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.
Looking at the increasing quality requirements and the potential for time and cost savings in almost all injection molding processes the classical way of optimizing a process has to be reviewed. New and innovative software solutions for process optimization and quality forecasting therefore plays an important role and helps to answer common questions to the shop floor managers: Is the current machine setting the best one in terms of cycle time and process capability? Is there a potential to save time material or energy? Which machine parameters have the highest influence on the quality? A new software solution using self generating neuronal networks now respond to these questions and supports users without requiring a deep mathematical background. It offers a pragmatic solution to be used by all participants on the shop floor level. Practical experience confirmed that on average 10% reduction in cycle time can be achieved.
Looking at the increasing quality requirements and the potential for time and cost savings in almost all injection molding processes the classical way of optimizing a process has to be reviewed. New and innovative software solutions for process optimization and quality forecasting therefore plays an important role and helps to answer common questions to the shop floor managers: Is the current machine setting the best one in terms of cycle time and process capability? Is there a potential to save time, material or energy? Which machine parameters have the highest influence on the quality? A new software solution using self generating neuronal networks now respond to these questions and supports users without requiring a deep mathematical background. It offers a pragmatic solution to be used by all participants on the shop floor level. Practical experience confirmed that on average 10% reduction in cycle time can be achieved.
During its manufacturing cycle a thermoplastic injection-molded part can be exposed to heat at various times. This has an influence on the inner and therefore on the mechanical properties of the part. Regarding these effects an integrative simulation approach has been developed at the Institute of Plastics Processing at RWTH Aachen University. It includes the development of a user-defined non-linear material model which takes into account the local distribution of the inner properties depending on the processing conditions and heat treatment. This paper deals with the main aspects of the material model and with the linking of the process simulation and the structural analysis using a universal data format.
A new type of single-screw extruder with grooved barrel in the feeding and the melting section called “HELIBAR®” was successfully introduced in recent years. The grooved feeding section is typically cooled passively by ambient air. The performance of a 35 mm D. 34 L/D HELIBAR was evaluated by running PP PC and ABS in pellet form HMW-HDPE in powder form and HDPE as a blend of pellet and regrind. One barrier-type single-stage screw was used for all resins. The output rates of this extruder were 3-4 times higher than those expected for the same size extruder with smooth barrel while the specific output rates (output rate per RPM) were more than twice and virtually independent of screw speed or head pressure. Furthermore this extruder had excellent stability of the output rate and the melt temperature.
A new type of single-screw extruder with grooved barrel in the feeding and the melting section, called 'HELIBARR', was successfully introduced in recent years. The grooved feeding section is typically cooled passively by ambient air. The performance of a 35 mm D., 34 L/D HELIBAR was evaluated by running PP, PC and ABS in pellet form, HMW-HDPE in powder form, and HDPE as a blend of pellet and regrind. One barrier-type single-stage screw was used for all resins. The output rates of this extruder were 3-4 times higher than those expected for the same size extruder with smooth barrel, while the specific output rates (output rate per RPM) were more than twice and virtually independent of screw speed or head pressure. Furthermore, this extruder had excellent stability of the output rate and the melt temperature.
This paper is a continuation of work presented at ANTEC 2009 . It looks into the initial steps of the development of a self-optimizing hot-tool welding machine. A new machine concept permits the specimen to be pulled in a direction opposite to the joining direction. Using this feature it is possible to assess the strength of the weld directly at the hot plate welding machine. The strength was measured while the material was still in the molten state. In order to use these results for a selfoptimization it was necessary to establish a correlation between the short-time strength of the parts in the cooled state and their short-time strength in the still molten state. Using this concept, the control system of the welding machine can be adapted to find an optimum processing window with just a few test welds. The results show that the optimum of the parameter settings can be defined by measuring the tear forces on the welding machine. Based on these results a self-optimization and quality assurance during the running hot-tool welding process can be developed and tested.
