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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Reduction of Styrene Evolution from Thermoset Polyester Resin Composites
The incomplete reaction of polyester resins in fiber reinforced composites results in residual styrene monomer that slowly evolves from the polymer matrix over many years. In cars and trucks where extensive use of such composites are open to the interior of the passenger compartment the odor of styrene can become strong enough to be objectionable to the vehicle occupants. A design goal for the development of coupe sports car which makes extensive use of polyester SMC and liquid molded composites was to assure that the styrene concentration in the passenger compartment is not offensive. Simple test methods were devised to assess styrene evolution at the material component and vehicle levels. Through the systematic study of resin paste formulations process modifications coatings and part design features this design goal was met before the launch of the vehicle.
Characterization of High Performance Short Carbon Fiber / Epoxy Systems: Effect of Fiber Length
This paper seeks to quantify the influence of fiber length on the mechanical properties of discontinuous carbon fiber/ epoxy laminates produced by compression molding. New interest is being generated toward low-cost composite material forms for aerospace applications. The high-volume carbon fiber content combined with aerospace-qualified epoxy resins opens up opportunities for more aircraft parts to be made of non-metallic materials. The Boeing 787 Dreamliner uses this material form for the manufacturing of the structural window frames. This material-process combination is ideal for large volume production of three-dimensional parts allowing for the molding of complex contours thickness variations and stiffening ribs. Interesting relationships between fiber length and tensile compressive and flexural moduli and strengths are observed.
Recent Developments in UV Stable SMC Technology
The desire for weatherable sheet molding compound for use in a wide range of applications is growing due to the potential of eliminating paint or coatings on the molded article. The elimination of paint or protective coatings can result in significant cost savings and an improved environmental profile for the article. These savings can be realized if existing coating facilities are at capacity or if a green field investment is being considered. Weatherable sheet molding compound (SMC) technology has been previously available but has been designed for specific applications. Transfer of this technology into other application areas has resulted in some performance issues. This paper discusses new developments in weatherable sheet molding compound technology that allow its use in a wider range of application areas.
From Process Modeling to Elastic Property Prediction for Long-Fiber Inection-Molded Thermoplastics
This paper presents an experimental-modeling approach to predict the elastic properties of long-fiber injection-molded thermoplastics (LFTs). The approach accounts for fiber length and orientation distributions in LFTs. LFT samples were injection-molded for the study and fiber length and orientation distributions were measured at different locations for use in the computation of the composite properties. The current fiber orientation model was assessed to determine its capability to predict fiber orientation in LFTs. Predicted fiber orientations for the studied LFT samples were also used in the calculation of the elastic properties of these samples and the predicted overall moduli were then compared with the experimental results. The elastic property prediction was based on the Eshelby-Mori-Tanaka method combined with the orientation averaging technique. The predictions agree reasonably well with the experimental LFT data.
Strain Rate Effects on the Energy Absorption of Rapidly Manufactured Composite Tubes
As a result of recent increases in fuel prices and the growing number of accident fatalities the two major concerns of the automotive industry and their customers are now occupant safety and fuel economy [1 2]. Increasing the amount of energy and optimizing the manner in which energy is absorbed within vehicle crush zones can improve occupant survivability in the event of a crash while fuel economy is improved through a reduction in weight. Axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). This paper presents results from the tests conducted at quasi-static rates at Deakin University Victoria Australia and intermediate rate tests performed at the Oak Ridge National Laboratory Tennessee USA. The quasi-static tests were conducted at 10mm/min (1.67x10-4m/s) using 5 different forms of initiation. Tests at intermediate rates were performed at speeds of 0.25m/s 0.5m/s 0.75m/s 1m/s 2m/s and 4m/s. Quasi-static tests of tubular specimens showed high specific energy absorption (SEA) values with 86 kJ/kg for Carbon/Epoxy specimens. The SEA of the Glass/Polypropylene specimens was measured to be 29 kJ/kg. Results from the intermediate test rates showed that SEA values did not fall below 55kJ/kg for carbon specimens or 35kJ/kg for the Glass/Polypropylene specimens. When compared with typical steel and aluminium SEA values of 15kJ/kg and 30kJ/kg respectively the benefits of using composite materials in crash structures is apparent.
Toward the Development of a Test Standard for Characterizing the Energy Absorption of Composite Materials: Part II
One of the key factors preventing the widespread adoption of composites in primary crash structures is the absence of specialized test methods for the characterization of specific energy absorption (SEA). Aside from thin-walled tubular specimens a limited number of attempts have been made at developing test specimens that are easier to manufacture. The possibility to employ a self-stabilizing corrugated plate specimen has been previously presented. In this study results from three corrugated plate geometries are compared with those of a flat plate specimen. The latter is tested using ad hoc developed support fixture which is based on an initial concept proposed by NASA/ Army. Preliminary results show that the flat specimen SEA results do not agree with those of the corrugated ones thus emphasizing the complex nature of SEA.
New Technology for Coating of a Polymeric Catalyst onto a Metallic Substrate
This work is based on coating a polymeric catalyst onto a metallic substrate by using of a surface coating technology. We have used adhesion promoters (Silane compounds) under sol-gel process in order to achieve maximum stability of coating and suitable strength properties. Structural packings produced by this method would have unique physical properties and may be used in catalytic distillation.
Thermal and Electrical Conductivity of Carbon/Liquid Crystal Polymer Composites for Fuel Cell Bipolar Plates
One emerging market for thermally and electrically conductive resins is for bipolar plates for use in fuel cells. Bipolar plates require high thermal and electrical conductivity. In this study, carbon black and synthetic graphite were added to a liquid crystal polymer and the resulting composites were tested for thermal and electrical conductivity. Single filler composites containing 2.5 to 15 wt% carbon black and 10 to 75 wt% synthetic graphite were tested.
