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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MODELING AVERAGE CAVITY TEMPERATURE USING ARTIFICIAL NEURAL NETWORKS
Average cavity temperature has been shown to be a suitable control variable in obtaining repeatable part quality. Existing control schemes for average cavity temperature use on-line and off-line identification techniques to formulate system models. These models are often linearized about a specific operating region and introduce inaccuracies in control due to process nonlinearities. This work presents an online artificial neural network black-box system identification routine to model the nonlinear dynamics of the average cavity temperature with respect to mold and process conditions.
LOW-DENSITY POLYETHYLENE COMPOSITES FILLED WITH CERAMIC FILLERS FOR ELECTRONIC PACKAGING APPLICATIONS
This study details the fabrication of linear low-density polythene (LLDPE)-based composite materials containing silicon carbide (SiC) and boron nitride (BN) filler particles. The composites were created by using a twin-screw compounder, and evaluated based on their morphology, as well as their thermal, electrical, and mechanical properties. Overall, the addition of ceramic fillers increased the thermal conductivity of the composites, without compromising the electrical resistivity, which is desirable for electronic packaging and heat management components in microelectronics.
THE MULTIFUNCTIONAL CHARACTERISTICS OF CARBONACEOUS FILLER-REINFORCED POLY(PHENYLENE SULFIDE) COMPOSITES
Poly(phenylene sulfide) (PPS) composites, reinforced by carbon fibers (CFs) and multiwall carbon nanotubes (MWCNTs), were fabricated through melt compounding. Their thermal, electrical, and mechanical properties were systematically studied as functions of filler contents and properties. The electrical percolation thresholds for CFs and MWCNTs were identified; however, the thermal percolation thresholds could not be achieved. This illustrates different requirements are needed in carbonaceous filler network to promote different functional performances of the composites.
MICROCRYSTALLINE CELLULOSE COMPOSITES OF POLY(LACTIC ACID)/POLY(ETHYLENE GLYCOL) OR POLYPROPYLENE CREATED VIA SOLID-STATE SHEAR PULVERIZATION
Hybrids of poly(lactic acid) (PLA) or polypropylene (PP) with microcrystalline cellulose (MCC) were created using solid-state shear pulverization (SSSP). For the PLA composite, this was followed with melt processing (MP) with added polyethylene glycol (PEG). We demonstrate a synergistic effect of MCC and PEG in enhancing the crystallization kinetics of PLA. Additionally, an SSSP processed 80/20 wt% PP/MCC composite was successfully injection molded into a bottle cap, which shows excellent MCC dispersion and stiffness.
SYNTHESIS AND CHARACTERIZATION OF A NOVEL, HIGHLY BROMINATED, FLAME RETARDANT POLYMER
A novel brominated polymer was synthesized from pentabromo-6-ethoxybenzene vinyl ether using cationic polymerization. The thermal and rheological properties of the polymer (i.e. PBrVE) were compared to the commercial brominated flame retardant, poly(pentabromobenzyl acrylate) (PBrBA). The glass transition temperature of PBrVE was determined to be 103 C which was 57 C lower than that of PBrBA. The higher molecular mobility of PBrVE resulted in lower melt viscosity in blends with PBT. Characterization of the PBT blends using transmission electron microscopy indicated higher compatibility between PBT and PBrVE as compared to PBT and PBrBA.
PROCESSING LINEAR POLYPROPYLENE-CLAY NANOCOMPOSITES WITH SILANE COUPLING AGENTS
Two different grades of organically modified montmorillonite were treated with several aminosilanes before compounding with a linear polypropylene (MFR=4) and a high molecular weight PP-g-MA in the same proportions in all cases. This treatment served to promote reactive coupling of the polymeric compatibilizer (PP-g-MA) to the nanolayer edges alone in some cases or to the nanolayer faces as well as edges in other cases. Edge coupling alone or coupling at the faces and edges give rise to different effects on the morphology and melt rheology ƒ??particularly strain hardening in extensional flow of the nanocomposites.
BARRIER PROPERTIES AND CHARACTERISTICS OF POLYGLYCOLIC ACID FOR UN-ORIENTED AND ORIENTED FILMS
Measurement of oxygen permeability of biodegradable polyglycolic acid (PGA) un-oriented amorphous and crystallized films, and oriented films showed superior values versus general barrier materials. The effect of orientation and crystallization was investigated, showing that oxygen permeability was dependent upon the polymer's free volume and its degree of crystallinity. By stretching an un-oriented amorphous film, PGA chains became highly oriented, resulting in increased temperatures of glass transition and tan?? peak. PGAƒ??s carbon dioxide barrier was tested using PET/PGA multilayer bottles, with 1 and 3wt% PGA bottles showing 1.5 and 2.5 times better gas barrier, respectively, versus a PET monolayer bottle.
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.
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