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.
G. Tosello, A. Gava, H.N. Hansen, G. Lucchetta, May 2007
The insufficient entanglement of the molecular chains and the stress amplification at the v-notch of a weld line compromise the mechanical strength of a plastic product, also in the micro scale. To investigate the influence of process parameters on the weld lines formation, a special micro cavity was designed and manufactured by ?EDM (Electro Discharge Machining). Weld lines were quantitatively characterized both in the two-dimensional (direction and position) and three-dimensional range (surface topography characterization). Results showed that shape and position of weld lines are mainly influenced by mold temperature and injection speed.
Laser welding has proved an appropriate method for joining plastic parts. The increasing trend towards greater freedom of design, integration of ever more functions, and therefore more complex modules is putting increasing pressure on joining technology, and is thereby promoting the development and introduction of novel technologies.Laser welding of plastics is a suitable complement to established joining processes, and thereby opens up new fields of application. This has been demonstrated by numerous applications for small and even for larger components.Compared to alternative joining methods the contact free method has the advantage that hardly any flash or no flash is being produced, which means that joints with a high quality visual appearance can be produced. The laser is clearly superior to alternative processes, even for joining 3D geometries produced by coupling to a robot. The heat-affected zone is only a few #m deep and reduces the risk of surface flaws.The following paper is a case study for the introduction of the Laser welding process for electro-pneumatic valves. It describes the process development from the initial tests to the In-Line integration in mass production.
Measurements and simulation of three birefringence components and of the gas/polymer interface distribution in gas-assisted injection molding (GAIM) of a tubular geometry are presented. The governing equations of the process are derived using a nonlinear viscoelastic model and solved using a hybrid finite element/finite difference/control volume method (FEM/FD/CV). The measurements were carried out on polystyrene moldings before and after annealing. Simulation and experimental results indicate that the birefringence is high in the gas penetration region and low in the region where the gas did not penetrate.
Zaneta Brocka, Ernst Schmachtenberg, Gottfried W. Ehrenstein, May 2007
Electron beam irradiation primarily leads to cross linking in the amorphous fraction of semi-crystalline thermoplastics. As a result, there is a change in morphology and an improvement in mechanical and thermo dynamical properties. This effect can be utilized for tribologically stressed parts as micro parts and gear wheels. These parts feature an unfavorable relationship of part/volume leading to a disadvantageous formation of morphology and crystallinity. Experimental work shows the potentials of radiation cross linked polyamides. Due to cross linking in particular the thermal-mechanical and tribological properties are shifted into a range, which enables the employment of this substrate for application at elevated temperatures. Furthermore, the investigations on PA6 and PA66 show that a lower crystallinity degree leads to better results of cross linking via electron beam radiation and to an improvement of abrasion resistance.
Jan Spoormaker, Erik Andreassen, Anton Heidweiller, May 2007
The new European Failure Analysis and Prevention Special Interest Group (FAPSIG) is creating a database with failure cases. The members share this database and contribute with their own failure investigations. The two main groups are Failure Causes and Failure Mechanisms. Failure Causes are subdivided in: Stress concentrations, low mass and/or mould temperature, highly stressed weld lines, faulty ribbing; too high stiffness of construction elements, incorrect joining, and incorrect material selection.Failure Mechanisms are subdivided in: Creep and stress relaxation, wear, fatigue, UV degradation, chemical attack, environmental stress cracking.The paper will present some examples for designers of plastic products.
Chelsea A. Braybrook, Jennifer A. Lee, Philip J. Bates, Marianna Kontopoulou, May 2007
A newly constructed sliding plate rheometer (SPR) is used to investigate the high frequency linear viscoelastic properties of two polypropylene (PP) resins with widely differing melt flow rates. Extrapolation of rheological measurements obtained on a traditional parallel plate rheometer to frequencies obtained on the SPR, through use of the generalized Maxwell and Cross models, was used to assess the performance of the high frequency SPR. Good agreement between the extrapolated and measured data demonstrates the ability of the SPR to measure the high frequency rheological properties of PP.
