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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Introduction to Possible Hybrid Veneer Composite Laminated Panels
In the current research, hybrid laminates having veneer facesheets and natural fibre composite cores were fabricated to investigate their fire and mechanical properties and to observe a suitable combination. Wool and flax fibres were selected for fibre reinforcement. Ammonium polyphosphate (APP) was used as the primary flame retardant for all the composites. The mechanical performance of the flax fibre reinforced fire retardant polypropylene (flax-FRPP) and fire retardant wool-polypropylene (FR-wool-PP) hybrid layered panels were further studied and compared to plywood made similarly. The results showed that hybrid laminates have better fire properties and the hybrid layered veneer composites can have significant structural applications if proper bonding between the composite and the veneer layers can be achieved. The tensile properties showed a reduction in Young’s modulus and ultimate tensile strength, though the wool-veneer hybrid laminates outperformed the flax-veneer ones. Moreover, the impact test showed that the wool-veneer hybrid laminates had the best resistance when compared to all the veneer-based samples tested. The results point towards the possibility of manufacturing a superior fire-resistant hybrid veneer composite laminate.
Enhanced Dispersion of Lignin in Pet Polyols for Improved Thermal Insulation of Polyurethane Foams
The incorporation of technical lignin, a multifunctional natural polymer, into rigid polyurethane foam (RPUF) for the enhancement of thermal insulation performance has gained increasing interest in academia and industry. However, the structural complexity of technical lignin hinders its dispersion in the polyols commonly used for the preparation of RPUF. Poor dispersion of technical lignin in polyols inhibits the chemical reactions and limits the potential improvement in the thermal and mechanical properties of RPUF. Herein we report enhanced dispersion of unmodified kraft lignin, at a loading of 3 wt % in a mixture of glycerol and an aromatic polyester polyol (20:80) for the preparation of RPUF. It has improved the insulation property by 30% while retaining its mechanical performance compared to the control RPUF without lignin. Such a level of improvement, to the best of our knowledge, has not been reported in RPUF using chemically unmodified lignin to date. This is attributed to the enhanced dispersion of the kraft lignin in the polyol blend causing changes in the cell morphology of the resultant RPUF, as supported by microscopic and rheological analysis. To this end, the insights into the influence of kraft lignin on the polyol-precursor on the properties of the RPUF are discussed.
Controlled Release of Essential Oils Using Laminar Nanoclay and Halloysite / Essential Oil Composite
The preparation and characterization of a multilayer film reservoir with clay/essential oil (EO) composites was described. The goal is to analyze the potential use of these reservoirs with clay/EOs composites as aroma-controlled release for various applications such as pesticide or attractant for pest control as well as antimicrobial control. Two types of clays were analyzed, porous halloysite (HNT) and octadecyl modified montmorillonite (MMT) nanoclay; as well as two types of essential oils, orange (OO) and thyme oil (TO). The DRX results confirmed that MMT clay presented higher thyme oil adsorption and better interactions than orange oil. Clay/EO composites encapsulated in multilayer film showed a prolongated aroma release during longer times. Polyamide (PA) barrier layer thickness has an effect on the liberation of the volatile compounds through the multilayer film.
Variability Levers in ASTM D-2863 Results for Styrenic Foams
ASTM D-2863 is a small-scale fire performance classification test, part of ASTM C-578 standard for polystyrene rigid thermal insulations, with a binary pass/fail outcome at a given oxygen concentration level. When applied to foams, the test is highly variable and is easy to manipulate, putting its accuracy as a test method into question. In this work, macro-imaging was used to closely monitor the foam – flame interaction to gain a better understanding of variability levers. For example, one of the levers is duration of flame application to a sample. Our imaging studies indicate that the pass / fail boundary oxygen level is strongly correlated with the flame application duration.
