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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ANALYSIS OF MORPHOLOGY ON INJECTION MOLDED POLY (?æ-CAPROLACTONE) TISSUE ENGINEERING SCAFFOLDS
PCL/NaCl and PCL/PEO/NaCl were injection molded. The water soluble, sacrificial polymer, PEO, and NaCl particulates in the blend were leached by deionized water to produce porous and interconnected microstructure. The effect of leaching time on porous morphology and porosity was investigated. Results showed that PCL/NaCl blend composites had a relatively slow leaching rate due to a lack of connectivity between NaCl particulates. For PCL/PEO/NaCl blend composites, most of the PEO and NaCl particulates can be removed in a short time. This is because the leached PEO domains provide interconnected channels that allow water to reach and leach embedded NaCl particulates.
DEVELOPMENT OF COMPOSITE PIPES FOR RISER APPLICATION IN DEEP WATER
This work deals with the development of composite pipes for riser application in deep water. Initially, an epoxy resin system was toughened by rubber CTBN addition (10 wt%) as a way of improving the flexibility of future risers. Mechanical and thermal analyses were carried out for characterizing the polymeric systems. The influence of matrix toughening and the number of composite layers on the mechanical behavior of the tubes were studied using hydrostatic and split-disk tests. In both tests, the results indicate that the matrix plays an important role in composite fracture processes
THE USE OF PRESSURIZED WATER PELLETS AND SUPERCRITICAL NITROGEN IN INJECTION MOLDING
In injection molding, cycle time, and warpage are critical factors for process economics and product quality. This work focuses on reducing cycle time, and warpage by utilizing water containing polymer pellets. Pellets were prepared by compounding a water carrier particle via extrusion, followed by a batch pressurizing process at a controlled pressure and temperature. Water containing polymer pellets were molded with and without supercritical nitrogen to further decrease the cycle time and minimize warpage. Preliminary results showed that the cycle time and part warpage could be reduced without a major effect on the mechanical properties.
FEM PARAMETRIC STUDY ON EFFECT OF CONSTITUTIVE BEHAVIOR ON SCRATCH VISIBILITY RESISTANCE OF POLYMERS
Three-dimensional finite element method (FEM) parametric study was performed to investigate the effect of asymmetric constitutive behavior on scratch visibility resistance of polymers. The scratch depth and shoulder height of the groove formed during the scratch, which is related to the scratch visibility resistance of polymers, is simulated by considering different asymmetric constitutive behaviors. The simulation results indicate that compressive behavior dominates the scratch visibility resistance of a polymer. Implication of the present findings for designing scratch resistant polymers is discussed.
MAINTAINING A STABLE ENGINEERED NANO-COMPOSITES PROCESS THROUGH MATERIAL CHARACTERIZATION
There is excitement regarding the application of nanomaterials (NMs) in composites. The use of carbon nanotubes (CTNs), nanoparticles (NPs), or other NMs in composite epoxy materials increase strength and elasticity, and reduce the weight of the end product. Nano Composite Epoxy materials will introduce new and unique composite characteristics for industry and consumers. Characterizing NMs during their composite processing is quite different than characterizing previous bulk composite additives. There are additional concerns and characteristics to be aware of with NMs. This paper is an overview of nanomaterial characterization needed to ensure a stable nano-composite epoxy process from beginning to end.
MULTI-LAYER BLOWN FILMS FOR THERMOFORMED FOOD PACKAGING APPLICATIONS
Polyethylene and nylon are used in thermo-formable, multilayer films for food packaging. Through this study, we have developed film structures with up to 30% less nylon and equivalent or better oxygen and moisture barriers than a commercial pizza packaging film structure. These structures exhibited good thermoforming behavior at several draw ratios. We have applied three thermoform-ability indices for the assessment of a filmƒ??s thermoform-ability in this study. One of them was the dimensional thermoform-ability index reported by NOVA Chemicals Corp. The combination of all three indices provides rapid and accurate assessment of the thermoform-ability of film structures.
MONOLAYER AND MULTILAYER POLYOLEFIN FILMS INCORPORATING POLYMERIC MICROSPHERES
Monolayer and multilayer high density polyethylene (HDPE) and polypropylene (PP) blown and cast films were processed with 1.6%, 2.4% and 3.3% microspheres by weight. The films were analyzed for density, tensile properties and tear strength. The multilayer blown films for both polyolefins showed the most decrease in density with the highest loading of microspheres. The monolayer and multilayer HDPE films showed a significant increase in Young's modulus with low loadings of microspheres for both cast and blown films while the PP values decreased for all microsphere films.
