SPE Library
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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Dynamic Variable Gate of Mold and its Application to Injection Molded Part Quality
Min-Chi Chiu, May 2020
As sensors evolve, their application has expanded. Mold related processes and technologies have become a focus of technology research and development. Mounting sensors in the mold cavity has become a trend in recent years. Since heretofore data has largely been limited to feedback data from the injection molding machine, control of the sensor data is the key to exploring the filling behavior of the molten melt in the cavity.In this study we created a dynamic variable-gate design in the mold. In combination with sensors to collect real-time data in the mold cavity during the injection stage, experiments were conducted to explore the course of shear heat and pressure drop generated by the melt passing through the gate when the gate thickness is varied. Therefore, the dynamic variable-gate design parameters such as gate thickness, advance delay time, and forward distance are discussed herein. To understand whether the gate thickness changes in the injection process, the influence of different parameters on the product shrinkage, product weight, and tensile strength are explored.
Effect of Coating Anisotropy on Scratch Behavior
Mohammad Hossain, May 2020
Three-dimensional finite element method (FEM) modeling has been carried out in this study to investigatethe scratch-induced surface deformation and damage mechanisms in composite coatings applied on polymer substrate. Composite coating systems with anisotropic properties and variation in thicknessare considered in the numerical framework to study the influence of coating anisotropy and layer thickness on scratch behavior. The results show that coating anisotropysignificantly affectsthe scratch resistance of coating systems. Implications of the numerical findings on scratch resistance of coating systems are discussed.
Effect of Long-Chain Branching on Scratch Behavior of Polypropylene
Chia-Ying Tsai, May 2020
The effect of long-chain branching (LCB) on scratch behavior of polypropylene (PP) was investigated. In this study, the model LCB PP samples were modified viareactive extrusion process by incorporating increasing amount of polyfunctional monomerin PP. Small amplitude oscillatory shear results show that LCB level in PP increases with increasing polyfunctional monomer introduced. Moreover, increasing LCB content slightly improves the tensile strength of PP. ASTM D7027/ISO19252 standard scratch test was employed to determine the scratch resistance of the model LCB PPs. It is found that incorporation of LCB delays the onset of fish-scale formation.
Effect of Photoinitiator Concentration and Curing Time on Soybean Polyethylene Glycol Resins
Kaetlyn Byers, May 2020
Bioprinting, a subset of additive manufacturing, utilizes bioinks, which is a combination of biomaterials and live cells, to produce functional tissue. Soybean oil is a plant polymer with promising biomaterial properties for development as a bioink. Soybean oil is low cost, has excellent biodegradation, biocompatibility and low immunogenicity.Additionally, suboptimal soybean properties such as mechanical and bioactive properties can be altered and improved when combined with other polymers. The curing of resins formulated from a combination of soybean oil epoxidized acrylate and poly(ethylene glycol) diacrylate was investigated with different concentrations of the photoinitiator diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide/2-hydroxy-2-methylpropiophenone, blend (DPH) and at different curing times. Visual observations of the cured resins indicated that as the photoinitiator concentration and curing time were varied, the resins exhibited changes in flexibility and rigidity / brittleness.
Effect of Shear Rate and Draw Down Ratio on tensile Properties of Thermally Conductive Polymer
Kyle Arsenault | Szetong de Cleir | Hadyn Beirne | Cory Albrecht | Stephen Esposito, May 2020
The use of thermallyconductivepolymersto replaceconventionaltubingmaterialshas the potentialto improveefficiencyof heat exchangedevices. Inthis study,a designof experimentswas conductedto understandthe effectsofextrusionon physicalpropertiesof thermallyconductivetubingfor an MCS.Shearrates and draw downratioswere independentlyvaried,and the tensilepropertiesof the resultingtubingwere measuredand comparedto determinethe effectof each.It was foundthat, in accordancewith previousliterature,shearrate had no substantialeffecton tensilepropertieswhile draw downratiohad a positiverelationshipwith tensileproperties
Effect of Ultrasonic Extrusion On Properties of Colloids Containing Epoxidized Soybean Oil and Clay
Avraam Isayev, May 2020
Colloid prepared with epoxidized soybean oil (ESO) and organically modified montmorillonite (OMMT) has been processed using an ultrasonic twin-screw extruder under various ultrasonic amplitudes and screw rotation speeds. Ultrasonic treatment has significantly increased OMMT dispersion in ESO, according to WAXD and rheological data. Yield strength, storage and loss modulus, complex viscosity and relaxation time of the colloid have been increased with increase of ultrasonic amplitude. Under certain high ultrasonic amplitudes, increase of one to two orders of magnitude have been observed. Creep and recoverable compliance have been decreased with the increase of ultrasonic amplitude. The tremendous changes in rheological properties of the colloid is a result of significantly improved OMMT dispersion with the aid of ultrasonic treatment. With no or low ultrasonic treatment, a higher screw rotation speed has improved OMMT dispersion since it brings more mixing effect. However, at high ultrasonic amplitudes, a higher rotation disrupts jet flow and has led to less dispersion improvement compared with the same colloid extruded at a lower rotation speed.