A fluorescence technique is used to determine critical micelle concentrations (CMCs) of styrene-containing block and gradient copolymers dispersed within a homopolymer. Block copolymer composition and molecular weight are varied to determine what factors impact the CMC. Gradient copolymers are shown to have higher CMCs than block copolymers due to the gradient in comonomer composition along the copolymer backbone. Gradient copolymers can be more effective as compatibilizing agents, as they are less likely to be trapped within micelles upon melt processing
For high-class applications (e.g. automotive interior) metal decorated plastic parts impress the customers with a metallic look and cool-touch haptics. Producing these parts has been a highly complex process. The in-mould lamination process of metal sheets allows a shortened process chain. In the process the injected melt adheres to a primer system on the metal surface. Furthermore the pressurized melt causes a forming of the metal sheet. This new technology enables a one-step production of metal decorated plastic parts. This paper describes design principles for metal (stainless steel and aluminum) decorated parts first. Then the effects of the injection molding process parameters on the forming quality are shown. An approach to simulate the forming process is presented and evaluated by test results.
A micro-injection molding machine was used to obtain micro-moldings of high density polyethylene, polyoxymethylene, and polycarbonate, in order to study the effects of processing conditions on the microstructural characteristics and mechanical properties. The samples were microtomed and examined using a polarized light microscope for evaluation of morphology. Various microstructural features, such as morphological layer thickness and crystalline polymorphs, were observed and analyzed, in light of the thermo-mechanical history. These features were also correlated with both macro and local mechanical properties.
The generation of process knowledge for the discontinuous compounding of TPE in internal mixers enabling companies of the rubber industries to produce TPE with defined material properties is the aim of the presented project. The properties of TPE strongly depend on its morphology. To adjust the material properties during the mixing in an internal mixer, it is important to understand how the morphology is influenced. Therefore, the melting of the thermoplastic phase and the dynamic vulcanisation of the elastomeric phase are investigated in dependence of the process parameters. The morphology of the TPE is then correlated with the material properties.
Polymer Injection Forming (PIF) is a new technology to manufacture sheet metal/polymer macro-composite components in a one-operation production process. During the process a metal blank is formed inside an injection mold by means of the pressure of the molten polymer.Changing from velocity control to pressure control just before the mold is filled is a common practice in the traditional injection molding process. In this paper different switchover strategies for the PIF process were investigated. Shot to shot consistency obtained by these methods was evaluated by means of process variations in terms of cavity melt pressure.
A primary attribute of pigmentary titanium dioxide is its ability to ensure opacity while providing a white background in a variety of plastic matrices. The mixing behavior of titanium dioxide at high solids loadings in a renewably resourced polymer was evaluated via compounding processing data and viscosity performance at various temperatures. The study involved the determination of the viscosity behavior of several different surface treated titania pigments when compounded in a polytrimethylene terephthalate resin containing 37% renewably sourced material, by weight, derived from corn.
An environmentally benign process to produce high performance polymeric foams from poly(arylene ether sulfone) was developed. The high performance polymeric foams were produced by utilizing carbon dioxide and water as the physical blowing agents because they are plasticizers for the polymer. By controlling the vitrification of the poly(arylene ether sulfone) through the diffusion of the plasticizers and foaming temperature the cell size and foam density could be readily varied. The foam density varied between 15 to 85% of the unfoamedpolymer and cell sizes ranged between 1 to 200 ?¬m. Theaffect of the cell size and density on tensile properties will be discussed.
Electrospinning has been recognized as simple and efficient method to produce micron and nanometer-sized fibers. The technique utilizes electrostatic forces to draw an electrically charged polymer solution jet into fine fiber. To stretch and align the electrospun fibers in one direction, additional mechanical drawing force was provided with the aid of a rotating disc, used as a collector for the deposited fibers. Due to the fine cross sectional area, the solution jet is subjected to high elongational stress and this phenomenon is anticipated to be capable of inducing structural modification within the polymer. In the presented work, poly(L-lactide) (PLLA) with different molecular weight (Mw) were electrospun into nanofibers. Different take-up velocities were applied by a disc collector. The thermal behavior of electrospun PLLA fibers was studied using modulated differential scanning calorimetry (MDSC) and higher ƒ??H was observed for fibers collected with higher Mw and take-up velocity. The molecular orientation was confirmed to be aligned in the fiber direction by 2D wide-angle X-ray diffraction (WAXD) and polarized fourier transform infrared (PFTIR). The degree of molecular orientation increased with increasing take-up velocity. To characterize the mechanical properties, single electrospun PLLA nanofibers were evaluated using a Nanotensile Tester.