STUDY ON THE DEGRADATION RATE OF POLYANHYDRIDE (POLY(SEBACIC ACID), DIACETOXY TERMINATED, PSADT) FOR POTENTIAL DRUG DELIVERY AND TISSUE ENGINEERING SCAFFOLD APPLICATIONS
The degradation rate of polyanhydride (poly(sebacic acid), diacetoxy terminated) is investigated. PSADT tablets are formed using a compression molding device under three different processing temperatures, then immersed into phosphate buffer saline (PBS) for degradation experiments. The mechanisms of degradation and the degradation rate are characterized by the change in molecular weight, reduction in specimen mass, and decrease of specimen thickness. The surface morphology at different degradation times is observed by scanning electron microscope (SEM). The results show that PSADT exhibits the behavior of surface erosion due to the fact that near zero-order degradation kinetics was observed in its degradation process.
SUPERIOR RESISTANCE TO THERMO-OXIDATIVE AND CHEMICAL DEGRADATION IN POLYAMIDES
DuPont's SHIELD Technology allows polyamide resins to be used at higher temperatures than previously achieved. This technology combines several innovations: a new polymer backbone, polymer modifications and additives to enhance performance. The resistance to thermo-oxidative damage and chemical degradation is superior to standard polyamide resins. Examples of improved performance include: Improved air oven aging - retaining >50% of initial mechanical properties after 1000 hours atC Improved fluid aging resistance - maintaining >75% of its impact strength after 5000 hrs at 150C in hot oil. ƒ?› Improved CaCl2 resistance, resisting cracks three times the number of cycles of standard glass-reinforced nylons
AN EASY METHOD TO MONITOR LACTIDE POLYMERIZATION WITH A BORON FLUORESCENT PROBE
The solvent-free controlled ring-opening polymerization (ROP) of lactide is commercially important. A fluorescent dye, difluoroboron 4-methoxydibenzoylmethane (BF2dbmOMe) is employed to probe lactide bulk ROP by measuring the emission from solidified aliquots at room temperature. During polymerization, the fluorescence of BF2dbmOMe in solid-state aliquots exhibited a systematic shift from yellow to blue, accompanied by a reduction in decay lifetime. The fluorescence color change is sensitive to monomer conversion, not polymer molecular weight. The long-wavelength emission with perceivably longer lifetimes arises from BF2dbmOMe dye aggregates, while the dissolved individual dye molecules are responsible for the blue fluorescence with a shorter lifetime.
STABILIZATION OF POLY(BUTYLENE TEREPHTHALATE) FOR DURABLE APPLICATIONS
PBT is an engineering plastic used in molding applications where protection against demanding temperature or light exposure environments is necessary to retain useful properties. Heat & light stabilization of PBT was assessed under thermal aging or light exposures. PBT specimens were subjected to oven aging for 600 hours. The loss rate of physical properties, melt stability, and changes in discoloration were observed. Hindered phenolic antioxidants and phosphite stabilizers were evaluated, providing improved physical properties and reduced discoloration. PBT was subjected to WOM & outdoor light weathering. Protection was possible with a UV-absorber or combined with a hindered amine light stabilizer.
MULTIFUNCTIONAL NANOPAPER FOR WEAR RESISTANT AND CONDUCTIVE APPLICATIONS
Fiber reinforced polymer composites are used in a wide variety of applications such as aerospace, military, defense, and wind energy industries. In many applications, solid particle erosion damage can be a critical issue. In this study, a novel method of fabricating low-cost nanoparticle thin films or nanopapers for use as a surface protective layer for fiber reinforced polymer composites was developed. Inclusion of these nanopapers through current manufacturing methods has shown increases in solid particle erosion protection of up to 7x. The nanopapers have also shown to increase surface electrical conductivity by as much as 16 orders of magnitude.
SYNTHESIS OF HIGH ION-EXCHANGE NANOPARTICLES BY EMULSION COPOLYMERIZATION OF QUATERNARY ALKYL AMMONIUM MODIFIED SULFONATED STYRENE AND DVB FOR COMPOSITE PEM APPLICATION
High ion-exchange capacity (IEC) crosslinked nanoparticles were synthesized by an emulsion copolymerization of divinylbenzene and sulfonated styrene (SS) for application as the proton conducting phase in composite proton exchange membranes. The effects of the counterion of the sulfonated styrene monomer, the surfactant and the crosslinking on the ability to stabilize the emulsion to high IEC were studied. Water-insoluble nanoparticles with IEC as high as 5.2 meq/g were achieved using sulfonated styrene with a quaternary alkyl ammonium cation, a non-ionic surfactant and a crosslinking agent in the emulsion formulation. Nanoparticles with diameters of 20 160 nm were achieved.