Electro-Spun PVP (POLYVINYLPYRROLIDONE) Nanofibers: An Experimental Investigation
Utkarsh, May 2020
Electrospinning is a well-established and straightforward method of manufacturing nanofibers from different materials like polymers, ceramics, and metals. In the current study, Polyvinylpyrrolidone (PVP) nanofibers were produced using the electrospinning process. The process control parameters viz. polymer concentration, voltage, collecting drum rotational speed, flow rate and collecting distance were studied to obtain the minimum fiber diameter for sound absorption applications. The effects of these electrospinning parameters on morphology and diameter of fibers were investigated. The minimum fiber diameter was found to be regulated by two main parameters, i.e. polymer concentration and voltage applied that both had significant effects on fiber morphology. On the other hand, flow rate, rpm, and collecting distance had the least significant effects compared to the other two. This work offers a promising attempt in the open literature to carefully study the effect of electrospinning control parameters in PVP nanofiber fabrication.
Encapsulation of Hybrid Flexible Electronics Through Compression Molding of Polyester Films
Justin Limkaichong, May 2020
In the rising field of hybrid flexible electronics, there has been a focus on embedment in clothes and other portable applications, bringing to the forefront, a need to effectively protect these devices. A main concern is to have an innocuous process that does not damage sensitive microchips, incur substrate deformation, or alter the overall design of the flexible electronics. An encapsulation method utilizing a clear, stretchable, and heat stable film that is compatible with existing flexible electronic substrates is desired. This study utilized a “silicone sandwich” mold around a polyester film as an encapsulant material to ceramic chip. The effect of temperature, pressure, and dwell time on the material flow profiles during the film's lamination process were studied. A DOE was conducted both in the laboratory and with a matching simulation to study the amount of structural and thermal forces experienced by the sandwich mold. Lamination without film deterioration or chip damage was achieved with proper control of the compression molding machine.
Energy Transfer Single-Screw Extruder Design For Peroxide-Containing Polyolefin Compositions
Qian Gou, May 2020
Peroxide-containing ethylenic polymers are used in many power cable applications. The processes involve extrusion of the polymer compositions to form one or more layers on a conductor, followed by crosslinking in a continuous vulcanization step. To extrude the composition, it is critical to maintain a low discharge temperature so that the peroxide does not decompose significantly during the extrusion process, so as to prevent premature crosslinking. However, with a low discharge temperature, the rate is usually reduced; for some formulations, the rate reduction is dramatic. This paper describes an energy transfer (ET) screw design that enables high rates at acceptably low melt discharge temperatures, or alternatively, yields significantly lower melt discharge temperatures at a given rate than a conventional Maddock mixing screw. The design simulations of the new ET screw were validated experimentally.
Engineering Impact Modification of Polypropylene for Low-temp/High-strain rate Loading Conditions
Chinmay Saraf, May 2020
This communication presents a systematic investigation of polypropylene (PP) formulations modified using SEBS (Styrene-ethylene/butylene-styrene) and POE (Polyolefinic elastomer) block copolymers for impact modification. Impact performance of PP formulations containing POE, SEBS+POE and SEBS is compared under extreme conditions (high strain rate at -15°C and -30°C) and during quasi-static fracture tests at 25°C. Present work also discusses the effect of talc reinforcement on the fracture toughness of these formulations. The focus of the present work is to investigate the failure mechanisms of these formulations and understand how it correlates with the size, shape and other morphological features of the phase-separated SEBS and/or POE domains. The results show that the formation of crazes is the major energy absorbing mechanism at subzero temperatures. The 1 um domain sizes for SEBS modified PP leads to the stabilized craze formation and the highest fracture energy absorption amongst all the formulations investigated. It is shown that the effective stiffness of the dispersed phase and optimum particle size controls the damage density and energy absorption for polypropylene under extreme conditions.
