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

PRECISE INJECTION MOLDING OF BIO-ABSORBABLE HAP/PLA COMPOSITES

Kazuyasu Uchiumi, Tetsuo Takayama, Hiroshi Ito, May 2012

Hydroxyapatite (HAp)/ polylactic acid (PLA) composites with different particle size distribution were fabricated using microinjection and hot compression molding. Physical properties such as mechanical and heat properties of the composites were also investigated, as were improvement mechanisms attributable to mixing particle size distribution. Flexural strength of neat PLA molded parts at room temperature was about 80 MPa, whereas that of HAp/PLA parts was 48–49 MPa, suggesting that flexural strength decreased because of dispersed HAp particles. The reduction of flexural strength apparently depended on the HAp particle size. The flexural modulus of neat PLA parts was about 3.0 GPa at room temperature, whereas that of HAp/PLA parts was 4.0–4.8 GPa, suggesting that the flexural modulus was higher because of the dispersed HAp particles. The flexural modulus of composites with bimodal particle size distribution was greater than that of composites with a monomodal particle size distribution. The height of microneedles of composites with a bimodal particle size distribution was slightly greater because of the lubricant effect of HAp.

STUDY OF THE INJECTION MOLDING TECHNOLOGY FOR THE NON-CIRCULAR LENS

Chung-Chih Lin, Jen-Yu Shie, Hsin-Shu Peng, May 2012

Compared to symmetrical and circular lenses, non-circular lenses have more issues on controlling process parameters during injection molding process. Unbalanced filling pattern and thickness variance in lens typically result in more defects which become a critical challenge in product developments. A study of non-circular lens with an aspherical contour through computer simulation assistance and design of experiments was presented. A non-circular lens and two convex lenses were assembled into a barrel to form an optical modulus for a mini projector. The optical characteristic of mini projector was dominated directly by the accuracy of the optical modulus. In this study, a reasonable injection speed which could reduce melt viscosity in molding process was calculated by simulation software and then design of experiments was conducted to investigate the influences of the molding conditions on the part quality experimentally. This study provides a systematical way to predict in which area a defect occurs and determine the optimal molding parameters based on simulation results and statistical experiments.

PREDICTION OF THE FLASHING MOMENT BY THE STRUCTURAL ANALYSIS IN CONJUNCTION WITH THE MOLDING ANALYSIS

Jae-Hyuk Choi, Joon Sung Tae, Byung-Ohk Rhee, Hyung-pil Park, Baeg-Soon Cha, May 2012

The contact-pressure-sensor detected the mold deformation caused by cavity pressure, but failed to predict the flashing moment. In this work, we tried to predict the flashing moment by the structural analysis in conjunction with the molding analysis. The pressure from the molding analysis was input to the structural analysis. The strain at the sensor location showed a close trend of the change. The stress at the parting edge showed the possible moment of the flashing.

DYNAMIC BEHAVIOR AND EXPERIMENTAL VALIDATION OF CELL NUCLEATION AND GROWING MECHANISM IN MICROCELLULAR INJECTION MOLDING PROCESS

Tai-Yi Shun, Yuan-Jung Chang, Chao-Tsai Huang, David Hsu, Rong-Yu Chang, May 2012

We present the recent development of three-dimensional prediction of dynamic behavior of cell nucleation and growing mechanism, and the effect of nucleation-growing competition in microcellular injection molding process. Simulations of microcellular foaming process of injection molding are carried out for polyolefins with supercritical fluids (SCFs) carbon dioxide and nitrogen. In addition, we validate simulation results with experimental results to prove the capability of 3D prediction of microcellular foaming process and further compare simulations of microcellular injection molding and conventional molding to provide insights and economic guidance into design and manufacturing of injection molding products.

TEMPERATURE INVESTIGATION IN REAL HOT RUNNER SYSTEM USING A TRUE 3D NUMERICAL METHOD

Tzu-Chau Chen, Yan-Chen Chiu, Wei-Da Wang, Chao-Tsai Huang, Cheng-Li Hsu, Chen-Yang Lin, Lung-Wen Kao, May 2012

Hot runner technology has been the solutions to the molding problems on many plastic injection products, such as automobile bumper, LCD/TV cover, bottle cap and so on. However, the mechanism behind the hot runner system is too complicated to be fully understood. In addition, there exist some critical issues in the current hot runner technology, such as temperture control issues, flow imbalance, and material degradation. As a result, the simulation technolgy is highly needed for hot runner designers and makers to examine their designs before the real manufacturing. Through simulation analyses, designers and manufafctuers are able to catch the potential issues on their hot runner systems and revise their designs. Hot runner simulation technology helps with the investigations into the behavior in hot runner system. In this paper, a true 3D numerical method is proposed and applied to investigate the temperature behavior in a real hot runner system for PC material. The experiment is conducted and the simulating result is compared with that from the experiment for the validation purpose.