EVALUATION OF PROPERTY-PERFORMANCE RELATIONSHIPS OF POLYURETHANE FOAMS USED IN AUTOMOTIVE SEATING APPLICATIONS
High resiliency polyurethane foams are used to provide superior comfort in automotive seat designs. A modified Voigt viscoelastic model is used to simulate vibrational transmissivity (dynamic comfort) during ride. The model links dynamic comfort to foam parameters of dynamic modulus and damping. The results from the simulations show that low dynamic modulus coupled with high damping gives optimal comfort. The simulation results also confirm that thinner seating negatively affects dynamic comfort. A dynamic oscillatory hysteresis analysis is used to obtain both the dynamic modulus and damping parameter. There was reasonable agreement between experimentally measured and model predicted vibrational transmissivity.
REINFORCEMENT OF POLYPROPYLENE SPUN FIBERS BY POSS NANOPARTICLES
The molecules of polyhedral oligomeric silsesquioxane (POSS) containing silanol functionalities interacted by hydrogen bonding with sorbitol nucleating agent and formed low viscosity liquid complex during melt processing and finally turned into cylindrical nanoparticles in spun fibers of isotactic polypropylene (iPP). It was found that at the optimum combination of POSS (typically 2-5 wt%) and sorbitol nucleating agent (typically 1 wt%), iPP compounds can be spun into fibers with 40% reduction in diameter compared to unfilled PP, 60% increase in tensile strength and modulus, and 100% increase in yield stress.
SEMICRYSTALLINE POLYAMIDE ENGINEERING THERMOPLASTICS BASED ON THE RENEWABLE MONOMER, 1,9-NONANE DIAMINE
A series of poly(1,9-nonamethylene adipamide-co-1,9-nonamethylene terephthalamide) copolymers were produced using melt polymerization and the thermal properties and crystal structure characterized. The results obtained confirmed that the copolymers exhibit isomorphism. As expected, glass transition temperature and the apparent melting temperature increased with increasing terephthalmide content. Using the difference in the apparent melting temperature to the crystallization temperature as a measure of relative crystallization rate, it was observed that crystallization rate decreased as the terephthalamide content of the copolymer was increased from 0 to 50 mole percent but then sharply increased when increased beyond 50 mole percent.
THERMO-MECHANICAL PROPERTIES AND THERMAL DEGRADATION CONTROL OF POLY (LACTIC ACID) AND POLY (LACTIC ACID)/CLAY/WOOD NANOCOMPOSITES
Poly (lactic acid) is an important biopolymer with suitable mechanical properties for construction and packaging applications. The mechanical and thermal properties of PLA can be tailored by compounding reinforcing fillers. PLA nanocomposites based on nanoclay and/or wood flour were prepared by melt extrusion of PLA. Three compatibilizers - maleated polyethylene, maleated polypropylene and maleated poly (lactic acid) were used in PLA/clay/wood nanocomposites. Approaches to control PLA thermal degradation during melt extrusion were examined. Residual catalyst deactivation and molecular weight control by chain extenders were believed to be the most effective and feasible methods.
PVC-CACO3 NANOCOMPOSITES PRODUCED BY IN-SITU COUPLING USING TITANATE COUPLING AGENT IN TWIN-SCREW EXTRUDER
This study focused on the effect of titanate coupling agent to the mechanical and fracture properties of PVC nano-CaCO3 composites. The titanate coupling agent is introduced into the PVC nanocomposite through in-situ coupling technique, where the titanate mixed with PVC resin and nano-CaCO3 particles during dry mixing and relies on the high shear force during extrusion to induce coupling reactions and dispersions. This enabled the process to be transferred into existing PVC manufacturing technology. The composites morphology and mechanical properties are examined to understand the effect of titanate coupling agent to the PVC nanoCaCO3 composites.
A STATISTICAL STUDY OF THE COMPATIBILITY AND CURING OF DEVULCANIZED RUBBER AND POLYPROPYLENE
The usage of waste tire rubber crumb as a dispersed phase in a thermoplastic matrix has been a topic of study for a long time. Inspite of using compatibilizers the properties achieved using polypropylene (PP) and waste ground rubber tire (GRT) crumb composites remained inferior. Devulcanized rubber (DR) being more relatively similar to virgin rubber is supposed to perform better than GRT and hence should be a better material for commercializing. This paper presents a statistical analysis of compatibility between DR and PP and also studies the effectiveness of a sulphur cure system in compatibilization.
UNDERSTANDING THERMALLY INDUCED WRINKLING IN DECORATIVE FILM LAMINATED SHEETS
The development of wrinkles in decorative film laminates during processing operations like thermoforming was the focused of this paper so that we may understand the driving factors and develop strategies to overcome. A threshold temperature was identified for our film under which no wrinkles formed, related to the stiffness of its different construction layers. Heating rate was also noted by this study to be an important parameter in wrinkling. The effect is believed to be related to the rate of change in stiffness between the different construction layers in relation to building thermal stresses.
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