In-Line Laminate Decorative Thermoplastic Composite Panel
In this paper, a decorative material was first applied onto the light weight reinforced thermoplastic (LWRT) composite core mat during the core manufacturing, and then followed by a consolidation process through the calender rolls. This method is defined as an in-line lamination process with a finished A-surface panel in comparison with conventional off-line decorative materials lamination process, in which the decorative layer is applied in a separate process from core manufacture. Decorative layers with two patterns, namely woodgrain and marble, have been studied. The adhesion performance between the decorative skin material and LWRT composite substrate has been evaluated by 180° peel adhesion test following ASTM standard D903. The separation between the decorative layer and the substrate was difficult to initiate, which demonstrates an outstanding adhesion between the two components. A stylus method quantitatively confirmed the decorative surface is smooth and able to cover the core’s texture. Flatwise tensile test results by ASTM standard C297 method showed the decorative panels could not be delaminated, indicating strong bonding between decorative skin material and core mat. Materials produced with the woodgrain pattern were tested to have better flexural strength and stiffness than the sample made with marble decorative pattern material. In addition, flame retardancy results showed the laminated decorative panels can meet ASTM E84 requirement of Class C and above. The decorative material with custom design provides the decorative A-surface with an appearance of wood, stone, textile or other natural materials as desired, opening a window for the LWRT composite to be used inside an RV such as the interior layer of sidewall and ceiling.
Biocarbon Hybrid Composites for High-Temperature Automotive Applications
Automotive manufacturers have been increasing use of natural fiber composites to reduce vehicle weight and respond to consumer demand for environmentally friendly products. However, the low thermal stability of natural fibers can limit their use to low-processing-temperature polymers and low-temperature automotive environments. Pyrolysis of biomass results in the formation of a porous substance called biocarbon, which can improve composite thermal performance, eliminate odor, and reduce hydrophilicity. The objective of this study was to investigate the effects of biocarbon on the performance of biocarbon-glass fiber hybrid composites for use in under-the-hood automotive applications. This study evaluated the macroscopic (mechanical performance, density) and microscopic (SEM) characteristics of biocarbon-hybrid composites with varying loading level and biocarbon type. Biocarbon-hybrid composites were approximately 10-13% lighter than currently used fan-and-shroud materials and the addition of biocarbon content improved composite flexural strength & modulus.
The Study on Replacement of Steel Cord Reinforcements by Synthetic Fibers in Composite Materials
The emergence of new composite materials as replacements for metals has been demonstrated in many studies. Many products derived from steel-reinforced composite materials can potentially be modified by replacing the existing steel cord reinforcement with that of synthetic fibers such as carbon to overcome the problems involving dimension instability and the effect of creep which could pose problems in applications such as belts driving heavy machinery. In the present study, Carbon fiber reinforced in the TPU matrix was manufactured by compression molding and was tested for dynamic mechanical and tensile analysis. The results obtained with carbon/TPU are positive with respect to steel/TPU composites which proves that the carbon fibers can be a suitable replacement to the steel cords that are used in applications such as conveyor belts for providing the required tensile strength and creep resistance.
Influence of Processing Parameters on Fiber Length Degradation During Injection Molding
This work is focused on investigating the influence of processing parameters on the fiber breakage in the plasticizing unit of an injection molding machine. To determine the fiber length reduction, an injection molding machine is equipped with a special cylinder which can be opened over a length of 700 millimeters. This makes it possible to measure the fiber length along the screw channel and to analyze the influence of the melting behavior. Fiber length degradation is investigated for short fiber reinforced polypropylene with different fiber fractions under the variation of the processing parameters screw speed, barrel temperature and back pressure. The results show a negative influence on the fiber length for an increase in screw speed and back pressure as well as for a reduction of the barrel temperature.
Study on the Flow-Fiber Coupling and its Influence on the Shrinkage of FRP Injection Parts
The fiber-reinforced plastics (FRP) material has been applied into industry as one of the major lightweight technologies, especially for automotive or aerospace products. The reason why fibers can enhance plastics is because of their microstructures. One of those microstructures is fiber orientation distribution. Since the fiber orientations inside plastic matrix are very complex, they are not easy to be visualized and managed. In addition, there might be some interaction between flow and fiber during the injection molding processing, but not fully understood yet. In this study, the flow-fiber coupling effect on FRP injection parts has been investigated using a geometry system with three ASTM D638 specimens. The study methods include both numerical simulation and experimental observation. Results showed that in the presence of flow-fiber coupling the melt flow front advancement presents some variation, specifically at the geometrical corners of the system. Furthermore, through the fiber orientation distribution (FOD) study, the flow-fiber coupling effect is not significantly at the near gate region (NRG). It might result from too strong shear force to hold down the appearance of the flow-fiber interaction. However, at the end of filling region (EFR), the flow-fiber coupling effect tries to diminish the flow direction orientation tensor component A11 and enhance the cross-flow orientation tensor component A22 simultaneously. It ends up with the cross-flow direction dominant at the EFR. This orientation distribution behavior variation has been verified using micro-computerized tomography (micro-CT) scan and images analysis by AVIZO software. Finally, the flow-fiber coupling effect also verified based on the tensile stress testing and the shrinkage of the injected parts through different flow domains.