THE SKIN/CORE MATERIAL DISTRIBUTION OF A CO-INJECTION MOLDING PROCESS: THE EFFECT OF PROCESSING CONDITIONS AND MATERIAL SELECTION

Shih-Po Sun, Chih-Yu Hsu, Chao-Tsai Huang, Kuo-Chou Huang, Shi-Chang Tseng, May 2012

With the growing use of co-injection molding process, an understanding of skin/core material distribution in the cavity is essential. We presented numerical simulations concerning factors including filling ratio, material viscosity, and injection rate. Both core penetration behaviors and skin ratio uniformity from the material distribution profiles were compared. In addition to material distribution predictions, numerical simulation also revealed breakthrough points and cornering-effect locations. This is helpful for the part manufacturer to enhance the benefits of the co- injection process through the computer-aided simulation.

IN-SITU COMPATIBILIZATION OF HDPE-FUMED SILICA COMPOSITES: MORPHOLOGY, RHEOLOGY AND FILM BARRIER PROPERTIES

Sangita Nandi, Sanjukta Bose, Susanta Mitra, Anup K. Ghosh, May 2012

In the present study, HDPE-fumed silica (FS) composites were prepared by melt-mixing with different filler loading and in presence of PE-g-MA compatibilizer. Dynamic rheological properties and morphological analyses of the composites supported the plausible interfacial interaction between reactive groups of PE-g-MA and surface silanol groups of FS. Oxygen and water vapor permeability of the films made from composites were increased due to presence of FS as well as due to compatibilization.

ANALYSIS OF THE PROPERTIES AS CONTENT OF END-GROUP FOR POLYCARBONATE (PC) IN MELT POLYMERIZATION PROCESS

Su Ran Lee, Sanghyun Park, Byung Hoon Lim, Kwan Hwi Park, Byoung Ok Jang, May 2012

There are two processes to polymerize polycarbonate in the petrochemical industry: One is interfacial polymerization(interfacial PC) and the other is melt polymerization(melt PC). Recently, the latter is mostly used in that it is eco-friendly process. The most difference of product produced by two systems is the content of specific end-group. It is detected to a little bit value in interfacial polymerization, while it generally has more content in melt polymerization. It is supposed that the more content of the end-group is, the bigger change of the property induce as surrounding environment. In order to analyze an effect of the end-group, polycarbonate substituted to other end-group was made from melt PC using a suitable end-capping agent. And then, several properties were examined like melt index, viscosity and color. As the result, the end-capped PC showed less change of the properties than general melt PC, and it is similar to interfacial PC. It was verified that the properties of melt PC is adversely affected by the specific end-group.

MARKET SITUATION AND POSSIBILITIES FOR INFORMATION PROCUREMENT OF BIOPOLYMERS (BIOPOLYMER DATABASE)

Maren Bengs, H.J. Endres, A. Siebert-Raths, May 2012

In the last three years the production capacities of biopolymers increased threefold. The current trend in the development of biopolymers is towards bio-based and durable materials, it veers away from biodegradable and compostable materials. As a result of this change and the significant growing market there is a bottleneck regarding the availability of information and technical data of biopolymers. The biopolymer database offers a knowledge platform about biopolymers with producer data and newly measured comparable properties. The presented comprehensive database reflects the market situation and serves as connection between manufacturers, converters and end users.

IS RTC THE LONG AWAITED PANACEA FOR INJECTION MOLDED PARTS?