Synthesis and Characterization of Polyacrylamidechitosan Hydrogels
Polyacrylamide/chitosan hydrogels were synthesized in aqueous itaconic acid solution (1% w/w), in order to determine its swelling kinetics at various chitosan concentrations. Analysis of the hydrogel swelling behavior indicated that the network properties of the gel changed depending on the swelling pH, as well as the amount of chitosan, showing a decrease in swelling capacity when the chitosan concentration was increased; this behavior can be explained due to the presence of the chitosan ionic groups.
Techniques to Determine Resistance to Surface Damage on Decorated Plastics
Most consumers believe the price paid for a product is directly related to its inherent level of quality. With decorated plastics, how robust the product finish is before it becomes damaged or worn out" is an essential element of this perceived quality. This paper presents an introduction to the mechanisms of surface wear and scratch damage and the importance of conducting controlled laboratory tests. An overview of several commercially available instruments is offered including suggestions on how to recreate and measure "real-world" damage."
Polyurethane-Carbon Nanofiber Composites for Shape Memory Effects
Thermoplastic polyurethane-carbon nanofiber, TPU-CNF, composites were prepared in situ in a chaotic mixer. Two types of CNF with different levels of surface oxidation were mixed with a shape memory TPU. Electrical conductivity, thermal behavior, and mechanical properties were investigated. Electrical and thermal-induced shape recovery behaviors were evaluated. TPU with treated CNF showed better dispersion, crystallinity, tensile properties, and better shape memory properties such as higher shape recovery force than their counterparts with untreated CNF.
Rotomolding with Micro-Pellets when Using Aluminum Pigments
Rotomolding parts with aluminum pigments has been a challenge, as this process provides limited aesthetic effects. Rotomolding compounds made by fine micro-pelletization provided a good method of aluminum pigment incorporation. Our research was to determine the benefits and limitations of this manufacturing method.
Impact Resistance of Selected Immiscible Polymer Blends
Immiscible polymer blends were prepared by melt extrusion using a single screw extruder in the systems PS/HDPE and PS/PP to assess the effect of composition and morphology on tensile Young's modulus and impact resistance. Results from the work show that tensile modulus nearly follows rule of mixture behavior for both systems, although better performance is shown by the PS/PP blends. With regard to impact resistance, the PS/HDPE system showed poor, incompatible performance, whereas excellent impact resistance was noted in the PS/PP blends.
Modeling and Simulation of the Complex Flows in the Extrusion Process of Plastic Profile with Metal Insert
The extrusion technology of plastic profile with metal insert is recently an advanced plastic processing method. However, its mechanism research work is lagging behind. In this paper, we developed the mathematical model of the extrusion process and simulated the three-dimensional complex flows in the extrusion die by the finite element method based on the CFD theory. The change of the melt rheological properties versus different processing conditions was investigated and some practicable advice on the process operation was accordingly put forward.
Continuous Ultrasonic Process for Preparation of PET/LCP Blends
Wholly aromatic polyester, LCP, was blended with PET to produce self-reinforced composites using an ultrasonically assisted single screw compounding extruder. Ultrasonic intensity was varied to induce in-situ compatibilization in the blends and was found to decrease pressure, and affect morphological, rheological and mechanical properties. PET and LCP homopolymerization, as well as their copolymerization through possible esterification/ transesterification reactions leading to an increase in their viscosities and mechanical properties was observed in the melt state under certain conditions.
The Influence of Different Surface Roughness on Microfluidic Flow Time
With the maturity of MEMS technology, the size in micromachining technology has progressed from millimeter to micrometer. Therefore, the filling behavior, driving principle, flowing control caused by capillarity phenomena become crucial. This study utilizes different processes, in order to make the detailed tangent plane, the precise tangent plane, and the smooth tangent plane of the acrylic microchannel. Results show that as the surface roughness increased, the flow time is decreased, and the flow-front of microfluidic becomes more unsteady.
A Comparison Study of Inorganic Fillers on the Performance of Polypropylene (Part 2)
In part one of this study, we have reported the comparison between EMforceTM calcium carbonate with other inorganic fillers, such as talc and glass fiber in reinforcing polypropylene. In this study, we have investigated the combination between the EMforceTM calcium carbonate with talc for reinforcing polypropylene.
Impact of DIDP on Outdoor Weatherability of Flexible PVC
Recently, market forces have combined to reduce the supply and increase the cost of linear sidechain dialkyl phthalate plasticizers. Diisodecyl phthalate (DIDP) is, in many ways, an attractive alternative to these linear plasticizers but questions remain about its effects on weathering properties of flexible PVC. This paper looks at the effects of using DIDP or blends of DIDP with linear phthalate in flexible PVC exposed to outdoor weathering. Degradation mechanisms and additive packages to limit weathering damage are also discussed.
Mechanical, Electrical and Thermal Properties of MWCNT/Poly (Lactic Acid) Composites
The preparation of multi-walled carbon nanotube/ polylactide (PLA) composites is described. High electrical conductivity can be achieved at a low carbon nanotube loading. The carbon nanotube-induced crystallization can be controlled by the degree of the dispersion of carbon nanotubes in the PLA matrix.
Visualization and Modeling of Viscoelastic Drop Deformation and Breakup in Simple Shear Flow
The deformation and breakup of Boger-fluid drops in Newtonian liquids under simple shear flow were investigated by direct visualization using a specially designed Couette apparatus which enables visualization from two different directions (i.e. to get a 3-D image). Four types of breakup modes were observed. Boger-fluid drops can break up in simple shear flows along the flow axis or the vorticity axis. The breakup mode was found to depend on drop size, viscosity ratio, interfacial tension, matrix viscosity and drop phase viscoelasticity.
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