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Applied Rheology

SPE Library content related to rheology

BLENDING OF RECYCLE PE BLOWN FILM AND INJECTION MOULDING GRADES

Jeremy R. Austin, May 2010

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.

THE INFLUENCE OF THE PROCESSING CONDITIONS ON THE PS/MWCNT COMPOSITES PREPARED WITH TWIN SCREW EXTRUDER

Jian-Kang Wang, Xiang-Yang Liu , Han-Xiong Huang, May 2010

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.

ULTRASOUND ASSISTED MELT PROCESSING OF LCP/CNF NANOCOMPOSITES

Rishi Kumar , Avraam I. Isayev, May 2010

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.

CHARACTERIZATION OF RADIATION CROSSLINKED POLYETHYLENES

Ken Miyata, Yuuki Ichikawa, Keiji Katsuno, Akihiro Nishioka, Tomonori Koda, Go Murasawa, May 2010

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.

ULTRASONIC EXTRUSION AND FILM BLOWING OF PA6/CLAY NANOCOMPOSITES

Nan Chen, Mohammad Monirul Hasan, Takashi Kuboki, Chul B. Park, May 2010

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.

ULTRASONIC EXTRUSION AND FILM BLOWING OF LLDPE/CLAY NANOCOMPOSITES

H. C. Chen, S. C. Chen, P.M. Hsu, H. S. Peng, Y. C. Wang, May 2010

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.

EFFECTS OF E-BEAM IRRADIATION ON MELT BEHAVIOR OF POLY(LACTIC) ACID

Jon Lazarus , Anthony DiFonzo, May 2010

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.

INFLUENCE OF CROSSLINKING ON RHEOLOGICAL PROPERTIES OF ELASTOMER AND ITS FOAM EXTRUSION

N. Chen, J. Wang, R. Chu, C.B. Park, May 2010

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.

RHEOLOGICAL CHARACTERIZATION OF ETHYLENE VINYL ACETATE

O. Y. Alothman, May 2010

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.

RHEOLOGICAL BEHAVIOR OF SULFONATED POLYSTYRENE IONOMERS

Masaharu Nishiura, Makoto Sarata, Yuya Hidekuma, Masanori Okano, Asami Nakai, Hiroyuki Hamada, May 2010

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 COMPOSITES REINFORCED BY WHEAT AND RYE HUSK

Andrzej K. Bledzki , Abdullah A. Mamun , Adam Jaszkiewicza , Jürgen Volk, May 2010

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 COMPOSITES REINFORCED BY WHEAT AND RYE HUSK

Andrzej K. Bledzki , Abdullah A. Mamun , Adam Jaszkiewicza , Jürgen Volk, May 2010

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.

PRESSURE/FLOW PERFORMANCE OF VISCOELASTIC POLYMERIC MELTS IN CYLINDRICAL CHANNELS

Hossein Hosseini , Boris V. Berdyshev , Mohammad Mosaddegh, May 2010

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.

COMPARING THE RHEOLOGICAL PROPERTIES OF SELECTED POLYOLEFINS USING ROTATIONAL RHEOMETRY TO THOSE OBTAINED FROM MELT FLOW INDEX; A TRILOGY

Eric A. Koester, May 2010

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.

SONOPLAST NEW PROCESS AND MACHINERY FOR MICROPARTS MOLDING BASED ON ULTRASOUND EXCITATION

Esther Richards, Reza Rizvi, Andrew Chow, Hani Naguib, May 2010

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.

DYNAMIC CHARACTERISTICS OF PLUG ' ASSIST THERMOFORMING

Hossein Hosseini , Boris V. Berdyshev , Ekaterina M. Kromskaya, May 2010

Plug-assist thermoforming is a well known technique in polymer processing due to its interesting features. The dynamic value of driving-force for the stretching process is determined based on equilibrium equation. This amount of force is required for applying to a plug in order to stretch a sheet. It is used for calculation of the required theoretical work, and power of a plug-assist thermoforming process. By using a non-linear viscoelastic rheological model in the proposed mathematical model, its validity was examined by performing experimental tests on ABS sheets.