Ken Crow, Raymond Foad, May 2012

In contrast to conventional injection molding, where the tool is cooled continuously, in Rapid Temperature Cycle Molding RTC™ the cavity surface is rapidly heated to around the glass transition or melting temperature of the plastic before melt injection. Benefits are summarized and quantitative results cited. These include: achieving fine surface finish and gloss, including for foamed and filled materials (Ra for foamed ABS reduces from 1500 to 30 nm and for LGF PP from 1600 to 150nm); elimination of visible weld line defects; improved transcription of surface micro- features; improved optical properties in clear moldings; reduction of injection pressure, allowing longer flow paths, lower machine tonnage, part thickness reduction with reduced cooling time, and reduced molded-in stress. Implementation of the two leading technologies for implementation of RTC™ are described: heating with steam; or use of external induction heating to rapidly raise the cavity surface temperature, both followed by water cooling. A case study for RTC™ is described, leading to series production of a metalized part for a German automotive OEM. Performance requirements dictated a thin metalized layer (0.2 -0.3?m), formed by physical vapor deposition. This being insufficient to hide weld line defects, and use of a thick primer layer (15 ?m) being unacceptable, raising the cavity surface by RTC™ induction heating was trialed and shown to be entirely successful in removing defects.

NEW DEVELOPMENTS IN FIRE RETARDANCY OF STYRENIC COPOLYMERS

Pierre Georlette, Yakov Rachmilevitch, Yaniv Hirschsohn, Sergei Levchik, May 2012

Styrenic copolymers such as HIPS and ABS are taking a very important place in the electronic industry. As they burn easily, brominated flame retardants are used to improve their flame retardancy. This paper presents developments with tris(tribromophenyl) triazine showing its contribution to environment protection by lowering carbon foot print and by its non-blooming behavior. Tris(tribromophenyl) triazine flame retardant systems enable reduction or even elimination of antimony trioxide while maintaining a good level of properties.

ADVANCED COMPUTATIONAL TECHNIQUE FOR THE OPTIMIZATION OF SPIRAL MANDREL DIES

Kenny Saul, Johannes Wortberg, Peter Köhler, Marcin Humpa Uwe Klemme,, May 2012

The extrusion-die is one of the main components in an extrusion line and influences the product quality as well as the whole process efficiency. The requirements on extrusion-dies are versatile and the design of extrusion-dies is a very complex process with the necessity for huge know-how. Therefore the whole design process of a spiral-mandrel-die (SMD) based on a parametric 3D-CAD-mastermodel has been coupled with a 3D-CFD-simulation and implemented into a fully automized process. The flexibility of the extrusion dies to reach a high product quality for different materials is one of six criteria for the automatic interpretation of the extrusion die quality.

FIBER LENGTH REDUCTION AND HOMOGENEITY OF INJECTION-MOLDED SHORT FIBER REINFORCED THERMOPLASTICS WITH SPECIAL REGARD TO THE INFLUENCE OF A STATIC MIXING NOZZLE

Elmar Moritzer, Christoper Budde, Christoper Budde, May 2012

During the injection molding of fiber reinforced materials, the molded component's mechanical properties strongly depend on the resulting distribution of the fiber lengths in the component. Owing to various influencing factors in the injection molding process, the fiber lengths are shortened in comparison to the pellet's initial fiber lengths. Within the scope of the experimental investigations, the different influencing factors, especially the influence of the mixing nozzle, were identified and analyzed.

HIGH PRESCISION MICRO MOLDING INJECTION OF 2 COMPONENT LIQUID SILICONE

Bjoern Dormann, Christian Decker, Gabor Juettner, May 2012

For the production of micro parts with very small shot weights, the micro-injection molding has become an established technology with a variety of concepts. Currently, a trend can be seen that the special procedures will be introduced in the micro-injection molding. The micro injection molding machine , formicaPlast, is prepared for these usual procedures. It does not matter if the micro parts have to be produced as an one component or a two component part, the technology os available to serve the indsutry needs for a high automised micro injection molding process.Furthermore, the powder injection molding and the silicone injection molding is already possible to turn a standard formicaPlast machine. The liquid silicone injection molding requires certain changes to the machine, but these are very limited. The following article presents the possibilities of liquid silicone injection molding production for various tasks and batch sizes of the formicaPlast.

POLYMER NANOCOMPOSITE FOAM FOR TEXTILE APPLICATIONS

Shu-Kai Yeh, Yu-Che Liu, Wei-Zhe Wu, Kuang-Chin Chang, Wen-Jeng Guo, Sea-Fue Wang, May 2012

In this study, the foaming of nonwoven fabrics and bulk polymers was investigated. Four different polymers that are commonly used for textiles including were foamed by batch foaming. Among the polymers, TPU seems to be most promising since it possesses the highest cell density. In addition, nanoclay was added to TPU to promote nucleation. Well dispersed nanoclay served as excellent nucleation agents. The cell size decreased to 1?m while the cell density increased to 3*1011cells/cm3.

