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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Jian Wang , Marc Mangnus , Wallace Yau , Willem deGroot , Teresa Karjala , Mehmet Demirors, May 2010
The molecular structures of high pressure low density polyethylenes (LDPE) are notoriously difficult to characterize due to their highly long-chain branched (LCB) structure. The level and the distribution of the LCBs in LDPE vary with polymerization processes and reactor conditions and these changes may have significant effects on the rheological properties of these resins. A more refined structure ƒ?? property relationship for LDPE is greatly needed. In this study by combining advanced triple-detector gel permeation chromatography with rheological measurements the structure-property relationships of a broad range of LDPEs were investigated. Despite large variations in the molecular weights molecular weight distributions and the molecular structures of the samples some correlations between the solution and melt properties were observed which are consistent with rheological theories.
In this work, film blowing stability analysis has been performed theoretically by using minimum energy approach for non-Newtonian polymer melts considering non-isothermal processing conditions with the aim to understand the complicated link between processing conditions, machinery design and material properties.Specific attention has been paid to the investigation of the complicated links between polymer melt rheology (shear thinning, flow activation energy, Newtonian viscosity, melt strength), processing conditions (heat transfer coefficient, mass flow rate, die exit temperature, cooling air temperature) and film blowing stability. It has been found that the theoretical conclusions are in very good agreement with the experimental reality supporting the validity of the used numerical approach and film blowing model.
Juan D. Sierra , María Noriega , Silvio Ospina , Elkin Cardona, May 2010
This research work is focused on the effect of citrate plasticizers on thermal and viscoelastic properties of Polylactic acid (PLA). As expected the glass transition temperature decreases with addition of citrates demonstrating the effectiveness of citrates as a PLA plasticizer. It was observed that the decrease in glass transition temperature with the increase of citrate content behaves in exponential way. Viscoelasticity of PLA is considerably affected by the presence of citrate plasticizer. The zero shear-rate viscosity and pseudoplasticity index decrease could be correlated with the plasticizer content by using an exponential function.
S. Sanchez , R. Ibarra , F. Solis , L. Cordoba, May 2010
ABS/montmorillonite nanocomposites were obtained via conventional melt mixing by single screw capillary extrusion. Nanocomposites from 0.5 to 9 % Volumetric Fraction (VF) of nanoclay were formulated. Melt rheology shows a decrease in the Newtonian range as modified clay increases. The opposite is true for the viscosity at zero shear. Shear thinning behavior is observed as clay content is increased. From XRD, it is inferred an increase of nanoclay d-spacing independent from the clay content in samples from the capillary rheometer. TEM shows both intercalated and exfoliated clay structures obtained from capillary extrusion. The processing conditions in conventional equipment for plastics transformation, i.e. extrusion, may lead to obtain intercalated and exfoliated nanocomposites, without the need for complex tooling configuration.
Mechanical Spectral Hole Burning (MSHB) is a novel rheological technique to probe dynamic heterogeneity for polymeric materials, which exhibit relatively weak dielectric responses. In the present work, mechanical spectral hole burning (MSHB) was applied to a block copolymer and a series of polystyrene solutions in order to investigate its capability of detecting the heterogeneity and the possible relationship between the length scale of heterogeneity and hole properties. The results illustrate the power of MSHB to probe the dynamic heterogeneity of polymeric systems as evidenced by the presence or absence of mechanical holes in the vicinity of the order-disorder transition of a block copolymer. The results also suggest the hole properties are not governed by the length scale of the heterogeneity, rather they are dominated by the dynamics, i.e., whether the MSHB is performed in close to Rouse regime, rubbery plateau regime, transition regime from plateau to terminal region or the terminal flow regime.
W. Michaeli, Sebastian Hessner, Fritz Klaiber, May 2010
Thermoplastic urethanes (TPU) offer broad property range, processing flexibility, and biocompatibility for medical applications. Alcohol based disinfectants have a long history of effective and safe use. Expanding on earlier rheology molecular weight data indicating minimal reduction, we conducted a long term compatibility study covering all known urethane types in a hemo-dialysis setting with a simulated clinical exposure protocol for 90 days. After 90 days exposure, minor changes in physical properties on the catheter body and components were detected, often similar to the saline control. Most importantly, resultant properties far exceeded ISO requirements for catheters.
The time evolution of the interfacial area (Q) and the
elastic modulus (Gƒ??) in a 50/50 PS/SAN cocontinuous
blends was analyzed during annealing. Two regimes of
coarsening marked by different rates of growing of the
characteristic length (1/Q) and by different power laws
describing the decrease of Gƒ?? were identified. A
simplification to Doi-Ohta rheological model for small
deformations was proposed and its predictions were
compared to experimental results. Good agreement was
observed only for blends with relatively low interfacial
tension.