HIGH STRAIN RATE RHEOMETRY OF POLYMER MELTS RELEVANT TO MICROMOLDING AND THIN-WALLED INJECTION MOLDING

A L Kelly , B R Whiteside , T Gough , P D Coates, May 2010

The rheology of polymer melts has been measured at strain rates up to 107 s-1, relevant to micromolding and thin walled molding processes, using an instrumented high speed injection moulding machine. Deviations from shear thinning behavior were observed for commercial grades of polyethylene, polypropylene, polystyrene and PMMA, and shear thickening behavior occurred for some of the polymers examined. Off line parallel plate rheometry and twin bore capillary rheometry were used to provide rheological data at low and medium shear strain rates respectively. Measured shear viscosity was found to follow Newtonian behavior at low rates and shear thinning power law behavior at intermediate strain rates. At shear strain rates approaching or above 106 s-1, shear viscosity reached a rate-independent plateau, and in some cases shear thickened with further increase in strain rate. A relationship between the measured high strain rate rheological behavior and molecular structure was found, with polymers containing larger side groups reaching the rate independent plateau at lower strain rates than those with simpler structures. These results have implications for micromolding of particular polymer architectures.

THERMAL STABILIZATION OF BIODEGRADABLE POLY-HYDROXYBUTYRATE (PHB) IN MELT EXTRUSION PART 1: POLY-OLIGOMERIC-SILSESQUIOXANE

Y. Shaked , H. Dodiuk , S. Kenig , C. Schwier , S. McCarthy, May 2010

Poly-Oligomeric-Silsesquioxane POSS nano modifier was examined as a thermal stabilizer for PHB.Melt compounding of Poly-Hydroxy-Butyrate PHB copolymers with different POSS moieties was performed.Reactive and non-reactive POSS nano modifiers were used. The effect of modification on PHB thermal stability was evaluated by changes in rheology and molecular weight. POSS modifiers with unique core-shell structures were found to significantly reduce the loss in molecular weight during melt mixing possibly by decreasing viscous-heating effects.

DESIGN AND THEORETICAL ANALYSIS OF MINI-PLUNGER SPRAYER USED IN SW2502 FUSED DEPOSITION MODELING RAPID PROTOTYPING SYSTEM

Paul Mills, May 2010

The fused deposition modeling rapid prototyping system is based on the manufacturing principle of layer by layer. The sprayer is the key component. Based on the polymer rheological properties, the structure design and theoretical analysis of the mini-plunger sprayer of SW2502 fused deposition modeling system are studied. The plasticizing capacity of the mini-plunger sprayer is analyzed in theoretically. It is very important for the fused deposition modeling process to maintain a stable plasticizing capacity. The driving force of ABS feed is related to several parameters such as structure form of sprayer and material property, etc. The barrel and nozzle design should be fit for mobility, purity, and mechanical property of ABS feed. The modified ABS feed adopts self-pressure-adding driving method to decrease the pressure losses of barrel and nozzle. The plasticizing capacity of the sprayer is more than 20g/h.

MICROCELLULAR EXTRUSION FOAMING FOR LINEAR AND LONG-CHAIN-BRANCHED POLYLACTIDE

Wesley Petersen, Nicole Larson, May 2010

In this work, microcellular extrusion foaming for both linear and long-chain-branched (LCB) polylactide (PLA) was processed on a single-screw extrusion system with CO2 as a blowing agent. The rheological experiments were conducted on an advanced rheometric expansion system (ARES) rheometer to compare the rheological properties among linear and LCB-PLAs without blowing agent. The characterization for foamed samples shows that in comparison to the linear PLA, the LCB-PLA foams have larger volume expansion ratios, decreased cell-opening, smaller average cell sizes and higher cell densities, due to the higher viscosity, higher melt strength and higher crystallinity derived from long-chain branching.