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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T. Marchal, T. Burton, G. Franceschetti, J. De rijcke, C. Chauvin, H.M. Metwally, May 2007
In some industrial applications, like hydraulic hoses, a two-layer structure may be produced from the coextrusion of a soft Engineering Polyamide Alloy and a Thermoplastic Vulcanizate (TPV), like Santoprene™ Thermoplastic Rubber. As the inner layer, the polyamide component provides a barrier against oil at high temperatures; the TPV provides flexibility, resistance to abrasion as well as adhesion to the inner layer.Reaching a die design that yields the required concentricity and homogeneous material distribution in each layer is a challenge. The following two-step approach is here proposed. First a 3D numerical simulation using the POLYFLOW code confirms the current unsatisfactory extruded profile quality. A second extrusion simulation is next carried on a modified geometry to ensure proper flow balancing. A validation is performed for the coextrusion of a relevant Thermoplastic Rubber grade compatible with an Engineering Polyamide Alloy.
Eric van der Vegte, Marnix van Gurp, Hans Hoekstra, Alexander Stroeks, May 2007
The use of laser light energy to very locally weld plastic surfaces together has opened new possibilities for flexible design and assembly of plastics parts. However, this poses the challenge of applying a combination of transparent and absorbing plastic parts in order to use the laser light efficiently for local melting at the interface. Transparency is still a challenge in some cases, due to the scattering nature of certain plastics. This paper will focus on the optical requirements of the welded parts, but also on the physical aspects of the interface to form a strong weld.
The Rapid Crack Propagation régime in pressurised polyethylene pipe is limited by a critical temperature, which is determined mainly by the increasing resistance of the material to plane stress fracture. The Reversed Charpy and ASTM F2231 ‘Thin Charpy’ test methods are designed to index this property, at appropriately high rates, for quality control and material development purposes. This paper demonstrates that equivalent information can be derived from a procedure based on basic tensile drawing tests, via material properties which are more accessible to material design.
Adam Zerda, Kathryn Guggenheim, Beatrice Grau, Theo Hoeks, May 2007
Driven by weight savings, design freedom, manufacturing economics and pedestrian impact considerations, the use of plastics in automotive lighting has grown over the last decade to include all aspects of forward and rear lighting. Among these is the use of plastics in reflector applications where the molded plastic part is metallized, heated and expected to maintain high reflectivity and tight dimensional stability over time at use temperatures. In addition to the thermal properties of the plastic, other factors can affect the use temperature in such an application. The effects of metallization conditions, moisture and post-metallization aging are discussed as they affect the use temperature of a variety of high temperature thermoplastics.
Shu-Kai Yeh, Kwang-Jea Kim, Rakesh K. Gupta, May 2007
In this study, polypropylene grafted maleic anhydride (PP-g-MA) and styrene ethylene-co-butylene styrene block copolymer grafted maleic anhydride (SEBS-g-MA) were employed as coupling agents for polypropylene-based wood-plastic composites containing 50 wt% wood flour. Adding PP-g-MA to wood flour increased the tensile strength of the wood-plastic composite (WPC) by 60% and the reversed-notch Izod impact strength by 100%; the modulus remained essentially unchanged. By contrast, SEBS-g-MA had a greater effect on the impact strength but a smaller influence on the tensile strength; in addition, the modulus was reduced. On adding both PP-g-MA and SEBS-g-MA to the WPC, the impact strength increased by a factor of more than 2.5, but the tensile strength was not reduced. Since the incorporation of nanoclay increases the modulus of WPCs without decreasing the impact strength, the use of all three additives affords the possibility of manufacturing WPCs with high modulus and high impact strength.
A novel semi-interpenetrating polymer network (semi-IPN) electrolyte of polyurethane (PU) and polyether modified polysiloxane (PEMPS) with salt, LiClO4, were developed by using a solvent-free reactive process. The dissolution of LiClO4 in monomer and PEMPS was studied by using optical microscopy (OP), differential scanning calorimeter (DSC) and Fourier transform infra-red (FTIR) spectroscopy. The semi-IPN electrolytes of TPU/PEMPS were characterized by DSC and FTIR. The effect of PEMPS on the ionic conductivity of PU was also determined by using the modified LCR meter.
