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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Synthesis and Characterization of Some Novel Polyurethanes Based on Rigid or Flexible Aromatic Diisocyanates and Mixtures of Them
Polyurethane elastomers were synthesized with ethylene glycol as chain extender. The macrodiol was poly(ethylene adipate) MW = 2000 ± 50. Two isocyanates were employed: 4,4- diphenylmethane diisocyanate (MDI) and 4,4’ - dibenzyl diisocyanate (DBDI), alone or as mixtures. Materials were characterized by DMA, DSC and WAXS. Changes induced by varying the type and the number of isocyanates and the order of their introduction were followed. Crystallinity was strongly reduced when DBDI was mixed with MDI.
Interfacial Adhesion between Hydroxyapatite and Poly(?- Caprolactone) and Their Electrospun Composite Toughness
The interfacial adhesive strength between hydroxyapatite (HAP) and poly(?-caprolactone) (PCL) were determined using T-peel tests. Their composite fracture toughness was determined using essential work of fracture concept. Electrospinning techniques were employed to obtain nanometer scale PCL fibers with and without HAP reinforcements which also create micrometer-scale porosity in the structure. The effects of HAP morphology and HAP content on mechanical properties were evaluated.
Manipulating the Orientation at End of Fill
Orientation of polymer chains has been shown to have a major effect on component properties. The chain orientation at the end of fill of a component is different from most other areas. Overflows have been used in various areas of the plastics industry to improve weld line strength and provide a more consistent gas channel in gas-assist molding. This study will investigate if the use of overflows to change the orientation of the polymer chains provides a more capable molding condition.
Involving Non-Engineering Students with Engineering Students to Enhance the Learning Experience
Allowing engineering students to work with students of other disciplines offers them an experience they can take with them as they begin their career in industry. The college students take the project from concept to a manufactured product. At the beginning of the project, psychology students interact with sixth-grade students to determine the best features to include in a car. The marketing students will then create a display and video commercial for each car.
The Effect of Overflow Tabs on Affected Area
The purpose of this project was to determine the effect of overflow tabs on ‘affected area’. It was done because overflow tabs could prove to be very important in the medical industry, where tight tolerance parts are needed. Along with that industry, parts with limited gating locations could also use overflow tabs to provide more consistent flow throughout the part.
Rubber-Assisted Embossing Process
This study investigated a rubber-assisted embossing process for structuring thin polymer films. The main advantages of a rubber support instead of a hard counter tool include simplification of the embossing tool, protection of the embossing master, buildup of high pressure, and ease of mold separation. With rubber-assisted embossing, thin polystyrene films in a thickness of 25 ?m were accurately patterned with microgrooves of characteristic dimensions on the order of 100 ?m.
Fountain Flow in Water-Assisted Melt Filling
Water-assisted injection molding (WAIM) provides a new means to manufacture hollow parts at lower costs. However, little work has been done to understand how the polymer melt flows under applying high pressure water. Experimental investigations on the melt flow, especially the fountain flow during water-assisted melt filling in an emulated mold were conducted in this work. The experimental results revealed the formation of fountain flow during melt filling under applying high pressure water.
Freezeout in Extruder Melt Sections
When screw speed is increased, barrel cooling will result to maintain control of the set product temperature. This can lead to barrel temperatures below the crystallizing temperature of the polymer, and a thin layer of frozen polymer can accumulate on the barrel walls. The analysis of this frozen layer or freezeout" condition and an analytical expression for estimating the layer thickness is presented along with supporting data."
Flow Stability and Thickness Uniformity in Continuous Extrusion
For continuously extruded products, such as sheet and profile extrusions, thickness uniformity is a key quality factor, and it is directly linked to flow oscillations or flow disturbances at the die. Many sources of flow oscillations in the extrusion system are identified, and methods are shown on how to configure the melt delivery system to minimize their transmission to the die. These methods are illustrated with a model based on the theory of hydraulic transients.
Cyclic Data Leads to More Accurate Finite Element Analysis
Finite Element Analysis (FEA) is only as accurate as the material models employed and it must correctly represent application specifics for the FEA to be as precise as possible. Two areas of concern for FEAs of elastomers are cyclic versus non-cyclic testing, and, strain dependent models. Ideally the analyst should be able to choose a strain based non-cycled material model or cycled material model depending on whether the application is a static or semi-dynamic application.
