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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New Phosphorus Based Flame Retardants for Thin-Walled Applications
Building on more than 30 years expertise in phosphorus chemistry and flame retardants (FRs) for textiles, Thor (www.thor.com) has recently developed an extensive range of non-halogenated FRs dedicated to plastics applications. Cornerstones of the portfolio are two new substances, AFLAMMIT® PCO 700 and PCO 800 that have been registered under REACH and TSCA, and another proprietary high-performance FR, AFLAMMIT® PCO 900.
While they can be used in various polymers, thicknesses and applications, these new substances are expected to find commercial use primarily in polyolefin based thin-films, tapes or foams, where they fill the gap between traditional formulations (based on organic bromine or chlorine based FRs and antimony trioxide) and the available halogen-free additives, which are essentially limited in performance.
The paper will introduce the new AFLAMMIT® products and their synergistic combinations in a benchmark approach and will demonstrate their unique FR effectiveness. These new additives not only represent the first halogen-free alternatives to the widely used halogenated compounds in the targeted applications, but have also demonstrated to be successful in particular applications without halogen-free requirements, where performance based criteria are most important (i.e. highly flame-retarded films preserving transparency or light-weight FR thermoplastic foams).
Determination of the Compositions of Fully Biodegradable Ternary Blends with Near-Infrared Spectroscopy
Comparison between near-infrared (NIR) spectroscopy in diffuse reflectance and transmission modes for determination of the compositions in fully biodegradable poly-(lactic acid)/poly-(propylene carbonate)/poly-(butylene adipate-co-terephthalate) (PLA/PPC/PBAT) blends was made. Principal component analysis (PCA) was firstly performed to qualitatively examine the response of two modes to concentration change. Then partial least square (PLS) models were developed for quantitative evaluation based on root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP) and coefficient of determination (R2). The data showed that NIR spectroscopy in both modes succeeded in extracting information of concentration of complex fully biodegradable PLA/PPC/PBAT blends, whereas diffuse transmission mode presented better performance than diffuse reflectance mode.
Numerical Simulation for Insert Injection Molding of Oneconstituent Polypropylene Single-Polymer Composites
One-constituent polypropylene single-polymer composites (PP SPCs) possess matrix and reinforcement which are from the same kind of PP with identical chemical structure. One-constituent SPCs are characterized by lower density, lighter weight and better interfacial adhesion, which can fulfill the demands for fully recyclable engineering composites. Traditional SPCs preparation processes like hot compaction, film stacking, co-extruding have long cycle, narrow processing temperature window and difficult control of processing temperature. Insert injection molding can solve these issues with high effectiveness of preparing SPCs. In this article, we simulated and analyzed the insert injection molding process of one-constituent PP SPCs for testing the processing temperature window and mastering the temperature distribution inside the mold cavity. Numerical results of the insert injection molding process for oneconstituent PP SPCs were also compared with those of injection molding process for pure PP. Results of temperature, viscosity and warpage were all discussed which could be used to determine the optimum injection molding conditions.
Variation of Scratch Behaviors of Thermoplastic Polyolefins (TPO) Due to Thermal Degradation
Evaluating the effect of scratching speed and thermal degradation time acting on the scratch resistance of Thermoplastic Polyolefin (TPO) quantitatively using ASTM D7027-13 standard is the main theme of this paper. By measuring the critical normal load at a scratch mode transition point, scratch resistance of TPO is characterized. The test result showed that thermal degradation causes TPO to become susceptible to scratch. As scratch speed and thermal degradation time increase, critical points appeared faster which means the specimen failed at the lower load level.
Thermally Triggered Shape Memory Sensors via Nanolayered Coextrusion of Commercial Polymers Materials
A multilayered film polymer processing approach to produce one-way shape memory films and labels was demonstrated. Utilizing a relatively low cost, industrially scalable fabrication processes of multilayered film coextrusion and film embossing, 1”x1” areas of layered polymer films were loaded for thermally triggered film topography changes to produce passive sensing or anti-counterfeit labels. Customizability in the one-way thermally induced multilayered film shape memory was demonstrated via hidden text, changes in film optical transmission, and induction of custom laser diffraction patterns off the surface of encoded and recovered multilayered shape memory films.
