SPE Library
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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Conference Proceedings
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.
Blends of Polylactide with Thermoplastic Starch
Blends of polylactide with thermoplastic starch are prepared using a one-step extrusion process. These materials, subsequently processed via injection molding, possess interesting properties. The tensile properties in these samples are related to the composition of the blends and also to the glycerol plasticizer content in the thermoplastic starch. These materials possess an advantage for the environment since they are fully biodegradable and are derived principally from renewable sources.
Average Temperature or Mean Kinetic Temperature: Which One Applies?
Reaction rates are not proportional to temperature, but instead follow Arrhenius behavior. Consequently, for systems with varying temperature, the “average temperature” is erroneous and should not be used. Instead, the easily calculated “mean-kinetic temperature”, should be used. The difference between these temperatures can be significant and failure to understand the differences can lead to catastrophic consequences. Specific examples of the calculations and the consequences are discussed.
A Statistical Analysis of the Tensile Strength of Blown Film
Many processing parameters have an effect on the tensile strength of blown film. In this study a Taguchi L8 designed experiment was used as a screening design. This design allowed the determination of which processing parameters had the biggest effect on the tensile strength of blown film in both the machine and transverse directions. The processing parameters examined in this experiment were: materials, die temperature, take up roll speed, blower speed, air ring gap, extruder speed and air volume.
Study of CBA-Blown Bubble Nucleation and Life Span under High Pressure Gas Environment
This research investigated the bubble nucleation and life span phenomena occurring in chemical blowing agent (CBA)-based foaming of plastics under atmosphere and high pressure conditions. The behaviour of CBA-blown bubbles exposed to various pressure conditions was observed in a high pressure chamber using optical microscope-based digital image processing system. Critical experiments were conducted to explain the mechanisms of CBA-blown bubble nucleation.
Erroneous, Accelerated, UV-Aging Results
It has been found that some thermoplastic systems survive accelerated UV weathering but fail in true environmental conditions. This is because quartz filters pass artificially high levels of 275 nm - 340 nm light, but artificially lower levels of longer wavelengths. For systems that are more reactive to longer wavelengths, the accelerated exposure tests provide false assurances of true weatherability. A specific example of this phenomenon occurring within polypropylene will be shown and discussed in detail.
Critical Issues in Extrusion Foaming of Plastic/Woodfiber Composites
Foaming of plastic/wood-fiber composites (PWC) with a fine-celled structure can offer benefits such as improved ductility and impact strength, lowered material cost, and lowered weight, which can improve their utility in many applications. This paper presents the critical issues in extrusion foaming of PWC and proposes processing techniques and strategies for producing artificial wood with enhanced properties.
Rheological and Morphological Properties of VARTM (Vacuum Assisted Resin Transfer Molding) Epoxy Resins/Clay Nanocomposites
Three types of modified organoclay were incorporated into VARTM resins at various concentrations. A Rheometric Dynamic Analyzer was used to analyze the flow behavior of the resins, while the morphology of the clay was examined by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM). It was found that the viscosity of the resins increased after the addition of the clays and the clays were exfoliated into the matrix.
Influence of Viscosity Ratio on the Impact Properties of PS/HDPE Blends Prepared by Extrusion and Injection Molding
Blends of PS/HDPE were prepared by ribbon extrusion and injection molding. Three different PS and HDPE were used in order to modify the viscosity ratio (p). The impact properties and morphological study of test specimens are presented. The results indicate a different effect of the viscosity ratio depending of the processing method on the morphology and impact resistance. In general, it was observed better impact resistance in samples prepared by ribbon extrusion than the samples prepared by injection molding.
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