Penetration Length, Thickness and Crystallization Behavior of Water-Assisted Injection Molded Part
Water-assisted injection molding experiments were carried out on newly developed equipment in our lab. The effects of four processing parameters, short-shot size, melt temperature, water injection delay time, and water pressure, on the water penetration length and residual wall thickness of water-assisted injection molded polypropylene curved pipe were investigated. The crystallization behavior difference between the beginning and the end of the water channel of the curved pipe was analyzed using differential scanning calorimetry.
Shape Changing Mechanisms in Microprofile Extrusion
Profile extrusion is a well-established practice in the polymer industry. Adaptation of profile extrusion to microfabrication, however, is difficult due to scaling-related process changes. Particularly, the effect of surface tension increases as size reduces and could significantly contribute to cross-sectional shape change in microprofile extrusion. In this study, the role of surface tension in microprofile extrusion was numerically studied and compared with that of die swell. Strategies were proposed to reduce the surface tension influence and produce precision microprofiles.
Preparation of Nanoblend Polymer by Polymerization in Polymer and its Nano Cellular Foams
A new method of preparing polymer blends with nanoscale-islands is proposed. The polymethyl methacrylate (PMMA)/ polystyrene (PS) blend, which has PMMA slands dispersed in nanoscale order, was prepared by the method: dissolving MMA monomer and polymerizing the monomer in PS matrix could provide higher molecular weight of PMMA and create highly dispersed PMMA domains in PS matrix owing to gel effects and diffusion mixing. The resulting polymer blend was foamed with CO2. Nanocellular foam could be prepared using the polymer blend morphology as a template where bubble nucleation was localized in PMMA domains. The effects of blend ratio, foaming temperature and depressurization rate on bubble diameter as well as bubble density were investigated. The higher depressurization rate at lower foaming temperature made cell diameter smaller and the density larger. The higher PS composition in blend made the density larger. The cell 40-50 nm in average diameter and 8.5x1014 /cm3 was obtained as the finest nanocellular foams.
Optimization of Gasket Materials for Packaging Containers
The U.S Army Armament Research, Development and Engineering Center's (ARDEC) Packaging and Support Division, Picatinny Arsenal, New Jersey initiated a Product Improvement Program (PIP) to solve the deterioration problem in the gasket of the metal/plastic containers for mortar ammunition. This PIP was funded by PM-Mortars. The PIP addressed gasket material properties including: durometer, hardness, compression set, impact resistance, and other physical properties (app. A). The goal was to find a gasket material that would improve the seal, long-term storage, and transportation capability of both the PA154 (120-mm) and PA156/PA157 (81-mm) metal/plastic containers. Four materials that were recommended by ARDEC's Warhead, Energetics and Combat-support Armaments Center (WECAC) Material Laboratory were ethylene propylene diene (EPDM), styrene butadiene rubber (SBR), neoprene, and natural rubber (60). In addition, natural rubber (40), currently used on the 120-mm A154 metal/plastic container, was used as a baseline. The 60 and the 40 are the durometer reading. A down select process would be used to determine the best gasket candidate by good performance in environment and material testing.Based on successful testing, an engineering change proposal (ECP) will be submitted to implement the best gasket material in both the 120-mm and 81-mm metal/plastic containers.
Chemical Recycling of Pet with Solid State Shear Pulverization Technology
Post-consumer PET (polyethylene terephthalate) bottles have been recycled into film and sheet products ever since the Containers and Packing Recycling Law came into effect in 1997. There has been a growing need, however, for a chemical recycling process. In this process post-consumer PET bottles are recycled into monomers that can be used as feed stocks for the recycled production of PET bottles for beverages. This paper reveals a chemical recycling process using an alkali solution in order to depolymerize PET material in to its monomers (terephthalic acid and ethylene glycol) within a short time. Unlike ther researchers, we did not use the flakes of PET, but used powdered PET produced based on solid state shear pulverization (SSSP) technology to achieve maximum yield (98%) and purity (95%) of the monomers in a short reaction time. The powdered PET has unique physical properties that affect experiment conditions temperature and pressure. The resulting terephthalate salt was treated with sulfuric or hydrochloric acid to yield highly pure terephthalic acid. Results show that the best percentage conversion of PET flakes is 1.5mol/l NaOH for 2 hours in 200 °C and for PET powder 1 .5 mol/l NaOH for 1.5 hours in 150 °C.
