SPE Library
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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Conference Proceedings
Polydiacetelene Fiber Optic Pressure Sensors
M. Tabib-Azar, S. Angkaew, J. Lando, May 2000
Micro-opto-electro-mechanical sensors (MOEMS), where optics are integrated with micro-electro-mechanical systems (MEMS), are logical candidates for sensing flow, temperature and pressure in harsh environments. MOEMS offers small size, high frequency response, immunity to electromagnetic interference, and resistance to degradation from exposure to harsh environments. However, interfacing MEMS with fiber optics is quite challenging. Here we discuss the possibility of coating the fiber with a pressure sensitive polymer (polydiacetelene) to increase its coupling strength to a MEMS' deformable diaphragm. Interestingly, we noticed that the coated fiber, in this case, was itself sensitive to hydrostatic pressure and could be directly used as a pressure sensor. The sensitivity, reproducibility and the structure of this simple and inexpensive structure are discussed in this work.
Fiber-Optic Electric Field Sensors Using Polymer-Dispersed Liquid Crystal Coatings and Evanescent-Field Interactions
M. Tabib-Azar, B. Sutapun, T. Srikhirin, J. Lando, May 2000
A simple evanescent-field fiber- optic electric-field sensor is reported. The sensor is constructed by coating the exposed fiber-optic core with a polymer-dispersed liquid crystal (PDLC). The effective refractive index of the liquid-crystal polymeric coating [poly(methyl methacrylate)(PMMA)/E7] has a large dependence on the direction and the magnitude of an any electric field present. This dependence was large enough to enable simple transmission measurements to detect the presence of an applied electric field. By coating a PDLC film onto the exposed core of the optical fibers, we are able to detect an electric field. The sensors showed good sensitivity and reproducibility and a polarity dependence was observed. The time response of the device is dominated by the RC time constant of the structure rather than the response of the PDLC and is approximately 3 minutes with 15-20 minute relaxation time. Using an electric circuit model of the device we also discuss how these response times can be improved by many orders of magnitude.
The Effect of Molecular Structure on the Extensional Melt Rheology of Conventional and Metallocene Polyethylenes
Choon K. Chai, May 2000
Extensional melt rheology and processing characteristics of conventional high pressure low density polyethylene (LDPE) and Ziegler-Natta linear low density polyethylenes (LLDPE) are compared with both narrow and broad molecular weight distribution (MWD), long chain branched (LCB) metallocene polyethylenes. The effects of MWD and LCB on the melt behaviour of these different types of polymers will be presented in terms of their dynamic linear viscosities and their strain-hardening behaviour from transient tensile stress growth experiments. Film processability properties will also be discussed.
Method to Estimate Vibration Behavior of Fiber Reinforced Thermoplastic Parts
Takahisa Yasuzawa, Yoshinori Kanetoh, Teruo Tachibana, May 2000
Until now it has been difficult to estimate quantitatively the vibration behavior of FRTP parts using computer simulation. The reason was that the conventional simulation model did not express appropriately the damping properties of vibration (dependence on the temperature, amplitude, frequency and moisture content) and the orthotropic Young's modulus. Therefore, a new simulation model was proposed through measuring the damping factor of the specimen and the experimental modal analysis of the parts. Based on this model, the simulation result of the realistic vibration behavior on the FR-nylon product (e.g. air intake manifold) proved to be in good agreement with the experiment.
Improvement of Pentium-II Connector Support Design by CAE Tool
Thomas Hsieh, David C. Hsu, Alice S. Lin, Andy G. Day, Rong-Yeu Chang, May 2000
Weld line problem is crucial to a Pentium-II connector support part on appearance and mechanical consideration. In this work, a CAE tool is adopted during the product-development in order to detect potential weld line problem of the design. Various design revisions are proposed and tried on the computer. This approach is proved to be cost-and-time-effective to shorten time-to-marketing and avoid molding problem by improving design in advance.
In-Situ Production of Electrically Conductive Fibres in Polyaniline-SBS Blends
R.H. Cruz-Estrada, M.J. Folkes, May 2000
Electrically conductive polyaniline (PANI) was thermally blended with polystyrene-polybutadiene-polystyrene (SBS) at different weight compositions. The resultant blends were capillary extruded in order to generate a drawing process in the PANI. Microscopic analysis of the extrudates revealed that the PANI was deformed during the process to produce elongated structures. Electrical measurements showed the relationship between the electrical conductivity and the weight fraction of PANI in the blends.
Novel Fiber Surface Treatment for Use in Engineering Thermoplastic Composites
Jianwei Xu, Lawrence Acquarulo, Charles O'Neil, May 2000
A water-soluble polymer (Polyoxazoline) was used to treat nickel coated graphite (NCG) fiber and the treated fiber was then used to reinforce ABS, Polycarbonate and Polyetherimide. The water-soluble polymer improves the compatibility of the fiber in the thermoplastic resin matrix thereby providing an improved thermoplastic composite material with optimum mechanical and electrical performance.
