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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In-Mold Transient Measurement of Thermal Diffusivity for Foam and Filled Materials Using Injection Molded Cylinders
The objective of this study was to evaluate the thermal diffusivity for foams and glass-filled resins during the cooling phase of the injection molding cycle and compare the experimental values with the standard values obtained by other methods.An aluminum mold having three cylindrical shaped cavities were fabricated. A special channel cut was machined and extended to the cavity edge to insert the thermocouple co-axially at the center of the cavity. The melt temperature obtained by the data acquisition set up and analog output converted to the digital signal and thermal diffusivity data calculated from the collected signal output.
Innovations in Selected Commercially Significant Polymer Blends and Blending Processes
Since the invention of high-impact polystyrene over some 40 years ago, there have been a great deal of activity on innovative polymer blends to develop synergistic properties, and on innovative blending processes to maximize their unique characteristics. Some of these successes are of significant commercial importance. We have examined more closely the events and their implications on a few illustrious cases.In the area of polymer blend products, inventions of blends of amorphous polymers, semi-crystalline polymers, amorphous / semi-crystalline polymers will be selected for illustrations. In the area of compounding process, innovations that overcome difficulties such as coalescence, unfavorable blend viscosity ratio, and method of imparting interfacial properties will be discussed.In almost all cases, the inventions were made without knowing that a scientific breakthrough was made. Only following painstaking investigations were the scientific basis of the inventions finally uncovered.
Innovations in Thermoplastic Elastomers: The Santoprene® Story
Thermoplastic elastomers (TPEs) have been commercialized for over 40 years and numerous applications have been developed. Very few TPEs, however, provide the true characteristics of thermoset rubber -- low compression set, good oil resistance and low hardness. Santoprene® thermoplastic rubber is the first thermoplastic vulcanizate (TPV) with fully vulcanized rubber phase that provides true rubber characteristics while maintaining excellent thermoplastic processability. Santoprene® TPE has successfully penetrated many applications previously dominated by thermoset rubber. Today, TPVs have one of the highest growth rates in TPEs and the Santoprene® TPE franchise enjoys the leadership position in TPVs.The Santoprene® TPE story will be shared from how TPEs got started at Monsanto, the challenges, and achievement of commercial success.
Integrating Plastics Manufacturing and Experimental Mechanics Courses
This paper addresses the joint development of a system to demonstrate stress in truss structures. Student designed truss structures were used in an upper level experimental mechanics class experiment with rapid prototyping, to analyze stresses with the finite element method, and to visualize states of stress through the photo- elastic method.The truss member components were designed jointly and the plastics class was tasked with developing tooling and selection of materials for the manufacture of the truss members. The plastics class developed a series of truss molds to demonstrate the effect of weld lines, and location of gates on the performance of the truss members.
Interactions of Long-Fiber Reinforced Core Material with Woven Fabric Reinforced Facings during Direct-Forming of a Thermoplastic Sandwich-Structure
The material described in this paper is a combination of long-fiber and textile reinforced thermo-plastics processed by an innovative technique in one step.In order to evaluate the sandwich system an automotive component has been selected. The goal is to offer a cost effective material with increased and load oriented mechanical properties by combining the advantages of a commingled woven fabric with long fiber reinforced thermoplastics (LFT).Beside describing the development of a suitable process technique this paper describes interactions between the TWINTEX® facings and the core material during the forming process.
Interface and Encapsulation in Simultaneous Co-Injection Molding of Disk: Two-Dimensional Simulation and Experiment
A two-dimensional simulation and experimental study of the flow-rate controlled co-injection molding was carried out. A skin polymer was injected first and then both skin and core polymers were injected simultaneously into a center-gated disk cavity through a two-channel nozzle to obtain an encapsulated sandwich structure. The physical modelling and simulation were developed based on the Hele-Shaw approximation and kinematics of interface to describe the two-phase flow and the interface development. The effects of rheological properties and processing conditions on the material distribution, penetration behavior and breakthrough phenomena were investigated. The predicted and measured results were found to be in good agreement with each other.
Interfacial Tension and Coalescence Reduction in Compatibilized PP/HDPE Blends
In this paper the compatibilization of polypropylene (PP)/high-density polyethylene (HDPE) blend was studied through morphological and interfacial tension analysis. Three types of compatibilizers were tested: EPDM, EVA and SEBS. The morphology of the blends was studied by Scanning Electron Microscopy. The interfacial tension between the components of the blends was evaluated using small amplitude oscillatory shear analysis. Emulsion curves relating the average radius of the dispersed phase and the interfacial tension to the compatibilizer concentration added to the blend were obtained. It was shown that EPDM was more efficient as an emulsifier for PP/HDPE blend than EVA and SEBS. The relative role of interfacial tension reduction and coalescence reduction to particle size reduction was also addressed. It was observed that the role of coalescence reduction is small, mainly for PP/HDPE (90/10) blends compatibilized by EPDM, EVA and SEBS. The results indicated that the role of coalescence reduction to particle size reduction is lower for blends for which interfacial tension between its components is low at interface saturation.