The multilayered film coextrusion approach enabled actuation of the overall film topography changed, based on the highly regular sequential micro and nanolayering of two alternating polymer materials with differing glass transition and softening temperatures. Stemming from a synergy of the nanolayer thickness of highly ordered layered film structures and length scale of chemical bond thermal relaxations of the polymer materials, shape memory films and labels were created from commercial homopolymers that do not require block copolymer architectures or custom chemistry.
A Three-Layer Foamed Composite Prepared by Rotational Molding
A three-layer composite (polymer-fiber / polymerfoam / polymer-virgin) was made by rotational molding using a laboratory-scale biaxial rotational molding machine. The mold consists of a cylindrical stainless steel of five liters of volume. A linear medium density polyethylene (LMDPE) was used in all layers. In the composite layer a natural fiber (agave) was included and in the foam layer a chemical foaming agent (azodicarbonamide, ACA) was incorporated. The effect of the agave fiber and foaming agent contents was related to the tensile properties. The inner air mold temperature and rotomolding cycle time are reported.
Root Cause Analysis and Fixing of Coextruded Polyolefin Blown Film Defects
A blown film producer experienced a film production and quality defect which prevented it from making quality coextruded films. The problem was analyzed, the root cause was identified, and a solution was implemented. The root cause of the problem was the improper installation of the die assembly onto the rotator of the line which caused molten polymer pumped from the core extruder to leak from the entry of the core spiral mandrel into the entry of the outer skin spiral mandrel. The required fix was simply to adjust the position of the locating collar of the rotator so that the die assembly properly sealed onto the rotator. Following the implementation of the fix, the film producer was able to produce quality product with the desired structure.
A Research Framework for Cooling Rate-Dependent PVT Models
An expanded framework for the use of user-defined routines inside a commercial injection molding simulation package is presented. This functionality allows external academic researchers to directly modify the injection molding simulation and obtain results for any newly proposed PVT, viscosity or core shift (fluid structure interaction) models in complex parts and processes. A demonstration case is presented by implementing a PVT model which depends on cooling rate in addition to temperature and pressure. The effects on shrinkage predictions for an amorphous part are investigated and compared with actual molding data.
Warpage Simulation of Injection over-Molding Plastics on Continuous Fiber Reinforced Composites
Injection overmolding of thermoplastic over a continuous fiber reinforced composite is one of the new manufacturing approaches for automotive lightweighting which is emerging as a potential way to increase vehicle fuel economy. It not only takes advantage of excellent strength and stiffness properties of continuous fiber reinforced composite, but also has the advantage of forming complex and intricate functional shapes with the injection molding process. Warpage simulation of injection molding helps designers optimize the part and mold design, material choice and processing parameters, in order to meet tight dimensional tolerances for assembly purposes. In this paper, we extend our warpage simulations to account for the effects of orthotropic and fully anisotropic mechanical properties of continuous fiber reinforced composite inserts. The feature enhancement includes buckling and large deflection analyses of overmolded plastic components. The numerical results from Autodesk Moldflow simulation for two plastic parts injection over-molded
Verification of Numerical approach and experiment in Using PvT Properties of Polymer to control Injection Molded Products
Warpage is a common concern in injection-molded products. The usual way to find errors when troubleshooting is to adjust parameters repeatedly. This approach depends on the experience of the operator and lacks scientific rigor. This paper establishes another method for determining reductions in shrinkage and warpage caused by the packing phase in injection molding using Computer Aided Engineering (CAE) software.
Based on the PvT curve during injection molding simulation, the optimum packing pressure and packing time can be obtained to minimize the warpage caused by shrinkage. The influence of packing parameters was investigated in Moldex3D R14 and verified by experimental work. The results of the simulation and experiment showed good agreement, which means the warpage may be minimized using the PvT curve.
Optimizing Process Condition of Compression Molding: from Material Properties Characterization to Numerical Simulation
Herein, we present the recent development in viscosity measurement by squeeze flow method. We applied this technique to investigate to fiber reinforced plastic (FRP) systems including, polypropylene-based glass mat thermoplastic (PP-GMT), and thermosetting sheet molding compound (SMC). The effects of compression rate, temperature and curing time are systematically studied. In both cases, the squeeze flow data deviate from simple power law model, and is analyzed by the approach proposed by Laun et al (J. Rheol. 1992, 36, 743) . The results demonstrate the promising potential of viscosity measurement by squeeze flow method, and great relevance to industrially important process such as compression molding. The measured rheological material properties are then used in process simulation to obtain optimal process conditions of compression molding.