Crystalline Transitions in Nylon/Clay Nanocomposites
Tzong-Ming Wu, Chein-Shiun Liao, May 2000
Nylon 6-clay hybrid is a molecular composite of Nylon 6 and uniformly dispersed silicate monolayers of synthesized saponite. Nylon 6 has two crystalline forms, ? and ?. The a phase is the thermodynamically most stable crystalline form but the ? phase is not. In this study, the nylon 6/synthesized saponite has prepared by the intercalation of e-caprolactam and then exfoliating the layered synthetic saponite by subsequent polymerization. The DSC thermal analysis and X-ray diffraction methods were used to investigate the crystal structure change of nylon 6/synthesized saponite. The results indicate the presence of crystalline transition in nylon 6 nanocomposites. The effect of thermal annealing on the crystalline structure of nylon 6 nanocomposites in the range between Tg and Tm is also discussed.
Characterization of the Interfacial Regions in Multilayer Coatings by NEXAFS Microscopy
Carl G. Zimba, Harald Ade, A.P. Smith, May 2000
Characterization of polymer interfaces is an important analytical need in many areas of technology. Many techniques, that provide the requisite spatial resolution, provide limited quantitative chemical information. On the other hand, techniques, that provide the desired level of quantitative chemical information, have limited spatial resolution. A relatively new analytical tool, Near-Edge X-ray Absorption Fine Structure (NEXAFS) microscopy [1- 4], provides a unique combination of chemical specificity and spatial resolution that is particularly well-suited for characterization of interfaces in polymer coating, blends and composites. In this paper, the application of NEXAFS microscopy to a multilayer polymer coating is discussed.
Rheological and Blown Film Characterization of Binary Blends of Metallocene-Catalyzed LLDPEs
Rajendra K. Krishnaswamy, David C. Rohlfing, Bryan E. Hauger, May 2000
The advent of metallocene catalyst technology has created several opportunities in the worldwide packaging film marketplace. In this work, we explore the effects of blending two metallocene-catalyzed LLDPEs of reasonably differing molecular weights. Specifically, the shear rheology, quiescent and shear-induced crystallization characteristics, and blown film performance were investigated as a function of blend composition. The presence of small amounts of longer molecules was found to have significant effects on the shear-induced crystallization kinetics and blown film orientation of the blends; this was explained in terms of an increasing number of extended chain nuclei for crystallization with increasing molecular weight. Lastly, the biaxial orientation features in the crystalline and non-crystalline phases of the blend blown films were also characterized and used in explaining the Elmendorf tear and dart impact performance of the blown films.
High Performance Rigid Flexible Combinations Made of Thermoplastic and Liquid Silicone Rubber
S. Boßhammer, E. Henze, May 2000
The injection molding of LSR represents a cost-efficient process for the production of high quality rubber parts for technical applications. Due to excellent material properties at extreme temperatures silicone rubbers offer various advantages for the production of soft/rigid combinations in comparison to thermoplastic elastomers. A new kind of LSR is presented which exhibits excellent adhesion properties to engineering thermoplastics. The process and the adhesion mechanism is designed in a way that no mold coating is required. A systematic analysis of the injection molding process points out suitable material combinations and indicates the influence of process parameters on adhesion strength.
Simulation of the Filling and Curing Phase in Injection Molding of Liquid Silicone Rubber (LSR)
E. Haberstroh, W. Michaeli, E. Henze, May 2000
The injection molding of Liquid Silicone Rubber (LSR) represents a cost-efficient process for the production of high quality rubber parts. Due to the extreme thermal conditions in the mold and the very low material viscosity a precise subvolumetric filling of the cavity is required to avoid flash formation. Modeling flow properties, curing characteristics and as the pvT-behavior creates the basis for an unified simulation of the injection molding process. The implementation of these models into a process simulation software makes it possible to calculate the filling phase considering a subvolumetric filling and to simulate the course of cavity pressure during the heating phase.
Optimising Nano Filler Performance in Selected Nylons
Charles J. O’Neil, Lawrence A. Acquarulo, Jr., Jianwei Xu, May 2000
A class of polymer materials having significantly improved properties has emerged. This class of material is being referred to as polymer nano composites. Typical of this class is the nano clay filled Nylon 6 family. We have recently found that by exposing the nano clay filled Nylon 6 materials to ionizing irradiation at low levels, 3 - 5 megarads that we further improve the flex-modulus. We have also found that this technology can be applied to Nylon 12. This technology is new to the 12.
Analytical System for Measuring Thermally Generated VOC Emissions from Polymers
Q. Xiang, S. Mitra, S. Dey, M. Xanthos, May 2000
An analytical instrument and procedures were developed to investigate the thermally generated VOC emissions from different polymers with a flame ionization detector (FID). This system was applied to estimate the upper limit of VOC emissions from recyclable 100% carpet residue by exaggerating its thermal exposure at a predetermined temperature. The pattern of VOC emissions was also studied for the 100% carpet residue as well as its composite (80% carpet residue + 20% virgin LDPE), and virgin resins (PP and LDPE).
