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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Initial Expansion Behavior of Butane-Blown LDPE Foam at Extrusion Die Exit
A CCD camera was used to observe n-butane-blown LDPE foams at the extrusion die exit. The effects of butane content, nucleating-agent (talc) content, aging modifier (GMS), die temperature, and geometry on the initial expansion behavior of the foam extrudate were studied. A transparent section of the foam extrudate was found at certain die temperatures. The reasons for the existence of this transparent section and its effect on the processing conditions and material formulations are discussed.
The Manufacture of Aligned Poly(Acrylonitrile) Fibres by Electrospinning
Electrospinning is a process used to obtain nano-diameter randomly deposited fibres by electrostatically drawing a jet of polymer solution onto an electrically grounded metal sheet. This work reports on a novel method of obtaining aligned fibres of poly(acrylonitrile) (PAN) by means of an electrospinning process and investigates the effect of polymer solution concentration and take off speed on fibre diameter and molecular orientation.
Mechanical Properties of Short- and Long-Glass Fibrereinforced Polypropylene Compounds
The tensile and impact properties of two short- and two long-glass-fibre-reinforced polypropylene compounds were measured on injection-molded and machined specimens. It was found that mechanical properties were strongly dependent on the glass fibre length and orientation with respect to the flow direction.
Overview of Property Development in Layered Silicate Polymer Nanocomposites
This work reviews approaches to fabrication and property development in various layered silicate polymer nanocomposites, including the roles of thermodynamics and hydrodynamics in determining the nanoscale structure. Material is taken from the specific research of the author over the past decade, with emphasis on nanocomposites comprising polymer blends, as well as from some of his prior review papers (1, 2, 3).
Modeling and Process Optimization of Nano-Modified Simulant Energetic Materials
Nanofibers were added to simulant energetic materials via twin screw extrusion (TSE) to characterize the degree of dispersion of the fibers into a highly filled polymer composition. This work was an attempt to optimize process conditions resulting in maximum dispersion and minimal fiber breakage without excessive heat buildup. Theoretical melt temperatures were predicted via an energy balance equation. Trials showed the polymer viscosity could be reduced enough to allow the addition of the model filler and nanofibers in a single downstream feedport by gravity.
Exfoliation in Pa-6/Clay Nanocomposites by Melt Processing
Nanocomposites prepared by various methods were characterized using transmission electron microscopy, wide angle X-ray diffraction, mechanical testing and oxygen permeability measurements. Correlations were made between structural parameters (e.g. aspect ratio, dspacing) and the mechanical and barrier properties of the nanocomposites. Higher aspect ratios of filler lead to significant improvements in mechanical and barrier properties.
ESCR Thresholds Evaluated by Observation of Interfacial Surface Energies
This work probes a hypothesis for initiation of environmental stress cracking (ESCR) based on a thermodynamic criterion for localized stress induced swelling. The threshold metric involves observation of solid-vapor surface energy and contact angle of a liquid on a loaded polymer substrate and thus inference of solidliquid interfacial surface energy with respect to substrate stress. The intent is to develop a screening technique for ESCR that is not limited by the kinetics of the crazing event.
Solid-State Processing of Polymer in the Presence of Supercritical Carbon Dioxide
Open cell microporous bisphenol-A polycarbonate (PC) films are made by a novel, solvent-free processing: drawing PC in supercritical carbon dioxide (scCO2). The pore size is less than 1.0 micron and the porosity is in the range of 20%-70%, and is highly tunable. The porous film has mechanical properties nearly as high as the original film. The influence of temperature and pressure on drawability, porosity, and mechanical integrity are systematically studied.
Crystallinity and Orientation Development in Poly(L-Lactic Acid) Fibers during Annealing and Drawing
The crystallinity and orientation development in melt-spun poly(L-lactic acid) (PLLA) fibers are studied by in-situ synchrotron 2-D wide-angle x-ray scattering under various thermal and mechanical treatments. Crystalline orientation is evaluated from the azimuthal profiles of (200) and (203) diffractions. Crystallinity and orientation are found to be strongly dependent upon the take-up speeds of spinning. When fibers are heated above the glass transition, re-crystallization is observed. The effect of drawing above Tg on crystallinity and orientation are also characterized.
