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.
Electrospinning employs strong electric fields to create nanometer scale fibers. The fibers are collected as a non-woven fiber membrane with a very large surface area to volume ratio. Sulfonated polystyrene, enzymatically synthesized polyaniline and blends thereof, and dye-sensitized composite polymeric systems were electrospun and studied to optimize fiber formation. It is expected that these types of electrospun materials will find potential use as new lightweight electronic and photonic materials in numerous device applications.
Poly (ethylene naphthalate)/Poly (ethylene naphthalate)-poly (ethylene terephthalate) copolymer [PEN/(PEN-PET)] blends were investigated. It was found that introducing PEN-PET copolymer to PEN/PET blending system instead of using PET caused the lowering of transesterification reaction in melt mixing as compared to PEN/PET blends. As the duration of mixing gets longer, the transesterification difference between PEN/PET blends and PEN/(PEN-PET) blends becomes more evident. The increase of transesterification in PEN/(PEN-PET) blends with increasing mixing time resulted in the decrease of melting temperature, while glass transition temperature increased. In addition, our time resolved light scattering data shows that slower crystallization could be obtained in PEN/(PEN-PET) blends as compared to PEN/PET blends.
Screw design, injection site and operating conditions are critical parameters which influence peroxide injection efficiency during PP vis-breaking. A visual study in a clear barrel extruder was performed with water and corn-syrup to simulate the mixing of a low viscosity ratio system. Liquid injection of peroxide into PP was then performed in a 30 mm COTSE and compared to the normal pre-mixed peroxide method. Operating conditions were found to greatly influence degradation by shear and injection efficiency.
The evolution of the anisotropic structure of PPV films with stretching was studied by three characterization techniques: three dimensional refractive indices using waveguide, infrared dichroism and flatplate x-ray photography. The results show that the cast PPV film without stretching has a highly planar structure. One way stretching converts the film to a uniaxial structure.
The temperature distribution and the degree of cure in an epoxy system during the casting process, which is used in the connecting unit of high voltage cable, have been simulated using the FE solver of MARC including the programmed routines. The curing kinetics of the epoxy system used in the casting process was determined by DSC test, which was used as material input data of the developed program. To verify the developed simulation program, we have compared the simulated results for the simple model problem with those simulated by C-MOLD. The simulation results of real epoxy system for the connecting unit of the 400 kV cable, which is currently under development, are also presented for various processing conditions.
Super Small Outline Dual Inline Memory Module (SO-DIMM) is widely employed in the design of next generation notebook PC and portable electronic devices. The maximum warpage of the injection-molded connectors are required to be a low as 0.1mm in order to be compatible with the SMT (Surface Mount Technology) process. Design of Experiment method and computer simulation were utilized to investigate the complex interaction among final dimensions, mold design, grade of liquid crystalling polymer and injection molding conditions. By using the L9 orthogonal table, the most critical factor affecting the warpage was identified. The effects of other factors were also discussed.
Runner balance is one of the most important issues to be addressed for multi-cavity mold in the mold design phase. Poor runner sizing will lead to Christmas tree filling pattern and hence different residence time of plastic melt on each cavity. This leads to excessive packing pressure on small cavity and part weight variation. This problem becomes more crucial for the so-called family mold. In this work, the concept of flow balance index (FBI) is proposed to address this problem. Real industrial cases are studied by this new approach and are verified by molding trial results.
Cooling analysis has been the biggest obstacle in the simulation of the injection molding process, mostly due to the loss of convergence and enormous computation efforts encountered in the conventional boundary element method (BEM) approach. However, cooling analysis is not only essential in designing cooling channel layout, but also in optimizing the overall accuracy of filling, packing and warpage analyses. Fast Finite Element Method (FFEM) has been proved to provide excellent computation efficiency over the conventional BEM. A case study of complex car panel with FFEM is discussed in this paper.
For the proper design of cooling equipment and its dimensions in profile extrusion, it can be very useful to know the temperature fields inside the profile. To be able to understand the cooling process, a physical - mathematical model of heat transfer in the extruded profile must be used and the temperature field solved by an analytical or numerical method. There are only very few problems that can be solve analytically. We can say that some one-dimensional problems (not all) and very few two-dimensional problems can be solved analytically. For example, it is possible to solve a problem of cooling an extruded film or a thin plate. If the profile shape is more complicated, it is necessary to use a numerical method. One peculiar variable in all heat transfer simulations is the heat transfer coefficient. Its setting is important for the absolute results of the simulations. On the other hand, an approximate, but close, value of such a coefficient can cause some errors in the absolute temperatures but will still show the relative temperature distribution across the profile. In the majority of problems, the overall picture of the process is more important than knowing the exact temperature in a certain position. If a designer has a good picture about the cooling process, he/she can easily design the lengths of calibrators, their appropriate placing, the length of the cooling bath and so on. It is also possible to judge where the walls of the profile will probably bend. The designer can also decide what should be the cooling conditions, about the possible placement of infrared heaters, the length of the water bath and so on. In the case of a complicated profile it is almost impossible to imagine the temperature distribution inside the profile. In profile extrusion, any uneven cooling can cause bending, if not collapsing, of the profile. Therefore, knowing the relative temperature distribution may be more important than knowing exactly the temperature values. This presentat
This paper presents the application of CAE tools for a Blow Molding process. A description of the underlying theory is provided. The predicted thickness distribution for an example part is shown to have a good correlation with experimental measurements. The approach to parison thickness optimization is also demonstrated.