Load-Carrying Ability of Injection Molded Products with Holes
Anton J. Heidweiller, Marcel J.M. van der Zwet, May 2000
The mechanical loadability distribution around a molded-in hole in a polystyrene plate has been analyzed using flatwise bending. Four different injection molding conditions have been applied. Birefringence measurements have been carried out to analyze the molecular orientation. The weld line is the weakest point, but the loadability reduction is small when it is related to the loadability perpendicular to the molecular orientation. Almost no effect of variation of process conditions was found.
Thin-Wall Injection Molding
S.C. Chen, H.S. Peng, L.T. Huang, C.T. Chang, D.Y. Wei, R.C. Ruo, May 2000
A precision monitoring system for high speed thin-wall injection molding machine was build so that hydraulic pressure, nozzle pressure, injection speed, filling to packing switchover and cavity pressures can be monitored during the whole molding process. Tensile test specimens of 2.5 mm, 1.2 mm, 1 mm and 0.8 mm thick were molded. It was found that as part becomes thinner the pressure prediction of CAE simulation gets worse and the errors range from about 50% to more than 100%. Filling time, proper filling to packing switchover, gate size, holding pressure and mold temperature were found to be the critical factors to successful molding and part quality. When part becomes thinner, residual stress is higher and affects part strength more significantly. When molding industrial thin parts, the residual stress concentrates around gate area, bosses and area where part thickness varies. Thickness reduction for the housing of computer dictionary can be achieved without great reduction in structural performance when localized thinning design is implemented.
Parison Wall Control Systems for Extrusion Blow Molding Equipment
Michael Thielen, May 2000
For a uniform wallthickness and layerthickness distribution even in complex-shaped blowmolded articles the parison has to be adjusted accordingly. Important developments in recent years were: • The Static Flexible Deformable Ring" SFDR and the "Partial Wall Thickness Control" PWDS for sophisticated articles. • The "Wallthickness Location Control" WDLS controls the actual position of wall thickness points which may "wander" e.g. due to changing raw material conditions. • The "Radial Wallthickness Control" RWDS for wallthickness control in bows of 3-dimensionally bent (3D-) parts. • A uniform layer thickness distribution in multilayer parts is achieved with a gravimetric throughput control system. "
Viscoplastic Analysis of Hot Embossing in Microfabrication
Yi-Je Juang, L. James Lee, Kurt W. Koelling, May 2000
In MEMS (micro electromechanical system), the hot embossing process has been mentioned as one of the major fabrication techniques, which is capable of making polymer microstructures for both low volume prototyping and high volume production. This is due to its simple process, relatively low tooling cost, high replication accuracy, and relatively high throughput. In order to minimize the process cycle time, the embossing temperature is set slightly above the glass transition temperature (Tg), while the de-embossing temperature is slightly below Tg. Since the polymer is deformed near Tg, its flow behavior during molding is substantially different from that at high temperature processes such as injection molding and extrusion. Also, the residual stresses resulting from the thermal cycle and compression force will profoundly influence the replication accuracy and optical properties of the molded parts. In order to establish the relationship between the residual stresses, replication accuracy, rheological behavior, and processing variables, we carried out a viscoplastic analysis and a series of hot embossing experiments. Two optical polymers, polyvinyl butyral (PVB) and polycarbonate (PC) were used in this study. The rheological property was characterized through both dynamic and transient shear viscosity measurements using the RMS-800 and a tensile test. Optical and SEM photos of replicates were taken at different processing conditions to determine the replication accuracy and birefringence pattern.
Biodegradable Laminates and Composites Containing Starch and Poly(hydroxyester-ethers)
R.L. Shogren, J.W. Lawton, W.M. Doane, J.L. Willett, May 2000
Poly(hydroxyester-ethers) (PHEE) were added to a variety of thermoplastic starch composites in order to improve the mechanical and water-resistant properties of these systems. Thin film coatings of PHEE's were found to adhere well to starch sheets and foams and provided resistance to cold water over short periods of time (hours-days). Adhesion was decreased by high water or glycerol contents in the starch and was increased by addition of partially hydrolysed polyvinyl alcohol. Extruded starch foam peanuts containing 5-20% PHEE were found to have a thin surface layer consisting mainly of PHEE. This probably explains, at least in part, why the starch/PHEE foams have a higher expansion ratio, greater water resistance and reduced friability compared to foams made from starch alone.
A Gram of Prevention: Additives to Improve UV Stability and Processability of Rotomolded Parts
Thomas Steele, Leonard Davis, May 2000
As the size of the rotomolding market increases, so do customers expectations for a longer service life and alternative resins. Small amounts of UV stabilizers and antioxidants can greatly improve the service life of a molded part as well as address some of the special challenges present in the rotomolding industry today. This paper will address the current issues in rotomolding and how UV and AO technology can be used to provide protection to the molded part.
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