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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Comparing Models for the Glass Transition Temperatures of Compatible Polymer Mixtures
Various proposed equations relating glass transition temperature to composition are compared for:. Relative success in fitting unsymmetrical temperature-composition diagrams,. Number (and ease of establishing) required constants, and, Ability to be cast explicitly in either temperature or composition. A novel exponential form satisfies these criteria very well. It is contrasted with another author's equally successful but mechanically awkward form which is based on thermodynamic considerations
Break-Through in High Performance Ionomers: Morphology and Properties
Ethylene ionomers have been the material of choice for the golf ball cover and mantle applications due to the excellent resilience, high cut resistance, and good impact durability. The ethylene ionomers achieve the unique property characteristics through the development of network morphology. In this paper we discuss the development of ionomers with novel compositions, we present evidence of the effect of composition on morphology, and propose a model that accounts for the outstanding performance of these ionomers.
Characterization of LLDPE/Monmorillonite Nanocomposite
Physical properties, such as gas permeability, tensile property, and dispersion behavior of nanopowder of linear low density polyethylene and monmorillonite nanocomposite were investigated. Nanocomposites were prepared by twin screw extruder and internal mixer under various processing conditions. XRD was used to evaluate the degree of intercalation/exfoliation. Significant change of dispersion behavior of monmorillonite and physical properties were observed depending on the processing conditions
Mechanical Behavior of Thermoplastic Olefins (TPOs) during Three-Point Bend Impact
We have characterized the mechanical behavior of five commercially available thermoplastic olefins (TPOs) and a polypropylene homopolymer (PP) during quasi-static (1.7 x 10-5 m/s) and dynamic (2.2 and 8.9 m/s) three-point bend loading at -40, -30 and 22 °C. All materials tested stiffened significantly with increasing impact speed and decreasing temperatures. Flexural moduli increased 51 to 119 % with increasing impact speeds, while increases of 86 to 219 % were measured during low temperature tests.
Relation between Mobility and Diffusion Factors for Thermoset Cure
The temperature-modulated differential scanning calorimetry (TMDSC) response during cure of thermosetting materials is modeled using chemical reaction kinetics with diffusion control. Physical aging effects are incorporated into the model using the Tool-Narayanaswamy-Moynihan equations. We investigate the assumption that the mobility factor, which is often obtained from experimental TMDSC reversing heat flow data, is related to the diffusion factor.
Effect of Cure Cycle on Residual Stress Development in Thermosetting Materials
We have studied the effect of cure cycle on isotropic residual stress development stress development in thermosetting resins during cure and subsequent thermal cycling. We use a thick-walled tube to impose three-dimensional isotropic constraints on the resin. The strain at the outer surface of the load cell is monitored by strain gauges. Cure-induced stresses are much lower than expected from cure shrinkage due to the inability of the curing resin to sustain large tensile stresses in the rubbery state.
Effects of Ultrasonic Processing on the Thermal Behavior of Epoxy Polymers
Ultrasonic cavitation shows great promise in the development and fabrication of polymer composites, including nanocomposites. We report how the ultrasonic processing of two epoxies affected their curing behavior by undertaking systematic differential scanning calorimetry (DSC) and transmission-Fourier transform infrared (FTIR) measurements.
The Effect of Atmospheric Pressure Glow Discharge (APGD) Treatment on Polyetherimide, Polybutyleneterephthalate and Polyamides
In this work, polyamide, polyamide, polybutyleneterephthalate and polyetherimide films were treated in an APGD unit using various applied voltages, frequencies and dwell times. The results show changes in the surface chemistry (FTIR); the degree of change in dynamic contact angle was found to be dependent on the polymer type, dwell time and electrical characteristics of the plasma.
Evaluation of a Molecular-Based Yield Model for Glassy Networks
Results are presented from an experimental investigation to evaluate the validity of a new, molecular based yield model. The proposed model incorporates effects of test conditions such as stress state, strain rate and temperature, as well as the effects of molecular architecture. The effects of molecular architecture are quantified by parameters considering stiffness and cohesive strength of the network. Previously published data along with new results of yield in compression and plane strain are used to assess the validity of the proposed model.
Performance Comparison of a Custom Strain Gage Based Load Cell with a Rheometric Series Force Rebalance Transducer
Normal force measurement issues and the fragile nature of the 2K FRT are major problems with the current ARES Rheometer system. In an attempt to overcome these two issues a custom designed semiconductor strain gage based transducer was successfully installed in an ARES Rheometer. A comparison of the performance of a Rheometric Scientific series 2K FRT and the strain gage based transducer was performed. A comparison of sensitivity, accuracy and drift of data is shown for these two transducers.