Wade DePolo , Ronald D. Moffitt , Frederick L. Beyer , James M. Sands, May 2010
Flow simulations and coextrusion experiments were employed to characterize layer sequencing effects on the interfacial stability of coextruded five-layered films incorporating ballistic-resistant materials. A simple model of coextrusion was able to rank the relative coextrusion stability of multilayered structures qualitatively in terms of viscosity matching and viscoelastic considerations. However thermal analyses and coextrusion experiments revealed that the overriding factor determining coextrusion performance was the thermal stability and degradation characteristics of the materials utilized to produce the multilayered films. Therefore any predictive analysis of coextrusion should also consider appropriate degradation mechanisms and their affect upon melt rheology.
Wade DePolo , Ronald D. Moffitt , Frederick L. Beyer , James M. Sands, May 2010
Flow simulations and coextrusion experiments were employed to characterize layer sequencing effects on the interfacial stability of coextruded five-layered films incorporating ballistic-resistant materials. A simple model of coextrusion was able to rank the relative coextrusion stability of multilayered structures qualitatively in terms of viscosity matching and viscoelastic considerations. However, thermal analyses and coextrusion experiments revealed that the overriding factor determining coextrusion performance was the thermal stability and degradation characteristics of the materials utilized to produce the multilayered films. Therefore, any predictive analysis of coextrusion should also consider appropriate degradation mechanisms and their affect upon melt rheology.
D.S. Bangarusampath , Holger Ruckdäschel , Volker Altstädt , Jan K.W. Sandler , Milo S.P. Shaffer, May 2010
The inhomogeneous dispersion of carbonnanotubes (CNTs) acts as the main hindrance forexploiting the exceptional properties associated with CNTin polymer/CNT composites. However only fewsystematic studies clearly relate the structural featureswith the property profile of nanocomposites based ondifferent nanotube grades. The aim of this study thereforewas to process nanotube-based polymeric composites andto correlate their degree of dispersion with the resultingrheological (both shear and elongation) as well aselectrical behavior. A range of multi-wall carbonnanotubes (MWNT) and single-wall carbon nanotubes(SWNT) reinforced high temperature semi-crystallinepoly (ether ether ketone) (PEEK) were prepared by meltcompounding process. The composites with high degreeof nanotube dispersion shows nearly five orders ofmagnitude increase in storage modulus and an abruptincrease of ten orders magnitude in electrical conductivityby adding only 2 wt% of nanotubes. Additionally boththe melt strength and the elongational viscosity cansignificantly increase by incorporating nanotubes.However this increment effect strongly depends on thedegree of dispersion of nanotubes in the polymer matrix.As highlighted by the experimental results both thedispersion and interfacial interaction between the matrixand nanotubes are the key factors for improving theproperties of such nanocomposites.
Siti Fatimah Aminuddin , Leong Yew Wei , Hiroyuki Hamada, May 2010
Poly(ethylene terephthalate) (PET) is one of the most
important fibers for industrial production due to its high
performance low cost and recyclability. The amount of
waste that arise from post-consumer PET especially in the
beverage industry have made recycling of poly(ethylene
terephthalate) (PET) a beneficial effort in reducing
environmental pollution. Studies of blends and composites
using recycled PET have been carried out with several
polymeric materials like polyethylene and polystyrene. In
this work recycled poly(ethylene terephthalate)/ recycled
polypropylene (RPET/RPP) blends was subjected to
injection molding and then subjected to hydrothermal
treatment in water bath at below transition glass
temperature to determine the amount of moisture
absorption. As polypropylene tends to degrade at a faster
rate than poly(ethylene terephthalate) the results show
that defect of polypropylene effect the tensile strength and
modulus of the RPET/RPP blends.
Siti Fatimah Aminuddin , Leong Yew Wei , Hiroyuki Hamada, May 2010
Poly(ethylene terephthalate) (PET) is one of the most important fibers for industrial production due to its high performance,low cost, and recyclability. The amount of waste that arise from post-consumer PET especially in the beverage industry have made recycling of poly(ethylene terephthalate) (PET) a beneficial effort in reducing environmental pollution. Studies of blends and composites using recycled PET have been carried out with several polymeric materials, like polyethylene and polystyrene. In this work, recycled poly(ethylene terephthalate)/ recycled polypropylene (RPET/RPP) blends was subjected to injection molding and then subjected to hydrothermal treatment in water bath at below transition glass temperature to determine the amount of moisture absorption. As polypropylene tends to degrade at a faster rate than poly(ethylene terephthalate), the results show that defect of polypropylene effect the tensile strength and modulus of the RPET/RPP blends.
