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
Specific Mold Filling Characteristics of Highly Filled Phenolic Injection Molding Compounds
Sascha Englich, Thomas Scheffler, Michael Gehde, May 2013
The objective of the study is to analyze the influence of the mold filling behavior during injection molding of phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with changing the injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation.
Ultrasonic devulcanization of tire rubber of different particle sizes in twin-screw extruder
Avraam I. Isayev, Tian Liang, Todd Lewis, May 2013
The present study is devoted to ultrasonic devulcanization of tire rubber particles of 10 and 30 meshes by means of a new ultrasonic twin-screw extruder. Ultrasonic amplitude and devulcanization temperature were varied at a fixed frequency of 40 kHz. The die pressure and ultrasonic power consumption during devulcanization were recorded. Degree of devulcanization was investigated by measuring the crosslink density, gel fraction and revulcanization behavior. Rubber of 30 mesh exhibited a lower die pressure and higher degree of devulcanization than those of rubber of 10 mesh. Due to the higher level of devulcanization and lower viscosity of devulcanized rubbers at higher amplitudes, the temperature of devulcanized rubbers at the die was reduced with an increase of the ultrasonic amplitude. Cole-Cole plots, crosslink density and gel fraction of devulcanized and revulcanized rubbers, revulcanization behavior, and modulus of revulcanizates separated in two distinct groups based on the level of devulcanization and effect on molecular structure of devulcanized rubber. Revulcanizates with a greater degree of devulcanization exhibited higher elongation at break, while those with a lower degree of devulcanization exhibited higher strength and modulus. Revulcanizates of rubber of 30 mesh exhibited a consistently higher elongation at break. The normalized gel fraction versus normalized crosslink density was described by a unique function independent of the processing conditions and rubber particle size.
Sustainable Materials for Horticultural Application
Gowrishankar Srinivasan, David Grewell, Michael R. Kessler, William Graves, Schrader James, May 2013
Bioplastic materials were compounded utilizing soy, poly-lactic acid (PLA) and poly-hydroxyalkanoate (PHA) biopolymers along with ethanol industry co-products and biomass additives to manufacture horticultural plant containers. Various formulations and processing conditions were studied to improve mechanical properties of the plastics. These materials were developed and compounded at Iowa State University and subsequently injection molded into 4.5 inch greenhouse pots at R&D/Leverage, Lee's Summit, Missouri. The bioplastic pots were evaluated for their performance by studying plant growth of vegetable and ornament crops grown in them under greenhouse and field conditions. The pots were also characterized for degradation and water retention. Commercial polypropylene pots, 4.5” green color, were used as the control treatment for the study. Comprehensive growth studies along with degradation results identified numerous bioplastic types that performed as well as or better than commercial polypropylene plant containers. Among the different material types, SPA-PLA, a blend of soy and PLA resins, was observed to produce the best results in terms of plant growth compared to polypropylene plastic pots during plant production. This is attributed to the slow release of fertilizing compounds during the degradation of soy protein. Certain bioplastic pot types were observed to retain soil moisture content over a longer time period than pots made from other environmentally friendly materials, such as paper or peat moss. Such properties are considered beneficial during the plant production cycle when using horticultural pots because they require less watering.
Film Casting of LLDPE/Clay Nanocomposites Without and With Compatibilizer with the Aid of Ultrasonic Treatment
Setareh Niknezhad, Avraam I. Isayev, May 2013
One step process for ultrasonic compounding and film casting consisting of an ultrasonic extruder followed by a cast film machine was used to prepare cast films of linear low density polyethylene (LLDPE) and LLDPE/Clay 20A nanocomposites. Cast films of LLDPE, 90/10 LLDPE/compatibilizer, 95/5 LLDPE/Clay and 85/5/10 LLDPE/Clay/compatibilizer were prepared at take up speed of 1.524 cm/s (3 ft/min) and different ultrasonic amplitudes. The die pressure and ultrasonic power consumption were measured. X-ray patterns, NMR, FT-IR, thermal, and gas permeability properties of cast films were studied. The mechanical properties of the prepared films in the machine and transverse directions were measured. Cast films of LLDPE and 95/5 LLDPE/Clay nanocomposites were transparent, while cast films lost their transparency with addition of compatibilizers. The compatibilizer with higher maleic anhydride grafting showed better properties. The strength and oxygen permeability results improved significantly due to the addition of compatibilizer and ultrasonic treatments.
