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.
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.
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.
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.
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.
Intellectual property law has had a number of somewhat remarkable changes in recent years. For example, the scope and enforceability of patents in the United States has been modified with respect to what might be considered an “equivalent” to a claimed invention. The role of judges and juries in ascertaining the scope of a patent has been dramatically altered. This paper will identify these new and important changes in the law of intellectual property and how such issues should be considered by the community of plastics engineers.
A common problem affecting all thermoplastic parts is shrinkage and warpage. With two-shot molding the parts will have two materials with different properties molding onto one another. Through a design of experiments (DOE) the cause and effect of changing different processing parameters along with part dimensions and materials, can be used to determine the amount of warpage on the part.
Off odor issues in packaging materials can have significant financial implications. Gas chromatography with a combination of detection techniques, olfactory (GC/O), and mass spectrometry (GC/MS) can help solve such problems. A general problem is the low detection limits afforded by the sense of smell versus the instrumental detection limits of GC/MS. Various methods of sample introduction that enhance the GC/MS response allowing identification of odor relevant compounds will be discussed.
The pressure-volume-temperature (PVT) property of polymer/gas mixtures is critically important in the polymer foaming process. Accurately measured volume swelling of polymer/gas solutions is not yet available. The objective of this paper is to propose a novel methodology for measuring the volume swelling accurately. The preliminary result using PP/N2 and accuracy verification using a known volume sphere will be presented.
The foamability of thermoplastic vulcanizate (TPV) has been investigated in a customized foaming system using carbon dioxide (CO2) and nitrogen (N2) as a physical blowing agent. TPV or dynamic vulcanizate is a special class of thermoplastic elastomer that is produced by mixing a crosslinked rubber and a thermoplastic simultaneously. The influence of blowing agent content and the processing conditions on the expansion behaviour, the cell-number density and the foam structure are discussed.
It is usually reported that wood particles in wood/polymer composite foams can act as nucleating sites. Since high wood contents are used, it is difficult to determine exactly the effect of wood particles. In this study, LDPE was chemically foamed in a twin-screw extruder and small amounts of wood (0-5 phr) were added to determine their effect. Particle size was investigated using three mesh sizes: 45-61, 104-125 and 180-210 ?m. As expected, wood particles are acting as nucleating agents reducing substantially cell size and increasing cell density.
The contributions of shear and elongation to the measured pressure drop in flow of polypropylene melts through semi-hyperboloidal dies have been investigated with and without external lubrication. This was done with a set of dies having a fixed ratio of inlet area to outlet area and three different lengths. The flow curves obtained without lubrication have been analyzed for the dependence on length. Two distinct terms have been identified that represent the shear contributions to the measured pressure drop in unlubricated flow.
In order to investigate the effect of clay particles on the cell morphology of HDPE/clay nanocomposite foams, research on the batch foaming process of HDPE/clay nanocomposites using supercritical CO2 was conducted. Our study demonstrates that, in comparison with pure HDPE, nanocomposites produce much finer and more uniform cell structures. Additionally, an attempt to produce a nanocellular structure was successfully performed using HDPE/clay nanocomposites.
Natural crystalline graphite based graphite intercalated compounds [GICs] were exfoliated and milled into submicron graphite flakes. Graphite nanocomposites were fabricated with nylon 6 or nylon 66 resins. To examine the effectiveness of the exfoliated graphite as a reinforcement, composites with commercially available reinforcing materials were also fabricated and compared. The mechanical and electrical properties were investigated and exfoliated graphite showed comparable or better properties compared to the other reinforcing materials.
Intercalated and exfoliated high density polyethylene (HDPE)/clay nanocomposites were prepared by melt blending with and without the aid of maleated polyethylene (PE-g-MAn) as a compatiblizer. Their morphology was determined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of clay dispersion on the tensile properties and flammability of nanocomposites, especially those containing only a small amount of clay in the range of 0.05 ~ 1.0%, were investigated in this study.
The present paper introduces CET resins as an alternative for clear, sterilizable medical applications. CET resins are clear SMMA (styrene-methyl methacrylate) copolymers that compete with materials which include PMMA, polycarbonate, and PETG in medical applications and provides good scratch resistance and better sterilization properties when compared with impact acrylics, and slightly better resistance to alcohol, blood and lipids for medical applications when compared to PC as well.
The instantaneous images of preform during stretch blow molding were obtained by using a transparent mold and a digital camcorder. Delay time of preblow is a determining factor to the preform growth. Effect of sequence of stretch and blowing on the preform growth was investigated experimentally. Four types of perform growth were found. The axial thickness distributions of the bottle were also analyzed.
Responding to environmental, sustainability, business and market needs, DuPont has recently commercialized a new polymer platform Sorona®. Sorona® polymer is produced from fiber-grade 1,3- propanediol (PDO). It is a linear semi-crystalline polymer with a melting temperature of ~228°C and a glass transition temperature of about 50°C. (See Figure 1)
Polylactide (PLA) polymers are among the most promising plastic made from renewable resources. Thermal stablization of these polymers remains a challenging issue of their industrial processing. We have studied the effect of TNPP in the scope of preventing the molecular weight reduction of PLA at its processing temperature. The stabilizing effect of TNPP was found to strongly depend on the concentration used.
An artificial neural network (ANN) model based on the numerical simulation data was developed to build the relationship between parison thickness distributions and part thickness distributions. A real-coded genetic algorithm (GA) was used to search for the optimal parison thickness distributions to produce a blow molded part with a uniform thickness distribution. The results showed that the hybrid method was an effective algorithm to optimize the parison thickness.
A thermal model was developed for the perform reheating in the two-stage injection stretch blow molding. The temperature distributions through the thickness of the preform and along its length were obtained by solving the model with ANSYS finite element software. With the use of real-time temperature measuring system, experiments were carried out to obtain the temperature evolution within reheated preform as it rotated. The numerical results were compared with experimental data.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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