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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In recent years, polyethylene of raised temperature resistance (PE-RT) type materials have been used successfully in domestic hot and cold water piping systems. PE-RT has a unique molecular structure and crystalline microstructure, which provides excellent long- term hydrostatic strength at high temperatures due to tie molecule entanglement without cross-linking polyethylene chains. However, this is little basic research on the durability and degradation mechanism of PE-RT pipes, i.e. the oxidation mechanism of PE-RT pipes in the presence of active ion such as Cu or Fe. In this study, the oxidation and mechanical properties was evaluated by the acceleration degradation test in the presence of the copper ion. These difference and mechanism are discussed on the basis of the results of tensile test, chemiluminescence (CL) measurement, and scanning electron microscope (SEM) observation.
Yoshiaki Tabuchi, Yoshimichi Fujii, Hiroyuki Nishimura, Kazushi Yamada, May 2014
This paper describes the weight change rate and mechanical properties of GFRP after the immersion test in 10% sodium hydroxide and 30% hydrochloric acid solutions and vapors at 40°C. The bending stress and the flexural modulus of the sample immerged in 10% sodium hydroxide solution for one month greatly decreased although these of the sample immerged in 30% hydrochloric acid solution for one month did not change. The generation of the acoustic emission (AE) started early at the bending test for the sample immerged in 10% sodium hydroxide solution. It was also found that there was a large difference of ultrasonic echo level between before and after immerged samples in 10% sodium hydroxide solution.
Fire-safety requirements, especially in the transportation and the electronics industries, are becoming stricter and stricter, meaning that more and more plastic materials include flame retardants (FR) among their constituent elements. This FR process is an endothermic reaction combined with intumescence or foam formation. When welding plastics, the welding process involves high temperatures above the plastication temperature of the thermoplastics, which can inadvertently activate the FR-reaction. This reaction can result in a lower welding strength. In this study the activation of FR-reactions in thermoplastic materials and the strength of the resulting joint will be considered. Joints were welded using three of the most commonly used processes in the industry: ultrasonic welding, laser transmission welding and hot plate welding. The results show the influence of the material, the process parameters, the welding process, the temperature and the ratio of FR-material to non-FR-material on the strength of the welded joint. For example, higher temperatures in the hot plate welding process or higher laser energy in the laser transmission welding result in lower-strength connections because of a higher activation rate of the FR-material. However, the FR-material is not activated during ultrasonic welding. Here, the lower-strength connection results from the FR-material as a filler material and not because of FR activation.
Zhenhao Xi, Xinyi Sha, Tao Liu, Ling Zhao, May 2014
Microcellular injection molding of polypropylene and glass fiber composites (PP-1684/GF-950) was performed using supercritical nitrogen as the physical blowing agent. Based on design of experiment (DOE) matrices, the influences of GF content and operating conditions on cell structure, GF orientation and mechanical properties of molded samples were studied systematically. The results showed the cell morphology and GF orientation of foaming parts were definitely influenced by the cooling and shear effects. The mechanical properties of foamed PP/GF composites could be effectively enhanced by improving the cell morphology, dispersion state and orientation of the GF at optimal weight percentage wGF/wPP=11.8%. And the optimal conditions for injection molding were obtained by analyzing the signal-to-noise (S/N) ratio analysis of the mechanical properties of the molded samples, which were a shot size of 36 mm, a supercritical N2 weight percentage of 0.4%, an injection speed of 52 mm/s, a melt temperature of 190 °C, and a mold temperature of 70 °C. The molded specimens of PP-GF composites, produced under those optimal conditions, exhibited very uniform fiber dispersion and microcellular structures with an average cell size less than 30 ?m. And the mechanical properties normalized by weight ratio of the microcellular samples were increased significantly, especially the impact strength.
Peter S. Dias, Rocio S. Garay, Dennis Lipinski, Ed Catalina, May 2014
A new technology from Braskem extends the use of clear polypropylene for thin-walled injection molding applications. Typical high melt-flow rate random copolymers have very poor impact resistance at low temperatures, and commercially available impact copolymers produce opaque containers. A new developmental grade from Braskem, PRISMA 1911, was developed to have high melt flow, relatively high stiffness, high impact, and excellent transparency. The goal of this paper is to compare this new grade with conventional impact copolymers, with random copolymers, and with blends of random copolymers and polyolefin elastomers.
The response of polymeric materials under long-term loading will vary due to several interrelated factors including time, temperature, and the magnitude of loading experienced by the material. A common failure mode encountered in plastic parts under long-term loading is creep rupture. Creep rupture describes a slow-crack growth failure in polymeric parts that is a consequence of molecular disentanglement over time as a result of exposure to continuous stress. This time-related phenomenon can lead to unexpected failures in plastic parts after days, months, or years in service. While creep rupture is more predictable and better understood under constant stress loading, creep rupture resulting from a constant strain condition is frequently encountered in several applications and is more complex to interpret. This complexity is due to the competing mechanisms of plastic creep and stress relaxation. This paper will provide insight into several long-term material behaviors in polymeric materials, with an emphasis on a scenario involving creep rupture as a result of constant strain over time.
