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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
SIMULATIONS AND EXPERIMENTAL STUDIES OF INTERFACE DISTRIBUTION
AND BIRIFRINGENCE IN THE SEQUENTIAL CO-INJECTION MOLDING
OF AMORPHOUS POLYMERS
2D numerical simulations of the interface distribution
and flow birefringence for combinations of PS PC and
PMMA in sequential co-injection molding of a centergated
disk were performed. A hybrid control volume/finite
element/finite different method with modeling based on
nonlinear viscoelastic constitutive equation and stressoptical
rule was used. Free quenching was performed and
thermal birefringence was measured. Interface distribution
and birefringence in moldings were measured. The
thermal birefringence is added to the flow birefringence to
obtain the birefringence. The simulation results for the
interface distribution and birefringence qualitatively match
with experimental results.
SIMULATIONS AND EXPERIMENTAL STUDIES OF INTERFACE DISTRIBUTION AND BIRIFRINGENCE IN THE SEQUENTIAL CO-INJECTION MOLDING OF AMORPHOUS POLYMERS
2D numerical simulations of the interface distributionand flow birefringence for combinations of PS, PC andPMMA in sequential co-injection molding of a centergateddisk were performed. A hybrid control volume/finiteelement/finite different method with modeling based onnonlinear viscoelastic constitutive equation and stressopticalrule was used. Free quenching was performed andthermal birefringence was measured. Interface distributionand birefringence in moldings were measured. Thethermal birefringence is added to the flow birefringence toobtain the birefringence. The simulation results for theinterface distribution and birefringence qualitatively matchwith experimental results.
OPPORTUNITIES FOR PLASTICS MATERIALS AND PROCESSES FOR UNDER-THE-HOOD APPLICATIONS
There is an increasing demand for light weight low system/part cost high fuel efficiency recyclability low manufacturing cost and freedom of parts consolidation for under the hood parts.This presentation will discuss state of the art for several key applications such as HVAC components radiator components fan-shroud assemblies/modules air intake manifolds engine (or ƒ??beautyƒ?) covers rocker panels and other multi-functional assemblies etc.Plastics have made significant inroads in valve covers and air-intake manifolds. In valve covers (also called rocker or cam covers) thermoplastics are replacing thermosets. Advances in thermoset materials will also be discussed. The reason for using other technologies other than conventional injection molding such as thermoforming blow molding water/gas injection molding etc. will be discussed for above mentioned applications. For example future air-intake manifolds may utilize laser welding to join two shell halves with less potential damage to sensitive electronics than with vibration welding.To reduce part weight technologies like thin wall molding microcellular foaming and nanocomposite molding will be discussed. There is a need for high flow materials with high temperature capabilities.Opportunities for several material families such as polyamide Polyolefinic materials PPS PPA etc are discussed. Integration need such as fan/shroud with partial or full front end module instrument module with HVAC integration cam cover with gasket and oil/air separator into one lower-cost module; air-intake manifold and rocker panel into a single multi-functional assembly. etc; will be briefly discussed.
DEVELOPMENT OF A PRESSURE DRIVEN MICRO-RHEOMETER
A pressure driven micro-rheometer was developed. It uses 80 mg of material to measure the viscosity of polymer melts at shear rates ranging from ten to several thousands s-1. The maximum shear rate can be extended to several 104 s-1 with 200 mg of sample. The main part of the rheometer consists of two sample reservoirs connected through a slit channel (H = 0.1 mm W = 1 mm L=5 mm) and two pistons. The double piston arrangement enables using the same material repeatedly by the reciprocating flow of the polymer melt from one reservoir to the other.In addition by using a very thin slit channel the viscosity of polymer melts can be measured over a wide range of shear rates whilst using only a small quantity of material.Measured viscosity was in good agreement with that by a capillary rheometer and it was found that slip is negligible in the slit die used in this study.
THE MECHANICAL/THERMAL PROPERTIES OF MICROCELLULAR INJECTION MOLDED POLY-LACTIC-ACID(PLA) NANOCOMPOSITES
This study investigated the influence of montmorillonite (MMT) content on the mechanical/thermal properties of microcellular injection molded Polylactide (PLA)/clay nanocomposites. Carbondioxide (CO2) was the blowing agent. The PLA/MMTnanocomposites were prepared by twin screw extrusion.The results showed that as MMT content is increased tensile strength impact strength and cell density decrease.This is caused by the speed degradation of PLA due to the addition of MMT. MMT decreases the crystallization temperature but increases the decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the clay increases as MMT content increases. TEM pictures showed that the MMT is well dispersed within the PLA matrix.
