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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Rheology
SPE Library content related to rheology
Dispersion in nanocomposites
Re-agglomeration of carbon nanotube fillers does not affect a polymer's mechanical properties.
Determining drug solubility in polymer by rheological methods
Using flow characterization techniques to assess drug solubility in polymer is faster and more accurate than thermal or microscopic approaches.
Capillary flow of low-density polyethylene
Low-density polyethylene melts in capillary flow show large vortices and high-pressure drops due to the highly viscoelastic nature of the melt and the pressure dependence of the viscosity.
Improved properties of hybrid epoxy nanocomposites
Using both halloysite and recycled cellulose fibers as fillers in epoxy composites enhances their thermal stability, mechanical, and fracture properties.
THE CHARACTERISTICS OF IMMISCIBLE POLYMER BLENDS WITH MWNT
The electrical, rheological properties and phase behavior of multiwalled carbon nanotube (MWNT) filled with Polypropylene(PP)/Polystyrene(PS) blends were investigated. Based on the matrix polymer, two kinds of masterbatch chips were used to prepare ternary blends, and the influence of the kinds of masterbatch were confirmed on the phase morphology of ternary blends and the distribution of MWNT in ternary blends.
ENHANCEMENT OF MELT ELASTICITY OF LONG-CHAIN BRANCHED POLYETHYLENE BY BLENDING A LINEAR POLYETHYLENE
The rheological properties are studied for binary blends composed of a long-chain branched polyethylene and a linear polyethylene. It is found that the blends containing a linear polyethylene with high shear viscosity exhibit enhanced elasticity in the molten state, which is attributed to the prolonged relaxation time for entanglement couplings between a linear polymer and a branched polymer.
IN-SITU COMPATIBILIZATION OF HDPE-FUMED SILICA COMPOSITES: MORPHOLOGY, RHEOLOGY AND FILM BARRIER PROPERTIES
In the present study, HDPE-fumed silica (FS) composites were prepared by melt-mixing with different filler loading and in presence of PE-g-MA compatibilizer. Dynamic rheological properties and morphological analyses of the composites supported the plausible interfacial interaction between reactive groups of PE-g-MA and surface silanol groups of FS. Oxygen and water vapor permeability of the films made from composites were increased due to presence of FS as well as due to compatibilization.
RHEOLOGICAL AND MECHANICAL PROPERTIES OF POLYMER BLENDS, RADIOPAQUE FILLERS AND COUPLING AGENT
This work studied the effect of blending two different grades of thermoplastic polyurethanes with a constant percentage of radiopaque filler (bismuth subcarbonate) and varying percentages of filler. A titanate binding agent was added to the blend to investigate the impact of improved polymer/filler adhesion. The results showed that varying grades of thermoplastic polyurethane in conjunction with different filler loadings can modulate the physical properties of the compound.
FOLLOWING CHEMICAL REACTIONS WITH RHEOMETRY AND SIMULTANEOUS FTIR-SPECTROSCOPY
A new combination of a rheometer and a FTIR-spectrometer will be presented. The Rheonaut module allows the coupling of the Thermo Scientific HAAKE MARS rheometer with an FTIR-spectrometer. With this set-up, samples can be characterized rheologically while IR-spectra are being recorded simultaneously. To test this concept, polymerization reactions have been followed with the combination of the HAAKE MARS and the Rheonaut module. Details of the instrument set-up as well as selected results will be presented.
PRACTICAL USE OF CREEP TEST TO OBTAIN THE RHEOLOGICAL DATA AT LOW FREQUENCY RANGE FOR POLYETHYLENE
The creep test was applied to obtain rheological information in low-frequency range that is not reachable by use of the frequency sweep test for polyethylene industrial research and development. The test time scale and the applying stress were considered to make the measurement on a large group of samples. By testing several high molecular weight resins having broad molecular weight distribution or long chain branching, we demonstrated utility of this methodology.
SUREFLO®: A NEW AND HIGHLY EFFECTIVE PROCESS ADDITIVE FOR THERMOPLASTICS
In this paper, we explore the effects of a new process additive, SureFlo®, on the rheological and crystallization behavior of semi-crystalline polyolefins. It was found that SureFlo® can dramatically lower melt viscosities and delay crystallization, resulting in improved processability of the polymer. As we show in a finite-element simulation of a typical injection molding process, the use of 7 wt- % SureFlo® results in significant decrease in fill time and increases productivity by ~20%.
SWELLING OF PLA MELT DUE TO CO2 DISSOLUTION
The superior mechanical properties of microcellular foams such as, heat resistance, lightweight and high performance to weigh ratio, are important factors to be considered with respect to the automotive industry and foaming industries. Therefore, an understanding of the thermophysical and rheological properties of polymer/gas mixtures is critically important. This paper focuses on the pure PLA 3001D volume swelling measurement and its comparison with varying talc content. Effect of D content on swelling ratio is also discussed.