Gradient copolymers have great versatility in terms ofsequence distribution of monomers along the polymerbackbone for control over their level of nanophaseheterogeneity and flow properties. Using a gradientcomposition rather than a block-type distribution, it ispossible to design longer chains which undergonanophase segregation at lower temperatures yet becomemore homogeneous and melt processible at accessibletemperatures. These behaviors are investigated for a rangeof block and gradient architectures using melt rheologyand small-angle x-ray scattering.
As demand for product differentiation and customization increase, UV ink jet has shown the ability to meet even the most challenging design requirements. Not only do UV jet inks allow for the customization of desired parts, but they retain all the traditional UV advantages of rapid cure, solvent elimination, etc. UV ink jet has been used to decorate substrates as diverse as plastic, wood, glass, metal, and ceramics. Formulators are continuously working to improve UV jet inks to operate under many and various challenging conditions. UV jet inks have been able to overcome such challenging requirements as extreme deformation, chemical resistance, and abrasion resistance while maintaining the inherent characteristics that make the products jettable. UV ink jet has proven to be an exceedingly versatile technology that can be applied in a broad range of applications.
Compression of the bulk solids feed resin is important in solids conveying in single screw extruders. The compressive stresses in the solid bed act with friction to produce solids conveying flow. Classically, the stresses have been assumed isotropic. However, a laboratory test given here demonstrates the biaxial stress in solids feed. Measurements were made of the biaxial stresses during compression for HDPE, LDPE, LLDPE, PET pellets, and PET powder, and the results are correlated with some extruder solids conveying performance.
In this paper we study the dynamic behavior of a concentrated short glass fiber suspension subject to simple shear flow. In particular we are interested in determining the relationship between the stress growth functions (shear and first normal stress) and the evolution of the fibersƒ?? orientation distribution within the sample.Stress growth experiments in start up of flow are performed on a Rheometrics Mechanical Spectrometer (RMS-800). Samples at rest are deformed at a constant strain rate for a specified time (i.e. strain) that correlates various points of interest on a stress growth vs. strain plot.The sample temperature is then lowered below the suspension melt temperature ƒ??freezingƒ? the fiber orientation which is then characterized using confocal laser microscopy. The experimental results are compared to predictions based on the generalized Jeffery equation.It is found that the theory over predicts the rate at which the fiber orientation evolves.
To understand better the effects of comonomer distribution profiles on blown film properties, single site catalyzed (SSC) bi-component (narrow MWD homopolymer blended with narrow MWD copolymer) octene polyethylenes were prepared to exhibit both narrow MWD and highly reverse comonomer distribution profiles (final density of 0.917 to 0.930 g/cm3). Their blown film properties were compared with those from PE resins having conventional comonomer distribution profiles including hexene mPE and SSC octene PE. Blown film structure-property relationships are presented, and the excellent toughness results are generally explainable with the tie chain concept. However, exceptions exist for some MD tear strength data.
DSC and TGA are two of the most widely used methods for studying thermal oxidative stability of polymers. Previous studies have shown that comparable Oxidative Induction Times ( OIT) can be obtained by either method. However since the two methods measure totally different sample properties during the oxidation process we conducted a more detailed study beyond the OIT quantity. Polymers which undergo chain scission and crosslinking are compared with both techniques. A further elaboration of a more general kinetics model was also attempted. Result of these evaluations toward assessing the oxidative stability and possible shelf life prediction will be presented
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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