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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Fast Prediction of Crystallinity in Injection Molding during the Packing Stage
Being able to predict products’ degrees of crystallinity, and thereby optimize their crystallization processes, is of great significance for producing high quality polymeric products in injection molding. Injection molding simulation software can simulate polymers’ density results during the packing stage, and these predicted density results can be used to calculate polymers’ crystallinity results. Based on this idea, a novel method was proposed to predict the degree of crystallinity for polymers during the packing stage. For this method, pressure and temperature results were first simulated using injection molding simulation software, and then the density results were calculated based on a pressure–volume–temperature (PVT) model. Next, the crystallinity results were solved according to the densities of the fully crystalline part and the purely amorphous part. Finally, a real part in production was conducted as a case study to verify the proposed crystallinity prediction method. Experimental results showed that the proposed method was both correct and effective.
Automotive Glazing – Polymeric Systems Providing Enhanced Design Freedom and Functionality
Automotive glazing using engineering thermoplastics (ETP) is an area of immense interest for the automotive industry as it provides unique opportunity to redefine the overall appearance and styling of the vehicle in addition to light weighting. Typical transparent parts seen on a car such as the side moving windows, rear windshield, rear quarter windows (RQWs), panoramic sunroof and the lift-gate (or tailgate) are traditionally made of tempered or laminated glass. Use of ETP materials that are transparent like polycarbonate (PC) can offer comparable functional performances at reduced system cost in addition to significant weight reduction. Such parts made of PC are virtually unbreakable, have good weatherability and scratch resistance imparted through proprietary surface coating technology. The advanced molding process used to manufacture such large transparent part is termed as 2-shot injection-compression colding (2K-ICM). This paper focuses on identifying the critical molding process variables and capturing their effect on the final part quality. The emphasis is on minimizing the combined part warpage and maintaining lower levels of residual stress in the part. By performing a simulation-based design-of-experiments (DOE) study, the relationship between the process parameters on the part warpage is elucidated. Finally, through a regression analysis, an estimate of the warpage is made using the mathematical model.
Study on Fabrication of CNT-Based Conductive Products via Melt Differential 3D Printer
Circuit and anti-electrostatic products via 3D printing technology exhibit unparalleled advantages over other manufacturing technologies, because it can precisely control the shape of the path and structure. The existing FDM device has a flexible buckling failure phenomenon, difficult to fabricate elastomers and other soft products. A new polymer melt differential 3D printing device was designed in this paper, and the experimental research of printing conductive products with polylacide (PLA)/ carbon nano tube (CNT) composites was made. The result showed that the conductivity of the composites can reach to 1.6 S/cm (10wt%CNT) and the composites also possesses excellent printing performance. Polymer melt differential 3D printer was used to fabricate the conductive circuits with the substrate of paper, the composite circuit has strong interface bonding force with the substrate. Then the anti-static shell of the designed pattern with multilayers were printed, the SEM images show that the shaping precision and bonding between the layers are to meet the practical requirements. The results show that the polymer melt differential 3D printer can be satisfied to printing conductive PLA/CNT composites products, which can provide the theoretical basis and technical guidance for the accurate printing of circuit and anti-electrostatic products.
Preliminary Study of Changeover Time in a Twin-Screw Extruder
Changeover times differ from ‘pulsed’ tracer residence time distributions in that the starting and ending materials may have different viscosities, densities, and processing properties. Changeover times for twin-screw extruders are relatively unstudied, yet have far-reaching impacts for transient operations in the polymer processing industry. In this work, we examine the changeover of polyethylene and polystyrene in a twin-screw extruder using an online Raman detector. The detected changeover times were generally longer than the residence times found for analogous ‘pulsed’ experiments. Viscosity ratio (between ending and starting materials) and throughput have a significant effect on changeover time, whereas screw speed does not.
Farmlands for Plastics, Textiles, Dyes or Food: Are Bio-Based Materials Really Sustainable?
This presentation aims to contribute to an honest dialog on sustainability of oil-based vs bio-based materials in a consumer context that often includes significant “greenwashing” based on misinformation. This consumer context has raised consumers’ expectations and has put undue burden on many industries and in particular on the plastic and textile industries. Textile companies have tried to find a niche or “green” appeal in this increasingly competitive market; therefore, some are using labels such as “Sustainable”, “Eco-friendly”, “Eco-fashions” etc. As a result of high competition and low margin of profit, some companies have adapted practices such as creative marking and creative reporting/labeling that makes the consumer feel good about a “sustainable” choice, while the carbon footprint, or overall environmental impact, of the products or their production processes on the environment is not significantly better, and in some cases is even worse, than the alternative. Therefore, consumers either have false assumptions about the products they purchase, or are receiving conflicting information and are confused. Consumers are not the only ones that are confused; some members of industry have a hard time sorting out information on sustainability and, in turn, making decisions about where to invest their resources to create more sustainable products. This presentation will attempt to shed some light on these issues and raise some serious questions.
