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.
Comparative study of shear-induced crystallization among injection molded polypropylene (PP) composites from vetiver grass, rossells, and sisal were examined. Shear viscosity among PP composites from vetiver grass, rossells, and sisal were investigated. Results indicated that the vetiver grass-PP composite had lower Tc, than those of rosells-PP, and sisal-PP composites. The %crystallinity of vetiver grass-PP was higher than those of rossells-PP and sisal-PP composites. However, the normalized thickness of the skin layer in vetiver grass-PP, rossells-PP, and sisal-PP composites showed insignificantly differences. In addition, the effect of fiber content on the normalized thickness of skin layer was elucidated. It was found that an increase of fiber contents led to a decrease in normalized thickness of skin layer and degree of crystallinity of the composites.
The influence of a small amount of external inertia on the evolution of a slender bubble in an extensional flow has been theoretically studied. The unsteady problem is governed by two parameters: The capillary number and the Reynolds number for the external flow. The unsteady shape of the bubble, described by a single partial differential equation, was transformed into a system of ordinary differential equations which was numerically solved. Contrary to the case where inertia is absent and breakup is not possible, a small amount of external inertia, above some critical level, can cause the bubble to break. We found the breakup mechanism to be that of center pinching.
We have developed new fabrication tools that enable us to study optimal properties of grafted polymers. These methods employ microfluidic technology to deliver well-defined mixtures and sequences of monomers to an initiator-functionalized surface. The resulting grafted polymer libraries exhibit gradual, systematic changes in composition, chain length and architecture. Gradients of grafted block copolymer prepared via these techniques reveal composition regimes that switch" their surface properties in response to solvent exposure. Moreover our unique ability to prepare statistical copolymer composition gradients provides comprehensive maps of complex surface chemistry that were previously impossible."
Linear and branched hydrophilic additives of various molecular weights and functional group densities were added to polypropylene (PP) as surface modifiers to make blend films through solution drop coating and heat pressing from melt-blended mixtures. Water contact angles on the film surfaces were measured over time to investigate the additive migration behavior. In particular, PP-additive blend films made through melt blending exhibited lower water contact angles than those made through solution drop coating. Ciba® IRGASURF HL560, linear polyethylene glycols (PEGs) and multi-arm polyethylene oxides (PEOs) were found to generate favorable wettability on the PP films, and all showed loss of durability when immersed in water.
Present work deals with manufacturing and studying of self-reinforced thick-walled isotactic polypropylene products. Self-reinforcement based on flow-induced crystallization was achieved by continuous extrusion under particular flow and processing conditions - high percentage of elongational flow, high pressure and low temperature. The structure and resulting properties of extrudates were subsequently studied. Fibrous and highly oriented morphology, outstanding storage modulus in wide range of temperatures and reasonable thermal stability were found.
Business and patent laws of the United States are enforced by the criminal and civil courts at both the state and federal levels. The legal process utilizes technical experts such as qualified plastics engineers serving as expert witnesses to help resolve these disputes.This paper is divided into two parts. The first part notes some of the basic responsibilities and qualifications of expert witnesses and the second covers some case histories including the Gore vs. Bush election trial that took place in 2000 in Florida, where a SPE member was an expert witness.There are over a million references on “google.com” to the words ‘federal expert witness qualifications’. Many of the current laws about expert witnesses are based on a 1993 Supreme Court case1, and subsequent court rulings.
Thermoforming process is one of the most popular techniques in the polymer processing. Wide applications of thermoforming are due to its high performance, simplicity, compactness and relatively low-cost equipment. The fundamental defect inherent to the thermoforming technology is warpage of the products during their application which becomes particularly apparent under high temperatures. The warpage defect is understood as the process of non-uniform (heterogeneous) change of the geometric dimensions of products in time resulting in a change (distortion) of their original form. The results of this work allow us to find out the causes of this warpage and ascertain the conditions that give rise to this defect, thereby making it possible to work out valid recommendations for its partial and, in some cases, complete elimination.
Identification of the delamination in fiber-reinforced composites, often used as aerospace and civil structures, is critical for structural health monitoring. It is well known that such a delamination affects the spectral characteristics (natural frequencies or mode shapes) of these structures. This study aims at developing numerical detection tools for identifying a single delamination in composite beam from its spectral data. The proposed mathematical models of delaminated composite beams will lead to the solutions of novel inverse transcendental eigenvalue problems (ITEP). Numerical techniques are developed here to solve such ITEP. It is demonstrated here that successful identification of damage parameters can be realized with finite number of spectral data set.
Conventional electropolishing (EP) of Cu involves anodic oxidation and dissolution in a stirred electrolyte solution. Rate and planarization efficiency are governed by diffusion across the stagnant boundary layer. We developed a membrane-mediated electropolishing process (MMEP) in which the substrate is covered by de-ionized water and separated from electrolyte and cathode by a charge-selective membrane. Ion transport occurs by electro-migration of cations across a thin layer of water which is established at the substrate/membrane interface by lubrication mechanics. MMEP provides high removal rates and much higher planarization efficiencies than EP. In addition it consumes no reagents, generates no waste and leaves the substrate uncontaminated.
The morphology, gas permeability and physical/ mechanical properties of synthetic ?-zirconium phosphate based epoxy nanocomposites with variations in degree of exfoliation are investigated. The state of exfoliation and dispersion is directly confirmed by transmission electron microscopy (TEM) at different locations of the samples. The fundamental structure-property relationship of ?-ZrP reinforced epoxy nanocomposites as a function of degree of exfoliation of ?-ZrP layer structure is discussed.
