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.
Multilayer coextrusion is a process in which two or more polymers are extruded and joined together in a feedblock or die to form a single structure with multiple layers. This paper will discuss the proper techniques for using rheology data to design coextrusion dies based on experimental rheology data for monolayer and multilayer structures.
This paper describes an algorithm used to determine a single viscosity correlation from capillary rheometer experiments. One can choose any one of seven commonly used models for shear thinning fluids. The program then determines the constants in the chosen model which best describes all of the experimental data in a statistical (i.e., least sum of squares) sense. By comparing the results from several different models, one can determine in a matter of minutes the model, which best describes the measured rheology data.
A data acquisition suite capable of monitoring a number of process dynamics at high sampling rates has been installed onto a commercial micromoulding machine. Data was collected during moulding of products of mass 25mg - 0.3mg over a range of process conditions. Results of high shear rate rheology and evaluation of possible material degredation are presented. An investigation into the repeatability of the process has been performed and the paper discusses which process parameter is most suitable as an indicator of moulding conditions which can be used in a process monitoring capacity.
An in-depth experimental and theoretical study of many important factors governing the rheological properties of liquid crystal polymers, Xydars (SRT-300, SRT-400, and SRT-900) is carried out by Advanced Rheometric Expansion System (ARES Spectrometer) in the parallel plate-plate configuration over a wide range of frequency, temp and strain level in the steady shear and dynamic conditions.
Several published rheological approaches to detect the presence of long-chain branching (LCB) in commercial polyolefin resins were assessed. In particular, the suitability, feasibility, and applicability of these approaches in detecting low levels of LCB (( 0.01 LCB/1000C) were the basis of the assessment. Nine methods were evaluated using two sets of metallocene polyethylenes.
The rheological properties of molten LDPE and mPE foams were measured in small amplitude oscillatory shear flow. The foam samples were prepared by injection molding and the effect of injection conditions on the resultant cell structure is discussed. The linear viscoelastic behavior of the foams is well described by the Palierne emulsion model (1) without the use of any fitting parameter. It is shown that the linear viscoelastic properties of LDPE and mPE foams depend only on the properties of the polymer matrix and on the gas volume fraction.
The vetiver-polypropylene (PP) composites were prepared at various ratios of vetiver contents. Vetiver grass was prepared as vetiver leaves and vetiver fiber. The effect of vetiver contents on thermal, rheological, mechanical and morphological properties of the composites were studied. Vetiver grass was treated by chemical treatments and the effect of chemical treatments on these properties was elucidated.
Ultra low-density expanded polystyrene is obtained by an optimum formulation or by extended exposure to atmospheric steam. A polystyrene resin is rheologically modified to have both ease of flow and resistance against collapse. The collapse resistance is imparted either by light crosslinking of the resin with a silane compound or by adding a small amount of polyphenylene ether. Extended exposure to steam permits continuous extension of cell walls by reducing orientation. An expanded polystyrene loose fill material having an expansion ratio exceeding 200 has been achieved.
The rheological, thermal and mechanical behavior of polypropylene (PP) and high density polyethylene (HDPE) filled with sea shells composites at different concentrations of filler were investigated. The composites were prepared by extrusion and injection molding. Most filler addition to composites promoted a slightly increase on the melt viscosity, improve the tensile modulus and the thermal stability in all composites studied.
This paper presents a study on the processing condition and characterization of foamed HDPE/PP blends. The blends were foamed with different blowing agent concentrations using a twin-screw extruder. A chemical blowing agent (azodicarbonamide) and activator agent (ZnO) were selected and the morphological, rheological and mechanical properties of the resulting foams are presented.
Unique additives enable increases in the Gardner impact strength of polyolefins by a factor of 10 while maintaining up to 90% of the material flexural modulus. The effects of resin and additive loading level are addressed in a statistically designed experiment. Physical performance, rheological effects, thermal characterization, and morphological characterization are reported.
The dynamic rheological properties of two types of thermoplastic elastomer (TPE) compounds were studied at ambient and processing temperatures. The linear viscoelastic properties of Thermoplastic Vulcanisates (TPV) and PP/SEBS compounds can be described using models based on mechanical mixing rules. The results were evaluated as a function of composition.
In this work the rheological properties of polymer have been studied by molecular dynamics simulation. Couette flow with various shear rates are used to investigate the degree of slip, shear viscosity and normal stress difference. The fluid consists of chains of n-hexadecane and is confined between two structured gold atomic walls. Isothermal simulations (350K) of 4 to 1 unsteady extrusion flow with various extrusion rates are conducted.
A range of unplasticised polyvinylchloride (uPVC) profile extrusion grade formulations, containing calcium/zinc, organotin and lead based stabiliser systems were blended with different concentrations of TiO2. Rheological analysis showed that the concentration of TiO2 (2phr - 8phr) had little effect on viscosity over the shear rate (200-1000s-1) and temperature range (170 – 190°C) studied. Mechanical analysis showed higher tensile and flexural modulii for the organotin stabilised formulations.
Resins used in profile extrusion require high viscosity at low shear rates to improve melt strength and low viscosity at high shear rates to prevent melt fracture. This paper discusses the development of copolyester resins with the desirable rheological properties, as well as good optical and physical properties. The processing, biocompatibility, and sterilization of these resins will also be discussed.
Barium sulphate (BaSO4) is widely used as a radiopaque additive for medical grade PVC tubing in surgical procedures. The rheological characteristics and mechanical performance of two different medical grade PVCs containing BaSO4 (10-15 % w/w) having two different mean particle sizes (1 and 40 micron) was investigated. The results show significant change in melt viscosity, tensile properties and phase transitions (Tan ? max) with increase in BaSO4 concentration.
We have applied thermal, mechanical, and rheological techniques in the product development for medical elastomers with success. In this presentation, examples of actual product application will be used to illustrate the utility of these techniques and to demonstrate the derived information that was used in developing successful elastomeric related medical products.
A continuous process for decrosslinking high resiliency polyurethane foam in an extruder with ultrasonic devices was developed. Rheological, structural and NMR relaxation and diffusion characterizations of decrosslinked foam were performed. The decrosslinked foam was blended with the virgin polyurethane rubber (PUR) and cured and the blend properties were investigated.
The incorporation of radiopaque barium sulphate (BaSO4) in medical tubing products is a challenge to extrusion processers. The effect of BaSO4 concentration (0-25% by weight) on the rheology and mechanical properties of three different metallocene catalysed polyethylenes were studied. The results show significant change in melt viscosity, tensile properties and phase transition (Tan ? max) with increase in BaSO4 concentration.
Polyolefin elastomers based on metallocene technology are excellent impact modifiers for polypropylene. This study looks at how density and melt rheology of polyolefin elastomers affect clarity and impact performance of clarified polypropylenes with 2, 10, and 35 MFR. Optimum clarity and improved impact performance are achieved by matching rheology and density of polyolefin elastomers with polypropylene.
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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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