SPE Library

Rheological computer experiments, involving small amplitude oscillatory shear flows for liquid n-hexadecane, are performed using non-equilibrium molecular dynamics methodology. In particular, the so-called Cox-Merz rule, which suggests that the magnitude of the complex viscosity with respect to frequency is equal to that of the steady shear viscosity with respect to shear rate, is validated. At different frequencies, the complex viscosity, including both dynamic and out-of-phase parts, varies significantly with respect to temperature. ?ÿ

In this work, two different HDPEs were investigated from rheological as well as die drool phenomenon point of view. It has been revealed that long-chain branching and low polymer melt elasticity significantly reduce die drool phenomena at the die exit region.

The affects on the mechanical and rheological properties of blends of recycled blown film (BM) and injection moulded milk containers (IM) were studied. Tensile, flexural and thermal properties remained unchanged with resultant increasing MFI. Anomalous results appear to occur between the 80/20% w/w (BM/IM) and 60/40% w/w (BM/IM) blends as confirmed by GPC, MFI and density.

Due to the recent interest on citrates as a biodegradable plasticizer for Polylactic acid PLA, several PLA blends that were plasticized with tributyl citrate TBC were prepared in a co-rotating twin screw extruder. A range of 12.4 to 22.5% by weight was considered for the plasticizer content. The thermal, rheological and mechanical properties were correlated with the plasticizer content and compared with pure Polylactic acid. Additionally, the change of these properties as a function of postproduction time was studied and correlated with the plasticizer permanence.

Polystyrene/multi-wall carbon nanotube composites, PS/MWCNT, were prepared with co-rotating twin screw extruder. PS/MWCNT was prepared by diluting highly concentrated MWCNT masterbatch chips. We investigated rheological and mechanical properties of PS/MWCNT composites. Rheological and mechanical properties of PS/MWCNT composites depended on concentration of PS/MWCNT and processing conditions such as screw speed, feeding rate.

The topography of the inner surface of small bore extruded tubes used in fluid handling applications can affect flow rates, fluid turbulence and biofilm adherence. Quantitative surface roughness analysis of tubes manufactured from different polymers has shown that the inner surface topography is related to the polymer molecular variables, rheological properties and extrusion processing conditions. Surface energy analysis of these surfaces has also been shown to be related to polymer type as well as surface roughness.

Ultrasound assisted twin screw extrusion process was developed to disperse carbon nanofibers (CNFs) in a polymer matrix. CNFs were separately added into the melt stage to reduce the breakage of CNFs and to avoid intense stresses in the feed zone. The effect of ultrasound and CNFs loading on die pressure, rheological, mechanical, electrical and morphological properties of liquid crystalline polymer (LCP) filled with 2-20 wt% CNFs was studied.Ultrasonic treatment caused a reduction in die pressure with decrease in electrical percolation threshold value of treated samples.

Tyco Electronics has over fifty years of experience in the field of radiation crosslinked polymers. We have incorporated the use of rheological and solvent swelling techniques to characterize crosslinked networks. Insufficient beam dose or processing errors can result in materials that appear crosslinked upon initial testing, but are not fully crosslinked. We evaluated various characterization methods on three different morphologies of polyethylene (HDPE, LDPE and VLDPE). Each method had its own strengths and limitations.

Polyamide 6 (PA6)/Clay 30B nanocomposites of various concentrations were prepared at different amplitudes using an ultrasonic extruder. The die pressure and ultrasonic power consumption were measured. X-ray patterns, thermal, mechanical and rheological properties of extruded nanocomposites were obtained. Films were manufactured from prepared nanocomposites by film blowing process and their structural and mechanical properties in the machine and transverse directions were studied.

LLDPE/Clay 20A nanocomposites of various concentrations were prepared at different amplitudes using an ultrasonic extruder. The die pressure and ultrasonic power consumption were measured. X-ray patterns, thermal, mechanical and rheological properties of extruded nanocomposites were measured. Films were manufactured from prepared nanocomposites by film blowing process and their structural and mechanical properties in the machine and transverse directions were studied.

In this paper the effects of ionizing radiation on poly(lactic acid) PLA will be investigated. The PLA used in this experiment is a NatureWorks LLC extrusion and thermoforming polylactide resin product code 2002D. Its rheological properties will be investigated. This team worked in conjunction with Mr. Song Cheng and Scott Goetz of Sterigenics and Professor John Bartolomucci of the Pennsylvania College of Technology. The material was irradiated using electron beam radiation. The material was then tested to obtain rheological properties at various dosage levels.

