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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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%.
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.
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-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.
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.
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).
The double percolation structure was used to produce thermally conductive polymeric composites including high density poly (methyl methacrylate) (PMMA)/polyethylene (HDPE)/ carbon nanofiber (CNF) and polypropylene (PP)/PMMA/boron nitride (BN) composites. Microscopy images showed that for both systems, most of fillers were in PMMA phase, confirming the hypothesis of the filler location by the thermodynamic theory. The thermal conductivity of the PMMA/HDPE/ CNF composite was higher than that of the HDPE/CNF and the PMMA/CNF composites with the same content of fillers loading when the CNF concentration got to 16 wt%. In addition, a similar phenomenon was also found when the BN concentration was above 10% in term of the PP/PMMA/BN composites. This study proved that double percolation structure was a useful way to improve the thermal conductivity of the polymer composites.
Injection molded composites have been used effectively in automobiles, but there is still a need for the development of lighter and greener materials. Hybrid composites, composites with multiple kinds and length scales of fillers, present the opportunity for exciting new material breakthroughs and the opportunity for finely engineer the performance of the manufactured materials. This study presents the structural testing results for a hybrid composite composed of a blend of glass fibers with graphene nano-platelets within a PA6 matrix. This blend is chosen to meet the high demands of the automotive industry for select under the hood applications. The results presented in this work demonstrate that the addition of less than 1% by mass of graphene nanoparticles can allow the reduction of glass fillers by nearly 25% with only a minimal reduction in performance while reducing the density increase relative to the neat polymer by nearly 20%.
With growing applications of polymer nanocomposites, the need to manufacture cost-effective nanocomposites is increasing. In this work, we report economical nanocomposites from polyethylene (PE) using graphene (GnP) and carbon fiber (CF) waste. The nanocomposites were prepared by simultaneously mixing PE, GnP and CF in a melt blender where CF appeared to be randomly dispersed along with GnP in PE matrix. A delayed crystallization was observed when nanocomposites were crystallized from the melts non-isothermally. The crystallization data was well explained using Avrami model. Moreover, the hybrid filler (CF and GnP together) showed better mechanical performance with increasing CF/GnP ratio.
In an effort to avoid freeze-drying or solvent blending techniques and better leverage the fact that preparation of cellulose nanocrystals (CNCs) result in aqueous dispersions, we investigated a water-assisted melt compounding approach to disperse cellulose nanocrystals in polypropylene. A simple, water-based cetyltrimethylammonium bromide (CTAB) treatment of CNCs was used to reduce their hydrophilicity and inhibit hydrogen bonding. The aqueous suspension of treated CNCs was then blended with polypropylene in a thermokinetic mixer with various levels of a maleated polypropylene (MAPP) as a dispersing agent. CNC dispersion was evaluated by optical microscopy, scanning electron microscopy, and rheology. CTAB treatment alone was insufficient to provide good dispersion but dispersion improved greatly with increasing MAPP content. At the highest levels of MAPP, agglomerates were still present but nearly all were well below 1 µm in size. However, despite a CNC content of 8%, little rheological evidence of a network structure was found that would suggest well-dispersed nanocomposites.
Highly crosslinked, typically brittle epoxide/amine thermosets are commonly toughened with high Tg thermoplastics to afford phase separated morphologies that provide increased toughness without sacrificing high temperature performance. The typically low molecular weight thermoplastics are solubilized into the uncured thermoset system, and as the epoxide:amine reaction proceeds, the rapid molecular weight increase of the thermoset phase leads to a loss of solubility of the thermoplastic and initiates phase separation. The morphology development of reaction induced phase separation (RIPS) occurs between the initiation of phase separation and gelation. The development of these phase separated morphologies is altered by the cure prescription, the time between initiation and gelation, and breadth and depth of the rheological well during cure, all of which alter the growth and coarsening of phase separated domains. In this work, networks are prepared adjusting the loading level of thermoplastics to form a wide variety of network types, including droplet dispersed, network-like pattern co-continuous, and co-continuous networks. The morphology of networks is characterized using optical microscopy, scanning electron microscopy, and the phase separation and cure of the networks is monitored with rheokinetics studies. Cure rates of 1 and 5 °C/min are examined. Thermomechanical analysis confirms network type, and the effects of cure schedule, viscosity, loading level on RIPS morphology development is correlated to control phase separation during cure and target desired morphologies.
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