In this study, a method to reduce the warpage of injection molded parts by optimizing the distribution of their wall thickness is proposed. The method is based on an optimization procedure consisting of mold flow analysis, a parameterization tool for geometry manipulation and an evolutionary optimization algorithm. Starting with the initial design for the mold cavity, the procedure modifies the wall thickness distribution at user-defined area-sections. The result is an STL-file of the optimized design. Application on a warpage demonstrator reveals the effectiveness and plausibility of the proposed optimization procedure.
Nora C. Restrepo Zapata, Tim A. Osswald, Juan Pablo Hernandez Ortiz, May 2014
The decomposition kinetics of p’,p-oxybis benzene sulfonyl hydrazide (OBSH) and the change of its behavior when mixed with additives and rubber are determined by using thermal analysis. This study uses Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) to understand the exothermic reaction. Different kinetic models were evaluated using the least-square method to determine activation energies and reaction variables. As a result, it was found that the Kamal-Sourour model is the most accurate reaction model, confirming the information found in literature.
Hongyu Chen, Mark J. Cieslinski, Donald G. Baird, May 2014
This work is concerned with the effect that the ratio of initial pellet length to screw channel width, or diameter, has on the percent of glass fiber breakage during processing in the screw. Experiments were carried out on a lab-scale single screw extruder. Data has been fit using an exponential decay model with a kinetic decay constant and a critical length value. This empirical model has been tested on glass fiber breakage in another size screw with a diameter 1.66 times larger than that of our single screw extruder and reasonable agreement with the empirical exponential decay model and experimental results are observed. For carbon fiber, similar breakage trends were observed.
Maryam Emami, John Vlachopoulos, Michael Thompson, May 2014
This work explores the influence of rheological properties on polymer foam development in non-pressurized systems. To understand the complex contributions of rheology on different stages of the foam processing in such systems, visualization studies were conducted using a polymer-foaming microscopy setup. Morphological analysis was used to determine the rheological processing window in terms of shear viscosity, elastic modulus, melt strength and strain-hardening, intended for the production of foams with greater foam expansion and more uniform bubble size distribution.
The science of Tribology is generally known only to certain specialists who focus on its study and the effects on industrial materials. It can drive many decisions that are made daily by the injection mold designer. In many molds there are assemblies that benefit from optimizing a surface, to minimize the effect of wear, which can be the result of one surface coming in moving contact with another. The basics of Tribology are important for all designers to understand because it may improve the longevity, of the assembly, through design or to advise the end user of adequate, required maintenance. Component longevity is the goal, but ultimately cost savings is the outcome, when replacement components and lost man-hours make an assembly unaffordable to maintain and maintenance replacements are required too often. When Tribology knowledge can be used to extend the life of specific components so they will last longer and insure the assembly’s practical life, everyone benefits. This paper will review basic definitions, concepts the designer should have in mind, the effect on industrial materials and verification methods. At the very least, this information will lead to an understanding that additional testing and analysis may be required for verification of product life.
Plant-based bio-fibers can reduce the weight of automotive composites if technical hurdles such as the rampant moisture uptake and loss of composite mechanical properties with exposure to moisture can be controlled. Pacific Northwest National Laboratory is developing chemical additives for thermoset resins that enable dramatic reduction in bio-fiber composite moisture uptake and loss of mechanical properties following exposure.
This review of recent work and technical developments by researchers at University of Maine discusses the opportunities challenges innovations and properties of micro- and nanocellulose fiber-filled thermoplastic composites (particularly engineering thermoplastic composites with melting points above 220C) and hydrophobic (polypropylene- and polyethylene-based) polymer composites.
This presentation reports an innovative and sustainable approach to fiber surface treatment that improves the fire resistance of cellulosic fiber/ epoxy composites made with flax fiber. This new approach not only retards burning of cellulosic fiber but also produces self-extinguishing cellulosic-fiber composites. The low-cost treatment was carried out in aqueous solutions using non-toxic inorganic chemicals
This presentation will summarize Oak Ridge National Laboratory’s (ORNL’s) research activities related to additive manufacturing (AM). ORNL’s Manufacturing Demonstration Facility is exploring the use and further development of a wide range of AM technologies with basic research tasks focused on 1) new material development 2) in-situ process monitoring and control and 3) expansion of system capabilities. Use of AM across various industries will be highlighted as well as how ORNL is developing new technology in this space.
This paper describes the recycling of automotive headliner postindustrial waste into useful composite panels. The process relies on granulating the waste blending it with a 100% solids VOC-free MDI isocyanate adhesive and thermally molding the mixture under pressure using atmospheric moisture as the curing agent.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
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
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.