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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Conference Proceedings
FOAMING OF LDPE/SILICA NANOCOMPOSITES: IMPROVING THE CELLULAR
STRUCTURE AND MECHANICAL PROPERTIES
Low density polyethylene/nano-silica nanocomposites has
been foamed using an improved compression molding
process. Different amounts of nanosilica (from 1 to 9 % by
weight) were used. A high level of particle dispersion was
achieved both in the solid precursor and in the foams. It
was found a significant increment of the mechanical
properties both in solids and foams; being the increase in
properties more significant in the foams. A reduction in
cell size has been observed with the addition of nanosilica.
Cell sizes in the microcellular range were obtained.
FOAMING OF LDPE/SILICA NANOCOMPOSITES: IMPROVING THE CELLULAR STRUCTURE AND MECHANICAL PROPERTIES
Low density polyethylene/nano-silica nanocomposites has been foamed using an improved compression molding process. Different amounts of nanosilica (from 1 to 9 % by weight) were used. A high level of particle dispersion was achieved both in the solid precursor and in the foams. It was found a significant increment of the mechanical properties both in solids and foams; being the increase in properties more significant in the foams. A reduction in cell size has been observed with the addition of nanosilica.Cell sizes in the microcellular range were obtained.
MECHANICAL HOLE BURNING SPECTROSCOPY IN POLYMERIC SYSTEMS - A NOVEL TECHNIQUE TO CHARACTERIZE DYNAMIC HETEROGENEITY
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.
LONG TERM POLYURETHANE CATHETER ALCOHOL COMPATIBILITY I, PHYSICAL AND RHEOLOGICAL STUDIES
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.
QUALITY ANALYSIS OF INJECTION-COMPRESSION MOULDED OPTICAL
LENSES
The manufacturing of optical components by
injection moulding and injection-compression moulding
is a serious challenge for mould and machine technology
as well as for process control. Polymer lenses were
manufactured with a modularly designed injectioncompression
mould base thus different injectioncompression
moulding technologies could be examined.
To evaluate the quality of optical parts the accuracy of the
moulded geometry as well as the resulting optical
performance has been analysed. At present a geometrical
moulding accuracy in the lower micron range has been
achieved. Overall injection-compression moulded lenses
showed a better optical performance than injection
moulded lenses.
QUALITY ANALYSIS OF INJECTION-COMPRESSION MOULDED OPTICAL LENSES
The manufacturing of optical components by injection moulding and injection-compression moulding is a serious challenge for mould and machine technology as well as for process control. Polymer lenses were manufactured with a modularly designed injection-compression mould base, thus different injection-compression moulding technologies could be examined. To evaluate the quality of optical parts the accuracy of the moulded geometry as well as the resulting optical performance has been analysed. At present a geometrical moulding accuracy in the lower micron range has been achieved. Overall injection-compression moulded lenses showed a better optical performance than injection moulded lenses.
UTILIZING ADVANCED SIMULATION AND MELT MANAGEMENT
TECHNOLOGIES TO RE-DEFINE THE INDUSTRY STANDARD
Plastic products are occasionally designed in such a
way that due to required injection locations and polymer
flow traits the product will inherit certain quality defects.
Two specific defects that if generated could often
constitute a non-conforming product are weak weld lines
and burn marks. Initial process alterations can be utilized
in order to minimize or eliminate defects; however more
costly mold or product alterations are often necessary.
This paper presents a case study of how plastic flow
simulation and the latest in melt management technologies
can be utilized in order to create products that re-define
the industries approach to handling these specific product
defects.
UTILIZING ADVANCED SIMULATION AND MELT MANAGEMENT TECHNOLOGIES TO RE-DEFINE THE INDUSTRY STANDARD
Plastic products are occasionally designed in such a way that, due to required injection locations and polymer flow traits, the product will inherit certain quality defects. Two specific defects that if generated could often constitute a non-conforming product are weak weld lines and burn marks. Initial process alterations can be utilized in order to minimize or eliminate defects; however more costly mold or product alterations are often necessary. This paper presents a case study of how plastic flow simulation and the latest in melt management technologies can be utilized in order to create products that re-define the industries approach to handling these specific product defects.
A METHOD TO OBTAIN BALANCED FLOW IN PROFILE EXTRUSION DIES
One of the problems encountered in the extrusion of
complex profiles is the unbalanced flow of polymer melt
as it leaves the die. In this study a systematic method to
obtain balanced flow is proposed by using a CFD tool.
