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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UNDERSTANDING THE CHALLENGES OF BONDING TPE MEDICAL TUBING TO TRADITIONAL CONNECTORS
The non or low polarity of TPEs is typically referenced as the main contributor to their poor bondability. This paper highlights additional technical factors in poor bondability with traditional solvents and commercial adhesives. Medical tubing OEMs focus on TPEs from 65A to 85A hardness depending on the specific application requirements. TPE hardness and modulus are shown to have significant influence on bonding strength. Often overlooked, ƒ??Poisson Effectƒ? is shown to be an important factor to cause low retention values with soft flexible TPEs. To overcome these challenges, we developed 3 patent pending bonding systems that significantly improve the bonding strength.
SOLID AND MICROCELLULAR RECYCLED POLY(ETHYLENE TEREPHTHALATE) (PET) BLENDS WITH CHAIN EXTENDERS (CE) AND NANOCLAY
Recycled poly(ethylene terephthalate) (RPET) chain extender (CE) and nanoclay were prepared via conventional and microcellular injection molding processes. The effects of CE loading levels and the simultaneous addition of nanoclay on the thermal and mechanical properties and cell morphology of the microcellular components were noted. The addition of 1.3 wt% CE enhanced the tensile properties and viscosity of RPET. The higher amount of CE (at 3 wt%) enhanced the viscosity, but margin of improvement in mechanical properties diminished. While the solid RPET and CE blends were fairly ductile, the samples with nanoclay and all microcellular specimens showed brittle fractural behavior.
IMPACT OF FIBER ORIENTATION ON PHYSICAL PROPERTIES OF GLASS-FILLED POLYBUTYLENE TEREPHTHALATE
A combination of experimental observations and simulation methods has been used to determine the effect of side- and end-gate locations, respectively, on tensile stress at break for glass-filled polybutylene terephthalate (PBT) polymer. A hypothesis based on the stress distribution in the molded bars of two respective geometries has been presented. Simulation techniques using C-mold software has been used to confirm the hypothesis. The two sets of data together show that stress non-uniformity in the bars can play a role in determining the location and path of failure.
VARIABILITY IN STANDARD TWO-PROBE AND FOUR-PROBE ELECTRICAL RESISTIVITY MEASUREMENTS OF CARBON NANOTUBE COMPOSITES
This study characterizes sources of variability in electrical resistivity measurements of polycarbonate (PC) and carbon nanotube (CNT) composites. A two-probe measurement configuration in compliance with ASTM D 257 and ESD STM 11.11/11.12 was modified by incrementally applying additional force to the probe. This modification was found to significantly reduce variability attributable to contact resistance. A four-point probe measurement configuration in compliance with ASTM F 43-93 and ASTM F 84-98 was used to characterize local variations in resistivity within injection molded disks.
DESIGN AND INJECTION MOLDING FACTORS THAT AFFECT OVERMOLDING BOND STRENGTH
The product development team should always be asking the question: How strong does the bond strength need to be for a product design. Some products get used once and do not require high performance bond strength, while others are handled often and require higher bond stength. This paper focuses on both the design and molding factors that affect the ultimate bond strength between a polar plastic substrate and an overmolding TPE compound. It reviews not only ultimate bond strength, but factors that influence bond strength consistency. This information is important to both the product designer and the injection molder.
POLYMER DEGRADATION DURING CONTOUR LASER TRANSMISSION WELDING
This paper presents an experimental technique for assessing material degradation during contour laser transmission welding. Polymer is characterized using thermal gravimetric analysis (TGA). The experimental TGA degradation data are fitted to a kinetic model using the Freeman-Carroll technique. This model allows the fraction of degraded material to be predicted as a function of temperature and time. A FEM model is then used to predict temperature as a function of time at the weld for different laser and material parameters. The two models are combined to estimate material degradation at the weld interface. These results are related to experimental observations.
SYNTHESIS AND THERMAL STABILITY STUDIES OF NOVEL THERMALLY STABLE EPOXY-POLYURETHANE COMPOSITES
A series of hydroxyl terminated bisphenol-A type novolac epoxy resins modified with benzoic acid (MEP) were prepared. The chemical structures of MEP were characterized using FTIR analyses. And epoxy-polyurethane composites were also obtained by curing reaction among MEP, cross linker polyisocyanate IL1351 and phthalic anhydride. The thermal stability of cured products was studied by thermogravimetric analysis (TGA). The thermal stability of the cured MEP with different ring-opening rate, cured bisphenol-A type novolac epoxy resins and cured alkyd polyol A450 were compared.