Sang Ki Park, Seong Hun KIM, Jin Taek Hwang, May 2007
Multiwall carbon nanotube (MWCNT) reinforced thermotropic liquid crystalline polymer (TLCP) nanocomposites were prepared by a melt compounding process. Incorporation of small quantity of the MWCNT improved the thermal stability of MWCNT reinforced TLCP nanocomposites. The rheological behavior of TLCP/MWCNT nanocomposites was dependent on the MWCNT content. The complex viscosity and storage modulus of TLCP/MWCNT nanocomposites increased with increasing MWCNT, resulting from physical interactions such as the nanotube-polymer matrix interactions and the nanotube-nanotube interactions. This increment effect was more significant at lower frequencies.
Helmut Potente, Hans-Peter Heim, Sebastian Kleineheismann, May 2007
In comparison to normal single screw extruders, the short extruder has completely different screw and barrel geometries that allow the plasticization of polymers over a very short screw length (L/D < 5). Experimental investigations demonstrated the influence of screw speed, throughput and die pressure on the plasticization process. Due to the fact that this extruder does not require external heating, except heating of the die, a characterization of the operating point is carried out with help of an energy balance of the extruder.
Hachmi Ben Daly, Hend Ben Hadj Salah, Kenneth Cole, Johanne Denault, Abdelwaheb Dogui, May 2007
The behavior of two polypropylene nanocomposites when immersed in distilled water or sea water at four different temperatures was studied and compared with that of neat PP. The nanocomposites showed a higher water diffusion rate and equilibrium moisture content. Nevertheless, because of their superior initial mechanical properties, after 42 days exposure they were still equivalent to unexposed PP. X-ray diffraction and infrared spectroscopy were applied to characterize the surfaces of the exposed specimens.
Han-Xiong Huang, Geng-Qun Huang, Jiong-Cheng Li, Deng-Hui Ling, May 2007
The use of simulation software to predict the process of blow molding can save considerable time and money in the product development and is becoming more widespread. However, for parison formation simulation, the current finite element (FE) software is suitable only for the situation where the die gap is fixed. In this work, a new method was proposed to apply the FE simulation to the varying die gap parison formation. In order to evaluate the availability of the new method, the predicted parison thickness distributions were compared with the experimental results. It is demonstrated that the new method has certain accuracy and reliability in predicting the parison thickness from a varying die gap.
MEMS and micro-fluidic technology are two of the fastest growing areas of micro and nanotechnology. The rapid fabrication of micro features is crucial to their continued growth. Previous studies of through transmission laser embossing showed that it produces high accuracy replication but there are difficulties with de-molding. Previous ultrasonic embossing studies showed that it produced rapid heating and the ultrasonic afterburst was effective for de-molding without damage to the part or mold. By combining ultrasonic with laser embossing we take advantage of the high precision of laser embossing with the rapid initial heating and ease of de-molding using an ultrasonic afterburst.
Kissinger method of kinetic analysis was modified for crystallization of polymer from melt to include both the uncrystallized concentration and differential temperature as the driving forces. The modified expression allowed an apparent energy presumably related to the growth behavior of the crystalline structure to be determined. From non-isothermal crystallization data the apparent energy of a polypropylene copolymer increased moderately from 2.98 to 3.44 KJ/mole as the talc content increased from 0 to 1%. The variation of apparent energy was correlated with the Avrami and Ozawa exponents. Both the modified Avrami exponent and the Ozawa exponent measured at Tc increased with talc content and cooling rate suggesting the increase of complexity in nucleation and growth due to talc.
Hybrid polymer nanocomposites based on polyhedral oligomeric silsesquioxane (POSS®) molecules with improved surface properties are of interest for a wide range of engineering applications. POSS molecules exhibit remarkable ability to modify polymer surfaces. Nylon 6/POSS Nanocomposites based on two different classes of POSS, a closed cage octaisobutyl POSS and an open cage trisilanolphenyl POSS, were prepared via extrusion. Surface topography and friction properties were evaluated utilizing atomic force microscopy. Contact angle investigation reveals enhanced hydrophobicity. Relative surface friction of Nylon 6 was also reduced by 45% by the appropriate selection of POSS molecules.