Mold Maintenance: A Strategy for Optimizing Mold Performance
Randy Winton, May 2013
All mold builders perform mold repair, usually on molds they built. But few strategize to also offer ongoing mold maintenance services. A system has been developed for training and certifying mold builders and to put in place a documentation software system that enables them to serve as an extension of molders' toolrooms, thus freeing up a molder's employees for only the most specialized on- site emergency mold repair work. This system, dubbed 'Certified Maintenance Provider', consists of training, software installation, and subsequent auditing, in order to position a mold builder to become a source for maintenance within the immediate region.
Approach to Fabricating Thermoplastic Polyurethane Blends and Foams with Tunable Properties
Haoyang Mi, Xin Jing, Lih-Sheng Turng, Xiang-Fang Peng, May 2013
Thermoplastic polyurethane (TPU) has been widely used in many applications because of its broad property range. In this paper, twin screw extrusion was used to produce TPU blends with tunable properties; the foamed samples were produced by microcellular injection molding (a.k.a. MuCell). Multiple tests were performed to confirm the miscibility and tunability of the blends. Fourier transform infrared spectroscopy (FTIR) was used to verify the presence of soft and hard segments in the three blends. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), combined with scanning electron microscopy (SEM), confirmed that soft and hard TPU were miscible at ratios of 2:1 and 1:2, but immiscible at a ratio of 1:1. Rigidity increased while the shape recovery rate decreased with increasing hard TPU content. The blend ratio influenced the foaming morphology as well as other mechanical properties of the foamed samples. Decomposition, as investigated by thermogravimetric analysis (TGA), and degradation, as measured in a phosphate buffered saline (PBS) solution, were also studied. It was found that TPU or blends with more hard segments decomposed and degraded faster.
Mold Alignment: Testing Engineered Options
Kenneth T. Rumore, May 2013
Molds are exposed to harsh conditions, as molding presses typically have platen sag which causes mold misalignment. For decades, this misalignment has been countered by leader pins and bushings used to bring the mold halves “close” and interlocks mounted on the mold parting line to bring alignment “home”. With the amount of weight hitting at each mold cycle, often for millions of cycles, interlocks have been prone to wear, galling, and eventual failure. This paper will disclose the engineering route and analytical method, versus an anecdotal approach, used to develop an interlock that has exponentially surpassed performance of other configurations.
Manufacturing of Polypropylene/Ground Tire Rubber Thermoplastic Elastomers by Ultrasonically Aided Extrusion
Jieruo Liu, Avram I. Isayev, May 2013
Compounding ground tire rubber (GTR) with thermoplastic polyolefins, such as polypropylene (PP), is a possible way to manufacture thermoplastic elastomers and also to recycle waste tires, thus solving a major environmental problem. The effect of ultrasonic treatment on the mechanical, rheological and morphological properties of PP and PP/GTR (ground tire rubber) blends in an ultrasonic single screw extruder (SSE) and an ultrasonic twin screw extruder (TSE) were investigated. PP and GTR was fixed at a ratio of 50:50. The treatment was carried out under amplitude of 5, 7.5 and 10 ?m, and at a flow rate of 2 lbs/hr. Pressure and ultrasonic power consumption were measured. Mechanical and rheological properties of untreated and ultrasonically treated PP indicated that TSE provided more degradation than in SSE. For 40 mesh blends from SSE, the mechanical properties improved with increasing ultrasonic amplitude. The viscosity indicated very little dependence on ultrasonic amplitude, which is evidence a formation of covalent bonds between PP and GTR. Viscosity of 140 mesh blends was lower than that of 40 mesh blends from both SSE and TSE, indicating a larger degree of degradation of blends with smaller rubber particle size. In addition, with smaller rubber particle size, much better elongation at break is obtained which indicates better adhesion between PP and GTR.
Validation of an Analytical Method to Estimate the Bulk Melt Temperature from In-Mold Temperature Data
Gabriel A. Mendible, Stephen Johnston, May 2013
An analytical method for estimating the bulk melt temperature in the injection molding process by means of in-mold temperature sensors data has been validated. The method was evaluated for experimental data and data acquired with a computer simulation of the process. The simulation considered the heat flux and heat accumulation throughout the cycle in the mold. For the simulation, a full 3D model of the mold geometry was developed. Most trends correlated for both simulated and experimental data; however, the magnitude of the predictions varied due to the sensitivity of the analysis to the parameters.
Dynamic Uni-Layer Melting Model
Trevor Spika, Munekatsu Kamiya, Hirotsugu Marumoto, May 2013
Traditional screw design theory is based on formation of a solid-bed of resin between the screw flights. Melting the solid bed is primarily accomplished by shear heating in the screw compression zone. However, there are several problems related to controlling this melting method. The research here will show how removing the screw compression zone and preventing solid bed formation allows for; 1) eliminating melt over-heating from shear heating, 2) improves melting efficiency, 3) increases melt stability, and 4) reduces material residence time. This melting model has been applied to a wide range of plastic materials and has been implemented in both injection molding and extrusion.