Suchada Rianmora, Chana Raksiri, Supasit Rodkwan, Kunnayut Eiamsa-ard, May 2007
Development in design of mould using reverse engineering can reduce lead time and increase the quality of mould inspection. For two methods used: touch probe on machining center and portable arm coordinate measuring machine, these are used along software that is capable of measuring three-dimensional coordinate and analyzing the results. The first inspection is done on the machine during production (inline) then another is examined after production (offline). The experiment result demonstrates in terms of accuracy there is no significant difference between two measurement methods. Nevertheless, the portable arm CMM has an advantage in its simplicity, and require less operation and lead time.
Ralf Kühn, U. Burkhardt, Peter Heidemeyer, May 2007
Melting and incorporation of high viscous particles into a low molecular matrix is a difficult process due to differing requirements for melting and homogenizing. Melting is preferably done by using high shear rate and stress in combination with a small residence time. These facts lead to a fast turning small machine. Homogenizing on the other hand requires elongational flow, high viscosity and a significant amount of residence time which leads to a low revolution speed. By using a two step compounding system one can meet the differing constraints at the same time. Optimization of efficiency in pressure build-up can be done effectively by using state of the art CFD calculation methods.
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.
Kim McLoughlin Senior Research Engineer, Global Materials Science Braskem
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Kim drives technology programs at Braskem to develop advanced polyolefins with improved recyclability and sustainability. As Principal Investigator on a REMADE-funded collaboration, Kim leads a diverse industry-academic team that is developing a process to recycle elastomers as secondary feedstock. Kim has a PhD in Chemical Engineering from Cornell. She is an inventor on more than 25 patents and applications for novel polyolefin technologies. Kim is on the Board of Directors of SPE’s Thermoplastic Materials & Foams Division, where she has served as Education Chair and Councilor.
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Gamini has a BS and PhD from Purdue University in Materials Engineering and Sustainability. He joined Penn State as a Post Doctorate Scholar in 2020 prior to his professorship appointment. He works closely with PA plastics manufacturers to implement sustainability programs in their plants.
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Tom Giovannetti holds a Degree in Mechanical Engineering from The University of Tulsa and for the last 26 years has worked for Chevron Phillips Chemical Company. Tom started his plastics career by designing various injection molded products for the chemical industry including explosion proof plugs and receptacles, panel boards and detonation arrestors for 24 inch pipelines. Tom also holds a patent for design of a polyphenylene sulfide sleeve in a nylon coolant cross-over of an air intake manifold and is a Certified Plastic Technologist through the Society of Plastic Engineers. Tom serves on the Oklahoma Section Board as Councilor, is also the past president of the local Oklahoma SPE Section, and as well serves on the SPE Injection Molding Division board.
Joseph Lawrence, Ph.D. Senior Director and Research Professor University of Toledo
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Dr. Joseph Lawrence is a Research Professor and Senior Director of the Polymer Institute and the Center for Materials and Sensor Characterization at the University of Toledo. He is a Chemical Engineer by training and after working in the process industry, he has been engaged in polymers and composites research for 18+ years. In the Polymer Institute he leads research on renewably sourced polymers, plastics recycling, and additive manufacturing. He is also the lead investigator of the Polyesters and Barrier Materials Research Consortium funded by industry. Dr. Lawrence has advised 20 graduate students, mentored 8 staff scientists and several undergraduate students. He is a peer reviewer in several journals, has authored 30+ peer-reviewed publications and serves on the board of the Injection Molding Division of SPE.
Matt Hammernik Northeast Account Manager Hasco America
A Resin Supplier’s Perspective on Partnerships for the Circular Economy
About the Speaker
Matt Hammernik serves as Hasco America’s Northeast Area Account Manager covering the states Michigan, Ohio, Indiana, and Kentucky. He started with Hasco America at the beginning of March 2022. Matt started in the Injection Mold Industry roughly 10 years ago as an estimator quoting injection mold base steel, components and machining. He advanced into outside sales and has been serving molders, mold builders and mold makers for about 7 years.
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