Enhanced Filling of Injection Molds By Microstructured Cavity Surfaces
Magnus Orth, May 2020
The main objective of this paper is to evaluate the influence of microstructured injection mold cavity walls on cavity filling. Thermoplastic material has been tested with a variety of micro structured molds. The area density of the structures has been varied and the flow length of the plastic melt using constant filling pressure has been measured. Microstructures applied on one side of the injection mold significantly extend the flow length of the molten plastic. In addition, depending on the processing viscosity, there is an optimum structure area density for the longest possible flow paths. This knowledge is therefore valuable in production to realize longer flow paths with the same machine technology.
Enhancement of Binding Matrix Stiffness In Composite Filament Co-Extrusion Additive Manufacturing
Chethan Savandaiah, May 2020
The Flexural modulus and strength are an intrinsic aspect of parts produced via dual matrix composite filament co-extrusion (CFC) based additive manufacturing. In this research work, the main objective is to optimize thermoplastic’s (TP) flexural properties by reinforcing it with particulate fillers for CFC printed parts. Accordingly, an effort has been made in this respect and neat Polyamide-6 (PA6) and its composite (PA6.CF) was chosen as a binding matrix for CFC flexural specimens. The PA6 binding matrix is reinforced with particulate carbon fibers (PCF). To improve the compatibility between the PCF and matrix, stearyl titanate coupling agent (1.5 wt. %) was utilized. Constraints such as defects and porosity are of critical attributes and play a vital role in defining the mechanical performance of the 3D printed parts. Herein, the printed specimens were subjected to a non-destructive testing method: micro-computed thermography (µ-CT). PA6 and reinforced PA6 specimen revealed similar porosity and defect volume. Furthermore, the three-point bending test results of 3D printed CFC composite with PA6.CF as a binding matrix showed approx. 46% increase in flexural stiffness and 27% increase in flexural strength when compared to CFC specimens printed with neat PA6 as a binding matrix. In addition, the cryo-fractured fractography of carbon composite filament, an epoxy-based thermo-cured continuous carbon fiber, revealed even distribution of carbon fibers with no visible voids.
Erucamide Slip Analysis in Polyethylene by GC using a Nitrogen Chemiluminescence Detector
Garry Yamashita, May 2020
Additives are commonly used in polyethylene applications to provide processing and long-term stability as well as to enhance or modify polymer performance for specific physical properties. Slip agents are one type of modifier used to alter the coefficient of friction in polyethylene films. Fatty amide based slip agents function by migrating to the surface of the film to provide a lubricating layer which enables the film surfaces to slide more easily across one another and when in contact with blown film extrusion and conversion equipment to facilitate processing. A combination of direct (e.g. XRF) and indirect (e.g. HPLC) analytical methodologies are used to measure the additive types and levels used for polyethylene applications. For slip agent analysis, the fatty amide is typically separated from the polymer matrix using an extraction technique (e.g. Soxhlet, Microwave, ASE) or by use of total polymer dissolution followed by polymer precipitation. The extract is then filtered and analyzed by a chromatographic technique, typically, HPLC-UV, GC-FID, or GC-MS. In some instances, polymer matrix signals from oligomers or other additives can interfere with the analysis. Furthermore, the slip agents from various suppliers are a mixture of fatty amides so analysis of the erucamide peak requires inherent knowledge of the specific amide distribution for the supplied slip agent. In this paper, a new and novel use of a gas chromatograph with a nitrogen chemiluminescence detector will be presented which illustrates a universal calibration of erucamide slip agents that compensates for the various amide distribution profiles from three different suppliers. This approach can also be extended to other slip agents such as behenamide and oleamide.
Evaluation of Mesh Interface and Immersed Boundary Models For the Optimisation of Mixing Elements
Malte Schön, May 2020
Mesh interface and immersed boundary models are presented as simplifications for the simulative design of dynamic mixing elements for single screw extruders. These simplifications have great potential to cut complexity and cost in both drafting and computation. Results for distributive mixing are compared quantitatively and qualitatively to a non-simplified 3D model. It is found that good agreement with the 3D model is achieved when the simplified models’ throughputs are adjusted for mass conservation.