High Tg Polymer/Electroactive Organic Compound Blends for LED/PV Applications
The utilization of high Tg polymers to sequester low molecular weight electroactive organic compounds in the active layers of light emitting diode and photovoltaic devices has been demonstrated. The high Tg polymer allows for increasing the layer Tg, decreasing the crystallization rate, improving the mechanical properties and offering the capability of employing low cost fabrication processes. LED and PV device data demonstrating the concept will be presented.
Understanding and Control of Sharkskin
The sharkskin instability remains an unsolved problem in extrusion because the exit singularity induces a complex set of interactions that leads to the rough surface. We review the significant progress over the past decade, focusing on the elucidation of the flow and stress fields at the die exit. We review two critical areas; first an elucidation of the nature of the flow boundary condition for the polymer near the wall at the exit; in particular the question of whether there is a stick or slip boundary condition. Second, we discuss the reasons for the elimination of the instability upon changing the boundary condition to that of slip.
Fabrication and Characterization of Structure Membranes for Proton Transport
Polymer blend technology was used to create highly anisotropic membranes for fuel cell applications. An important factor for creating structures of high proton conductivity and low methanol permeability was the application of electric fields of selected magnitude and frequency during the formation of the membrane.
Thermal and Electrical Analysis of Vapor Grown Carbon Nanofiber/Polyoxymethylene (VGCNF/POM) Composites
Vapor grown carbon nanofiber (VGCNF) reinforced polyoxymethylene (POM) composites were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The electrical resistivity was also analyzed. The thermal stability of the composites was affected by VGCNFs. A drop of 14 orders of magnitude of volume resistivity was obtained by inclusion of 5 wt% VGCNFs. VGCNFs were shown to act as defects, the crystallinity was lowered and the crystallization was delayed.
Smart Adhesion: Controlling Polymer Interfaces through Patterning
To understand the role of patterned geometries/topographies in controlling polymer adhesion and release, we fabricate controlled structures ranging from the nanometer to micron length scales on polymer surfaces. Our initial results focus on the effect of patterned arrays of micron-scale posts and holes on the adhesion of polydimethylsiloxane layers. To facilitate the exploration of the large, possibly non-continuous parameter space presented by this problem, we rely upon combinatorial methodologies to effectively screen multiparameter maps.
Micro-Thermomechanical Properties of Composite Polymer Surfaces as Probed by Scanning Probe Microscopy
We present an overview of the microprobing approaches based on scanning probe techniques to study surface micro- and nano- thermomechanical properties. We focus on polymer composites and nanocomposites, ultrathin polymer coatings, and polymer multiphase molecules. We briefly review state-of-the art developments in the field of contact surface nanoprobing, scanning thermal microscopy analysis.
High Resolution Polymer Microscopy at GE's Global Research Center
High resolution imaging of nano-engineered polymer systems is critical for advanced technology programs at GE. We will discuss scanning probe microscopy (SPM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) of self-assembled block co-polymers and polymer nano-composites. SEM and TEM with energy-filtered imaging of constituent phases in polymer blends will also be discussed. New SPM techniques involving electrical and hot-stage characterization and the use of Six Sigma methodology will be highlighted.
Confocal Raman Imaging of Heterogeneous Polymeric Materials
Confocal Raman microscopy is a powerful tool for the characterization of spatial variations in material properties including chemical composition and crystallinity. The design of a custom Raman microscope will be described, as will applications of this technique to the characterization of the chemical microstructure and morphology of heterogeneous polymeric materials.
Near Field Infrared Microscopy of Polymer Surfaces
We report recent results of the near field microscopy of polymers. Spatial resolution of chemical content at 100th the wavelength of light has been used to compare compositional imaging using infrared near field microscopy with the more commonly used method of AFM phase imaging.
Thermomechanical Probing of Molecular Mobilities in Nanoconfined and Structurally Constrained Polymeric Systems
The molecular mobility in nanoconfined and structurally constrained polymeric systems is a vital parameter in the advancement of future technological applications. We employed two scanning force microscopy methods, with which thermally activated structural transitions and molecular relaxation processes of ultrathin polymer films were examined. The potentials of these methods are illustrated involving polyelectrolyte membranes, dendronized nonlinear optical polymers and thin glassy homopolymer films.
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