In this paper, the effect of crosslinking on the flow properties in foam extrusion and injection molding was studied using. The change in flow resistance of Ethylene-Vinyl Acetate (EVA) from partial crosslinking of the resin was characterized, with and without the influence of the dissolved blowing agent. The shear and extensional viscosities of the resin were approximated through the analysis of the pressure drop across a Hele-Shaw die channel. The influence of blowing agent on the viscosity of the EVA resin was also investigated.

The behavior of melt flow of Ethylene Vinyl Acetate was studied using a capillary rheometer. The true flow curves were obtained by applying the Bagley correction into the apparent flow curves. It was found that EVA follows the typical pseudoplastic behavior with power indices within the range of polyethyleneƒ??s power indices. Moreover, end pressure losses were estimated.

The rheological behavior of the alkali metal salts of oligomeric (Mw = 4 kg/mol) sulfonated polystyrene ionomers (SPS) was characterized using dynamic and steady shear measurements. Sulfonation increased the melt viscosity of the PS, by as much as 4 orders of magnitude, and the zero shear viscosity scaled with the Coulombic strength of the cation Although Mw was below the entanglement molecular weight, the ionomer melts exhibited strong elastic behavior.

PLA-composite materials were prepared by injection moulding process through high speed hot-cool melt compounding process with 40 wt% loads of husk. Chain extender (Joncryl ADR 4368) has been used during the melt mixer. To characterize the composites materials morphology mechanical (tensile flexural and charpy) thermal (crystallinity Tg and Tm) and rheological (melt flow rate viscosity) properties were studied and the properties were compared to soft wood fibre composite’s properties.

PLA-composite materials were prepared by injection moulding process through high speed hot-cool melt compounding process with 40 wt% loads of husk.Chain extender (Joncryl ADR 4368) has been used during the melt mixer. To characterize the composites materials, morphology, mechanical (tensile, flexural and charpy) thermal (crystallinity, Tg and Tm) and rheological (melt flow rate, viscosity) properties were studied and the properties were compared to soft wood fibre compositeƒ??s properties.

The complex time and temperature dependent melt rheology of Poly (Hydroxy Butanoic Acid) or PHB copolymers is an important consideration for their extrusion. In this effort, we report the influence of temperature profile and screw design on the process stability, melt temperature, melt pressure, output rate and molecular weight retention using highly-instrumented commercial-scale extruders with smooth-bore feed sections. One important outcome of this investigation is screw design guidelines for the extrusion of PHB copolymers.

One of the most widespread practical methods of polymer processing is the extrusion method that is based on pressing a polymeric melt through channels of the molding tool which have different geometrical crosssections.The basic performance of extrusion is based on the pressure/flow performance which sets functional correlation between volumetric flow rate of a polymer medium pressed through a molding tool and created pressure drop. Arguments of this correlation are the rheological parameters of polymer and the geometrical characteristics of the channel in which the polymeric melt flows. In this paper a viscoelastic model with a corrected strain energy function is implemented. The comparison of revealed theoretical expression in this paper with the experimental data for flow of polymeric melts in cylindrical channels with various cross-sections demonstrates a good convergence over a wide range of pressure.

This paper is the third in a series which was previously presented in ANTEC08(1) and ANTEC09(2). These papers showed different applications of the melt flow index, MFI, equipment. These applications included the temperature and/or shear sensitivity, extrudate (die) swell, melt density, melt strength, thermal degradation, and processability of polyolefins. In the current paper, the relation between the measured values via MFI equipment will be related to the viscoelastic properties measured by rotational rheometer. For example, the extrudate swell will be compared to the elastic properties of some polyolefins. Additionally, the processability will be analyzed via the relationships of viscosity, shear rate, and temperature. Moreover, some molecular structure parameters are indentified and then are used to interpret some of the properties measured by the MFI equipment.

Injection molding although widely extended as one of the main replication technologies has shown important limitations when applied to the manufacture of plastic parts in the micro and mini scale. The present work describes a new moulding process based on the fusion ofthat has been thermoplastics materials via ultrasounds developed in the Sonoplast European project. First experimental achievements led to an innovative concept of mould and ultrasound moulding machine for the production of plastic parts (micro and mini). In addition the molding process management is simplified and directed by few machine parameters differing from conventional injection molding. The ultrasound molding process is extremely fast and with reduced filling pressures achieves a very good reproduction of the mould micro details. Besides it has been possible to obtain reductions about 50% on sprue volumes (around 0,16 g of plastic per shot) comparing with a conventional microinjection machine. Moreover, process energy consumption and power requirements are between 500 and 1200J and 200 and 500W, respectively. Finally, rheological analysis showed that no noticeable degradation process occurred after processing; equally, tensile testing gave better mechanical performance retention, comparing with traditional microinjection processes.