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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Conference Proceedings
Electrospinning: Preparation of Aligned and Oriented Polyacrylonitrile Nanofibers
Sian F. Fennessey, Richard J. Farris, May 2004
Partially aligned and oriented Polyacrylonitrile (PAN) nanofibers were prepared from solution with dimethylformamide by electrospinning with the purpose of preparing carbon nanofibers for the reinforcement of thin films. Aligned (+) birefringent fibers with diameters between 0.27-0.29?m (FESEM) were prepared from a 15wt% solution, electrospun at 16kV, and collected onto a wheel rotating with a surface velocity of 3.5-12.3m/s. The molecular orientation within the fibers was examined by X-ray diffraction (WAXD) and dichroism (FTIR). A maximum chain orientation parameter, f, of 0.23 was determined for collection speeds between 8.1-9.8m/s. Twisted yarns of aligned PAN nanofibers with twist angles between 1.1° and 16.8° were prepared. The ultimate strength and modulus of the twisted yarns increased with increasing angle of twist to a maximum of 162 ±8.5 MPa and 5.9 ±0.3 GPa, respectively, at an angle of 9.3°.
Influence of Nanoparticles on the Shrinkage Control of Low Profile Unsaturated Polyester Composites
Liqun Xu, L. James Lee, May 2004
Unsaturated polyester (UP) resins are one of the most widely used materials in fabricated composites. However, a number of problems caused by their high polymerization shrinkage have limited their growth in many new markets. Our research results showed that 1-3 wt% of nanoclay can provide excellent volume shrinkage control of UP resin systems containing polyvinyl acetate (PVAc) as a low profile additive (LPA) in room temperature molding processes. Nanoclay residing in the LPA-rich phase led to a higher reaction rate and earlier onset of micro-cracking in the resin system. Consequently, an earlier volume expansion during curing was observed in the reactive dilatometry experiment, resulting in better shrinkage control.
Precise Control of Strain Hardening in Uniaxially Deformed Rubbery State Polymer Films through the Addition of Nanoparticles
Jake H. Mulligan, Miko Cakmak, May 2004
The effect of deformation temperature on fundamental deformation-structure relationships in amorphous compression molded and melt cast Poly(lactic acid) (PLA) films with varying nanoclay loadings were investigated using a stretch birefringence apparatus that allows for direct measurement of true stress, true strain, and birefringence. Behavior of the crystalline phase was elucidated with WAXD. Relationships between stress, strain, and birefringence are strongly affected by stretching temperature, clay loading, and film production methodology. The effect of these variables on the molecular mechanisms of uniaxial deformation in rubbery state PLA films and its affect on the various levels of structure are elucidated in this study.Our studies indicate that the introduction of a relatively small fraction nanoparticles leads to strain hardening at lower values of true strain when the films are stretched from rubbery state. This allows the self-leveling mechanism that helps obtain uniform film thicknesses, to be tailored to specific need of the process and application.
The Effect of Injection Speed on the Weld Line Properties of Jute Fiber/Poly (Butylene) Succinate Biodegradable Composites
U.S. Ishiaku, Y.W. Leong, O.A. Khondker, A. Nakai, H. Hamada, May 2004
This presentation focuses on effects of injection speed and weld line on the properties of PBS/Jute fiber composites. It was found that toughness especially elongation at break is sensitive to the presence of weld line while tensile modulus and flexural properties are little affected. The presence of jute fibers improved toughness i.e. retention of EB and impact strength across the weld line. Ultrahigh speed injection facilitated the recovery of EB and hence toughness. Morphological studies with SEM revealed that some of the jute fibers were aligned across the weld line.
Recycled Newspaper and Chicken Feathers as Reinforcement Fiber in Bio-Composite Materials
M.A. Dweib, T.A. Bullions, A.C. Loos, R.P. Wool, May 2004
Nonwoven mats of cellulose and keratin fiber were manufactured from recycled kraft paper, newspaper, and processed chicken feathers using a wetlay process. Hybrid fiber mats were produced by mixing different ratios of the three fiber types together in the wetlay process. Composite materials were manufactured by infiltrating these mats with an acrylated epoxidized soybean oil- (AESO) based resin using vacuum assisted resin transfer molding (VARTM). The room temperature cured composite panels contained between 16 and 25% by weight fiber depending on the original mat structure. The fiber mats contained 0 to 50 wt% recycled milled newspaper, 40 to 100 wt% pulp fiber recycled from kraft paper and 0 to 60 wt% cleaned and chopped feathers. These composites are low cost, environmentally friendly, derived from renewable resources, energy efficient, and could be used in many applications such as civil infrastructure, automotive and trucking, temporary roadway matting.
