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In order to control metering accuracy and homogeneity of the very small quantities of melt in micro-injection molding process, and combine the advantages of micro-injection molding with conventional injection molding, differential injection molding method that uses conventional injection molding systems with a separate differential unit have been developed. The novel method can realize production of multi microplastic products. By using conventional injection molding with reciprocating screw injection systems, better plastication effect and mixing performance can be achieved. A planetary gear pump was employed as the differential unit, high metering accuracy could be achieved.
Reinhild Hoffschlaq, Voler Schoppner, Jens Kruqmann, May 2011
In this paper hot plate and infrared welding are considered with respect to their attainable strengths and cycle times. In recent years, the use of flame retardant polypropylene has also become more important. Further studies show that the amount of flame retardant has a large effect on the weld strength. The welding factor drops from 0.68 (PP T20) to 0.43 (PP T20 FR). In the first part of the paper, the two welding processes are compared. Based on these results, a second study is then presented which considers the influence of various operating mechanisms of flame retardants on polymers' weldability.
Christian Hopmann, Walter Michaeli, Dominik Obeloer, May 2011
Currently, a new foaming process for injection molding is developed at the Institute of Plastics Processing (IKV) Aachen, Germany. In this process, the plasticizing unit of an injection molding machine is pressurized with a blowing agent. In this paper, the effects of the type of material, its melt temperature, the type of blowing agent and the pressure are examined with regard to the foaming of the part. The influences of these parameters on the foam structure, the part's surface and the possible weight reduction are determined.
Bead boundaries are potential fracture paths when a polymeric bead foam product is broken into pieces by force; the inter-bead bonding between beads tends to determine the mechanical properties of bead product. In our previous study, the formation mechanism of the inter-bead bonding in expanded polypropylene (EPP) bead foam processing with the steam chest molding process was proposed based on DSC simulation as well as tensile strength tests of products. In this study, the effect of skin layer on the density and tensile strength variations are assessed, and the mechanism of skin layer formation is proposed.
In this study, a regular and high pressure DSC were used to quantificationally assess the crystallinity development of PLA resin during the non-isothermal and isothermal crystallization processes. It is found that the plasticization effect of compressed CO2 could decrease linearly the Tg, and the increased chain mobility enhanced the crystallization dynamic of PLA at lower temperatures, while suppressed it at higher temperatures. Talc is one kind of nucleating agent and is often used in the polymeric foaming process. Its effect on the crystallization dynamic of PLA resin at various gas pressures was also investigated.
In this study, a block PP (BPP) copolymer with linear structure was selected and the nano-silica was used to challenge the fabrication of PP foam with uniform cell structure, high cell density and high expansion ratio . BPP foam exhibited poor cell morphology and low cell density at different die temperatures. An introduction of small amount of nanosilica dramatically improved the foaming behavior of BPP. Furthermore, the presence of nanosilica broadened the foaming window of BPP obviously. The effect of foaming on the dispersion of nanosilica in BPP matrix was also investigated in this study.
Patrick C. Lee, Laura Dietsche, Joseph Dooley, Hossam Metwally, May 2011
This study shows how the flow uniformity from a film die can be improved by modifying the geometry of the die using a 3-D FEM optimization technique. A DOE is constructed based on the number of adjustable geometric parameters, and FEM simulations are run for the DOE cases. A response surface model is then created based on the DOE results, and is used to optimize the geometry to meet the desired objectives of uniform flow and minimal pressure drop. FEM simulations using the optimized geometry predict a more uniform flow at the die exit than simulations using the baseline geometry.
Jose Carrillo-Baeza, Ricardo Gamboa Castellanos, Pedro Gonzalez-Chi, May 2011
The aim of this work is to analyze the effect of adding a polymeric matrix to a weaved aramid textile for general applications in a bullet proof shield. Resistance to frontal impact with high speed projectiles was compared in two arrangements; woven aramid fibers and another composite made of the same fibers with a polypropylene matrix. The methodology for this comparison consisted in establishing a fixed impact energy (93 Joules) using an arrangement of Kevlar?? 129 with and without thermoplastic matrix, in order to find the corresponding configuration to its ballistic limit at that energy.
Maziar Derakhshandeh, Savvas Hatzikiriakos, May 2011
In this paper, the effects of shearing, uniaxial extension and temperature on the flow induced crystallization of a high-density polyethylene (HDPE) are examined using rheometry. Extensional flow found to be a stronger stimulus for polymer crystallization compared with that of simple shear. Generally, strain and strain rate found to enhance crystallization in both simple shear and elongation at temperatures around the meting point. At temperatures well above the melting point, polymer crystallized under elongational flow while there was no crystallization under simple shear flows.
PLA was melt-blended with polycarbonate (PC) modified with high molecular weight bisphenol A type modifier. Both the mechanical properties and the thermal properties were investigated. The blends showed two distinct glass transition behaviors. Glass transition temperatures of the PLA phase were literally not changed. On the other hand, the glass transition temperature of the PC phase moved toward Tg of PLA with the addition of the modifiers, suggesting some degree of interactions. Microscopic observations revealed non-uniformly dispersed PC inclusions in the PLA matrix, confirming that phase separation has occurred.
