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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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.
FATIGUE PROPERTIES OF AN OLEFIN THERMOPLASTIC ELASTOMER IN COMPARISON WITH OTHER THERMOPLASTIC ELASTOMERS
This paper discusses the dynamic fatigue properties of an olefin thermoplastic elastomer (TPE-O) and how it compares with flexible PVC (f-PVC) and styrene block copolymers based thermoplastic elastomers (TPE-S). The fatigue properties were investigated measuring the change of hysteresis properties as samples are subject to cyclic loads in air at room temperature. Material elastic features are investigated using dynamic mechanical analysis and compression set methods. The effect of aging on physical properties of materials is also investigated. The advantages of the TPE-O in fatigue resistance are discussed and attributed to its structure and morphology.
THE DEVELOPMENT OF A EMBOSS-PATTERNED TPO SHEET CROSSLINKED BY ELECTRON BEAM IRRADIATION FOR AUTOMOBILE INTERIOR SKIN
The economical male vacuum forming process helps to make parts with emboss patterns price competitive, but emboss pattern loss is greater than that observed with a female vacuum forming process. In this study, we developed a emboss-patterned thermoplastic olefin(TPO) sheet crosslinked by electron beam irradiation, to minimize emboss pattern loss incurred during part forming in the male vacuum process by optimizing electron beam irradiation dose and materials compositon in the sheet and the results indicated the improvement of the retention rate of emboss patterns by three-fold with an electron beam irradiation dose of 80 kGy.
PREVENTING CRACKING FAILURES IN PC, ABS, AND PC/ABS BLENDS IN MEDICAL, PHARMACEUTICAL, AND CONSUMER DEVICE APPLICATIONS
Polycarbonate and Acrylonitrile Butadiene Styrene are materials of choice for many medical, pharmaceutical, and consumer products because of their durability, stability, and high-quality surface finish. As these materials become widely used, failures are occurring more frequently and in situations where generally accepted design approaches and validation testing suggests the materials should perform quite well. This paper will discuss reasons why these failures occur as well as design methodology and life prediction techniques for preventing future failures.
MECHANICAL AND THERMAL PROPERTIES OF AN EPOXY RESIN REINFORCED WITH DIFFERENT NANOCLAYS
High intensive mixing techniques and/or long ultrasonication periods of time are normally used to prepare epopy clay nanocomposites. However this approach is not practical. In this work epoxy clay nanocomposites were prepared using a combination of short times of ultrasonication and hand mixing, therefore making clay chemistry to govern over possible differences in the composite properties. Several types of nanoclay were used in order to investigate clay chemistry on thermal and mechanical properties of the nanocomposites. Flexural test proved to be more sensitive than tensile testing in determining the effect of type and clay content.
PRECISE, HIGH-SPEED, HOT-PLATE WELDING; CONTROL TO THE THIRD POWER
In general, conventional hot-plate welding has not kept pace with technology advancements that other widely used plastics joining technologies have experienced. Extol will describe recent advancements in the hot-plate welding process which provide the capability for high-speed welding with precise force, heat and speed control. Each of these key variables (force, heat, and speed) will be discussed with respect to advances in machine design that facilitated precision control resulting in improving the process. These improvements also contributed to more efficient tool design, process setup, cycle time improvements and process innovations allowing for flexibility in product design and material selection.
A STUDY ON THE MEASUREMENT OF RHEO-OPTICAL BEHAVIOR IN AMORPHOUS TRANSPARENT POLYMERS
In the present study, rheo-optical and mechanical properties of amorphous polymers (PS, PC and COC) widely used in engineering field have been investigated. The storage stress-optical coefficient of polystyrene(PS) showed the sign change as the frequency increased. On the other hand, the sign of stress-optical coefficient over the whole frequency region is always positive with respect to polycarbonate(PC). For COC's of different composition, even though the glass transition temperature can vary, the stress-optical coefficient of COCƒ??s with different composition stays almost constant at two extremes.
THE EFFECT OF ELECTRON BEAM IRRADIATION ON HDPE/EPDM BLENDS WITH TRIALLYL CYANURATE
Blends formed of 80 wt% of high-density polyethylene (HDPE) and 20 wt% of ethylene-propylene diene monomer (EPDM) have been added with 3 wt% of triallyl cyanurate (TAC). The thermal and mechanical properties were followed up as a function of e-beam irradiation dose. The results obtained that the values of gel contents, decomposition temperature, tensile strength, and impact strength increase with increasing irradiation dose up to 100 or 150 kGy and then decreased. Additionally, the effect of cross-linking agent of TAC was observed in upgrading of various properties.
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