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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Selective Compatibilization for Stiffer High Impact TPO / Clay Nanocomposites
Different compatibilization strategies from master batch mixing using a twin-screw extruder with various coupling agents were investigated to improve the stiffness of nanocomposites based on a high impact TPO (n-Izod > 600 J/m) with 2% and 4% of organoclay content. Three coupling agents based on grafted maleic anhydride polymers (gMA) were used to tailor the compatibility of the organoclays to either or both the rubbery domains and the polyolefin matrix. A detailed microstructural of the different nanocomposites revealed the preferential presence of organoclays in the rubbery domains the matrix or both depending on the masterbatch sequential compounding strategy i.e. the type of coupling agent(s) mixed with the type of organoclay. As anticipated the presence of organoclays in both the matrix for improved tensile properties (Young’s modulus and stress and strain at yield) and in the rubbery domains for higher impact resistance (n-Izod at 0 and 23°C and flat sheet impact at -40°C). A control experiment on a blend of PP and an ethylene-propylene copolymer with a PPgMA coupling agent and organoclay compounded in a similar fashion led to the usually improved tensile properties but reduced impact resistance. In this case the organoclay was found present in the matrix only as the coupling agent used could not compatibilize the organoclay to the copolymer phase. It is concluded that organoclays act on the rubbery phase to increase its toughening effect in the TPO presumably by increasing the cavitation stress of the TPO.
Synthesis of Bipolar Plates for Fuel Cells Based on Exfoliated Graphene Nanoplatelets Filled Polymeric Nanocomposites
The objective of this research is to investigate the potential of using exfoliated graphene nanoplatelets (GNP) as the conductive filler to construct highly conductive polymeric nanocomposites to substitute for conventional metallic and graphite bipolar plates in the polymer electrolyte membrane (PEM) fuel cells. High density polyethylene (HDPE) was selected as the polymer matrix and solid state ball milling (SSBM) followed by compression molding was applied to fabricate HDPE/GNP nanocomposites. Results showed that HDPE/GNP nanocomposites made by this method exhibited excellent flexural properties and low gas permeability with GNP loadings up to 60wt% which successfully meet the DOE requirements for bipolar plates. However it was found that using GNP alone as a single conductive filler was insufficient to achieve the required electrical conductivity (>100 S/cm). Combining GNP with a minor second conductive filler such as carbon black (CB) and carbon nano-tubes(CNT) could substantially enhance the electrical conductivity of the resulting nanocomposites. At the same time the processing time of SSBM is considered as a crucial parameter in optimizing the various properties of the final nanocomposites. It is believed that the bipolar plates made from HDPE/GNP nanocomposites will allow lighter weight of PEM fuel cells with enhanced performance which is particularly suited for automotive applications.
Thermoplastic vs. Thermoset Matrices for High-Temperature Out-of-Autoclave Composites Applications
The high-temperature high-mechanical performance end of the composite materials spectrum–so-called advanced composites–has long been dominated by thermoset matrices primarily epoxy and urethane chemistries with carbon or aramid continuous-strand unidirectional fiber or fabric weave reinforcements. However that is starting to change as thermoplastic resin suppliers begin to investigate and more aggressively position their own high-temperature offsets in this segment–not just as lower cost lower weight faster processing replacement for thermosets but as direct metal replacements themselves. By offering molders and OEMs the option to produce performance parts with higher productivity thermoplastic matrices that do not need to be polymerized in the tool numerous benefits are gained including reducing cycle times volatile-organic compound (VOC) emissions energy consumption spoilage and finishing steps–all of which help drive down costs and make advanced composites more affordable for higher volume applications than metals. This can be particularly attractive for processors without autoclaves or without sufficient auto clave resources to process traditional high-performance thermoset composite matrices or where producing parts via these or other traditional thermoset processes are difficult and/or costly. This paper will provide an overview of current market pressures supporting the growth of high-performance thermoplastics and then will review various processing options for both thermoset and thermoplastic high-performance composites. Next several short case histories involving conversions to thermoplastic matrices directly from metals will be presented. Lastfuture trends that could impact this segment will also be considered.