Simulation of Fatigue Crack Growth of HDPE Using Crack Layer Theory; Effect of Loading Frequency
The crack layer (CL) theory has the ability to estimate the slow crack growth (SCG) behavior on the basis of the theoretical background. This theory considers the interaction between crack and damages in front of the crack tip. It facilitates the reflecting damage mechanisms which appear different depending on the material. However, the applicability of this theory has not been investigated sufficiently yet, with regard to the various loading conditions. For this purpose, the critical CL parameters with the loading conditions must be specified. In this study, the discontinuous fatigue crack growth (FCG) tests with various loading frequencies are simulated by using CL theory. The two CL parameters are changed to fit the tests, and the relationship between loading frequency and CL parameters are constructed. It would be beneficial for industrial use of CL theory.
Numerical Prediction of Stiffness and Strength of a Highly Complex Topology Optimized Thermoplastic Part designed for 3D Printing
Additive manufacturing or 3D printing has revolutionized the way companies manufacture products by allowing the manufacturing of shapes considered impossible to manufacture until now. This gives the advantage of designing the parts with materials positioned in exact locations as is required from its performance loading conditions. However, while this technology is beneficial from weight-to-performance perspective, this results in highly complex shapes which are difficult to discretize for finite element analysis and performance predictions. This difficulty is even more pronounced while predicting failure strength of the topology optimized 3D printed part in addition to part stiffness.
Typically, explicit solvers are used to predict highly nonlinear events such as component failures. Traditionally, hexahedral elements are used in explicit solvers due to the higher accuracy and lower cost of simulations compared to tetrahedral elements for similar element dimensions. However, highly complex shapes generated through topology optimization are prohibitively difficult to model using hexahedral elements. This paper deals with prediction of stiffness and failure strength of a part of highly complex geometry arrived through topology optimization using advanced higher order tetrahedral elements in LS-DYNA explicit solver. Use of tetrahedral elements allows the discretization to be almost fully automated. Equivalent analysis without explicit material failure is also performed using Abaqus implicit solver for benchmarking. The predictions are compared with actual physical test results for the 3D printed parts which exhibit good correlation.
Fiber Length Degradation of Glass Fiber Reinforced Polypropylene during Shearing
This paper contains investigations of the influence of the fiber concentration on the degradation of fiber length during shearing. For this examination, compounds of polypropylene and glass fibers have been manufactured which contain 20%, 30%, or 40% glass fibers by weight. At the start of the investigations, the initial fiber lengths are determined in each compound, which in terms of mass average ranges from 446 ?m to 663 ?m. Afterwards, the compounds are exposed to a drag flow in a Couette rheometer; this flow is generated in a shearing gap between a rotating piston and the corresponding cylinder. The investigations are carried out for varying lengths of shear time and varying rotational speeds. At each experimental interval, specimens are taken and optically analyzed to determine fiber length. With this method, the fiber length degradation over time can be determined, as well as its relation to the fiber content and the occurring shear rate.
Development of an Inline Plasma Treatment during Injection Molding Process
In order to fulfill continually increasing requirements in optical and haptic applications, in particular requirements for the functionality of injection molded components, it is frequently necessary to make use of additional processing steps such as coating, bonding, or two-component injection molding. However, due to the low surface energy of many polymers, the necessary adhesive strength cannot be achieved without further modification. One typical surface treatment for increasing the surface polarity of plastics and improved adhesion properties is atmospheric pressure (AP) plasma treatment. Typical applications of this method use CNC-automated machinery, which enables good results to be achieved with a high degree of consistence, but which unfortunately are difficult to implement for inline application.
With that in mind, the goal of the research presented here was to develop a surface treatment process which makes inline plasma surface modification during an injection molding process possible. This contribution describes the development and investigation of surface treatment with a stationary plasma jet, as well as the integration of this technology in the injection molding process.