DYNAMIC MECHANICAL ANALYSIS OF FDM RAPID PROTOTYPING PROCESSED POLYCARBONATE MATERIAL
This paper aims to investigate the dynamic mechanical properties of Polycarbonate material processed by Fused Deposition Modeling (FDM) rapid prototyping process. Frequency sweep is performed in Dynamic Mechanical Analysis (DMA) 2980 equipment to get modulus, damping and viscosity values. The effects of FDM parameters (built style, raster width, and raster angle) over these properties are presented. Frequency sweep experiment is done with the range of 10 Hz to 100 Hz in three different isothermal temperatures. It is found that solid normal built style gives more modulus and viscosity values than the other built styles.
EXFOLIATION AIDS FOR PREPARATION OF POLYMER-LAYERED SILICATE NANOCOMPOSITES
The use of supercritical CO2 and two cosolvents were examined to aid exfoliation of an organoclay within a thermoplastic polyolefin. The study examined the manner in which the gas environment was used in the presence of the clay, compatibilizer and matrix. This was done with an extensional flow mixer. The results of the work showed that supercritical CO2 was most effectively utilized when in the presence of the organoclay and compatibilizer as it melted. Both water and ethanol were effective cosolvents, producing smaller tactoids with a narrower size distribution. Ethanol was found to be the most effective as a cosolvent.
HOT MELT MIXING OF INDOMETHACIN AND SOLUPLUS FOR ORAL DELIVERY
An amorphous solid suspension for oral drug delivery was prepared via Hot Melt mixing 30wt% of Indomethacin (INM) with Soluplus. The melt mixed sample was characterized through optical microscopy, DSC, FR-IR and XRD. Dissolution test showed that INM release was pH-dependent; in the case of the amorphous solid suspension within 1h 90% of INM was released at pH7.4, while only 0.02% at pH1.2, probably a consequence of hydrogen bonds formed between INM and the polymer. The fastest release was obtained from the foamed amorphous solid suspension, followed by un-foamed amorphous solid suspension, then pure INM and finally the physical mixture.
EFFECT OF THE ADDITION OF CARBON NANOTUBES WITH POLYSTYRENE GRAFTING ON THE GLASS TRANSITION BEHAVIOR OF POLYSTYRENE
The effect of single-walled carbon nanotubes on the glass transition of polystyrene with and without polystyrene grafting has been quantified. Three different molecular weights, 2,800, 15,000 and 50,000 g/mol, of polystyrene were grafted to the nanotubes with the weight fractions of grafted chains approximately the same. Composites with 50 K grafted nanotubes were statistically identical in terms of the glass transition temperature and change in heat capacity. Composites with lower molecular weight grafted nanotubes did show significant differences vs. the composites with ungrafted nanotubes, especially in terms of the change in heat capacity.
EFFECT OF MOLECULAR WEIGHT DISTRIBUTION ON THE WELD-LINE INTERFACE IN INJECTION MOLDED POLYPROPYLENE
On the basis of a coarse-grained molecular dynamics with bead-spring polymer chain model, we investigated an interdiffusion of macromolecules of the separated flow fronts and stress-strain behavior under simple extensional deformation of the interfacial region. In polydisperse system, it is predicted that depletion of long chains takes place at the interface where short chains preferentially locate. Significant improvement of interfacial strength is predicted when molecular weight distribution is narrow enough to have a considerable overlap between long chains belonging to each phase separated by the interface. The calculation result reproduced the experiment on the interfacial strength of polyolefin material.
A GREEN PROCESS FOR THE SYNTHESIS OF MESOPOROUS SILICA MATERIALS
In this paper, mesoporous silica and functionalized silicas were prepared by a green template, polyamidoamine (PAMAM) dendrimers. Three silane coupling agents, 3-triethoxysilylpropyl- amine (APTES), -methylacryloyl oxypropyl trimethoxysilane (MAPTMS) and N-[3-(trimethoxysilyl)propyl]ethylenediamine (AEAPTMS) were used for modification on pore surface. The characters of synthesized silicas were investigated in detail. The results showed that controllable pore diameters, narrow pore size distributions, high surface area and pore volume were achieved. The PAMAM template can be feasibly removed by using water extraction.