Fire Survival Cable: Understanding of Lab Scale to Manufacturing Scale Cable Validation
In order to successfully develop fire survival cable products it is important to have a good understanding of the relationship between lab scale material development testing and production-scale cable capability. Research and development work on fire survival cables has been active for more than a decade and today many commercial products exist in the market for these applications. However each fire survival cable design, application type and testing protocol is designed to be different to meet specific regional standards and customer requirements. In this work, we have demonstrated lab scale understanding of ceramic formation in silicone compounds and translated to large scale IEC 60331- 21 fire survival cable test validation, while also meeting other electrical, mechanical and heat ageing requirements.
Investigation on Warpage and Sink Mark for Injection Moulded Parts Using Taguchi Method
Injection molding is a complex process for many production engineers as it involves selection of many process parameters to produce quality products to meet customer requirements. Determination of the optimal process parameters in injection moulding is an important design task as it influences part quality, production rate, and production cost and energy consumption. The purpose of this paper is to investigate the effect of selected process parameters in injection moulding on part quality. The paper applies Taguchi’s parametric design and analysis of variance (ANOVA) technique to study the effect of process settings of plastic injection molding on part quality. Experimental data are used to identify the relationship between the injection molding process parameters and product quality. Mold surface temperature, melt temperature, mold open time and ejection temperature are selected as the process control parameters. Warpage and sink mark depth are selected as the multi-product quality characteristics.
Using Infrared Temperature Sensors to Study Temperature Changes of PVC during Flow with the Incorporation of Melt Rotation Technology
Infrared temperature sensors were used to study the effect of mold rotation technology on the plastic melt temperature and shear-burning that commonly occurs with PVC. Inserts were designed and built so that areas of high shear could be introduced during flow through a runner, as well as provide for the incorporation of melt rotation technology. A DOE was used to investigate how factors such as melt temperature, residence time, injection rate, and packing rate affected the temperature at various points along the flow path. It was found that the use of melt rotation technology could allow more uniform temperatures after the point of rotation without causing a larger problem with shear-burning.
Interlaminar Fracture Toughness of Woven Glass Fiber-Epoxy Laminates with Carbon Nanotube Buckypapers
In this paper we present the potential of applying buckypapers (BP) films for the improvement of the interlaminar fracture toughness of laminated composites. We experimentally investigated the effect of interposing BP between plies on the interlaminar fracture behavior of glass fiber / epoxy woven fabric composite laminates. Crack propagation was examined during mode I - fracture testing using double cantilever beam (DCB) specimens prepared with different types of BP placed at the midplane.
While lower fracture toughness values were determined when using BP prepared with untreated carbon nanotubes (CNT) and graphene nanoplatelets (GNP) - CNT/GNP – (hybrid filler at a weight ratio CNT/GNP=80/20), a slight increase in toughness was observed employing BP prepared with oxidized CNT (CNT-ox). Morphological analysis of the fracture surfaces indicated that this increase in toughness was related to fracture phenomena that were enabled by the presence of BP film. Cohesive failure of the BP film and fiber bridging positively contributed to the increase in toughness observed in the case of composites reinforced with BP-CNT-ox.
The adhesive failure mode of BP-CNT/GNP was different from the cohesive mode characteristic of BPCNT- ox, indicating the importance of promoting cohesive failure of the BP, as it enables a more effective energy dissipation mechanism.
Thermoplastic Polyurethane Chitosan / Cellulose Nanocrystals Composites for Wound Healing Applications
This research is concerned with creating an antibacterial wound dressing material by introducing naturally-derived chitosan into thermoplastic polyurethane (TPU) matrix. Chitosan is a promising filler to improve the antibacterial properties of wound dressing materials including TPU. A combination of chitosan with cellulose nano-crystals (CNCs) can help meeting the mechanical design requirements of wound dressing applications. TPU nanocomposites modified with CNCs were prepared by using an optimized solution casting method. Morphological analysis carried out through scanning electron microscopy (SEM) showed that CNCs are well distributed within the matrix up to a filler amount of 2wt%. Thermal analyses indicated that the incorporation of nanofillers leads to significant changes in the glass transition temperature and melting behavior characteristic of the hard segments. Rheological analyses performed on molten TPU incorporating CNCs indicated that the presence of the filler favors shear-thinning behavior.