Mechanical Properties and Crystallization of Talc Filled Poly(Lactic Acid)/Poly(Butylene Succinate) Blend Composites
Weraporn Pivsa-Art, Supaphorn Thumsorn, Sommai Pivsa-Art, Hideki Yamane, Hitomi Ohara, May 2013
Poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) were blended in a twin screw extruder at various contents of PBS from 0-30 wt% with 0-20 wt% of talc by the extrusion process. The effects of PBS and talc contents on crystallization behavior and mechanical performances of PLA/PBS talc composites were investigated. The non-isothermal crystallization of the PLA/PBS/talc composites was carried out by a differential scanning calorimetry. The mechanical performances of the composites were investigated by tensile and impact testing. The incorporation of talc increase tensile modulus and perform constantly impact strength of the composites. In this study, the relationship between crystallization behavior and mechanical property was also elucidated.
Preparation and Properties of Polyethermide (PEI)/ Graphite Composites with Ultrasound Assisted Extrusion
Jing Zhong, Avraam I. Isayev, May 2013
Polymeric composites containing carbon materials, such as carbon nanofibers (CNF), carbon nanotubes (CNT), graphite, expanded graphite, graphene, were extensively studied. However, the agglomeration of carbon fillers makes their dispersion challenging and limits their potential use. In this paper, an ultrasound assisted twin screw extruder was developed to prepare polyetherimide (PEI)/graphite composites with untreated nature graphite (UG), modified graphite (MG) and expanded graphite (EG). The effect of ultrasound on rheological, mechanical and electrical properties of PEI filled with up to 10 wt% graphite was investigated. For PEI/UG composite, ultrasound showed little effect on these properties. However, for PEI/MG and PEI/EG composites, the storage moduli (G’), loss moduli (G”) and complex viscosity were all increased and damping characteristics were decreased with application of ultrasound. The PEI/EG showed an electrical percolation between 2.5 to 5 wt%, but PEI/UG and PEI/MG did not show any percolation even at 10 wt% graphite concentration due to their large particle size and agglomeration. Ultrasonic treatment improved the electrical conductivity of PEI/EG and reduced percolation threshold, but did not show any effect on electrical properties of PEI/UG and PEI/MG. Mechanical properties of all these composites showed slight differences with ultrasonic treatment.
Design of Injection Moldable Load Bearing Helical Springs with Polyethermide
Gurulingamurthy Haralur, Subramanya Naglapura, May 2013
Polyetherimide (PEI) (ULTEM®) with Tg of 217 °C, has intrinsic property of high tensile stiffness, tensile strength and retention of these properties at very high temperatures along with good creep resistance. These properties enable PEI’s, for engineering applications and increasingly being used for metal replacement. One such application is injection moldable load bearing helical. This article discusses designing of helical spring with rectangular cross section, using polyetherimide with glass fiber, as reinforcing filler, effect to glass fiber amount and fiber distribution in calculating the spring constant [K] and comparing the model to experimentally measured values. The fatigue performance of the spring is also presented.
Thermal and Rheological Characterization of Polylactic Acid
Wei Zheng, May 2013
The thermal and rheological properties of polylactic acid are investigated using differential scanning calorimetry and parallel plate rheometer. Polylactic acid is found to be able to crystalize both on cooling and on heating, and the extent of crystallization depends on the scan rates used. If the material is cooled faster than 30 K/min, the crystallization disappears on cooling. If the material is cooled slower than 2 K/min, no cold-crystallization is observed on heating regardless of the heating rate used. Additionally, rheological measurements are performed at different temperatures. Master curves are successfully constructed using time-temperature superposition.
Fiber Attritiion and Orientation Productions of a Fiber Filled Polymer Through a Gate: a Mechanistic Approach
Luisa F. Lopez, Daniel Ramirez, Tim Osswald, May 2013
In this work, a mechanistic fiber model is used to study the behavior of fibers as they move through the gate of an injection mold. The model represents fibers as chains of interconnected beam elements and includes effects such as fiber flexibility, interaction between fibers and fiber attrition. The ability to successfully injection mold a fiber reinforced part is affected by the gate design. Therefore, it is important to model flow through the gate in order to adequately study the filling and packing of the part. The simulations show how the deceleration of the melt as it leaves the gate and enters the mold cavity results in fiber buckling and damage.
