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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Blends of Polycarbonate with Co-Polycarbonate of Bisphenol a and 4, 4’-Dihydroxydiphenyl
In comparison to a bisphenol A (BPA) based polycarbonate and a co-polycarbonate of BPA and 4, 4’-dihydroxydiphenyl, transparent blends of polycarbonate with 20 to 40 weight % of copolycarbonate have a higher notched Izod impact strength at low temperatures and thick section.Surprisingly, a blend containing 70% of copolycarbonate has shown more resistance to embrittlement after heat aging at 130°C for 20 days than all other blends. Its resistance to embrittlement is, indeed, comparable to the outstanding resistance of co-polycarbonate by itself.
Biocomposites: Sustainable, Value-Added Biobased Materials
Polymeric and composite materials from plant derived fiber (Natural/Bio-fiber) and crop-derived plastics (Bio-plastic) are novel materials of the 21st century and have the potential to be of great importance to the materials world, not only as a solution to growing environmental threat but also as a solution to alleviating the uncertainty of petroleum supply. As this new generation of biobased polymers enters the commercial market, success in competing with established petroleum based polymers will depend on their performance, properties and cost as determined primarily in the commercial marketplace. While environmental consciousness continues to grow, and some governmental programs have been established to assist with the entrée of biobased materials into the marketplace. E.g., the US Research and Development Act of 2000 along with Presidential Executive Orders 13134 & 13104 and the “Farm Bill” signed by President Bush on May 13, 2002, have a goal of achieving a performance/cost ratio competitive with petroleum-based polymers for value-added applications. The technology road map for plant/crop-based renewable resources 2020, sponsored by the U.S. Department of Agriculture (USDA) and the U.S. Department of Energy (DOE), has set a goal of increasing the utilization of basic chemicals from biobased renewable resources of 10% by 2020, and further increase to 50% by 2050.While the chemistry, reaction pathways and processing steps to producing biobased chemicals and polymers are relatively straight forward, it is the use of these materials in high performance, value-added applications that will be critically important to achieve sustainability and economic viability. The most promising path to achieve sustainability and economic viability is through the addition of biofibers to biobased polymers to produce biocomposites. Research underway in the Composite Materials and Structures Center at Michigan State University and other Universities has been directed at defining, de
Biobased Nanocomposites from Organo-Clay and Blends of Unsaturated Polyester and Functionalized Vegetable Oil
Biobased neat unsaturated polyester materials containing epoxidized methyl soyate (EMS) and their clay nanocomposites were processed with cobalt naphthenate as a promoter and 2-butanone peroxide as an initiator. A certain amount of unsaturated polyester resin (UPE) was replaced by EMS. The combination of the UPE and EMS resulted in an excellent combination, to a new biobased thermoset material showing relatively high elastic modulus and the constant glass transition temperature with up to 25 wt.% replacements with EMS. Izod impact strength was almost constant while changing the amount of EMS and adding clay nanoplatelets.
Microwave Processing of Chopped Natural Fiber Composites and Their Thermal and Morphological Characterizations
Experiments have been performed to investigate the effectiveness of microwave curing of natural fiber reinforced composites. Industrial hemp, flax, kenaf, henequen and glass (15 weight percent) reinforced epoxy (diglycidyl ether of bisphenol-A (DGEBA) cured with diaminodiphenyl sulfone (DDS)) composites were studied. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and environmental scanning electron microscopy (ESEM) were used to investigate material properties. Samples were processed using both microwave and thermal curing for comparison. Several composites reached a greater final extent of cure with microwave curing. ESEM micrographs indicate a lack of bonding at the interfaces between the fibers and the matrix.