THE APPLICATION OF DENDRIMER IN ULTRAHIGH MOLECULAR WEIGHT POLYETHYLENE PROCESSING
In this paper, poly(amido amine) (PAMAM) dendrimer, its lauryl quaternary ammonium salt and steary quaternary ammonium salt were used for blending modification of ultrahigh molecular weight polyethylene. The effects of modifiers on viscosity reduction, crystalline properties were investigated by torque rheometer, differential scanning calorimetry, X-ray diffraction analysis, etc. The results showed that three modifiers could decrease the melt viscosity of UHMWPE, which could be further explained from the view of distanglement.
ELECTRON BEAM IRRADIATION OF PP/EPDM BLEND: ULTRASONIC PREPARATION METHOD AND THEIR CHARACTERISTICS.
Electron beam crosslinked PP/EPDM prepared by melt compounding has been developed. To improve the compatibility of blend, high intensity ultrasound is imposed during processing. The tensile strength increase continuously with increasing irradiation dose and elongation at break is decreased with radiation. Moreover, as compatibility of blend is enhanced, Youngƒ??s modulus, tensile strength and elongation at break also increased. Thermogravimetric analysis shows that thermal stability of PP/EPDM blend is enhanced with irradiation dose and improvement of compatibility. The improvement in the properties of blend is attributed to the enhanced compatibility and the formation of radiation induced crosslinking.
DEVELOPMENT OF REACTIVE BLEND WITH SUPERCRITICAL CARBON DIOXIDE
A reactive extrusion process for immiscible PP/PS blend with peroxide and multifunctional agent in the presence of supercritical carbon dioxide was studied. Supercritical carbon dioxide was used in reactive extrusion to assist the diffusion of agent into polymer matrix. The PP/PS blends were investigated by rheological measurement, scanning electron microscopy and thermal property. The results indicate that complex viscosity and storage modulus of blend are increased by adding peroxide and multifunctional agent. Moreover, analysis of the products revealed that the use of supercritical carbon dioxide led to improved compatibility.
THE STUDY ON GRAPHENE OXIDE AS A HETEROGENEOUS NUCLEATION AGENT IN SUPERCRITIAL CARBON DIOXIDE FOAMING
Graphene oxide (GO) was prepared by oxidation of graphite using the Hummers method, and was modified by isocyanate to obtain dispersed GO sheets in dimethylformamide. Polystyrene (PS)/GO composites were prepared by solution blending, and their morphologies and properties were characterized. The addition of GO increased the glass transition temperature, storage modulus, and thermal stability of the composites compared with PS. Foams of PS and PS/GO composites were prepared by supercritical carbon dioxide foaming. The composite foams exhibited slightly higher cell density and smaller cell size compared with the PS foam, indicating the GO sheets can act as heterogeneous nucleation agents.
FEED ENHANCEMENT TECHNOLOGY FOR LOW BULK DENSITY MATERIAL INTO CO-ROTATING TWIN-SCREW COMPOUNDING EXTRUDERS
Effectively feeding low bulk density material into a co-rotating twin-screw has always been challenging. With the introduction of even finer particle size fillers as well as new generations of reactor resins, the issue has become even more problematic. Unit operations within the compounding process where material is more susceptible to fluidization are: transfer from storage vessel to feeders, from feeder to twin-screw and within the feed zone conveying section of the extruder. This paper will review a new Feed Enhancement Technology (FET) that provides significant improvement for the introduction of fine particle / low bulk density materials into the extruder.
INTEGRATIVE SIMULATION OF THERMOPLASTIC PARTS BY TAKING INTO ACCOUNT MOLECULAR ORIENTATION
The mechanical properties of thermoplastic parts are greatly influenced by the inner properties of the material in these parts. In order to take into account their effects an integrative simulation approach has been developed at the Institute of Plastics Processing at RWTH Aachen University. This approach until now has been focused on the local distribution of the microstructure and crystallinity depending on the processing conditions. This paper deals with the enhancement of the simulation approach that leads to a consideration of the anisotropic effects of molecular orientation in thermoplastic parts.
A STUDY OF INJECTION MOLDING OF THE BARREL FOR THE OPTICAL LENSES
A study of the barrel for the optical lenses based on the design of experiments is presented. The barrel provides an installation space for lenses to assembly. Therefore the optical characteristic of the mini projector is dominated directly by the lenses and the barrel. In this study, we analyzed the effect of the part thickness on the warpage by commercial software and investigated the influences of the molding conditions on the part quality experimentally. The study provides a systematical way to predict in which area a defect lies and determine the optimal injection velocity and holding pressure through statistical experiments.
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