MEASUREMENT AND MODELING OF PLANAR AND UNIAXIAL EXTENSIONAL VISCOSITIES FOR LDPE POLYMER MELT
In this work, novel patent pending rectangle and circular orifice dies have been used in order to determine planar and uniaxial extensional viscosities for extrusion coating LDPE through entrance pressure drop determination on conventional twin bore capillary rheometr. It has been revealed that the uniaxial extensional viscosity/uniaxial extensional strain hardening is higher in comparison with the planar extensional viscosity and recently proposed non-Newtonian fluid model can described the measured rheological data reasonably well.
THERMOFORMABLE LIQUID CRYSTAL POLYMER (LCP)
Thermoforming is an economical process for forming large shape products. High performance liquid crystal polymer (LCP) has high thermal stability, excellent dimensional stability and high chemical resistance, which offers new application opportunities in demanding applications. In this paper, a new thermoformable LCP resin is compared with injection molding LCP on mechanical, thermal and rheological properties. Sheet extrusion and thermoforming process conditions are discussed.
THE EFFECT OF POLYHYDROXYBUTYRATE-CO-VALERATE (PHBV) CONTENT ON THERMAL, RHEOLOGICAL, MECHANICAL PROPERTIES AND FOAMING BEHAVIOR OF POLYLACTIC ACID (PLA)
This paper examines the effect of PHBV content on the properties of PLA-PHBV blends and their foams. PLA and PHBV blends were manufactured in various compositions via compounding, and their tensile, thermal and rheological properties and their foam morphologies were characterized. The results indicated that although PLA and PHBV are immiscible, the addition of small quantities of PHBV (up to 30 wt%) lead to a finer and more homogenous cellular morphology.
THE EFFECT OF CO2 ON THE MELT FRACTURE BEHAVIOR OF FOAMED PLA
The melt fracture behavior of foamed Polylactic acid (PLA) with the presence of blowing agent is studied in this investigation. A CCD camera is utilized to examine how foaming processing parameters such as blowing agent content, mass flow rate and temperature can affect melt fracture behavior. Images captured are used to analyze severity and nature of extrudate distortion.
PREDICTING CAPILLARY DIE SWELL OF HIGH MOLECULAR WEIGHT HDPE RESINS FOR BLOW MOLDING APPLICATIONS
Capillary die swell of high molecular weight HDPE resins was measured and compared to the prediction based on various rheological models. The predictions based on stress ratio per Leonov model tend to overestimate the capillary die swell while those through Wagner model underestimate. Predictions per Doi- Edwards model were applicable only at low shear rate. This study reveals the need to further assess damping parameters in addition to the relaxation spectrum.
GENERATION OF AN EMPIRICAL MODEL TO DESCRIBE THE EXPERIMENTAL EVOLUTION OF DRAG RATIO FOR A TWO PHASE HORIZONTAL PIPE FLOW OF NON-NEWTONIAN LIQUID (CARBOPOL)/AIR MIXTURE
The prediction of the pressure drop gradient and the evaluation of the drag reduction phenomenon observed during the piping multiphase flow of a Carbopol/Air mixture have been investigated. Viscous flow tests in rotational rheometers and pressure drop measurements in pipe lines have been carried out with both smooth and rough surfaces. The Power law model is used to predict the pressure drop gradient. The pressure drop gradient in the intermittent multiphase flow regimes can be predicted by modifying the classical approach of Lockhart and Martinelli with an empirical correction factor. An Empirical model with quadratic equation has been proposed to describe the experimental evolution of drag ratio as a function of Re'L / Re'TP.
RHEOLOGY AND MELT FRACTURE OF BIODEGRADABLE POLY (?-CAPROLACTONE) POLYESTERS
The viscoelastic behaviour of a number of commercial and newly synthesized linear biodegradable polyesters - poly (?-caprolactone) (PCLs) with different molecular characteristics was investigated using both rotational and capillary rheometry. The variation of the zero-shear viscosity and relaxation spectrum with molecular weight was studied in detail. The PCL processing instabilities were studied by capillary extrusion using a number of capillary dies having various diameter and length-to- diameter ratios. Sharkskin and gross melt fracture was observed at different shear rates depending on the molecular characteristics of the resins and the geometrical details of the capillary dies.
DEVELOPMENT OF A METHOD FOR MEASURING THE THERMAL CONTACT RESISTANCE AND THERMAL CONDUCTIVITY OF ELECTRONIC MOLDING COMPOUNDS
The process simulation of thermoset molding processes (e.g. transfer molding, liquid injection molding) becomes increasingly important, because it can significantly reduce the cost of product development. This demands the correct determination of heat transfer and rheological coefficients. The aim of this study was the designing and construction of an apparatus which can measure the thermal contact resistance and thermal conductivity of epoxy molding compounds in the same circumstances which they encounter during processing.
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