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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Rhological Properties of Water Molecules Nano-Jet Printing Process
This study investigates the performance of nanojet printing processes by molecular dynamic simulation. By compressing water molecules in the Au nozzle, the whole nanojet printing process for different operation conditions are simulated. Distributions of velocity, temperature, pressure, density, and so on, are also discussed in this study. The results form various systems show that the lower operational temperatures make nanojet processes more stable and thus reduce satellite droplets. Results that show various features can help understand these processes.
Direct Visualization of Conventional Injection Molding
A transparent mould with two injection locations, allowing flow visualization on both conventional and two materials injection molding, was used in this research.The aim of this work is to monitor and assess the polymer melt behavior under controlled processing conditions, during the filling and holding stages of the molding cycle. Visual access in the mould is allowed by the sapphire windows, surrounding the cavity. Visualization results are combined with local pressure and temperature measurements and compared with Moldflow MPI software simulations.
Determination of Gate Locations in Computer-Aided Injection Molding Analysis
With increase of injection molding CAE and adoption of 3D mesh which takes more computation time in analysis, gate location optimization in shortest time and smallest resources becomes most important issue. This paper discusses about the process of determining the gate locations using injection molding CAE, and the technologies developed for the optimization, which controls flow balance and weldline of molded parts.
A Statistical Approach to Plastic Pipe Production
In this study, the effects of process parameters of plastic pipe production to the plastic pipe's wall thickness were examined. Process and wall thickness data were collected in a regular time period and statistical calculation made according to these data. X-R control schemes drawn and process capability indices were calculated. Data points, which were out of control in a statistical manner, were determined and process parameters which causes these variations determined.
PLA/TPS Blends with Improved Ductility
Blending Polylactide (PLA) and thermoplastic starch (TPS) generally leads to brittle materials. It was found however that if the blends are properly compatibilized through reactive extrusion and plasticized, the TPS phase can significantly increase the ductility of the material leading to materials with elongation at break in excess of 200%. This paper examines compatibilization and plasticization strategies to combine PLA and TPS into useful injection moldable materials.
Determination of Valid Minimum Dimensions of DDENT Specimens to Evaluate the Essential Work of Fracture (EWF) of Polyethylenes
We studied how the dimensions of test specimens affect EWF results. One grade of commercial HDPE was evaluated. We demonstrate that reductions of ? 20 to 30% of conventional dimensions used for DDENT geometry allow reproducible and valid results, similar to those obtained with larger specimens. Results show that it is not possible to reduce dimensions more than 30% and still comply with geometric validations related to EWF.
Processing Conditions and Thermal Properties of Poly(Lactic Acid)
Poly(lactic acid) (PLA) is an excellent biodegradable polymer that is widely used. The processing conditions of PLA were established by developing a Molding Area Diagram (MAD) on a Roboshot® injection molding machine with different mold temperatures. Isothermal bulk crystallization kinetics of the PLA with 1weight% of talc as a nucleating agent was studied on DSC.
Crystallization of UV-Irradiated ?-Nucleated Polypropylene
The work deals with crystallization of photodegraded polypropylene containing various amounts of ?-nucleating agent. Samples were irradiated by UV-light, melted and subsequently non-isothermally crystallized. The results showed that the crystallization temperature decreased with increasing irradiation time. The irradiation caused the splitting of crystallization exotherms into two peaks indicating two crystallization mechanisms. The presence of ?-nucleating agent in the material suppressed the peak splitting.
The Use of Annodised Aluminum as a Rotational Moulding Tool Material
This paper presents the results from investigations into the differences in moulding with a novel anodised machined aluminium mould material and a conventional machined aluminium mould material. Significant differences in terms of cycletime were observed between the moulding carried out with the anodised moulding and the conventional aluminium mould surface material with no change in the shrinkage, part appearance or mechanical properties noted between either.
