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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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.
Bimodal Poly(Ethylene Terephthalate) Blends: Effect of Molecular Weight Distribution on Material Properties
This study presents an investigation of bimodal poly(ethylene terephthalate) blends using injectionmolded parts. The blends were characterized for intrinsic viscosity, molecular weight distribution, crystallization, and tensile mechanical properties. The data shows that injection molding preserves the intended bimodal molecular weight distribution, despite typical inherent material degradation from processing. Our results show that the maximum effect was observed when the high molecular weight component is at 10 wt.%.
Effects of Processing Parameters on Colour Variation and Pigment Dispersion during the Compounding in Polycarbonate Grades
The objective of this work is to study the variations of how independent processing parameters such as temperature, speed, and feed rate affect the dependent responses for consistent output colour (L*, a*, b*, dE*). In this study, the compounded material was processed on an intermeshing twin-screw extruder (TSE) and injection molded to evaluate their effect on the colour stability, rheology and dispersion of the polycarbonate resins. Focus was extended to the interaction of the speed, which correlates to the dispersion and colour changes.
Antimicrobial Additives for the Healthcare Market: An Overview
This presentation will cover what an antimicrobial additive is and how this class of additives differs from disinfectants. Furthermore, what types of chemistries are commonly encountered will be discussed. Lastly the current global regulations that cover the use of antimicrobials will be covered.
Direct Extrusion of PVC on the Planetary Roller Extruder
When processing PVC via the direct extrusion method, the polymer is fed continuously into a compounder without prior stabilization. Additives like stabilizers, plasticizers, lubricants, fillers and others are added simultaneously, but separately, thus stabilization and mixing takes place in the compounder. This approach requires a carefully balanced setup of the first section of the extruder, which differs considerably to conventional PVC dry-blend processing.
Understanding Dimensional Variation in Common Mechanical Processes, How It Differs in Plastic Parts, and Minimizing It
This paper breaks down the causes of variation in mechanical parts into its constituents. It then distinguishes the variation in other processes from plastic parts where the material selection, design rules, tooling and processing have a much greater effect on variation. Once these differences are understood, two very powerful CAD based tools are introduced to be used to minimize the tolerance build up.
Influence of Rheology on Part Dimensions and Production in Injection Molding
The present work was conducted to assess the influence of polymer viscosity variation from batch to batch on the part dimensions and production interruptions. The results show however that parameters such as mold temperature, barrel temperature profile and holding pressure have much more influence on these two production quality indicators than the polymer viscosity.
Cellular Polymers for Oil/Water Mixtures Separation – Evaluation of Process Conditions
This study investigates the usage of cellular polymers for large scale oil/water separation. The model polyester polyurethane foam was characterized for sustainability and oil adsorption efficacy in a batch system. The temporal mass uptake and its efficacy were experimentally optimized at various temperatures and stirring speeds. With favorable surface, morphology, and bulk properties in conjunction with process conditions, and a mass uptake of 21 g/g of foam, this polymer lends itself as a very promising material for oil adsorption.
Self-Assembled Protein-Rubber Nanocomposites
Gliadin from wheat was compounded in synthetic isoprene rubber (IR) to form a reinforcing nanophase in situ. The compounded protein aggregated into ß-sheets, which varied in quantity based on compounding conditions and protein preparation. At all conditions studied, the protein-filled IR exhibited higher modulus compared to unfilled IR. XRD revealed the crystal structure of ß-sheets.
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