Internal Stress and Stretchability in Blown Oriented Polystyrene Films
Blown oriented polystyrene films was stretched along one direction and subsequently cross-deformed by stretching along the perpendicular direction, the cross-deformed film showed enhanced ductility with pronounced yield softening. Stress relaxation performed in both forward and cross directions showed power law relationship between the stress rate and relaxation time. The internal stress of cross deformation was significantly lower than that of the forward deformation at the same strain. The enhancement in ductility may be attributed to the lowering of internal stress during cross deformation. The stretchability upon film blowing is discussed in the light of the role of internal stress in biaxial deformation.
Introduction of a New Rheological Long Chain Branching Index for Isotactic Polypropylene Melts
A new rheological index for long chain branching (LCB), grheo, is introduced. The method is implemented for isotactic polypropylene (iPP) melts.Using statistical analysis, the average molecular weight (MW) and molecular weight distribution (MWD) values of a large number of linear iPPs (including metallocene and iPP blends) as well as iPPs with LCB are correlated with the crossover point coordinates and the four parameters from the Carreau-Yasuda equation. This allows us to define (independently of MWD and MW) grheo, whose value is one for a linear iPP and decreases with increasing LCB content.
Investigation for Injection Molding of Long Glass Fiber Reinforced Polypropylene
Four glass fiber reinforced polypropylene (PP) with various lengths of chopped glass fiber and pellet as well as one long-fiber compound PP pellet and short-fiber compound PP were injection molded to determine the fiber distribution and orientation of injection molded parts and the glass fiber length distribution.A custom-made screw was designed to minimize the damage of glass fiber after injection molding. The results were also compared with adhesive ability between compounded and uncompounded plastics. The molded parts were tested for their tensile strength, elongation, flexural strength, and impact strength. Other tests, including fiber length distributions and SEM, were also investigated.
Investigation of Applicability of Two Biodegradable Polymers for Mechanical Applications
Three types of specimens of a polyester-amide and a poly-hydroxybutyrate have been tensile and tensile-impact tested. Important geometrical parameters for these specimens are wall thickness and gate dimensions, as well as a weld line in one specimen type. Explanation of the combined influence of geometry and injection molding settings on tensile behavior was in agreement with tensile-impact results. This influence was maintained after 20 months of storage in closed boxes but minor embrittlement was found for all specimen types and both materials. The beneficial effect of annealing on strain at break for all poly-hydroxybutyrate specimens was also shown.
Investigation of Microstructure Developed in Injection Molded Nylon 6 Nanocomposites
The spatial variation of the microstructure developed along the thickness of injection-molded unfilled nylon 6 and nylon 6 nanocomposites are presented using small-angle laser light scattering (SALS) Hv-Vv patterns and micro beam wide angle X-Ray scattering (WAXS) patterns along with corresponding polarized optical microscopy pictures. The microstructure of unfilled nylon 6 changes from undeformed to deformed spherulitic case by the introduction of nanoparticles. The local spherulitic structure of the injection-molded samples from skin to core is addressed by their sizes and aspect ratios. These experiments indicate the development of significant chain orientation levels with the minor axis of the spherulites fluctuating in and out of the flow direction throughout the injection-molded part for the filled systems even at high temperatures.
Investigation of Optimum Conditions of Thin-Wall Injection Molding Process
Optimum conditions of thin-wall injection molding process of a cellular-phone cover are investigated via the use of computer-aided-engineering simulation and experimental measurements. CAE simulation using C-MOLD and a set of experimental tests based on design of experiments (Taguchi's method) scheduling are performed to determine optimum process conditions of an injection-molding machine by minimizing the shrinkage and warpage of the molded part. Effects of various process parameters of the injection-molding machine on the shrinkage and warpage of the molded part are also examined.
An Investigation of the Impact Behaviour of Rotomoulded Polyethylenes over a Wide Temperature Range
This paper examines the relationship between the impact strength of rotationally moulded polyethylene parts and the dynamic mechanical properties. A range of conventional linear low density polyethylene powders (LLDPE) and metallocene polyethylene powders (MPE) were rotationally moulded and tested. Falling weight impact tests were carried out over a temperature range from -60ºC to 20ºC. Dynamic mechanical thermal analysis (DMTA) was carried out from -100 to 90ºC, at different frequencies. Transitions evident in DMTA results are used to explain sub-zero maxima in the impact strength of the polymers tested.