The American plastics industry is in the Ability Age created by outsourcing, industry consolidation, the power of Wall Street, the Information Age, and dynamically changing rules and environments.The challenges of this age are continually making right decisions and providing leading global valued growth while facing dynamically changing rules and environments. The opportunity of this age is having sufficient resources and information to act quickly.Coming from this age will be a new set of hypotheses aimed to continually make right decisions and provide leading global valued growth. One such hypothesis on using internal emerging technologies to lead outsourcing is proposed in this paper.
We report one rheological and microstructural investigation of dispersions of polyethylene microgels in squalane. Emphasis in literature has mainly been limited to systems that depend largely on polymer-solvent interactions and little is known of systems that exhibit both intra- and inter-particle crystallinity. The majority of similar reported systems are prepared using a bottom-up approach while the described system is prepared from recycled bulk XLPE via mechanical grinding and fragmentation by sonic energy. Bulk rheological properties and particle surface interactions are explored using conventional rotational and oscillatory rheometry.
M.Y. Serry Ahmed, Y.H. Lee, C.B. Park, N. Atalla, May 2007
High internal phase emulsion (HIPE) polymerization foaming process is controlled for production of novel foams with various microcellular structures and morphologies. In this study, organoclay, C10A and C20A and natural clay, Sodium montmorillonite (NaMMT) was introduced at different concentrations to control the microcellular morphology, cell size and open cell content. Scanning electron microscopy was used to observe the microcellular morphology and open cell contents, volume expansion ratio and cell sizes where evaluated. It was found that the open cell content increased as organoclay content increased, due to lowering the viscosity ratio of dispersed to continuous phases due to the addition of high molecular weight clay into the oil phase of emulsion. A correlation for the open cell content and volume expansion ratio depending on clay content was attempted and the result was quite satisfactory.
Han Jian, Yan Chenguang, Shen Changyu, Liu Chuntai, May 2007
The effect of processing conditions on the birefringence distribution in Polystyrene injection molded parts with weld lines was investigated. The gapwise averaged birefringence of injection molded parts was measured by photoelasticity method. Birefringence at weldline area generated by different obstacles was also investigated. It was found that melt temperature and packing pressure are the two dominant factors that determine the birefringence development of the molded parts. Birefringence distribution has an appreciable distinction at weldline area, which is attributed to the molecule orientation distribution, local flow behavior and melt meeting angle at the melt front.
Michael W. Alabran, Joey L. Mead, Carol M.F. Barry, David J. Carter, Ahmed A. Busnaina, May 2007
The effect of tooling geometry and processing conditions on the ability to injection mold nanoscale features was investigated for thermoplastic polyurethanes (TPUs). While pattern geometry was not as critical as feature size in determining good replication, TPUs exhibited enhanced replication quality when compared to a polycarbonate control. Melt temperature was limited by polymer degradation, but increasing mold temperatures provided better replication. Very high mold temperatures, however, did not improve replication and were detrimental to cycle time.
In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included melt blending, solvent casting and microencapsulation from w/o/w systems at concentrations up to 10 wt%. The modified polymers were characterized rheologically and by TGA to determine process and thermal stability, respectively, and by DSC to determine miscibility and types of the polymer-ionic liquid interactions. Potential applications in plasticization, lubrication and emulsification are discussed for selected polymer-ionic liquid combinations.
Batch trials were performed on a kneader reactor where a bulk co-polymerization was carried out. Polymerization conversion, viscosity build, reaction kinetics, and heat transfer calculations were performed using the experimental data from the batch trials. A continuous process was proposed for this bulk copolymerization and the models and results from the batch trials were used in designing the continuous process. Predictions of the continuous process using the batch trial data are compared to the actual continuous process, with a focus on polymer conversion, heat transfer, and torque prediction.
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