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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David Bigio, Rajath Mudalamane, Yue Huang, Saeid Zerafati, May 2000
The mechanical properties of glass-fiber reinforced thermoplastics depends largely on the post-processing fiber length distribution. The traditional method of compounding in an extruder followed by injection molding causes considerable fiber attrition. In this study, the benefits of using a novel type of machine -the Twin-screw Injection Molding Machine (T.I.M.E.) - is investigated. The effects of operating conditions such as screw speed, glass-fiber content and extent of screw fill, on the final fiber lengths and distribution are studied. Optical microscopy and image analysis methods were used to analyze the processed parts.
Nikos G. Pantelelis, Athanasios Bikas, Andreas E. Kanarachos, May 2000
At the present paper a new system with the aim to improve the RTM process has been developed and presented. The system is based on the assistance of the resin flow with mould-inducing mechanical vibrations. Potential advantages of the proposed method are the improvement of the quality of the composite part (reduction of voids and reach areas), decrease of the filling time and/ or the maximum applied flow pressure. A test apparatus has been set up at NTUA to study the various mechanisms that relate the resin flow through the preform mat, the curing and the external vibrations. The project is progressing well and initial results are very promising and will be presented at the conference.
Recent economic trends in the PVC market have pushed producers to reduce costs and improve productivity. Areas were sought where peroxide expertise can be utilized to develop new initiators that can help. Consequently a new developmental, fast peroxide for PVC, D-174, is being introduced which is reactive at lower polymerization temperatures, gives a more square heat profile and produces shorter polymerization cycle times for the PVC manufacturer.
Charlie Y. Lin, Michael C. Chen, Aspy K. Mehta, May 2000
The entry of metallocene-based products into polypropylene cast film is at a stage where potential in various markets is only now being assessed. The current thrust is to bring forward a set of differential properties to complement effectively Ziegler-Natta based poly-propylene cast film products. This study reviews the structure features of metallocene polymers and reports some potential benefits in cast film applications.
An unsteady-state, one-dimensional heat conduction model is used to calculate the temperature profiles in the melt and the substrate(s) when they come into contact in the nip of the extrusion coating or lamination process. The model helps answer such questions as: • Is the melt totally quenched in the nip? • Will the substrate(s) be exposed to temperatures above which shrinkage occurs? Will the temperatures promote post-crystallization? The answers to these questions aid in the understanding of adhesion, curling and optical problems in extrusion coating.
Ethylene copolymer resin (ECR) modifiers play an important role in low smoke PVC. As high molecular weight flexibilizers these resins reduce smoke and add strength and low temperature flexibility. This combination allows compounders to increase the flame-retardant additives without compromising strength or flexibility or by adding liquids which increase smoke. This paper is presented to demonstrate these attributes versus liquid plasticizers used in PVC compounds.
A new family of Surlyn® ionomers containing reactive functional groups is being developed for polymer modification, e.g., modifying nylon for blow-molding applications. Compared to existing ionomers, the new ionomers exhibit a higher degree of compatibility with nylon. One of the unique features of the new modifier is that the new ionomers can be dispersed in nylon in an extremely fine particle size and narrow size distribution. This has a profound effect on both the melt rheology and the mechanical properties of the modified nylon. Most significantly, the new ionomer imparts a truly shear thinning melt viscosity of the modified nylon 6. The paper discusses the dispersion of the new ionomer in nylon 6 as analyzed by SAXS and TEM and the melt rheology behavior of the modified nylon 6 and briefly highlights the effectiveness of the new ionomer to modify nylon 6 for the demanding blow-molding applications.
Prakash S. Sonti, Saleh A. Jabarin, Michael R. Cameron, May 2000
Room temperature viscoelastic behavior of PET beverage containers was studied. Internal pressures result in an increase of the container volume. By assuming a cylindrical geometry, stresses can be computed and linear strains can be estimated from the volumetric changes. A time-dependent creep compliance was determined for 2-L freestanding containers under various internal pressure loads. These values match favorably with uniaxial creep measurements. From isochronous plots, the viscoelastic behavior is shown to be linear over a limited range of pressures. The creep curves show all the characteristics of simple linear viscoelastic models such as instantaneous elastic response, retarded elastic response and permanent deformation.
Multilayer coextrusion is a process in which two or more polymers are extruded and joined together in a feedblock or die to form a single structure with multiple layers. These layers should be uniform in thickness across the structure for best performance. However, layer thickness non-uniformities have been observed in many coextruded products. Previous work has shown these layer thickness variations can occur due to viscosity differences between the polymers in the layers and/or elastic effects that introduce secondary flows. The objective of this work was to experimentally measure the secondary flow velocities in a square channel using a unique coextrusion feedblock that produces annular rings instead of planar layers.
L.J. Effler, N.R. MacMurdo, G.R. Marchand, May 2000
In traditional calcium stearate/paraffin wax systems, higher levels of wax leads to lower melt temperatures, higher gloss, and higher impact properties of the extruded sheet or profile. Unfortunately, higher levels of wax also leads to longer PVC fusion times, and an increased tendency to develop die plate out. However, recent work with ester lubricant systems, in PVC formulations using chlorinated polyethylene, have shown that lower extrusion temperatures, pressures and torque can be achieved without sacrificing fusion time or increasing the risk of die plate out. All while maintaining or enhancing gloss and impact properties.
C. Drew, X. Wang, K. Senecal, H. Schreuder-Gibson, J. He, S. Tripathy, L. Samuelson, May 2000
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.
Runqing Ou, Robert Samuels, Xingwu Wang, Richard Gregory, May 2000
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.
Hon Seong Koo, Seong Jin Park, Won Bae Kim, Cheol Min Kim, Young Kil Ha, Young Seong Kim, May 2000
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.
Kun-Chih Chen, Rong-Yeu Chang, David C. Hsu, Alice S. Lin, Kelly Lu, May 2000
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.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.