Thermal and Mechanical Properties of Functional Monomer Modified Soy Protein Plastic by Reactive Extrusion Technology
Wanjun Liu, A.K. Mohanty, M. Misra, L.T. Drzal, May 2004
Chemical modification of soy plastic with monomers such as maleic anhydride, glycidyl methacrylate and styrene was accomplished by using reactive extrusion technology. Thermal and mechanical properties of modified soy protein plastic were characterized by using Differential Scanning Calorimetry, Dynamic Mechanical Analyzer and United Testing System. It was found that the denaturation temperature, the glass transition temperature and ( relaxation temperature of soy flour plastic changed and hence tensile properties of modified soy protein plastic improved.
Mechanical Properties of Hybrid Polyester Composites
Igor ?ati?, Zvonko Glavina, Maja Rujni?-Sokele, May 2004
There are different reasons why the production of polyester composites with natural reinforcements, like jute can be of interest. One of them is to fabricate the hybrid composites with cheap waste jute sacks as reinforcements in combination with glass mat. The laminates have been fabricated with a different number of jute and glass mat layers and different type of polyester resins. Also, the content of cross-linking agent has been varied. As the indicator of change of mechanical properties, tensile and flexural strength as well as tensile and flexural modulus have been determined. Based on the planned experiments and statistical analysis it can be concluded that in comparison with glass mat polyester composites, the mechanical properties of hybrid composites in optimal combination of glass and jute reinforcements are lower, but at the same time the laminates are 15 to 20% cheaper.
Process Induced Orientation of Nanolayers in Polyolefin Nanocomposites
Sharad Kumar, K. Jayaraman, May 2004
Polypropylene nanocomposites with layered silicates have been prepared with and without edge functionalization by melt processing. The resulting composites were subjected to uniaxial extensional flow in the core of axisymmetric converging dies at strain rates of up to 5 s-1 and a Hencky strain of about 5. The edge treated clay led to a much greater level of exfoliation as determined by XRD, TEM and dynamic viscosity measurements. We observe that at the high strains, the nanolayers are predominantly oriented parallel to the flow direction in the core, in contrast to the perpendicular orientation reported by Okamoto et al. for uniaxial extension of nanocomposite strips to a strain of 1.3.
Kinetic Stability of the Well-Exfoliated State in Polypropylene-Clay Nanocomposites Made by Solid-State Shear Pulverization
Kosmas G. Kasimatis, John M. Torkelson, May 2004
Analysis by electron microscopy, x-ray diffraction/scattering and DSC has revealed that well-exfoliated states can be achieved in polypropylene (PP)-clay nanocomposites using a novel non-equilibrium processing method called solid-state shear pulverization (SSSP). Such well-exfoliated states cannot be achieved in PP/clay nanocomposites by melt processing. Nanocomposites made via SSSP have been found by x-ray and DSC analysis to remain well-exfoliated after 1.5 to 2 hr of annealing in the melt state of PP. Thus, even if a well-exfoliated state is not thermodynamically favored, it is kinetically stable over long times in the melt state.
Thermo-Kinetic Compounding of Polypropylene and Clay
T.G. Gopakumar, D.J.Y.S. Pagé, May 2004
Polypropylene (PP)/Montmorillonite (MMT) clay nanocomposites have been prepared by melt mixing PP and different levels of a predispersed organoclay masterbatch (PP/clay concentrate). Melt mixing was achieved using a Gelimat, a high-speed thermo-kinetic mixer. The Gelimat system is designed to handle difficult compounding and dispersion applications and can achieve mixing, heating and compounding products within a minute. Therefore, the thermal history of the compounded polymer is short, which limits degradation. The structure and properties of the nanocomposites prepared with a Gelimat were compared to ones prepared with a twin screw extruder. The structure and properties of PP/clay nanocomposites were compared by X-ray diffraction, mechanical testing and rheological analysis. Results indicate that a better exfoliation of the clay can be achieved with thermo-kinetic mixing when compared to extrusion, resulting in better mechanical properties.