The Influence of Color
Color is an essential part of life for human beings. It influences our bodies, our minds and our souls. Our physiological, psychological and emotional responses to color have been studied in great detail. Over time the appeal of colors changes, leading to color trends in the market place. As new colorant and special effect technologies become available, our color choices and preferences continually evolve. Studying color perception and trends could provide the edge we, as an industry, seek in better understanding the market place.
Relationship between Surface Microstructure and Improved Scratch Whitening Resistance of Thermoplastic Polyolefins for Automotive Applications
This paper will examine the scratch whitening resistance of PP rich, injection molded Thermoplastic Polyolefins (TPOs) for exterior automotive applications. Significant attention will be given to the influence of the molecular architecture of the polypropylene (PP) component on the surface morphology and resultant scratch whitening resistance of the injection molded part. Material parameters and surface crystallinity which contribute to enhanced scratch whitening resistance will be highlighted.
Shrinkage and Cooling Simulation of Injection Molded Parts in Melt Solidification Processes
The numerical prediction of three-dimensional warpage simulation during cooling process for injection molded parts before demolding is conducted in this paper. Similar to other warpage calculations, the energy equation for injection molded parts is solved together a thermal elastic models to investigate the shape deformation inside mold. Different from previous studies assuming melt cooling from solid state, the injection molded parts are cooled from fluidic state using a solidification model. Additionally, the influence of mold constrain is also taken into account.
Microstructural Characteristics of Micro-Injection Molded Thermoplastics
A micro-injection molding machine was used to obtain micro-moldings of polyethylene, in order to study the effects of processing conditions on some microstructural characteristics of the moldings. The processing variables were estimated, based on experimental data and on simulation results. Polarized light microscopy was used to evaluate morphology. Three-dimensional distribution of shrinkage was measured. Micro-mechanical properties (modulus and hardness) were measured with a nanoindenter. The microstructure and properties will be explained in light of the thermo-mechanical history.
Wetting Behavior of Polydimethylsiloxane (PDMS) Ionomer on Silica Surface
The wetting behavior of poly(dimethylsiloxane) (PDMS) ionomers on a silica surface was investigated. Spin-cast films of Li-salts of a carboxylated PDMS (Li- CPDMS) on silica resisted dewetting even after annealing at 120°C for 144 h, while the unmodified PDMS did not even form a homogeneous film.
Evaluation of Different Injection Molding Screw Designs for Better Color Mixing
Improved color mixing for injection molding can be improved by different variables. Screw speed, melt temperature, backpressure, barrel temperature profiles, screw design, dispersion discs, etc. can all influence color dispersion. This study will focus on the screw design and its affect on color mixing and its affect on other process parameters.
Modeling of Non-Isothermal High Stalk Film Blowing Process by Using Variational Principles for Non-Newtonian Fluids
In this work, the high stalk film blowing model derived by using variational principles has been used to investigate the effect of cooling on the HMW – HDPE bubble formation with respect to final film properties. Moreover, the effect of the molecular weight and long chain branching has been theoretically studied by the help of the newly proposed generalized Newtonian model.
Extrusion and Spinning of Nylon-6,6 / Supercritical Carbon Dioxide Mixtures
This work had two aspects. In the first one, the interaction between CO2 and nylon-6,6 melt is explored by investigating by the effects of CO2 on nylon-6,6 shear viscosity and hydrogen bonding. In the second one, an attempt is made to establish feasible conditions for spinning of nylon-6,6/CO2 mixtures, to produce nylon filaments. Extrusion and spinning experiments of nylon- 6,6 / CO2 were conducted on a twin- screw extruder line and the effects of carbon dioxide on viscosity and spun filaments morphology and tensile properties were investigated.
Engineering Plastics for Laser Welding
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.
Plane Stress Rapid Fracture Resistance of Pipe Grade PE: Estimation from Tensile Drawing Data
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.
Development of Semi-Interpenetrating Polymer Network Electrolytes of Polyurethane and Polysiloxane
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.
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