The properties of cyclic polyolefin films manufactured from several processing parameters were investigated. The cyclic polyolefin resin was newly synthesized by LGC in house, and the film was prepared by a solution casting method because of the high glass transition temperature of the resin. The processing parameters such as the peel-off strength were measured at various solvent concentrations for optimizing the film formation. The films having superb optical properties, excellent chemical resistance, low density, and high refractive index were successfully manufactured, and it was found that the films can be used not only for heat resisting film but also for various optical applications including TFT-LCD and lenses.
A continuous chaotic blender (CCB) has been used in prior work to produce alternating polymer layers with thicknesses below 100 nm, volumetrically align and localize nanoplatelets in multilayers, and assemble carbon black particles into conducting networks. In consideration of the nanoscale dimensions of these novel structured materials, similar processing methods have been applied in this paper to produce electrically conducting networks from a masterbatch of polypropylene (PP) and multiwall nanotubes (MWNTs). Nanocomposites were extruded as films in a continuous, industrially relevant process. Percolation was obtained at the minimum composition considered of 1 wt%. Structure in the nanocomposite films is related to processing conditions and electrical resistivities.
This paper presents the development of a threedimensional (3-D) injection molding filling simulation using different algorithms and finite element types. Two numerical models, the mixed model and the equal-order model, were used to solve the Stokes equations with three different tetrahedral elements (Taylor–Hood, MINI, and equal-order). The control volume scheme with the tetrahedral finite element mesh was used for tracking advancing melt fronts. The numerical simulation was validated for the mold filling of a precision optical lens. The numerical simulation agreed very well with the experimental results. As a new application area, a two-step, macro-micro filling approach was adopted for the filling analysis of a part with a micro-surface feature to handle both macro and micro dimensions while avoiding an excessive number of elements. Comparison between the numerical predictions and experimental data suggests that the flow velocity and heat transfer coefficient on the mold surface plays an important role in determining the flow behavior and penetration length within the micro feature.
A chemical storage tank holding nearly 100 tonnes of hot fluid failed suddenly in August 2003, after about 2 years from installation, and about 18 months actual use. Nobody was injured, but the flood caused substantial damage to the surrounding equipment. Inspection indicated that the failure started at a pipe outlet at the base, with delamination of the GRP wall. Analysis showed the wall to be too thin to support the load from the contents, and that failure was inevitable. Other design defects included poorly positioned piping and a badly designed bund wall, which contributed to the accident. The polyester resin matrix was totally inadequate to resist anticipated content temperature approaching and sometimes exceeding 90 C.
Many industrial and consumer products rely on battery power, with product failure inevitable if the battery container cracks. Electrolyte damage to surrounding equipment can be severe owing to the corrosive properties of most electrolytes. Failure of the container can be caused by internal or external problems, such as explosions of excess hydrogen gas or by external impacts. However, many problems are exacerbated by poor design of the container, including moulding under inappropriate conditions or by the presence of severe stress concentrations. Several case studies are described in which one or more of these factors caused product loss or personal injury.
Nylon is widely used as a bearing material, and many different grades have been developed for specific applications. Self-lubricated nylon is a robust grade which has found use in heavy duty bearings such as those used in swing bridges. The case study describes the failure of a bridge bearing, which was replaced owing to excessive deck movement .The steel pin on which the nylon sleeve bearing operated was found to be severely worn, while the sleeve was intact, but heavily contaminated. Sand had become embedded in the nylon surface and acted abrasively against the steel when the bearing moved. The nylon sleeve was at the limit of its specification, and a superior grade chosen for replacement.
Failure behavior of polypropylene block copolymer welded joints was investigated. Double V welded joints were performed using an automated hot gas welding machine, which is able to independently control welding parameters leading to reproducible welded joints. Uniaxial tensile tests and fracture mechanics experiments were carried out. From these results and complementary FEM analysis, the quality of welding rods and welding interfaces were assessed. By using different specimen configurations and optical microscopy the damage zones generated during mechanical solicitation of the joints were investigated. Welded joints coming up from three hot gas temperatures in the range of 230 to 260°C were analyzed.
REACH-RS (Research & Education Academy for Coaching/Mentoring High School – Rising Stars) introduces K-12 participants to the needs for enhanced inter-personal skills and technical proficiency in the areas of nanomaterials, multifunctional materials and processing through a series of in-lab assignments. In this project, a group of K-12 students in collaboration with PSU undergraduates injection molded blends of HDPE and carbon black, and tested the resultant ASTM-type, test bars for electrical conductivity, flammability resistance and mechanical properties. The generated stress-strain, electrical and flammability data were analyzed, and correlated to electromagnetic interference (EMI/RFI) applications.
In the present study morphology and properties of partly shrunk linear low density polyethylene (LLDPE) biaxially oriented films were studied. It is shown that the mechanical properties of the films as function of the thermal shrinkage behave differently in machine (MD) and transverse (TD) directions. A correlation between mechanical properties and orientation factors determined by Fourier Transform Infra-Red spectroscopy (FTIR) was found. On the basis of the thermal shrinkage behavior of the films as a function of temperature, the molecular orientation during double bubble process was explained in term of superposition of different orientation stages.
The electrically conductive acrylonitrile butadiene rubbers (NBR) containing a carbon black as a conductive additive were prepared to investigate electrical and mechanical properties in this study. We considered the effects of conductive carbon black loading and various temperatures on conductivity, acrylonitrile contents, crosslinking density of vulcanizates, and the existence of a plasticizer. The change in electrical conductivity with different amounts of carbon black of NBRs showed that there is a certain critical point which produces a significant decrease in electrical resistivity (increase in conductivity). The mechanical properties like tensile strength, elongation to break, and surface hardness of vulcanized NBRs were determined. We found that the percolation threshold region was 5 phr CB in the NBR/CB composites. It means that there are formed continuous electrical paths which are attributed conductive carbon black in the NBR/CB vulcanizates.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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