TPU films containing a combination of CNCs and chitosan were made through a solvent exchange method and solution casting. Current investigations are focused on the characterization of the mechanical properties, water absorption behavior and water-responsive mechanically adaptive properties of the hybrid TPU-CNC-chitosan composites.
Effect of Degradation Caused by Water Absorption on Mechanical Properties of Injection-Molded Glass Fiber Reinforced Polypropylene
Injection molded glass fiber reinforced polypropylene (GFPP) was immerged into hot water and its bending test was carried out to study about degradation of GFPP caused by water absorption. Although the water absorption of GFPP is low (about 0.2 wt%), it shows obvious decrease both in flexural modulus and flexural strength. Flexural strength decreases with the immersion time continuously, while flexural modulus shows rapid decrease during early period of immersion and then become constant. Another experiment in which the specimens were dried after immersion shows the flexural modulus after the early drop correlates with amount of water absorption and recovers by drying to the same level of immersed samples having the same amount of water absorption. That indicates there are different mechanisms while flexural strength decreases as a result of some irreversible degradation during water immersion, flexural modulus is just due to a reversible swelling by water absorption. And the rapid drop of modulus seems to be not caused by water absorption but by heat.
Improving PLA-based Material for FDM 3D-Printers Using Minerals (Principles and Method Development)
A method has been developed to study the performance and suitability of thermoplastic polymeric material for Additive Manufacturing (3D-printing) based on Fused Deposition Modeling (FDM). The method has been used to study the benefits of minerals for PLA-based material (filaments) that are commonly used in FDM 3D-printing. An optimized formulation has been presented that enhances the printing performance and print quality, reduces warpage and curling of the edges, and allows 3D-printed PLA objects to be annealed while maintaining their original shape and dimensions. The annealed PLA objects show significantly improved heat/temperature resistance and can withstand temperatures as high as 120ºC.
Development of Predictive and semi-gSEM Models of Backsheet Degradation under Multifactor Accelerated Weathering Exposure
Poly(ethylene terephthalate) (PET), with its high dielectric breakdown strength, is widely used in multilayer PV module backsheets as a core layer. However, it degrades due to ultraviolet light and humidity. Failures such as cracking and delamination in backsheets caused by weather-induced degradation may result not only in performance loss of the modules, but also loss of electrical insulation, which is a safety concern. Degradation of different grades of PET and two types of backsheets were studied and modeled under multi-factor accelerated weathering exposures. The formation of light absorbing chromophores, changes in the fundamental absorption edge of the polymers, and UV stabilizer bleaching were confirmed through UV-Vis optical spectroscopy. FTIR-ATR analysis showed that chain scission is the common mechanism under all exposure conditions. The degradation mechanisms determined from optical and chemical evaluations were then used to construct a set of degradation-pathway network models using semi-gSEM (semi-supervised generalized structural equation modeling) methodology using a
Soy Protein Isolate Films with Improved Mechanical Properties via Bio-Based Dialdehydecarboxymethyl Cellulose Crosslinking
Glycerol-plasticized soy protein isolate (SPI) films with dialdehyde carboxymethyl cellulose (DCMC) as crosslinking agent were solvent casted and tested for their mechanical properties. Results indicate that the addition of DCMC increased tensile strength (TS) up to 218%, suggesting effective crosslinking between SPI and DCMC. The significant improvements in the TS compared to other dialdehyde polysaccharide crosslinking agents such as the dialdehyde starch is due to higher compatibility of DCMC with SPI, which was confirmed by SEM imaging. Furthermore, based on stress-strain features, a hypothetical mechanism was proposed to illustrate the effect of the polymeric cross-linking agent.
Evaluation of Methodoligies Utilized to Determine the Pressure Drop throughout an Injection Mold
Two of the most common industry methods for evaluating the pressure drop through an injection mold during mold filling are investigated against an instrumented mold. The first is injection molding simulation and the second is the shop floor applied “Pressure Drop (Loss)” study method that is widely accepted as part of modern injection molding practices. The study finds that the shop floor method can significantly misrepresent the relative pressure developed through progressive regions of a mold. Injection molding simulation was found to provide a better agreement with the actual measured mold filling pressures.