DOSABLE SISAL FIBRES FOR THERMOPLASTIC COMPOSITES

Christoph Burgstaller, Manfred Q. Bachtrod, May 2012

The aim of this work was to improve the dosability of sisal fibers by coating sisal yarns with a film former prior to cutting, to yield dosable fiber bundles, which can be processed with standard plastics processing equipment and to evaluate the effectiveness of such fibers in a thermoplastic matrix. We found, that it is possible to produce such fiber bundles, which are properly dosable and yielded good properties in polypropylene matrix composites, although there is room for improvement via the selection of a film former, which is more compatible with the matrix.

NON-LINEAR STRESS-STRAIN AND DUCTILITY MODELING OF A POLYMER COMPOSITE WITH FILLERS

Sweta Somasi, Dev Barpanda, Nikhil Verghese, Ha Pham, May 2012

Traditional composite based micro-mechanics can be used to predict linear elastic properties for thermoset matrix system accounting for the effects of filler type, concentration and size. The focus of this paper is to understand the effect of rigid fillers on the constitutive properties of a fully cured epoxy thermoset polymer covering non- linear regime including failure. A methodology, using a combination of DIGIMAT and ABAQUS based FE-modeling was developed to fully capture the stress-strain behavior using a Leonov -based material model.

ANALYSIS OF NANOSTRUCTURES SYNTHESIZED BY USING RESIDUAL SOLIDS FROM WASTED TIRES AS CARBON SOURCE

Ricardo Mis-Fernandez, Carlos Rios-Soberanis, Jesus Arenas-Alatorre, Jose Azamar-Barrios, May 2012

This paper focuses on the synthesis and morphological characterization of carbon nanostructures obtained from the decomposition of residual solids waste tire (RSWT) in quartz tubes under reduced pressure (1.33 Pa) at 900 °C for 15 minutes. The synthesis exhibits, principally the formation of two phases: the first a fragmented solid black powder constituted by multi-walled carbon nanotubes (MWCNTs), onion-type fullerenes and spheres, the second a very bright metallic dark film. Analysis by microscopy (SEM and TEM) showed that the MWCNTs had an average diameter of approximately 25 nm and a length greater than 100 nm while the diameter of onion-type fullerenes was found to be 8 nm. The nanospheres showed different diameters, from 500 nm to 1.5 ?m and some have a metallic core surrounded by layers of carbon. The infrared spectra of the nanotubes exhibited absorption bands at 1631 and 1458 cm-1, corresponding to the double C=C and C-C bonds, and signals at 3438 and 1080 cm-1 that are related to the OH and C-O groups from oxidized graphite as it was identified in the dark film.

EFFECT OF NANOTUBE CHARACTERISTICS ON MULTIWALLED CARBON NANOTUBE/POLYAMIDE 6,6 COMPOSITES PREPARED BY MELT-MIXING

Brian P. Grady, Cristina Caamaño, Daniel E. Resasco, May 2012

Differential scanning calorimetry (DSC), x-ray diffraction, dynamic mechanical analysis (DMA) and electrical conductivity measurements were performed on multiwalled carbon nanotube/polyamide 6,6 composites with three different types of well-characterized tubes manufactured using fixed-bed catalytic processes. The tubes differed in diameter, number of walls and surface chemistry. There were not large differences in behavior with respect to modulus, maximum electrical conductivity and percolation threshold.

OVERVIEW OF THE TESTING PROGRAM ON FIBERS USED IN BALLISTIC APPLICATIONS

Walter G. McDonough, Amanda L. Forster, Haruki Kobayashi, JaeHyun Kim, Michael A. Riley, May 2012

The goal of this paper and presentation is to give an overview of the research effort to date being conducted at the National Institute of Standards and Technology on polymeric fibers used in soft body armor (SBA) and a discussion of future directions. The overview covers chemical and mechanical fiber testing, microscopy, and x-ray scattering as means to understand potential mechanisms of degradation in these materials. Tensile testing results at quasi-static and at high strain rates that are comparable to strain rates experienced during ballistic events are also presented.