Degradaton Mechanisms and Environmental Effects on Poly Pphenylenebenzobisoxazole (PBO) Fibers
Recent reports have shown the fibers made from polyp- phylenebenzobisoxazole show a significant reduction in properties after relatively mild exposure to environmental conditions. This paper discusses potential mechanisms responsible for the degradation and reports results on degradation of fiber properties due to various environmental exposure conditions.
Extrusion Pulverisation of Elastane Fibres
A novel ram extrusion process for the size reduction of various grades of poly(urethane urea) (PUU) fibres (elastane) is described in this work. The process was performed over a range of shear rates and temperatures. SEM and GPC analysis results showed significant reduction in both particle size and molecular weight of the poly(urethane urea) as a result of the extrusion pulverisation process.
Properties of the Oxidized HDPE Obtained from Continuous Extrusion Blow Molding Process Machinery
Deterioration of a barrel sleeve in a forwarding and solids compaction zone of a blow-moulding unit increases the heat exchange time and negatively affects the stability process.It has been shown that gel, formed by oxidation and structurization of high-density polyethylene (HDPE), sharply differs from HDPE in density, fluidity, dissolution of additives, and interaction with a metal surface.The research established the reason of worsening quality container and restoring stability of blow moulding.
Cellular Anisotropy in Mechanical Properties of Polyurethane Foam
We suggested that the cell shape in the polyurethane foam could be approximated to be the simple oval. We have investigated the relationship between the mechanical properties and the cell structure of the polyurethane foam. Deformation of cell structure was observed under the tensile load. Cellular anisotropy of the polyurethane was examined.
Continuous-Time Dynamic Exogenous Modeling from Plant Data
Dynamic models that describe strong physical relationships are typically difficult to create from plant data. The application of a recently developed method by Rollins, et al. for Hammerstein block-oriented modeling to 3M data revealed feasibility. The Hammerstein system consists of a nonlinear static block followed by a linear dynamic block.
Estimation of Distributions of Crystal Sizes from DSC Melting Traces for Polyethylene
Melting curves from differential scanning calorimetry are used to estimate crystal size distributions. The proposed theoretical analysis is applied to polyethylene polymers, especially for linear low-density polyethylene copolymers. Theoretical predictions are in agreement with experimental results. The corresponding melting temperature distribution characteristics are calculated from the crystal size number distribution.
Prediction of Heat Treatment Effects on Injection Moldings
A comprehensive study was conducted on the shrinkage of rectangular injection molded plates (HDPE and PS), using a 3-D thermovisco- elastic simulation of the process, to estimate shrinkage in the flow, cross-flow, and thickness directions. The simulation was then extended to estimate the effects of a post-molding heat cycle. The results were in good quantitative agreement with experimental results.
Polymer Composites Based on Agave Fibres
Low density polyethylene was blended with agave fibres of three sizes: 0.21, 0.81 and 1.11 mm. Fiber concentrations between 10 and 25% were used to produce composites using twin-screw extrusion and injection molding. To determine the effect of processing on mechanical properties, uniaxial traction and impact resistance were obtained, in relation with morphology and density. The results show that there is an optimum concentration and fibre length for each processing technique.
What is 6 Sigma - A Case Study of Designing a Color Center of Excellence
6 Sigma has been around for some time. It is being used to control products to decrease their defects. Here is how 6 Sigma can be used to design and sucessfully implement a Color Center of Excellence.
The Effect of Compatibilisation on the Rheology of Polyamide Blends
Blends of Nylon 6.6 with metallocene catalysed polyolefins have previously demonstrated phase separation and component immiscibility. This work investigates the effect of blend composition and of the addition of ethylene copolymer based physical and reactive compatibilisers on the rheological performance of these blends. The results demonstrate that the viscosity of the blends showed negative deviations from a simple log additivity rule but was dependent on both blend composition and compatibilisation.
Nano-Clay and Long Fiber Reinforced Phenolic Composites
High-performance phenolic composites are prepared by using both long fibers and nano-clays. First, Phenolicclay nanocomposites are synthesized by in-situ polymerization. Then, long carbon fibers are added into the phenolic nanocomposites to produce hybrid composites. Mechanical and thermal properties of such composites are compared with both long fiber-reinforced composites and polymer-layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites.
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