Experimental vs. Numerical Buckling/Post-Buckling Response of Cantilever Orthotropic Web Beams Under Tip Force
Abdul Halim, May 2020
A combined numerical and experimental study of lateral torsional buckling of orthotropic rectangular section beam is presented. Pre and post-buckling analysis of beams is studied using Abaqus Riks analysis and compared with experimental results. Timoshenko’s solution with replacement stiffnesses is adopted to calculate the lateral torsional buckling load of six orthotropic beams. Four laminated composite beams with 0 degree layups and two beams with 90 degree layups are prepared in lab. Beams had different length-to-height (l/h) ratios ranging from 6.67 to 20 to study its effect on the critical load. All beams are assumed cantilever and tested under a concentrated load at the free end. Two laser pointers mounted horizontally at the free end are used to measure twisting rotation of beam section (β) for every load increment. Load vs. β plots are generated and compared with numerical and analytical results. The proposed experimental technique could be adopted to study lateral-torsional buckling response of laminated beams with arbitrary fiber orientations (generally anisotropic) under different load and support conditions. The technique also helps to generate load vs. lateral and vertical deflection simultaneously while measuring the section twisting rotation angle (β).
Experimental Wear Data Acquisition for Condition Monitoring in Injection Molding Machines
Sebastian Fruth, May 2020
Condition Monitoring and Predictive Maintenance are big fields of research in the context of Industry 4.0. The ability of determining the state and predicting the lifetime of specific components can have a big economic impact. As datasets from production containing wear data are rare, it makes sense to generate this data in laboratory experiments. In this paper we present methods for implementing condition monitoring of injection molding screws and non-return valves. After developing key indicators, wear datasets are generated in laboratory experiments and the results are compared to the theoretical considerations.
Extension of the Rivlin Polynominal for the simulation of the non-linear material behaviour of TPE
Christoph Zimmermann, May 2020
The non-linear material behaviour of thermoplastic elastomers (TPE) show a considerably higher stiffness compared to pure elastomers due to the presence of the thermoplastic phase. The approximation of non-linear material behaviour via generally known hyperelastic material models illustrate some deficits regarding the initial stiffness and the course at higher deformation. In order to ensure a precise dimensioning of TPE parts via the finite element analysis (FEA), current hyperelastic material models have to be extended by user-defined formulations. For this purpose, the existing Rivlin polynomial is extended by an additional material parameter as exponent. This extension leads to a more accurate prediction of the non-linear material behaviour. Even the simple extended Neo-Hooke material model shows a good accuracy regarding the determined material behaviour and the initial stiffness of the used practical part.
Fabrication of Multifunctional PVDF/MWCNT Nanofibrous Membrane via Electrospinning for Membrane Bioreactors
Esrat Jahan, May 2020
Nanofibrous membranes in membrane technology applications for water and wastewater treatment have gained interests among researchers because of their high mechanical and chemical resistances. In this study, Polyvinylidene fluoride (PVDF) nanofibrous membranes were prepared by electrospinning method with 20 wt% PVDF solution. The effects of processing parameters including flow rate, applied voltage, tip-to-collector distance and presence of multiwalled carbon nanotube (MWCNT) on fibers morphology were observed using scanning electron microscopy. The changes of fiber diameters, pore size, and membrane porosity were investigated to investigate the characteristics of nanofibers as a function of processing parameters. The modified membranes with MWCNT were characterized with contact angle analyses and water filtration tests to evaluate the performance of the membranes.
Failure Analysis of an Outdoor Instrument Housing
Jeffrey Jansen, May 2020
Cracking occurred within the housing for a piece of weather monitoring instrumentation being used as part of field service trial. The cracking was observed within the bosses used to secure the housing section to the mounting hardware. The focus of this investigation was the determination of the nature and cause of the failure. The results obtained during the evaluation of the failed housing indicated that the cracking occurred through three separate mechanisms. Significant factors in the failure included aspects of design, manufacturing, and the service conditions. This paper will review the testing performed to characterize the failure modes and identify the causes of the cracking, while demonstrating the analytical procedures used in the investigation.
Failure Analysis of Polymer Coating Systems
Gaurav Nagalia, May 2020
Failure analysis of polymer coating systems can be challenging due to the fact that coating systems typically involve multiple and generally very thin layered components. The root-cause for the failure of a polymer coating can be attributed to many factors. Thus, it cannot be easily determined by inspection or observations, and significant amount of testing is often required to determine the root cause for the failure. Typically, failures can be caused by selection of improper coating system, or it can be caused by insufficient surface preparation, or it can be caused by application related issues. This paper attempts to provide a guide to performing failure analyses of polymer coatings by discussing two separate coating systems that utilized a polyvinylidene fluoride (PVDF) top coat and evaluates the fundamental root causes of failure. The importance of reviewing background information, performing site-inspections, conducting relevant laboratory and field testing, and utilizing published literature to reach a root-cause for the failure is high-lighted. In both cases, laboratory examinations revealed that while high performance coatings were utilized, their compatibility within the system and their susceptibility to hazards within their respective applications, were not accounted for, leading to poorly designed coating systems that eventually failed.
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