Elastic Films from Polyolefin Elastomers
Vistamaxx Specialty Elastomers, hereby referred to as Specialty Polyolefin Elastomers, or SPE polymers, are polyolefin elastomers with isotactic propylene crystallinity1, 2. These polymers contain a predominant (>80%) amount of propylene with isotactic propylene crystallinity, with the balance of the composition being ethylene and other ?-olefins. This new family of thermoplastic elastomers are highly elastic and exhibit excellent recovery from deformation. These polymers share the processability of conventional polyolefins such as polyethylene and isotactic polypropylene and can, thus, be easily formed into cast and blown films using conventional plastic processing processes. The paper will discuss the processing and elastic properties of elastic films made using these polymers.
Elastic Nonwoven Fabrics from Polyolefin Elastomers
Vistamaxx™ Specialty Elastomers, herein referred to as Specialty Polyolfin Elastomers, or SPE polymers, are polyolefin elastomers with isotactic propylene crystallinity. These polymers contain a predominant (>80%) amount of propylene with isotactic propylene crystallinity, with the balance of the composition being ethylene and other ?-olefins. This new family of thermoplastic elastomers are highly elastic and exhibit excellent recovery from deformation. These polymers share the processability of conventional polyolefins such as polyethylene and isotactic polypropylene and can, thus, be easily formed into spunbond and meltblown nonwoven fabrics using conventional plastic processing processes. The paper will discuss the processing and elastic properties of nonwoven fabrics made using these polymers, with an emphasis on the influence of polymer characteristics and processing conditions on the elastic behavior of the fabrics.
Soft TPO Formulations Containing Specialty Propylene Elastomers
Vistamaxx™ polymers are Specialty Propylene Elastomers (SPE) 1 containing isotactic propylene crystallinity. The presence of the iPP crystallinity renders these polymers very compatible with polypropylene (PP). When these polymers are blended with PP, the flexural modulus of the composition is substantially reduced at low weight fraction of SPE. This paper describes the physical, rheological and morphological characteristics of SPE/PP blends, comprising SPE resins of varying MFR and crystallinity. The SPE composition in blends with a 3 MFR PP homopolymer is varied from 20 wt. % to 90 wt. The performance data is analyzed using regression models, correlating the blend properties with SPE and PP type and content in the formulation. Our results indicate that the SPE type, particularly crystallinity, has a strong influence on the physical properties of the blend formulations.
Elastomeric Modification of an IR Cured Unsaturated Polyester Resin to Improve Mechanical Properties
An elastomeric modification of the “core layer” in an Unsaturated Polyester Resin reinforced with two fiber glass chopped strand mats, was used to improve impact resistance. Stress-strain and rheological properties were also measured to evaluate overall performance. Prior to resin-modifier mixing, either cis-polybutadiene or 1,7 octadiene were prereacted (10 min. or 20 min.) with styrene. The reinforced three layer samples were cured in a medium wave IR oven. Results show that both modifiers impart a considerable increase in impact resistance, with a small decrease in Young´s and storage moduli.
Elongational Viscosity as a Tool to Predict the Foamability of Polyolefins
The foaming of Polyolefin’s (PO) by direct gas injection is a delicate balance between the melt strength of the expanding polymer and the pressure of the blowing gas in the growing cells.Important parameters in this process are: melting and crystallization temperature of the polyolefin grade, viscosity in the crystallization temperature range and elongational viscosity in the crystallization temperature range. In particular the increase in elongational viscosity or so-called strain hardening is vital for a successful foam structure.This paper shows how the elongational viscosity is measured according to the Rheological Melt Extension (RME) method. The experimental conditions for LDPE, LLDPE, mPE Plastomers and PP are defined and used for a series of 25 PO grades.These experiments show that the strain hardening ratio (SHR) is influenced by the average molecular length, Molecular Weight Distribution (MWD) and the Long Chain Branching (LCB).