Mechanisms of Interfacial Adhesion in Metal-Polymer Composites
Hybrid materials featuring thermoplastic polymer composites in conjunction with metals can be used as structural materials in commercial tr ansport and military vehicles and for protection of buildings and infrastructure. C onstituent thermoplastics and metals have distinct advantages as protective materials however metals on their ow n are heavy hence hybrid materials offer option as lighter materials. This study focuses on the effect of surface treatments to improve adhesion between dissimilar materials such organic polymers with metal reinforcement materials. Surface energy was found to possess a direct relationship with the amount of polar groups on the surface of a modified polymer and free radicals on the metal surface. Higher surface energy correlates with superior interface adhesi on. This work establishes the ba sis that polar groups and free radicals improve adhesion between polymeric (thermoplastics) and metallic surfaces.
Super Lap Shear Joint Structural Test—Analysis Correlation Studies
Computer-aided engineering-based design methodologies have been utilized throughout the Automotive Composites Consortium Focal Project 4 to assess the vehicle level structural stiffness and impact performance of the composite underbody design proposals and to estimate the potential mass reduction for several candidate material scenarios. To increase confidence in the vehicle-level model predictions and to better understand the effect of temperature on hybrid composite-to-metal joint performance quasi-static structural joint coupon tests were simulated for the purpose of test analysis correlation and modeling methodology development.
Practical Rheology and its Role in Polymer Processing
Powerpoint Presentation at Polyolefin Conference 2011
Practical Rheology and its Role in Polymer Processing
Rheology is the science of material flow behavior, which is a very complex and multi-dimensional science. Even though it is complex, it also is quintessential to understand in order to optimize the processing of polymers. Knowing the difference between amorphous and crystalline polymers, what Melt Index really tells, and the effects of melt temperature on melt fracture are all important elements in the understanding of rheology. A simple understanding of what polymer rheology is and how shear and temperature can affect the flow characteristic of a polymer may make a big difference in the P & L of a company.
SOME EFFECTS OF BOUNDED INTERFACIAL GAPS ON THE STRENGTH OF CONTOUR LASER WELDED JOINTS
The present study examines the effects of bounded voids of different sizes and shapes on the strength and leakage of contour welds. Bounded voids are holes that are situated on the laser beam path, but whose melt flow is constrained from leaving the faying surface. The most significant result is that divot clusters can lead to quite high porosity in the interface, but even with that porosity, both high hydraulic burst test strengths and hermetic seals can be achieved.
STUDIES ON THE EFFECT OF RARE EARTH METAL TRI‹ª?ATES AS INITIATORS IN THE CATIONIC CURING OF DGEBA/PA SYSTEMS
A new class of cationic initiators, lanthanide triflates, has been studied in the cationic curing of DGEBA/PA mixtures. The reaction mechanism of the cationic curing of DGEBA/PA mixtures has been studied. The kinetics of this process has been evaluated by the Differential Scanning Calorimentry (DSC).The crosslinking degree is predicted from time and temperature of curing via the Gel-curve.
PRACTICAL PLASMA SURFACE PRE-TREATMENT TECHNOLOGY FOR HIGHER PROCESSING EFFICIENCIES
As new state-of-the-art flexible packaging technology is installed in its target markets and with processing costs under pressure to enable these technologies to ramp-up in 2011, surface pre-treatment technologies must become a key enabler relative to higher processing speed, wider widths, and requirements on inks and coatings to transfer and adhere to substrates at these speeds and widths. This paper presents evidence of new flexible packaging print performance opportunities using a new, revolutionary atmospheric plasma treatment (APT) technology.
ANALYSIS OF SHOCK RESPONSE OF SANDWICH COMPOSITES
Sandwich composites are being aggressively pursued as structural materials by various defense and commercial industries. These include navy, air force, army, automotive and sporting industries to name a few. The present work describes the compression and release response of a glass-fiber-reinforced polyester composite (GRP) under shock loading to 20 GPa. Shock experiments in GRP were performed at Sandia National Laboratories and the US Army Research Laboratory. GRP is a heterogeneous material.