The interdiffusion of two miscible polymers used to fabricate GRIN lenses, polymethylmethacrylate (PMMA) and poly(styrene-co-acrylonitrile) (SAN17) with 17% AN content, was studied as a function of contact time during a multilayer coextrusion process. Oxygen permeability increased from following the series model to following a miscible blend model as the number of layers increased from 17 to 1025. A model relating permeability and the interdiffusion state within the layers successfully predicted the observed permeability trends, and was used to determine the mutual diffusion coefficient of PMMA and SAN17.
Irene Howell, Steve McCartney, Garth Wilkes, Eugene Joseph, May 2011
Styrene-ethylene/butylene styrene (SEBS) block copolymers are used in a wide range of film and molded applications, particularly where good weatherability (i.e. UV resistance) is needed. These block copolymers also have poor moisture transport characteristics. NexarTM is a family of pentablock copolymers recently developed by Kraton Polymers LLC, whose properties include (a) high water vapor transport, (b) good mechanical integrity, both dry and wet, (c) thermal and chemical resistance, and (d) ion selectivity. The purpose of this work was to create elastomeric films that have moisture transport properties and, to investigate the structure and properties of SEBS / Nexar's blends
Ultrasonically assisted extrusion of styrene-butadiene rubber (SBR) compounds filled with carbon black (CB), carbon nanotube (CNT) and carbon nanofiber (CNF) was carried out. The effects of ultrasonic amplitude on extractable amount, swelling behavior, mechanical properties, abrasion, electrical resistivity and morphology were investigated. Ultrasonic treatment at certain amplitudes led to an increase of the crosslink density, modulus and tensile strength. Also, it caused a reduction in the electrical percolation threshold. A better dispersion of ZnO and creation of unique nanofiller agglomerates were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy.
Melt blowing is an extrusion process that starts with a material in resin form and creates a final web in one step. The microfibers produced in this process are in the 0.5 to 10 micron range in diameter. Applications for this technology include filtration, fluid absorption and sound management . Electrospinning is a process that is used to produce nanofibers, and most of the current work is focused on electrospinning from solutions. The work presented will deal with the structure property behavior of single component and multilayer layer melt blown webs, and melt electrospun submicron fibers and webs.
Joseph Dooley, Jeff Robacki, Steve Jenkins, Patrick C. Lee, Robert Wrisley, May 2011
Many polymers are extruded through blown film dies to produce monolayer and multilayer films. The most popular style of die in use today to produce blown films is the spiral mandrel die. This type of die can be used effectively for many polymers in structures containing up to approximately 10 layers. This paper will discuss technology in which layer multiplication techniques are combined with unique die geometries to produce microlayer blown film structures with significantly greater numbers of layers.
The achievable final volatile content within kneader devolatilization processes is highly dependent on the final melt temperature. For thermosensitive polymers the state of the art process performs poorly. The amount of dissipated energy leads to a heat up of the polymer, limiting the maximal kneader shaft speed and therefore volatile removal rate. This new process uses a suitable additional volatile compound to cool off the dissipated energy by evaporation using the off gas to strip and boost the mass transfer coefficient. A complex multi-parameter study is presented, to predict performance of industrial equipment from pilot scale data.
Aminul Islam, Hans Hansen, Stefania Gasparin, Martin Bondo, May 2011
Glass fibers are used to reinforce plastics and to improve their mechanical properties. But plastics filled with glass fibers are concern for molding of micro parts. The aim of this paper is to investigate the effects of glass fiber on the replication quality and mechanical properties of polymeric thin ribs. It investigates the effect of feature size and gate location on distribution of glass fibers inside the molded parts. The results from this work indicate that glass filled plastic materials have poor replication quality and non-homogeneous mechanical properties due to the non-uniform distribution and orientation of glass fibers.
In this review paper the fundamentals of polymer viscoelasticity will be explained and its applications to different polymers will be discussed. Firstly, the viscous-state properties like viscosity, shear thinning, Newtonian flow, and molecular structure will be explained. Secondly, the solid-state properties like the storage modulus, loss modulus, thermal stability, and molecular mobility will be clarified. The relation of these properties to the thermo-mechanical properties of different polymers and nano-composites will be reviewed as well. Finally, a successful story of using viscoelasticity as a failure analysis tool will be summarized.
Deepak Langhe, Christine LaPorte, Andrew Shaver, Donald Paul, Anne Hiltner, Eric Baer, May 2011
Layer-multiplying coextrusion technology was used to produce multilayered films of polystyrene (PS) and polycarbonate (PC). The multilayered films with PS layer thickness down to 20nm were extruded. The structural relaxation of polystyrene under PC confinement was investigated using two approaches. In the first method, the PS layers were cooled from the melt at different rates. The subsequent heating thermograms revealed that the relaxation of the PS was similar to the bulk sample. Another experiment included physical aging of PS layers below the Tg at 80?øC. The subsequent heating thermograms showed that the aging rate of PS remained unchanged under confinement.
Christian Hopmann, Walter Michaeli, Andreas Schobel, May 2011
An important basis for a development of technical elastomer parts is the numerical structure analysis for the mechanical dimensioning i.e. Finite-Element-Analysis (FEA). The mechanical properties of carbon-black filled elastomers are highly dependent on the load-condition (uniaxial, pure shear and equibiaxial). Standard material models do not take the load condition into account and describe the material behavior rather poorly. In order to describe the load condition-dependent mechanical material behaviour accurately, subroutines are developed for the FEA. The usage of these hyperelastic material models furthermore leads to a more accurate description of the mechanical behaviour for the examined carbon black filled rubber.
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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.