First the results of a production test that is performed for
a profile and the results of the CFD simulation compared
and it is seen that the velocity distribution at the die exit
is similar indicating an unbalanced flow. For the profile
to be produced a new die geometry which provides
balanced flow at the die exit is proposed by use of
numerical simulations. A balanced exit flow is achieved
by using flow separators.
A METHOD TO OBTAIN BALANCED FLOW IN PROFILE EXTRUSION DIES
One of the problems encountered in the extrusion of complex profiles is the unbalanced flow of polymer melt as it leaves the die. In this study, a systematic method to obtain balanced flow is proposed by using a CFD tool. First, the results of a production test that is performed for a profile and the results of the CFD simulation compared and it is seen that the velocity distribution at the die exit is similar, indicating an unbalanced flow. For the profile to be produced, a new die geometry which provides balanced flow at the die exit is proposed by use of numerical simulations. A balanced exit flow is achieved by using flow separators.
ENHANCED RESIN FOR METAL INSERT MOLDING APPLICATIONS
OEMs that manufacture cellular phones and portable music players require thin, stiff, structural parts. Until now, the main approach has been the use of die casting and glass-filled plastic. The use of metal insert molding (where plastic is injected around a thin metal insert) enables manufacturers to have ultra thin designs, reduce dependence on costly metal and die-cast parts, improve yield and tool life, and provide a superior surface finish for decoration. However, metal insert molding can lead to high molded-in stresses due to differential shrinkage of the plastic resin, which in turn can lead to stress cracking in the surrounding plastic, especially when exposed to various chemical environments and heat/humidity aging. Bayer MaterialScience has formulated a new Makroblend?? PC/PBT resin (UT5205) to successfully be used in the encapsulation of a sheet metal insert for cell phone and music player applications.
EFFECT OF ENVIRONMENTAL EXPOSURE ON MATERIALS BASED ON BLENDS
OF PLASTICIZED STARCH AND POLYPROPYLENE
Due to the recent demand for environmentally friendly
polymers and the duty to take advantage of renewable
natural resources when possible biopolymers have become
an important alternative to synthetic polymers. Starch
when using glycerol as a plasticizer has proven to be a
processable “green” polymer additive when compounded
with maleated polypropylene. In this study material was
characterized based on its ability to perform over five
months of exposure to natural conditions. The effects on
modulus and elongation with the addition of plasticized
starch in a polypropylene matrix were evaluated and are
presented.
EFFECT OF ENVIRONMENTAL EXPOSURE ON MATERIALS BASED ON BLENDS OF PLASTICIZED STARCH AND POLYPROPYLENE
Due to the recent demand for environmentally friendly polymers and the duty to take advantage of renewable natural resources when possible, biopolymers have become an important alternative to synthetic polymers. Starch when using glycerol as a plasticizer has proven to be a processable ƒ??greenƒ? polymer additive when compounded with maleated polypropylene. In this study, material was characterized based on its ability to perform over five months of exposure to natural conditions. The effects on modulus and elongation with the addition of plasticized starch, in a polypropylene matrix, were evaluated and are presented.
COCONTINUOUS BLENDS: CONNECTING RHEOLOGY TO MORPHOLOGY VIA 3D IMAGING.
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.
FATIGUE PROPERTIES OF JUTE FABRIC REINFORCED SHEET MOLDING COMPOUND (SMC) MOLDING
Recent earth environmental concern requires easy
recycle material system and the use of biodegradable
polymer and natural fiber is noticed in composite
materials. To apply the natural fiber for the structural parts
the use as reinforcement of Sheet Molding Compound
(SMC) is desirable because it is expected that SMC can be
used in various fields in terms of high productivity and
dimensional stability.
Considering that fiber reinforced composite is used
for structural part the design of the strength is very
difficult because the failure mechanism is complicated
considerably. In this study SMC that reinforcement was
jute cloth was prepared. The low-cycle bending fatigue
test and the cross sectional observation of fracture part
were performed. As a result the brittle crack propagation
in the interface around the fiber bundle was seen in the
specimen of warp and weft direction and the phenomenon
such as brittle crack propagation was not confirmed in the
specimen of 45-degree direction.