Injection Molded Novel Green Materials from the Byproduct of Corn Based Ethanol Industry
The corn gluten meal (CGM) is one of the major byproducts of ethanol industries. The current use of CGM is more towards livestock feed. This research looks forward in using CGM in making novel biodegradable plastics by blending with one petroleum-derived biodegradable polymer like poly (?-caprolactone), PCL. The CGM was plasticized with glycerol and destructurized with guanidine hydrochloride (GHCl) followed by blending with PCL. Extrusion followed by injection molding processing was adopted in fabricating the new blended green materials. The processing conditions affected the performance of the blends. The resulting green materials were studied for their mechanical properties using dynamic mechanical analyzer (DMA), united testing system (UTS) and izod impact tester.
Characteristics of the Vitrification in the TTT Diagram
Vitrification corresponds a solidification of a polymeric thermosetting material when the glass transition temperature Tg of the material precedes the experimental temperature T. Relating the vitrification progress at various isothermal temperatures to the cure time builds the Time- Temperature Transformation (TTT) diagram for thermosets. There are a number of possible routes in this diagram that could lead the material to a representative glass state, including the isothermal cure route, continuous heating route, cyclic heating route, and temperature cooling route after allotted cure. However, the glass transitions involved in the different routes are different in nature, even though the material may have the identical chemical conversion (?) and the same Tg. Such a behavior may lead to interesting density profiles of the thermosetting material upon curing that might introduce potential richness of other chemical/physical responses in the glassy state.
pCBT: A New Material for High Performance Composites in Automotive Applications
Cyclic oligomers of butylene terephthalate (CBT®) represent a new chemical route to semicrystalline thermoplastic polybutylene terephthalate (PBT). The oligomers of interest melt completely at about 150°C to produce a low viscosity fluid that is ideal for wetting and dispersing fibrous fillers and reinforcements thereby enabling the development of composites that were previously not possible when working with high viscosity commercial PBT. Introduction of catalyst to undiluted molten cyclic oligomer leads to rapid ring opening polymerization and the formation of high molecular weight thermoplastic PBT without the generation of volatile organic compounds. The polymer resulting from this polymerization will be hereby referred to as pCBT. Treatment of cyclic oligomers in this fashion results in pCBT thermoplastic resin with a high melting point (230°C) and physical performance similar to that of other commercially available PBT resins. The low viscosity oligomers enables the selection of processing technologies that are typically reserved for thermosetting systems that work in conjunction with easy flowing monomers or pre-polymers. The combination of excellent mechanical performance and the ability utilize processing techniques typically reserved for thermosets enables broad uses for these oligomers in a range of applications including; interior, exterior and structural automotive components. Additionally, the thermoplastic nature of pCBT holds promise to provide a low capital route to a new family of pCBT based recyclable materials made using a range of plastic processing technologies.
Flow Based Manipulation of Conductivity in Nanotube Composites
Nanotube composites are finding applications due to their ability to enhance the electrical conductivity of polymeric materials. They exhibit a percolation threshold in both rheological and electrical properties at concentrations of ~1/2 % by volume nanotube. We study the interrelationship between these two coupled transport properties by dielectric spectroscopy and rheology. We study an extruded rod and find that the nanotube network and the electrical conductivity become highly anisotropic. We find that the conductivity is quite sensitive to the shear field and becomes highly anisotropic.
High Clarity Linear Low Density Polyethylene for Packaging Applications
As packaging applications become more demanding, film extruders are searching for resins with a combination of properties, including strength, clarity and stiffness. Many conventional resins, such as high-pressure low density polyethylene are clear, but lack the overall balance of toughness and stiffness that many applications require. Linear low density polyethylenes provide increased toughness and stiffness, but most lack the high gloss and low haze required for clarity applications. To achieve better film clarity, some extruders use lower density linear polyethylenes or blend with high pressure polyethylenes, thus sacrificing stiffness and toughness. A new polyethylene that combines good stiffness, clarity and toughness is now available for these demanding applications. This polyethylene, a 0.926 g/cc density linear low density based polyethylene can be used to produce stiff, clear films that can be used in a variety of applications including shrink wrap, and form, fill and seal applications.