PPE MACROMONOMERS. IX. PERFORMANCE ENHANCEMENTS OF TRIALLYL ISOCYANURATE RESINS
Triallyl isocyanurate is a crosslinking agent in thermosets. By itself it is too brittle for practical uses. Several attempts to improve the properties of TAIC resins were unsuccessfully. PPE macromonomers have been reported to broadly enhanced performance of thermoset materials. Methacrylate-terminated PPE macromonomer was used to successfully enhance the performance of TAIC resins. The high Tg, increased toughness, low dielectric properties, low moisture absorption, and low density suggest utility in electronics.
INTERACTIONS OF STEARIC ACID WITH SELECT TITANIUM DIOXIDE PIGMENTS
The propensity of titanium dioxide to adsorb/desorb stearic acid can be evaluated through the adsorption isotherms. Heats of adsorption/desorption and quantities adsorbed/desorbed for stearic acid over a defined concentration range were measured via flow microcalorimetry for a variety of titanium dioxide pigments. The adsorption data were fitted to both a Langmuir and a modified form of the Freundlich adsorption model to obtain both capacity factors and intensity of adsorption parameters.
CHALLENGES IN TEACHING E-LEARNING COURSES FOR PLASTICS ENGINEERING TECHNOLOGY
Many universities offer online or E-learning courses. Engineering Technology courses are typically more applied or hands-on and do not lend themselves to an easy transition to E-learning. There are some techniques that can ease the transition to successfully teaching engineering technology in the online arena.
ADHESIVE IN-LINE DEGREE OF CURE MONITORING
A new light cure adhesive technology has been developed to confirm your adhesive has cured in your product assembly. This technology can be integrated into your production line for rapid, 100% part inspection. Unlike recent color changing adhesives which only indicate exposure to light, this technology provides you a quantifiable measurement of the degree of cure achieved. These light cure adhesives are cure on demand and achieve full cure in just a few seconds. Manufacturers and assemblers of products can now be assured their bonded assemblies are fully cured.
NATURAL FIBRE PULPING AND REFINING USING EXTRUSION TECHNOLOGY
A study on structural and mechanical properties of natural fibres using co-rotating intermeshing twin screw extruder for refining fibres is reported. Using low-cost raw materials for the preparation of bio-based and biodegradable composites for many industrial applications. A range of techniques used to characterise these materials will be discussed, including morphology, DSC, SEM, other experimental techniques like mechanical property evaluations will also be discussed.
A NEW SYSTEMATIC METHODOLOGY TO DETERMINE DRUG'S SOLUBILITY IN POLYMER
The solubility of a drug in a polymeric excipient dictates the process window of hot-melt extrusion (HME) and product stability during storage. In this study, a new systematic methodology has been developed to experimentally measure the solubility of a model drug in a pharmaceutical grade polymer at different temperatures. A phase diagram was constructed and could be explored to design the HME process. Flory-Huggins interaction parameter was calculated by Tdissolution depression method based on the phase diagram and was used for thermodynamic solubility calculation.
EFFECTS OF PROCESSING PARAMETERS ON COLOUR DURINGCOMPOUNDING
Producing a specific coloured plastic using extrusion compounding requires proper operating conditions. Changes in the operating conditions will affect colour. In present study, the operating conditions were varied in controlled manner to analyze their effect on colour for two different grade plastics. Three process parameters temperature, RPM, and feed rate were varied individually to five different levels while keeping all other parameters constant. Strong interactions were observed between operating conditions and the colour.
AN EFFICIENT SEARCH METHOD TO OPTIMIZE GATE LOCATION IN PLASTIC INJECTION MOLDING
A flow resistance search scheme (FR) was proposed to find the optimum gate location in injection molding. A search direction associated with flow resistance was developed based on the physical nature of mold-filling process. By moving gate along the direction with maximum flow resistance, the filling time could be reduced and uniform flow pattern was achieved. This methodology is as efficient as quasi-Newton method (QN), but it is favorable because it can be applied to part with complex geometry.
WELDING OF FLAME RETARDING PP
In this paper hot plate and infrared welding are considered with respect to their attainable strengths and cycle times. In recent years, the use of flame retardant polypropylene has also become more important. Further studies show that the amount of flame retardant has a large effect on the weld strength. The welding factor drops from 0.68 (PP T20) to 0.43 (PP T20 FR). In the first part of the paper, the two welding processes are compared. Based on these results, a second study is then presented which considers the influence of various operating mechanisms of flame retardants on polymers' weldability.
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