The macrokinetic of dynamic vulcanizetion was studied. Criteria for selection a cross-linked system and condition for conduction one-step dynamic vulcanizetion were suggested. The influence of the ratio of the basic components, the content of plasticizer and mineral filler on mechanical and processing properties of thermoplastic vulcanizates (TPV) was investigated. The ageing of TPV was connected with recrystallization of polypropylene (PP). The mechanism of TPV's deformation is proposed.
The objective of this paper is to document our study of injection molded part defects. The study of the defects is necessary in developing a training program for technicians and engineers. With this program one will be able to understand the causes of the defect and the steps required to eliminate it.
The comparative performances in three point bending and compression of syntactic foams comprising of epoxy resin and glass microballoons with the inclusion of chopped glass fibres of two different resin compatibility namely, epoxy and phenolic, are reported. The data showed that the compressive strength values differ marginally. As regards the flexural strength it increases for a change from epoxy to phenolic. When the properties of third syntactic foam with polyester compatible fibres was examined, it was found that the value was higher than the epoxy counterpart. This was attributed to the difference in the procedural route adopted for fabricating this latter foam.
Injection molding part designers are frequently faced with multiple quality and cost issues. These issues are usually in conflict with each other, and thus tradeoff needs to be made to reach a final compromised solution. Since evaluation of part quality and cost via injection molding simulation is very time-consuming, implementation of a conventional multi-criteria optimization procedure to injection molding problems is economically unfavorable. However, many injection molding problems dealing with multiple quality and cost issues can be modeled as constrained problems. By introducing a concept of Penalized Total Cost, such constrained problems are further simplified into bounded single-criterion problems. The bounded single-criterion problems are then optimized using a direct search-based optimization procedure. Strategies of modeling, transformation and optimization for these problems are discussed in this paper. A case study is provided.
There are many industrial applications in which shear and extensional behaviors of the material both play a role. This is true, for example, for flows in converging channels or flows in abrupt contractions typical of cable coating, fiber spinning or indeed flows in many plastics and rubber extrusion dies. Viscoelastic flow simulation has made it possible to predict these effects, at least qualitatively. Numerical simulations using a 3-mode PTT model reported here show a good quantitative agreement with experimentally measured pressure drops over a range of flow rates for both a short and a long conical capillary die. While this approach is physically meaningful, convergence at high Weissenberg number remains a challenge for the scientific community. This fact can sometimes justify the call for simpler, qualitative engineering approximations. By adding in the flow equations the dependence of the viscosity function on the third invariant of the rate of deformation tensor, it becomes possible to consider some effects of extensional viscosity in axisymmetric and 3D flows. We observe an increase in the pressure drop and the onset of recirculation patterns. We present numerical simulations of flow in a converging cone capillary and compare the results with available experimental data. We include simulation results for 3D die swell which show the influence of this extensional effect.
The effect of molecular reinforcement of diglycidyl ether of bisphenol F (DGEBP-F) epoxy by liquid crystalline (LC) diglycidyl ether of 4,4'-dihydroxybiphenol (DGE-DHBP) is investigated. The compositional effect of the LC moiety is related to mechanical properties. Tensile, impact and fracture toughness tests results are evaluated. Dynamic mechanical analysis is conducted to determine the effect of the DGE-DHBP on the glass transition and beta transition temperatures. Scanning electron microscopy of the fracture surface shows changes in failure mechanisms compared to the pure components. The results indicate that the mechanical properties of these blended samples are improved at 10-20% by weight of DGE-DHBP.
Damageability of automotive plastics, inflicted during events such as scratching, chipping, and compressive shearing, results in potentially high warranty costs and customer dissatisfaction. Polymer alloy composition, e.g., polymer-polymer interphase behavior and polymer-filler interactions, plays a major role in resultant damage resistance of a formed plastic part. Polymer processing, e.g., injection molding, also strongly affects the ability of a plastic surface to withstand such damage. This paper attempts to describe the role of polymer alloy composition, specifically filled- and unfilled-poly(olefin) blends, and final part processing behavior on surface damageability caused from scratching, chipping, and compressive shearing (gouging"). The role of interphase management e.g. control of miscibility between alloying agents appears to be the major factor affecting the ability of the plastic part to resist surface damage caused by external forces."
The recycling of post industrial ABS and PMMA was investigated. A material compound consisting of 100% post industrial (PI) recycled ABS and multicolored acrylic (PMMA) scrap from a manufacturing plants was blended and extruded. Test samples were injection molded and the test results were correlated to virgin material. Additionally, the material was used in injection molding of rear lamp housings in black and gray colors. The test results and economics are promising.
The effect of liquid crystalline networks on epoxy - glass fiber composites is investigated. Liquid crystalline epoxy resins (LCEs) have many advantages including outstanding high temperature stability, high lateral strength with high axial compressive strength. The matrix is obtained from in-situ curing of liquid crystalline diglycidyl ether of 4,4'-dihydroxybiphenol (DGE-DHBP) with diglycidyl ether of bisphenol F (DGEBP-F. Impact, tensile, and compressive results are compared between the unmodified and modified systems. Scanning electron microscopy is used to study the fracture surface to understand the mechanism of fracture and interphase formation between the fiber and matrix.
Poly-butyleneterephthalate (PBT) Fiber optic buffer tubes were manufactured while varying initial material Carboxyl Endgroup Concentration (CEC), initial moisture content, as well as extrusion linespeed and cooling profile. Mechanical tests on aged and unaged tubes were correlated to the state of material degradation through capillary rheometer experiments and Melt Flow Index (MFI) measurements. Incomplete drying and use of PBT with a high initial CEC are shown to lead to more rapid reduction of molecular weight during extrusion as well as poorer long-term hydrolytic stability. By proper selection of material and processing conditions, material lifetimes can be at least doubled.
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Brown, H. L. and Jones, D. H. 2016, May.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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