Renato Bonadiman, Ocileide Custódio da Silva, Marco Elísio Marques, Tommi Reinikainen, May 2010
The reactive extrusion of maleic anhydride grafted polypropylene (PP-g-MAH) with ethylenediamine (EDA) as coupling agent was carried out in a co-rotating twin-screw extruder to produce long chain branched polypropylene (LCBPP). Part of PP-g-MAH was replaced by maleic anhydride grafted high-density polyethylene (HDPE-g-MAH) or linear low-density polyethylene (LLDPE-g-MAH) to obtain hybrid long chain branched (LCB) polymers. Compared with the linear PP, PE and their blends, the LCB polyolefins exhibit excellent dynamic shear and transient extensional rheological characteristics such as increased dynamic modulus, higher low-frequency complex viscosity, significantly enhanced melt strength and strain-hardening behaviors. LCB polymers also have higher tensile strength, tensile modulus, impact strength and lower elongation at break than linear polymer and their blends. Supercritical carbon dioxide (scCO2) was introduced in the reactive extrusion process. With the presence of scCO2, the motor current of twin extruder was decreased and LCB polyolefins with lower MFR, higher complex viscosity and increased tensile strength and modulus were obtained. This indicates that the application of scCO2 can reduce the viscosity of melt in extruder, enhance the diffusion of reactive species, facilitate the reaction between functional groups, and increase the LCB density. The foaming behavior of both linear and LCB polyolefins were studied. The results show that cellular materials produced from the LCB polyolefins have higher weight reduction, smaller cell size and better mechanical properties than those produced from the linear polymers.
A key element in successfully molding high
quality PET (Polyethylene Terephthalate) preforms is the
delivery of molten plastic to each cavity in a rheologically
similar manner. This has been a significant challenge in
light of the shear/viscosity and crystalline behavior of
bottle grade PET in its molten state.
This paper will review the economics of molding
PET preforms the impact of improved performance on
profitability design philosophies for molding PET
preforms and hot runner technologies that are now
available to confront historical issues in the PET preform
molding process. These new technologies applied to
molding PET preforms will help converters improve their
bottom lines.
A key element in successfully molding high quality PET (Polyethylene Terephthalate) preforms is the delivery of molten plastic to each cavity in a rheologically similar manner. This has been a significant challenge in light of the shear/viscosity and crystalline behavior of bottle grade PET in its molten state. This paper will review the economics of molding PET preforms, the impact of improved performance on profitability, design philosophies for molding PET preforms and hot runner technologies that are now available to confront historical issues in the PET preform molding process. These new technologies, applied to molding PET preforms, will help converters improve their bottom lines.
Traditionally, the mold qualification procedure involves sampling the mold and establishing a process to make acceptable parts. Process engineering studies such as in-mold rheology, gate seal tests and generating process windows are most commonly performed. Design of Experiments (DOE) are conducted to study the effect of the molding factors on the quality of the part and sometimes to find the process to mold a part within the quality specifications. The process engineering studies and the DOEs are conducted independent of each other. This paper combines these techniques and introduces the concepts of the Aesthetic Process Window, the Dimensional Process Window and the Control Process Window.
Sunny Modi, Kurt Koelling, Yael Vodovotz, May 2010
The objective of this study was to characterize the thermal and rheological properties of Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) blended with Poly (L-lactic acid) (PLA) resin at different concentrations and relate these findings to potential food packaging applications. The thermal analysis showed increasing concentration of PHBV resulted in lower thermal stability of PLA. Several melting transitions for the blends were observed representative of phase separated polymers. The complex viscosity showed no improvements in the PHBV when compared to the blends.
Herman Suwardie, Min Yang, Peng Wang, Huiju Liu, Costas G. Gogos, May 2010
Solid dispersions made from mixing polymers and drug have caught a lot interest in recent years. One major technical barrier limiting broader applications of solid dispersions is the lack of drugƒ??s solubility data in polymer matrix. Furthermore, there is no standard or widely accepted method for the testing of drugƒ??s solubility. Zhang et. al?ÿ developed a novel method using Differential Scanning Calorimeter (DSC) recently. However, it requires tedious and delicate experimental work. Therefore, a new method via rheological characterization is explored in our laboratory. The steady from both oscillatory and capillary rheometer) and dynamic (oscillatory rheometer) viscosities of the drug-polymer system are measured for different drug concentrations at various temperatures. The rheological results presented not only can be utilized for process optimization and material characterization, such as molecular weight determination, but also provides valuable information on the drugƒ??s solubility in polymeric excipients.
Rajendra K. Krishnaswamy , Jason Baird , John P. Christiano, May 2010
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.
Sunny Modi , Kurt koelling , Yael Vodovotz, May 2010
PHB (Poly (3-hydroxybutyrate) families of naturally occurring polymers are extracted from micro-organisms.PHB behaves similarly to conventional thermoplastics, yet are fully biodegradable in common composting conditions.To improve flexibility for potential food packaging applications, PHB can be synthesized with various copolymers such as 3-hydroxyvalerate (HV). The objective of this study was to characterize the thermal and rheological properties of PHB synthesized with various valerate contents and relate these findings to potential food packaging applications.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
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
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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