Tensile Properties and Fracture Toughness of PP-Based Nanocomposites
Martin N. Bureau, Minh-Tan Ton-That, Florence Perrin-Sarazin, May 2004
The tensile properties and the fracture toughness, using the essential work of fracture method, of melt-compounded polymer nanocomposites (NCs) based on polypropylene with different organo-modified clays (montmorillonite) and maleic anhydride grafted PP coupling agents were studied. Improvements in tensile and fracture properties were observed, which were related to the level of dispersion of clay particles, both at the nano- and the micro-scale. Clay micro-particles acted as void nucleation sites within the PP matrix. The highest tensile properties and highest fracture toughness were obtained for the PP/clay compound showing high particle density with good particle-matrix adhesion, which led to intermediate void nucleation but extensive fibrillation.
Development of Polyolefin Nanocomposites: Relationship between Formulation, Processing, Structure and Performance
Minh-Tan Ton-That, Florence Perrin-Sarazin, Martin N. Bureau, Kenneth C. Cole, Johanne Denault, May 2004
The preparation of nanoclay-reinforced polyolefin nanocomposites by means of melt processing was investigated. Different formulations and processing conditions were used in order to optimize the chemical interaction between the polymer matrix and the clay so as to maximize the performance. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and differential thermal analysis (DTA) were used to study the chemical interactions between the polymer and the organo-nanoclay as well as the dispersion of the nanoclay. It was shown that the various parameters (chemistry and concentration of organo-intercalant, mixing conditions, and especially chemistry and concentration of coupling agent) all affect the ultimate performance and that the interactions between them must be taken into consideration in developing nanocomposite systems.
Polymer-Clay Nanocomposites Prepared in Supercritical Carbon Dioxide
Manuel Garcia-Leiner, Alan J. Lesser, May 2004
An alternative route to prepare polymer-clay nanocomposites using supercritical carbon dioxide (scCO2) is described. The presence of clay nanoparticles significantly influences the morphology, foaming process and crystallization of a polymer when processed in scCO2. Intercalated structures are successfully produced in the presence of scCO2 even when favorable interactions between the polymer and the clay are not present. The effect of scCO2 on the intercalation process is analyzed for a variety of polymer systems both with modified and unmodified clays. By controlling the hydrophilicity of the polymer and clay systems, specific understanding of the effect of scCO2 on the structure and morphology of the nanocomposites is obtained. Experimental results show significant increases in the clays d-spacings for scCO2-treated samples. This behavior is consistent regardless of the nature of the polymer, showing significant amounts of intercalation even in purely hydrophobic polymers.
Mechanical and Electrical Properties of Exfoliated Graphite-Platelet Polypropylene Nanocomposites
Kyriaki Kalaitzidou, Hiroyuki Fukushima, Lawrence T. Drzal, May 2004
Polypropylene based nanocomposites reinforced with up to 25 vol% exfoliated graphite nano-platelets were fabricated using extrusion and injection molding. The mechanical and electrical properties of the graphite nanocomposites were investigated and compared to the properties of polypropylene-based composites reinforced with other conductive materials, e.g., carbon black and carbon fibers. It was found that the graphite nano-platelets were the most effective at increasing the modulus of the polypropylene and comparable to the other materials in terms of percolation threshold.
In-Situ Wide-Angle X-Ray Scattering (WAXS) Analysis of Electrically Activated Polypropylene(PP)/Clay Nanocomposites
D.H. Kim, K.S. Cho, K.H. Ahn, S.J. Lee, J.H. Lim, Y.K. Kwon, May 2004
Recently we have invented a novel method for fabricating polypropylene (PP)/clay nanocomposites by applying the electric field. Electric field was found to facilitate destruction of the layer-stacking and separation of the silicate layers by the penetration of polymer chains into silicate galleries. This was evidenced by rheological measurements, X-ray diffraction and Transmission electron microscopy. From this observation, we could find that the microstructural change of PP/Clay nano-composites induced by the electric field is a very important factor to control the performance and morphology of the material. In this study, real-time evolution of PP/clay nanocomposites under electric field using in situ wide-angle X-ray scattering (WAXS) analysis will be presented. We designed a heating block equipped with electric circuits to apply electric field on the molten state of PP/clay composites. The real-time microstructural changes of PP/clay nanocomposites under AC electric field of 1kV/mm and 60 Hz were analyzed by the result of 2D WAXS data. This will be compared with that under DC electric field. We will present the kinetics of melt intercalation process under electric field.