UV Curable Ink-Jet Formulations for the Ever Expanding Realm of Industrial Applications
Digital inkjet printing has escaped the traditional confines of the graphic arts market and exploded into the realm of industrial applications. UV curable inkjet inks are enjoying the fastest growth due to their instantaneous cure, excellent jetting, and green" attributes. The industrial possibilities are limitless and each application requires a specific ink formulation to meet precise requirements. The inks must demonstrate robust characteristics including high flexibility and elongation abrasion resistance adhesion to a myriad of substrates including metals low surface energy plastics glass and ceramics as well as excellent lightfastness and rapid curing. This paper explores the challenges that a formulator encounters while pursuing industrial opportunities and offers suggestions to create inks that are a perfect match for each application."
Dynamic Mechanical and Dielectric Properties of Polypropylene Nanocomposites
In this work we report on the investigation of the dynamics of maleic anhydride grafted polypropylene (PPgMA) and PPgMA-based nanocomposites by means of dielectric relaxation spectroscopy (DRS) and dynamic mechanical thermal analysis (DMTA). We study the effects of different PPgMAs on the miscibility with the organoclay, and examine the effect of organically modified silicate filler on the dynamics of PPgMA. Our results suggest that the _-relaxation process, corresponding to the glass transition of PPgMA, is significantly affected by the clay loading. The increase in Tg is a direct result of polymer-filler interactions that reduce the polymer chain mobility. Furthermore, in the nanocomposite materials a separate high-temperature process due to Maxwell-Wagner-Sillars (MWS) polarization was observed with dielectric relaxation spectroscopy.
Efficiency of Graphite Additives on Friction and Wear Properties of Sintered Polyimide
The lubricating effect of graphite additives depends on the moisture content: under dry conditions graphite provides high friction and needs water molecules for smooth sliding. When used as internal lubricant for polyimide, also the chemical reactions in the polyimide bulk seem important. The inefficiency of graphite at low temperatures is related to hydrolysis reactions in the polyimide bulk, lowering the effective water content in the sliding interface. Imidisation at higher temperature allows for water supply by condensation reactions. Chemical reactions are demonstrated by Raman spectroscopy. Wear of graphite-filled polyimide manifests either as cleavage along the basal planes or embrittlement.
Novel Material Properties for Medical Applications via Ionizing Radiation
Traditionally, the medical device industry is concerned with degradation aspects of ionizing radiation with sterilization. However, these same radiation sources can also be used to create material properties un-obtainable by other methods. For example, radiation crosslinking produces packaging films from low melting polyolefins to render them steam autoclavable, or undergo minimum distortion at temperatures as high as 125° C. Or, soft, flexible material with extremely high toughness for angioplastic surgery created with high doses of radiation. In assembly operations, components with dissimilar materials can be joined in seconds upon the application of short wavelength ultraviolet radiation. In this presentation, we'll introduce the subject of radiation interaction with polymeric materials, using our own examples and commercial success stories to illustrate the utility of these radiation processes. In the mean time, a critical comparison will be made on the relative merit and disadvantages of each radiation source.
Design of Experiment to Optimize Absorber in Resin Welding Parameters
Through Transmission Laser Welding can be accomplished using either a coating or a weldable resin. As part of the weldable resin work, it was necessary to conduct a series of experiments to define optimum welding parameters. In one study, a DOE was conducted to determine the optimum welding parameters for polycarbonate and to develop a prediction equation which could be used in other tests. This DOE studied the effects of absorber concentration, energy density, thickness and pressure. The ability to weld the PC was achieved by blending a Clearweld® infrared absorber with PC resin and molding the parts into a weldable form. This paper summarizes the test procedures and results of the DOE.
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