Fitness for Use Testing of Eastman Tritan Copolyesters adn Other Transparant Plastics for Housewares Applications
Kaan Gunes, Brett Jones, May 2013
Use of transparent plastics is commonly preferred over glass in clear housewares applications due to their resistance to breakage, lighter weight, and design flexibility. Eastman Tritan™ copolyester is an alternative material to polycarbonate, styrene acrylonitrile (SAN), modified styrenics, and acrylics, which are traditionally used in housewares applications. In materials selection, it is important to connect generic datasheet information for materials with performance of materials in real use conditions through fitness for use (FFU) testing. Clarity, scratch resistance, heat resistance, toughness, chemical resistance, and dishwasher durability are some of the major attributes that are commonly compared in FFU testing of housewares. This paper discusses the respective pros and cons of materials, and demonstrates the excellent balance of properties of Tritan™ for durable housewares applications.
ESC of Polycarbonate Exposed to Hospital Disinfectants
Jennifer Hoffman, Brian E. Ralston, Ayyana M. Chakravartula, Maureen Reitman, May 2013
Handheld electronic devices, including wireless phones and diagnostic devices, are used in hospital settings where they are repeatedly exposed to cleaning agents and disinfectants. Polycarbonate (PC) and PC blends are common engineering thermoplastics used for device enclosures/components. While these materials are generally tough, certain chemical environments can contribute to catastrophic brittle failure at relatively low stress levels. The purpose of this paper is to illustrate the susceptibility of PC to hospital disinfectant chemicals and provide a practical example of stress-cracking in the PC housing of a handheld medical device.
Recent Innovations Using Electron Beam Radiation Processing: Property Improvement and Tailored Enhancement of Polymers for a Wide Range of New Applications
Daniel Yasenchak, Paul R. Minbiole, Shannon R. Wayne, May 2013
Polymers have a unique combination of properties, making them the material of choice for a wide range of applications in the market place. Research and development of polymer technology continues to expand the possible applications as well as the ability to create tailored solutions for specific needs. Ionizing radiation, especially from a highly-penetrating electron beam accelerator, is an effective and well-established tool used in the polymer industry to expand functionality, improve properties, and create custom-tailored solutions by the modification of polymers. There are two premier events in the world highlighting the latest research and development involving the irradiation of polymers: the International Meeting on Radiation Processing (IMRP) and the Ionizing Radiation and Polymers (IRaP) conference. This paper, based upon the most recent of these two conferences and other recent publications, will discuss how the use of polymers continues to expand through the use of electron beam processing and other forms of irradiation. Three areas of research and development will be highlighted: the expansion of mature technology into new arenas, the application of the technology to biopolymers, and additional novel applications which are being explored and largely still in their infancy.
The Mechanical Properties and Degree of Crystallinity of Biomedical-Grade PEEK
Christopher M. Yakacki, May 2013
The mechanical properties of two biomedical grades of polyetheretherketone (PEEK) from different manufacturers were compared with respect to degree of crystallinity. The polymer chemistry and structure of the two materials were verified using DSC, DMA, and FTIR. Modulus and strength were both showed to be proportional to the degree of crystallinity in annealed amorphous PEEK films ranging from 10 to 35%. Failure strain and toughness remained unaffected. Samples from PEEK-OPTIMA LT1 placards demonstrated a 22% higher modulus and 10% higher strength values compared to samples from Zeniva ZA-500 placards in strain-to-failure tests. The increase in mechanical properties was attributed to PEEK- OPTIMA LT1 having a higher degree of crystallinity. Finally, the degree of crystallinity was shown to vary between 27 and 36% within a spinal implant made from PEEK.
Continuous High Power Ultrasonic Extrusion of PEEK - CNT Nanocomposites
Todd M. Lewis, Avraam I. Isayev, May 2013
A micro-compounder using ultrasonic assisted technology has been developed and used for the dispersion of multi walled carbon nanotubes (CNTs) to produce polymer nanocomposites. This process is continuous and can be easily adapted to equipment that is currently being used commercially. The effects of compounding with and without ultrasound on torque, power consumption, rheological, morphological, mechanical and electrical properties in polyetheretherketone (PEEK) filled with 0-5 wt. % CNT were evaluated. Ultrasonically treated nanocomposites show increased viscosity with a slight improvement in mechanical properties. An electrical percolation of less than 1 wt. % was observed. Samples ultrasonically treated at 10 ?m showed a significant increase in viscosity due to improved dispersion at the molecular level. The incorporation of CNTs into PEEK showed up to a 15% increase in modulus with loadings up to 5 wt. % CNT and a significant decrease in electrical resistivity at CNT loading of 1 wt. %. The rheological percolation is observed to be between 2 and 5% and the electrical percolation is observed to be below 1 wt. % loading. Further investigation of the interaction between the CNTs and the matrix are in progress.

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