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 work presented here focuses on two key issue of nanocomposites: how to achieve high levels of exfoliation of the clay platelets and to what extent the resulting benefits can be explained by conventional composite theories, i.e., is there a nano-effect" whereby the platelets significantly alter the local properties of the matrix?"
A new technique was developed to promote clay exfoliation in an epoxy matrix. Both XRD and TEM microscopic examination results demonstrated that pristine clay could be well-dispersed and exfoliated in an epoxy resin through this technique. In this paper, the technical details and experimental evidences are presented.
Nacre, the inner layer of seashells is a biological nanocomposite having extraordinary mechanical properties. A multiscale modeling approach has been used to study the nano and microarchitecture of nacre to gain an understanding of the role of the architecture on the mechanical response. The role of biopolymers, mineral and various nuances in nacre and their effect on mechanical properties are presented in the paper.
Fracture behaviors of nanocomposites based on epoxy and highly exfoliated pristine clay were tested using double cantilever beam specimens. Micro-deformation mechanisms of the epoxy/clay composites under load were investigated using SEM and TEM. Numerous micro-cavities associated with clay particles are believed to be the major mechanism for the improved fracture toughness of the epoxy/clay nanocomposites.
Stress-strain relations of polymer nanocomposites at different strain rates were studied using polypropylene (PP) and calcium carbonate nanoparticles. The morphology and deformation mechanisms of nanocomposites were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Debonding and cavitation at the matrix/particle interfaces were identified as the major deformation mechanisms of the PP/CaCO3 nanocomposites under uniaxial tension.
The fracture behavior of core-shell rubber (CSR) toughened ?-zirconium phosphate (ZrP) epoxy nanocomposite is investigated. The combined use of ZrP and CSR can greatly improve both the modulus and fracture toughness of epoxy. The fracture mechanisms change from brittle fracture via ZrP delamination to matrix shear yield after addition of CSR. Approaches for producing toughened high performance polymer nanocomposites are discussed.
A group of epoxy nanocomposites with well-dispersed and highly exfoliated pristine clay was prepared by a new patent-pending technique. The nanocomposites exhibit much-improved modulus as well as fracture toughness compared to the neat epoxy. The morphology, deformation behavior and toughening mechanisms of the nanocomposites were studied.
Two different catalysed propylene-ethylene random copolymers containing a 0-8% red organic pigment were injection moulded. Mechanical analysis showed the Ziegler-Natta catalysed polymer to have lower tensile modulus, higher % elongation, lower break strength and higher impact strength than the metallocene copolymer. Thermal analysis highlighted the differences in the structure between the two propylene-ethylene copolymers.
With extraordinary mechanical properties, carbon nanofibers (CNF) are expected to serve as reinforcements for both lightweight and ultrastrong composite materials. In this study, we used CNF as the reinforcing nanoelements to synthesize polystyrene/CNF nanocomposites by the in-situ polymerization process. The obtained composites were further foamed using supercritical CO2 as the foaming agent. A homogeneous dispersion of CNF was observed and the final PS/CNF nanocomposite foam showed microcellular foam morphology.
A viscoplastic constitutive equation for inelastic deformation of polymers was formulated by combining the kinematic hardening creep theory of Malinin and Khadjinsky with the nonlinear kinematic hardening rule of Armstrong and Frederick. The nonlinear kinematic hardening rule was modified in order to describe peculiar inelastic deformation of polymers during unloading in particular. Experimental results for polyethylene were simulated by the constitutive equation and the validity of the modification was verified.
Effect of the content of PC/ABS and injection speed on the mechanical properties of PC/ABS ultra high-speed injection moldings, in which ABS content was varied, was investigated. Tensile modulus of near the surface evaluated using sliced specimen showed the highest values, and flexural modulus of the specimen was higher.
Fracture toughness of a polycarbonate plate was measured as a function of gamma radiation dose and loading rate using a SENB specimen. The fracture surfaces were analyzed by SEM. The test results showed that the material presents a ductile-to-brittle transition as the radiation dose and loading rate increase.
In this paper, the equivocal issue of scratch resistance of polymers is treated. Through experimental effort using a custom-built scratch test device, scratch hardness and scratch visibility are found to be the key considerations in quantifying the scratch resistance of a polymer. However, scratch hardness and scratch visibility are not necessarily interrelated. Care has to be taken to evaluate scratch resistance of polymers. Approaches for improving scratch resistance of polymers will also be discussed.
The structural formation of PET under uniaxial stretching above and below Tg using in-situ WAXD and SAXS by synchrotron radiations was studied. Some new insights into the strain-induced mesomorphic transition were obtained. These structural developments are closely related to the mechanical responses, which have not been observed previously.
The ratio of a polymer's craze strength to its yield strength is an excellent measure of toughness. It can be used to quantitatively compare materials and to predict how the ductile-brittle transition will change as a function of a variety of environmental and material variables.
We have investigated the mechanical properties of polyurethane foam with several foaming state. Moreover, image processing system was being developed to measure the cell shape and the area in the foam. We observed deformation of the cell structure under compressive loading. Effect of cell structure on mechanical properties was examined.
A novel testing technique is presented for the quantitative measurement of cavitation in polyethylene and talc-filled polypropylene, subjected to uniaxial tension. Both materials exhibit extensive dilatation in the plastic stage. In the case of neat polyethylene, the kinetics of cavitation is correlated with SEM observation of crazing within the stretched spherulitic microstructure. For talc-filled polypropylene, extensive cavitation makes him suitable for shock absorption.
Reduction in stress-whitening of polypropylene is critical for success in the clear packaging market. Other factors desired include stiffness and toughness. A fundamental study of stress-whitening, and key factors (resin and processing) is presented. A lab scale test method for quantifying stress whitening, validation of the method with extrusion blow molding (EBM), and the observed stress-whitening mechanisms are discussed.
A resin for BOPP (biaxially oriented polypropylene) film requires good stretchability in addition to general desirable properties of film. Although a HCPP (high crystalline polypropylene) or a nucleated polypropylene offers higher stiffness, its processability on a tenter line is significantly limited. This study introduces a novel HCPP resin that could improve processability while maintaining enhanced stiffness or toughness.
Comparisons between cutting and tear resistance of polyethylene terephthalate film are shown in relation to film properties and loading condition. Tear resistance is characterized by the essential work of fracture method in mode I as a function of test speed and temperature. Cutting resistance is characterized using non-standard test methodologies. Interrelationships between the two tests as well as the possibility of correlation to commercial slitting processes are discussed.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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