FATIGUE PROPERTIES OF JUTE FABRIC REINFORCED SHEET MOLDING COMPOUND (SMC) MOLDING
Recent earth environmental concern requires easy recycle material system, and the use of biodegradable polymer and natural fiber is noticed in composite materials. To apply the natural fiber for the structural parts, the use as reinforcement of Sheet Molding Compound (SMC) is desirable because it is expected that SMC can be used in various fields in terms of high productivity and dimensional stability.Considering that fiber reinforced composite is used for structural part, the design of the strength is very difficult because the failure mechanism is complicated considerably. In this study, SMC that reinforcement was jute cloth was prepared. The low-cycle bending fatigue test and the cross sectional observation of fracture part were performed. As a result, the brittle crack propagation in the interface around the fiber bundle was seen in the specimen of warp and weft direction, and the phenomenon such as brittle crack propagation was not confirmed in the specimen of 45-degree direction.
VISCOELASTICITY OF POLYMER/OLIGOMER ATHERMAL BLENDS
The viscoelastic properties of poly(ñ-ethyl styrene), its hexamer, and their athermal blends at various concentrations are studied. Master curves for the dynamic shear responses, G' and G are successfully constructed for both the pure materials and the blends indicating the validity of the time-temperature superposition principle. The shift factors used to construct the master curves show weaker dependence in the blends. The segmental dynamics appear unchanged by concentration which is different from the calorimetric studies where mixtures show obviously broadened glass transitions and depressed enthalpy overshoots."
MODELING THREE-DIMENSIONAL VISCOELASTIC FLOW AROUND A CLOSELY-SPACED LINEAR PERIODIC ARRAY OF CYLINDERS
A framework and code are being developed to simulate fiber and film processes; currently the code can handle three-dimensional, enclosed, isothermal, incompressible, creeping flow of a Giesekus fluid. The code is an extension of the parallel methods developed by Caola et al from two- to three-dimensional flows. The code has been tested on a benchmark problem that shows an elastically-driven flow transition from a twodimensional, steady flow to a three-dimensional, time periodic flow: flow around a closely-spaced linear periodic array of cylinders in a rectangular channel, a flow studied experimentally by Liu. Numerical simulations have been conducted in this geometry with the Oldroyd-B model, ?ý=0.67, wall separation distance 8-32 radii, and Deborah number from 0.1 to 1.1. The range of bounding wall edge effects on the flow field is shown to be 4 radii, and a small-magnitude overshoot in the primary velocity component near the wall can be observed, similar to the cat's ears observed by Poole et al in planar gradual-contraction expansion flow. The expected critical Weissenberg number of the flow transition has not yet been reached; the time integration to steady state diverges at moderate Weissenberg number. However, the velocity profile shows oscillatory behavior similar to what is reported at the flow transition.
RELIABILITY OF INKJET PRINTED AG TRACES SUBMITTED TO HIGH CURRENT DENSITY TEST
Printable electronics is a new emerging technology with
capabilities of producing high volumes, low price and
flexible electronics. However, a number of questions,
mainly related reliability of such devices, are still pending.
In this paper, metal nanoparticles based ink was printed on
flexible polyimide substrates. Samples were submitted to
high current density electrical test. Samples were tested
until failure generating reliability curves. Printed traces
presented low reliability probably due to the large amount
of pores and grain boundaries in its microstructure and
also because of the trace inhomogeneity. Thus, the
application of this technology depends on process
improvements.
BREAKTHROUGH INVENTIONS AND INNOVATIONS IN DIE DESIGN FOR
POLYMER PROCESSING
After a polymer has been converted from a solid to a
molten state it must be processed into a final shape to
have value to a customer. This final shape may be a
pellet a film a sheet a profile or many other final
geometries. This paper will discuss some of the
breakthrough inventions and innovations in die design that
are used to produce this vast array of final polymer
product shapes.
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The objective of this work was to develop an impactmodifier to improve the impact strength of poly(L-lactide)(PLLA). Graft copolymers of PLLA and polyethylene(PE) were synthesized via the ring-openingpolymerization of L-lactide initiated by PE modified withhydroxyl groups (macroPE). The macroPE was preparedvia the metallocene catalyzed copolymerization ofethylene and 5-hexen-1-ol. DSC and DMA on thecopolymers and PLLA blends indicated a two-phasepolymer system. The blends exhibited significantlyincreased loss moduli and maximum tan ƒ?? s whencompared to virgin PLLA indicating a high probability ofincreased impact toughness while the storage moduli ofthe blends remained approximately constant.
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