Effect of Electric Field on Alignment Behavior and Conductivity of Composite Membranes
Composite membranes of sulfonated crosslinked polystyrene particles have been made by aligning the particles under an electric field in a crosslinked poly(dimethyl siloxane) matrix following a procedure described by Oren et al. (2004). The purpose of this work, however, was to investigate the effects of electric field amplitude and frequency on alignment behavior. As expected, the particles aligned only by application of a certain minimum electric field for a given frequency. Impedance measurements indicated that the unaligned membranes showed capacitive behavior up to 8 wt % particles, which transformed to conductive behavior on alignment.
An Overview of Innovative Technologies based on 2004 Automotive Innovation Awards
This paper provides technical detail of key technologies selected as finalist during the 2004 Automotive Innovation Awards Ceremony. Process related innovations such as SIB Fuel Tank Assembly, Running Board, Simultaneous Shot Injection Molded Instrument Panel, Gas-Assist Towing Package and Material related innovations such as Static Dissipative Non-Slip Truck Bed liner, 3.7L V-6 Engine Valve Cover, Two-Shot Load Bearing Touch-Off Molding are discussed are discussed first. Exterior Applications such as Body Color Blow Moulded Running Board, Carbon Fiber Rear Deck Assembly, and Hybrid Plastic/Steel Truck Front Step Bumper are described followed by Interior applications such as Door Trim with Integrated Acoustic Chamber and Subwoofer, Low Density Glass Mat Soft Touch Interior and Instrument Panel Carrier are discussed in detail.
Three-Dimensional Simulation of Gas-Assisted Injection Molding
Gas-assisted injection molding has established itself as a successful injection molding technique. The flow behaviors in this process are dominated by three-dimensional effects that are not yet completely understood. Consequently, much process and part design in gas-assisted injection molding is accomplished heuristically. Accurate simulations of the flow behavior will both assist part manufacturers to obtain optimal part designs and aid understanding of this process. This paper presents three-dimensional simulation results of gas-assisted injection molding and compares results with experimental data.
Corner Effect in Warpage Simulation
This paper discusses additional “spring forward” or “corner effect” considerations that influence the warpage simulation of parts with corners or sharp curvatures. Incorporating these terms into warpage simulation may significantly improve the accuracy of the deflection prediction if the polymer shrinkage is anisotropic and the part geometry has prominent corners or curvatures.This corner effect must be explicitly modelled when the warpage analysis is performed on “mid-plane” and “dual domain” shell geometry representations; however, no special considerations are required when using true 3D warpage analysis.
Online Adaptive Injection Molding Process and Quality Control
An online adaptive control methodology was developed to control the process and quality variables in injection molding. A process variable, such as the cavity pressure or mold separation, was selected for the process control, which adaptively changed the fill-to-pack switchover point from shot to shot, and adjusted the hydraulic pressure during the pack/hold phase within one shot. Further, a more sophisticated online adaptive quality control scheme was investigated that incorporated direct online quality control and neural network models in the feedforward loop. The neural network models were extracted from computer-aided engineering (CAE) predictions. Incorporating CAE results in the online quality control fills the gap between a science-based product/process design and an empirics-based process/quality control on the shop floor. This methodology can also be applied to monitor and control other quality variables such as part dimensions.
Warpage Comparison between Microcellular and Conventional Injection Molding
This research investigated the effects of processing conditions on the shrinkage and warpage (S&W) behavior of a box-shaped part using conventional and microcellular injection molding. Two sets of 26-1 fractional factorial DOE were employed to perform and analyze the experiments. After the machine and material reached the steady state condition, molded samples were collected and measured using an optical coordinate measuring machine (CMM). The results suggest that the supercritical fluid (SCF) content (in terms of SCF dosage time) and the injection speed affect the S&W of microcellular injection molded parts the most, whereas hold pressure and hold time have a greater influence on the S&W of conventional injection molded parts. This study also quantitatively showed that, within the processing range studied, an increase in dimensional stability could be achieved with the microcellular injection molding process.
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