristic color shifts and slight losses in molecular weights, the polycarbonate resins showed excellent retention of properties after irradiation up to 60 kGy. Although the polycarbonate color shifts were greater than what was observed for a medical copolyester, the copolyester yielded greater viscosity losses after sterilization. The color shifts for Makrolon point to the polycarbonate rearrangement reactions which occur upon irradiation.
CONFIRMATION AND QUANTIFICATION OF LINEAR LOW-DENSITY POLYETHYLENE (LLDPE) AND MALEATED LINEAR LOW-DENSITY POLYETHYLENE (LLDPE-g-MA) INFUSED WITH NANOCLAY IN SUPERCRITICAL CARBON DIOXIDE
Nanoclay fillers have the ability to enhance the thermo-mechanical, barrier and flame resistant properties of Linear Low-Density Polyethylene (LLDPE). One method employed to successfully disperse nanoclay powders into polymers that is both inexpensive and deemed environmentally friendly is supercritical carbon dioxide processing. With supercritical carbon dioxide processing, Cloisite 93A was infused into LLDPE and Maleated LLDPE (LLDPE-g-MA). The infusion of Cloisite 93A was confirmed by XRD and FTIR analysis. In addition, XRD analysis suggests that clay intercalation was achieved for select runs. And FTIR analysis was used to determine the amount of nanoclay infused into the polymer.
FRACTURE OF RUBBER-TOUGHENED EPOXY ON METAL SUBSTRATES: EFFECT OF BONDLINE THICKNESS AND INFLUENCE OF BONDLINE NONUNIFORMITY
Fracture behavior of rubber toughened epoxy on metal substrates was investigated in this paper. The elastic-plastic behavior and mode I fracture resistance characteristics of the rubber-toughened epoxy were experimentally characterized. A cohesive zone based finite element model was developed to understand the influence of bonding thickness and nonuniform bonding layout on the fracture behavior. It was observed that the bondline thickness can affect the fracture behavior, particularly the fracture initiation, profoundly. It was also found that the nonuniformity in bond line can have significant impact on the crack propagation.
EFFECT OF EXTRUSION DEVOLATILIZATION ON THE STRUCTURE AND PROPERTIES OF AN END-CAPPED POLYPHENYLENE ETHER COPOLYMER
Methacrylate terminated telechelic polyphenylene ether copolymer is produced by reacting methacrylic acid anhydride with a telechelic PPE copolymer. The reaction takes place in a solvent which needs to be removed in an isolation step. The isolation can be done by precipitation with an anti-solvent or by removing the solvent in a devolatilization unit. Avoidance in the use of an anti-solvent is of interest to make the process more environmentally friendly. This paper describes the feasibility of the use of devolatilization extrusion for the isolation step and investigates the effect devolatilization extrusion has on the structure and properties of the copolymer.
EFFECT OF THERMOPLASTIC ELASTOMER PROPERTIES IN MOLDED MICROSCALE FEATURES
Preliminary investigation indicated that the hardness and viscosity of thermoplastic elastomers (TPEs) affected replication of microfeatures. Over several types of TPEs, a moderate hardness and viscosity demonstrated superior replication quality. In this work, further study for relationship between TPEs properties and replication quality was performed. Copolyesters (COPEs) with a range of hardness and viscosity were evaluated. Replication of the molded parts was characterized using microscopy, surface profilometry, and scanning electron microscopy.
ANTIBACTERIAL ACTIVITY OF CHITOSAN BIOMEMBRANES LOADED WITH NATURAL POLYPHENOLS ISOLATED FROM FRUITS
Chitosan biomembranes loaded with natural polyphenols isolated from cramberry presscake and pomegranate peels have been developed as a novel device for the controlled release of these well known phytonutrients. Characterization of biomembranes loaded with polyphenols was performed by thermal, morphological and crystallographic analysis. Addition of polyphenols into chitosan matrix modifies thermal behaviour and surface morphology of chitosan biomembranes. Release studies indicate that cross-linked chitosan biomembranes are a suitable controlled release system for natural polyphenols. Antimicrobial assays indicate that chitosan biomembranes loaded with polyphenols showed higher bioactivity than the polymer itself and for some cases, even higher than the positive control.
HOW POLYAMIDE BECAME KNOWN AS NYLON: AN EXAMINATION OF TRADEMARK GENERICISM AND ITS AFFECTS ON THE PLASTICS INDUSTRY
Trademarks play an integral role in our society. They serve as source identifiers which create marketability and drive the economy. Trademarks must be properly used and enforced or risk loss of distinctiveness thereby losing their value. One example of this is genericism. Owners of trademarks which are used by consumers as the name for the product itself, rather than as an indicator of source, may have to take special proactive measures to escape genericism. This paper discusses how to create a strong brand, how marks become generic and how to avoid having your mark become the next victim of genericism.
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.
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