Vibration-Assisted Liquid Composite Molding
Ronald F. Gibson, Emmanuel O. Ayorinde, May 2004
By oscillating the injected resin stream in liquid composite molding, the mold filling time can be significantly reduced. Flow enhancement is achieved because of the shear-thinning characteristics of typical polymer resins, as the effective shear rate of the resin is increased by oscillation of the resin within the fiber preform and the viscosity of the resin is correspondingly reduced. An experimental apparatus has been developed which consists of one-dimensional flow within a fiber preform and a vibrating piston which forces the inlet resin stream to oscillate. Experiments have been conducted using a polyacrylamide/water solution to simulate the polymer resin, and effects of oscillation amplitude, frequency and fiber volume fraction have been investigated. A simple analytical model has also been developed, and experimental results confirm the predicted trends in the amplitude, frequency and volume fraction effects on flow enhancement.
Rapid Surface Treatment of Reinforcing Fibers Using Ultraviolet Light Processing
Michael J. Rich, Per A. Askeland, Lawrence T. Drzal, May 2004
A fast, inexpensive and environmentally benign process requiring only UV light and air for the surface treatment (oxidation) of reinforcing fibers has been developed that represents a substantial improvement over existing methods. In this new method, fibers are subjected to short wavelength ultraviolet (UV) light producing ozone from atmospheric oxygen. UV photons can also react with ozone to create monatomic oxygen, a highly reactive chemical species which is available to oxidize the fibers. Additionally, the UV photons can break chemical bonds on the fiber surface creating favorable conditions for reaction with ozone and monatomic oxygen. The result of this two-fold process is the rapid oxidation of the fiber surface that is essential to promote favorable interactions with the matrix in polymer composites. The effect of UVO treatment on the surface chemistry, tensile strength, and interfacial adhesion of a PAN based carbon fiber and an aramid fiber is reported.
Water Diffusion Based Non-Destructive Evaluation (NDE) of PMR-II-50/M60J 4HS Weave Carbon Fabric Composite Materials under Stress-Thermal Cycling
Lawrence T. Drzal, Roger J. Morgan, May 2004
Due to the geometric complexity of woven fabric composite materials, conventional Non-Destructive Evaluation (NDE) methods such as x-radiography and acoustic emission (AE) do not show microcracks well inside the materials. In this study, a simple and cost effective water uptake test as a NDE methodology for PMR-II-50/M60J (polyimide/carbon fiber) 4HS weave fabric composites is suggested. The short term water uptake test for 24 hours at 80°C has been performed before and after stress-thermal cycling experiments with the TAMU developed conduction heated stress-thermal cycling apparatus. The woven composite materials’ non-Fickian model during short term water uptake, that is, the rate of uptake initially increases rapidly followed by quick slow down associated with diffusion in cure-induced voids and cracks was modified by the effective diffusivity depending on crack densities. The suggested crack densities dependent diffusion model was compared with the experimental data. The application of the water absorption induced NDE was also re-evaluated by comparing to the results of the literatures in terms of crack closure by swelling and unloading of the existing load and matrix dissolution by hot water.
Nanocomposite Polyetherimide with High Thermo Oxidative Stability
J. Lou, V. Harinath, J. Sankar, K. Roberts, L.Uitenham, May 2004
Selected fillers were incorporated to prepare polyetherimide composite. The influence of fillers on the thermo-oxidative stability of the composite was studied by thermogravimetric analysis. The results showed that at optical filler loading and characteristics, the polymer composite became superior in its thermo-oxidative stability that is very promising in widening the window of service temperature of polyimides for extremely high temperature conditions where most polymeric composites fail. The findings should prove useful in developing high-temperature polymer composites for aerospace and electronics applications.
Low Cost Processing of Carbon Fabric Reinforced Nylon Composites
Selvum Pillay, Haibin Ning, Uday K. Vaidya, Gregg M. Janowski, Klaus Gleich, May 2004
This manuscript describes the processing techniques and processing windows used to produce carbon fiber reinforced nylon matrix composite panels. Preliminary mechanical property measurements were also made. Anionic polyamide 6 resin (casting grade) was polymerized in situ after infusion. Careful time and temperature control were necessary to obtain total fiber impregnation with subsequent complete polymerization. These advances will permit the use of affordable thermoset manufacturing processes such as Vacuum Assisted Resin Transfer molding (VARTM) or Resin Transfer Molding (RTM) to produce thermoplastic-matrix composite structures.
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