Physical Analysis of Multifunctional Aerogels Made of Polymerized Silica Precursors With Stiff and Flexible Backbone
Aerogels made of polymerized silica precursors are an evolving class of porous materials with the potential to get functionalized by embedding graphene materials in their structure. Owing to their unique features they have shown promises for a wide range of applications namely electronics and biomedical devices. The mesoporous structure of these aerogels is defined during the sol-gel transition process which can be tailored by optimizing processing parameters. In this study, the main effort is to examine the comparison of the properties of the aerogels made of polymerized silica precursor with and without graphene nanoplatelets (GnP) and graphene oxide (GO).
Foam Injection Molded Lightweight PP Composite Foams Reinforced by Fibrillary PTFE With Outstanding
A facile way was reported to produce lightweight and strong foamed PP/polytetrafluoroethylene (PTFE) components. First, in-situ fibrillated PP/PTFE composites were prepared using a co-rotating twin-screw compounder. SEM analysis showed nanoscale reticular PTFE fibrils uniformly dispersed in PP matrix. DSC combined with online optical microscopy observation, and rheological analysis demonstrated PTFE fibrils pronouncedly improved crystallization and viscoelasticity, respectively. Thus, PP/PTFE foam showed obviously refined cell structure compared with PP foam. Thanks to the promoted crystallization and cellular morphology, PP/PTFE foam exhibited superior mechanical properties. PTFE fibrils facilitated to improve PP foam’s tensile strength and modulus. Therefore, lightweight and strong PP/PTFE foam, achieved by the flexible, efficient, and scale-up FIM technology, exhibits a promising prospect in applications.
Study of Mechanical and Machinability Behaviour of Natural Fibre Composites
This study aims to investigate the mechanical and machinability behaviour of three polypropylene (PP) based natural fibre reinforced composites (NFRCs) – Rice husk (RH)/PP, jute/PP and kenaf/PP composites. ASTM standards have been used to evaluate the mechanical properties of NFRCs. Scanning electron micrographs have enabled the assessment of fractured surfaces to understand the interaction at fibre/matrix interphase. Furthermore, cutting experiments have been performed to examine the machinability features concerning the surface roughness (Ra) and delamination (Fd). Among the NFRCs, kenaf/PP composites evidently displayed the best mechanical and machining performance. The generated mathematical models for predicting the machinability output responses have envisaged good accuracy.
Investigations of the Influence of Process Conditions on the Fiber Length Reduction for Recycled Carbon Fibers
A new carbon black product was developed at Birla Carbon with ultra-high jetness and bluish undertone for high color applications in plastics. The new product was demonstrated with improved jetness in various polymer systems over the existing high color products, especially achieving a 40% improvement in polyamide 6. The new product shows great potential for ultra-high jetness plastics applications including automotive, household appliances, and consumer electronics.
Effect of Glass Fibers on the Viscosielastic and Thermomechnical Properties of Poly(Ether Ether Ketone)
The effect of glass fiber on the viscoelastic properties, thermal stability, permittivity and volume resistivity, as well as stress relation behavior of poly(ether ether ketone) (PEEK) was investigated using dynamic rheology, TGA, broadband dielectric spectroscopy and DMA over a wide range to temperature. The complex viscosity of PEEK filled glass fiber with 30 wt.% increases by one order of magnitude at 360 oC compared to the unfilled PEEK indicating that the glass fibers inhabited the polymer chains motion and reduced the free volume at high temperature in the melt. The viscosity and dynamic moduli (G′ and G″) of both PEEK and 30 wt.% glass fiber filled PEEK were not very sensitivity to the temperature variation (i,e.; the viscosity, G′ and G″ slightly decreased with increasing temperature). The angular frequency dependence of complex viscosity was found to be well described by Carreau–Yasuda model. It was also observed that the thermal stability of PEEK improved significantly by adding glass fibers. In addition, the relaxation modulus master curve at 200 oC reference temperature for glass filled PEEK is significantly higher than that of pure PEEK due to the excellent reinforcement effect of the glass fibers.