Performance Enhancement of PEBAX Using Supercritical Fluid Extrusion for Biomedical Applications
An intravascular catheter system requires design specifications that needs to provide sufficient flexibility, to follow desired path required by the surgeon and adequate stiffness to travel along the curving path of vasculature. This paper presents the effects of sub-supercritical, near-supercritical and beyond supercritical carbon dioxide assisted extrusion process and their characterization to evaluate their thermal and dynamic mechanical properties using Pebax. A twin-screw-extruder using scCO2 can effectively generate foams, while providing excellent control over mechanical and thermal properties. The crystallization and melting behaviour of scCO2 assisted extrudates were investigated using differential scanning calorimeter technique (DSC) for various isothermal conditions. The mechanical performance was evaluated by using dynamic mechanical thermal analysis (DMA) and tensile test. A significant increase in dynamic modulus was observed for Pebax extruded at 800 psi and 1000psi, however, decreased resilience and toughness was noted for Pebax extruded at 1200psi.
Using ZeMac® Copolymers To Increase Performance and Processibility of High RV Nylon
Conventional polyamides with high relative viscosity called “high RV polyamides” or “high RV nylons” are prepared typically by a few large nylon-6 producers with solid state polymerization (SSP) process, which is time consuming and energy intensive and hence expensive. Such polyamides are linear molecules as are high RV polyamides produced by compounding with chain extenders with ?-? functional groups. However ZeMac® alternating copolymers of ethylene and maleic anhydride, which are unique with hundreds of pendant functional groups, can be compounded with low RV polyamides to form high RV polyamides which have a branched structure, confirmed by shear thinning rheology. The paper will cover this and performance and cost advantages of such branched polyamides over conventional SSP and linear polyamides for several high performance applications.
Energy-Efficient Processing of Rendered Animal Proteins as Value Added Bio-Crosslinkers in High-Strength Thermosets
Emergence of bovine spongiform encephalopathy (BSE) has inhibited the use of proteinaceous materials from rendering industry with regard to animal feed, pet food, and fertilizers. In recent times, extensive research has been done towards finding suitable, alternative, non-feed and non-fertilizer applications for these materials. In this regard, plastics from proteins, especially thermoplastics and derived composites, have emerged as a potentially suitable choice. However, poor mechanical properties, high moisture absorbing ability as well as inherit odor have limited their widespread application. In this study, we developed high-strength, and toughened thermoset polymers from proteinaceous material obtained from the rendering industry, such that they can be employed in high performance applications, such as automotive sector.
Improved Sand Erosion Resistance and Mechanical Properties of Multifunctional Carbon Nanofiber Nanopaper Enhanced Glass Fiber/Epoxy Composites
Multifunctional fiber reinforced epoxy composites with improved sand erosion resistance; mechanical properties and electromagnetic interference (EMI) shielding resistance have been fabricated and tested in this work. Preformed carbon nanofiber (CNF) thin film or nanopaper, made of dense and entangled nanofiber networks, was laminated on the surface of glass fiber reinforced epoxy composites (GFPRC) as a surface protection layer. Five times improvement in sand erosion resistance in terms of sand erosion rate, and up to 24% improvement in flexural strength was achieved after the incorporation of CNF nanopaper onto thin glass fiber/epoxy composite. The CNF nanopaper composite showed an EMI shielding resistance of 30–40 dB within a frequency range of 30 MHz to 1.5 GHz. This multifunctional composite material shows good potential for use in commercial electronics, housing, and the automotive industry.
Experimental Co-relation of Induction Welded Bead’s Burst Pressure using Finite Element Techniques
This report describes the results of a project focused on obtaining the yield stress at the weld bead of a vibration welded pressure vessel. The burst pressure of 0.508 bar was obtained from the hydrostatic pressure test data performed experimentally. The aim of this project is to verify the amount of stress generated at the weld bead as it is observed in the hydrostatic pressure test that the rupture occurs in this region and formulate a failure criterion. Additionally, the project investigates the best methodology of mesh by playing with the various parameters like geometric modelling, order of elements and type of contact in Hyper mesh 13.0 in order to obtain maximum correlation with experimental data. The material used for the vessel is Thermylene (a polypropylene composite material which is proprietary to Asahi Kasei Plastics NA) and a bonding resin compound for the bead. The analysis consists of Non-Linear Geometric Static simulation of applying 0.075 MPa of pressure (to get more data points in yield condition and observe geometric behavior) to the vessel using Finite Element Analysis. Both the full and quarter model was Meshed using Hypermesh and analyzed in ABAQUS. The results obtained from the analysis were displayed using stress plots.
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