Degradation Inspection of GFRP Storage Tank with Long-Term Use under Hydrochloric Acid
It is necessary to understand how much life the materials used as structural elements have. Therefore, two types of specimens, GFRP storage tank used under hydrochloric acid for 22 years and blank GFRP materials, were used as specimens in this study. We tried to evaluate the degradation mechanism of these specimens by using Optical microscope, SEM observation, ultrasonic measurement, and electrical resistance measurement. As results, it was found that the glass fibers of facing surface side with hydrochloric acid solution were dissolved by penetrating the hydrochloric acid and these parts had lower surface electrical resistance as compared with non-degradation parts because of losing the electrical resistance of glass fibers. In addition, the ultrasonic measurement revealed the decrease rate of intensity between the blank and GFRP storage tank samples was different. In this paper, the mechanism is discussed on the basis of these results.
Two-Shot Overmolding Cooling Simulation
Two-shot overmolding is a specialized injection molding process in which two polymer materials are molded together to form a single part. Two-shot overmolding has many advantages over conventional molding in that it is more cost effective, has a stronger bonding strength, and enhanced product quality. Despite these advantages, obtaining an optimal mold design is difficult due to the complexities of the process, e.g., the complicated rotational mechanism of the mold platens. Mold cooling simulation can be used for optimizing the design of the cooling system, minimizing cycle time, and eliminating defects in the final part. This paper outlines a tailored mold cooling solution for the transient and steady state simulations of the two-shot sequential overmolding process. The transient state solution and steady state solution are verified with a case study at the end of the paper.
Carbonization of polyacrylonitrile Nano Fiber by Cotton Candy Method
In this study we focused on r Carbon Nano Fiber (CNF) in the carbon-based nanomaterials’s field. CNFis expected to various applications. However, the CNF have a high cost of production. Therefore we are trying to reduce a cost to make a preparation of precursor of the CNF using Cotton Candy Method (CoCaM).
Cotton candy method (CoCaM) is novel method that can create a lot of nano fiber. CoCaM is a method of forming a fiber with only air injection. Therefore it is possible to make a cost saving by CoCaM, because it does not require heating and the electric field. We studied about carbonizing conditions for nanofibers. After carbonizing, the diameter of nano fiber decreased. Carbon nanofiber was maintaining the shape of the fiber. According to the result of raman spectrometry, it is revealed the high crystallinity of NCF.
Ultrasonic Measurement of Particle Concentration in Polystyrene/Glass Beads Composites by a Differential Scheme
The attenuation spectra obtained from ultrasonic measurement is applied to estimate the particle concentration in general purpose polystyrene (GPPS) /GB (glass beads) composites by a differential scheme. Composite samples with particle radium 80 ?m are tested at five volume fractions ranging from 6 % to 40 %. The longitudinal attenuation characteristics of these samples are found to depend markedly on the particle concentration and be consistent with the theoretical curve cased on the differential scheme. Combined with differential scheme, the attenuation spectra tested is used to determine the unknown particle concentration of two new samples. The predicted particle concentrations are found to be in remarkable agreement with the experimental results obtained by the ash content method.
Crystallinity Distribution Analysis by Raman Mapping for Polyethylene of Raised Temperature Resistance after Longterm Hot Water Immerssion Tests
Recently, plastic pipes for hot water supply plumbing such as polyethylene are require the higher performance for durability. Non cross-linked polyethylene of raised temperature resistance (PE-RT) is very promising because of its variety and recyclability. It is important that the degradation mechanism in hot water is understood for developing higher durablity pipes. But the systematic analysis of these aged samples has not been undertaken so far.
In this study, a PE-RT test piece was immersed for long term in hot water condition?60,90 and 110°C? up to 12000h. Tensile and thermal properties (DSC) were measured. The tensile strengths were increased up to 3000h and, after that, it reached an almost constant value at every test temperature. The change in heat of fusion by DSC increased in crystallinity which corresponded with these strength values. Tensile elongations at break did not vary much under 60 and 90°C condition. Also, it was very peculiar that elongations at break under 110°C condition were remarkably reduced up to 12000h.
Raman mapping method was used to examine the distribution of crystallinity. It was found the dispersion degree of crystallinity increased over test time from the analysis of Raman peak intensity ratio (crystal to amorphous) . The dispersion of 110°C test samples was remarkably increased and showed distribution curves with multiple components. The elongation decrease was assumed to be caused by this inhomogeneous crystallization by heat which may yield to deformation or defects in micro region structure of polyethylene.
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