Crystallization Behavior and Impact Performance of PA6 Based Nanocomposites
PA6-based in-situ nanofibrillar composites, containing polyphenylene sulfide (PPS) nanofibrillar domains with average diameter around 60 nm, were produced combining melt compounding and hot stretching. Then, effect of this fibrillar network on the crystallization behavior of PA6 composites was investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical microscopy (POM). Results indicated no significant increase in the composite’s crystallinity due to PPS nanofibrils; however, the nanofibrillar network did induce a significant difference in the crystallization curve with the evolution of a high temperature crystallization peak. The impact performance of nanofibrillated PPS-PA6 was improved with 3 wt.% PPS nanofibrils, which was explained by the interconnected fibril network and the formation of transcrystalline structures and small crystal size in the presence of the fibril network.
Effect of Filler Content on the Electrical Conductivity of Graphite Based Composites
This research work addresses the feasibility of employing thermoplastic composites as the substitute material for bipolar plates in a fuel cell. Bipolar plates are vital components of a proton exchange membrane (PEM) fuel cell assembly. Vigorous efforts are directed by manufacturers to reduce the size, weight, and cost of the bipolar plates. The carbon-based composites are comparatively cheaper, lightweight, and can easily be used for the production of bipolar plates. However, the bipolar plate material's electrical conductivity should be sufficient to conduct the electric current from one cell to another. The main purpose of this research was to study the effects of carbon content on the electrical conductivity of the composite material. The composite materials were produced by adding graphite particles into polypropylene matrix at different contents ranging from 60wt% to 84wt%. The through-plane electrical conductivity tests were carried out. While the electrical conductivity of the composites increased by increasing the graphite content. A sudden rise in electrical conductivity was also observed between 76wt% and 80wt%.
Advanced Simulation Methods for Prediction of Multi-Layer Non-Matching Fiber-Mat Applications In Resin Transfer Molding Process
The objective of this study is to use a simulation tool of resin transfer molding (RTM) process to get a comprehensive understanding of the permeabiliy measuring process. In order to varify the simulation tool’s capibility to simulate oil flow in non-matching fabric we build the mesh model of the measuring instrument cavity with the non-matching meshes in this study. This varifaciton case focuses on two properties of the RTM process, the arriving time and local pressure increasing trend in filling process. By using the simulation tools, we can observe the resin flow within the mold. The comparison between simulation and experiment result shows the reliability of simulation result. We expect that this study will help to clarify relevant issues and then reduce the trial-and-error time and materials.
Analysis of Contributive Forces In Intra-Laminar Shear of Continuous Fiber Reinforced Thermoplastics
Continuous fiber reinforced plastics offer excellent weight-specific properties, but their broad introduction to lightweight construction applications is still limited, among other things, due to insufficient accuracy of their processing simulations. A major reason for this is the limited availability of reliable material data and models. In this study, picture frame tests coupled with microscopic analysis are employed to separate the contributions of static weave deformation, lubricated rotational roving friction and roving compression and associated matrix relocation to the total intra-laminar shear forces. This approach allows for additional material insight and helps in developing suitable material models in an efficient way.
Bio-renewable Polyester/Graphene Nanocomposites
Bio-based polyesters are a new class of materials that are expected to replace their fossil-based homologues in the near future. In this study, nanocomposites of bio-renewable poly(ethylene 2,5-furandicarboxylate) (PEF) are reported with thermally reduced graphene (TRG) via melt blending method and compared with fossil-based PET/TRG nanocomposites. TRG was prepared from graphite oxide by simultaneous thermal exfoliation and reduction method and characterized. TRG was dispersed in PEF and PET via melt blending, and the nanocomposites were characterized for their thermal and morphological properties. The TRG exhibited strong interactions with PEF, increasing onset of thermal degradation by ~50°C and thermal degradation temperature by ~17°C. A strong nucleation was observed in both PEF and PET with the inclusion of TRG.
Computational Modeling of IR Heating of Composite-Material Parts
This paper explains the computational model developed in predicting the infrared heating of a composite material component. Computational Fluid Dynamics (CFD) technique is used in predicting heating behavior of a thermoplastic composite component. In-house testing facilities has been utilized to determine the radiation characteristic of the materials. The computational thermal model developed is validated by experimentally measured temperatures at key locations of sample plate during its heating. Comparisons between experimental data and numerical simulations showed good match between model & measurement. The developed model can be used as an effective tool in predicting the heater setting parameters for polymers/ composites heating in different application scenarios.
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