Investigation of the Local Residence Time Distribution in Special Mixing Elements for Co-Rotating Twin Screw Extruders
Tightly intermeshing, co-rotating twin-screw extruders are commonly employed for tasks requiring good mixing. Mixing involves several mechanisms: longitudinal mixing laminar shear mixing and dispersive mixing. This work focuses on the longitudinal mixing behavior investigated for special twin screw mixing elements.We used a model extruder where two residence time probes were mounted to the barrel. For the experiments we varied throughput, screw speed and the material. By applying a deconvolution algorithm we were able to determine the local residence time distribution in the measuring section. The residence time distributions of the mixing elements were compared to those of standard elements (e.g. conveying elements).
Investigation of the Processing Characteristics and Mechanical Properties of Metallocene Polyethylene Foams for Rotational Moulding
The object of this work is to investigate the foaming characteristics of Metallocene-catalysed polyethylenes for rotational moulding. This paper reports on the results of ongoing experimental investigations in which rheological and thermal parameters are related to the polymer structure and mechanical properties of metallocene polyethylene foams. Through adjustments to moulding conditions, the significant processing and physical material parameters, which optimise metallocene polyethylene foam structure, have been identified. The results obtained from equivalent conventional grades of polyethylene (PE) are used as a basis for comparison.
Isotropic Residual Stresses in Thermosetting Resins: A New Instrument for Direct Measurement
The development of isotropic residual stresses is important in thermoset cure. These stresses are conventionally determined by curing the material in a cylindrical tube having a large length-to-diameter ratio. Despite its popularity, questions arise whether the stresses are isotropic or not in this method. To surmount this ambiguity, we propose a new method of measuring the build-up of isotropic residual stresses by confining the thermoset resin in a spherical geometry, thereby maintaining a truly hydrostatic deformation on the material. This paper describes the method and presents preliminary results on a model epoxy resin.
The Job Seeker Trilogy Preparation - Resume - Interview
While this trilogy is of value to anyone seeking a career change, it will be especially helpful to those now re-entering the job market after 10, 15 and 20 plus years, long-term career employees who are discovering that the process of job searching has dramatically changed, both good and bad over that time. The computer and the internet have created new and better tools; resources with new protocols and methodology. Many initially are overwhelmed; and, most find themselves unprepared, adding more stress and frustration to the emotional impact of an unexpected termination. Worse, the search process has also become increasingly more impersonal, requiring a different mindset to be successful. I know firsthand, having ‘been theredone that’, from being in the same situation less than five years ago, after closing a product design & development group I founded and managed for 20-years. If I knew then what I know now, I would have proceeded differently – and that is what I wish to share with you, hopefully making your career move easier, more effective and more successful in a shorter time-line. There are three major components to any search, and while books have been written on each, this trilogy will present the essence of all three – Job Search Tools for the New Millennium, will cover mental preparation and becoming informed on the expanded resources and options now available; the second, Your 30-Second Window of Opportunity – the Power Resume, will help you prepare an effective and dynamic resume and cover letter; and the last, The Interview – It’s a Mating Game, So Know the Rules of Engagement, explores mastering the phone and onsite interview, with the appropriate follow up.
Joining Applications in Exterior Automotive Panels Made of TPO (Thermoplastic Olefin)
Metallocene-catalyzed polyolefin thermoplastics became available to product designers when production was scaled up from pilot-plant levels to industrial-quantity production in the middle 1990s. The first large volume use of this material, referred to in industry as TPO, was exterior body parts for 2002 model year vehicles. As designers made decisions about where and how to use the material, it logically followed that an answer was needed to the question of how best to assemble these parts. This paper gives an overview of several new or improved applications of thermoplastic joining technologies to these parts, including ultrasonic spot welding, vibration welding, thermal staking, and ultrasonic inserting.
Key Elements in the Survival of Plastics Recycling Industries
The growth of the plastics recycling industry was spurred by increased resin prices and the landfill crisis of the 1980's. Many of the recycling companies that started in the 1980's and 1990's quickly learned that economic recycling of plastic waste was a difficult and challenging task. For many of these companies, the problems were overwhelming and they went out of business. Those that survived into the 21st century are a unique group of entrepreneurs. The bulk of the survivors are small companies with sales under $20 million.In this study, 36 plastic recycling companies in the U.S. and Europe were evaluated to determine the elements that aided their survival. Three elements that were present in the majority of these companies were: an ability to develop and maintain their own technology, financial or technical support from external sources, and strong leaders who were determined to make the business survive. These companies are the models for their industry. The stories of these companies could be of particular value to the emerging automotive and electronic post-consumer plastics recycling industry.
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