EFFECT OF ORGANOCLAY ON THE MECHANICAL / THERMAL PROPERTIES OF MICROCELLULAR INJECTION MOLDED POLYSTYRENE-CLAY NANOCOMPOSITES
An organically modified montmorillonite was compounded with polystyrene (PS) in a twin-screw extruder. The organoclay polystyrene nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content on the mechanical and thermal properties was investigated. The results showed that when the MMT content was 1 wt% the nanocomposites have maximum tensile strength wear resistance and cell density. Moreover the addition of organoclay increases the glass transition and decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the nanocomposites decreases by comparison with the organoclay. TEM pictures showed that MMT is well dispersed within the PS matrix.
CONTROL OF DENSITY AND MODULUS IN DIE DRAWN PP COMPOSITES
Polymer chain orientation achieved through the die
drawing process has been shown to significantly improve
the mechanical properties of both filled and unfilled
polymer products1. However inclusion of filler particles
tends to result in localised cavitation and subsequent
propagation which reduces stiffness enhancements. By
tailoring production parameters such as rate temperature
and geometry it is possible to control both the modulus
and density of the final product to given specifications.
Within this paper we demonstrate the effects of die angle
and temperature on the final sample properties of a civil
engineering product and their optimisation to manufacture
a low density high stiffness component.
CONTROL OF DENSITY AND MODULUS IN DIE DRAWN PP COMPOSITES
Polymer chain orientation achieved through the die drawing process has been shown to significantly improve the mechanical properties of both filled and unfilled polymer products. However, inclusion of filler particles tends to result in localised cavitation and subsequent propagation, which reduces stiffness enhancements. By tailoring production parameters such as rate, temperature and geometry it is possible to control both the modulus and density of the final product to given specifications. Within this paper we demonstrate the effects of die angle and temperature on the final sample properties of a civil engineering product and their optimisation to manufacture a low density high stiffness component.
TEACHING MOLD DESIGN: FROM CONCEPT TO CREATION
Traditionally mold design has been taught on a
theoretical basis where student’s designs never leave the
drawing board. Today’s computer aided manufacturing
techniques allow for hands-on design projects. A junior level
mold design engineering class was revised to include an
intensive art-to-part project. Given constraints students
designed new plastic parts manufactured the tooling using
CAM software and CNC machining and injection molded
prototype parts. In addition to mold design students learned
machine tool practices and the difficulties associated with
commissioning new tools. The project required considerable
initial investment but was met with an overwhelmingly
positive response.
TEACHING MOLD DESIGN: FROM CONCEPT TO CREATION
Traditionally mold design has been taught on a theoretical basis where studentƒ??s designs never leave the drawing board. Todayƒ??s computer aided manufacturing techniques allow for hands-on design projects. A junior level mold design engineering class was revised to include an intensive art-to-part project. Given constraints, students designed new plastic parts, manufactured the tooling using CAM software and CNC machining, and injection molded prototype parts. In addition to mold design, students learned machine tool practices and the difficulties associated with commissioning new tools. The project required considerable initial investment, but was met with an overwhelmingly positive response.
ANALYSIS OF IN DIE CAVITATION DURING THE DIE DRAWING OF
COMPOSITE MATERIALS
Combining molecular orientation of polymer chains
with short glass fibre reinforcement has been shown to
significantly improve material stiffness in the direction of
orientation1. Replacement of the stiff glass fibres with
inorganic fillers also has the capability of improving
mechanical performance of oriented composites but at a
reduced production cost. Orientation is achieved via a
batch die drawing process 5 to 20 oC below the melt
temperature of the polypropylene inorganic composite
material. This experimental investigation has now been
extended to consider cavitation around particulates within
the composite material during the die drawing process
using macroscopic and microscopic finite element models
validated via image analysis and density measurements of
actual drawn components. Within this paper we
demonstrate the modelling route to achieve micro-scale
predictions of cavitation based on a macroscopic analysis
of the complete component through a technique known as
submodelling.
ANALYSIS OF IN DIE CAVITATION DURING THE DIE DRAWING OF COMPOSITE MATERIALS
Combining molecular orientation of polymer chains with short glass fibre reinforcement has been shown to significantly improve material stiffness in the direction of orientation. Replacement of the stiff glass fibres with inorganic fillers also has the capability of improving mechanical performance of oriented composites but at a reduced production cost. Orientation is achieved via a batch die drawing process 5 to 20 oC below the melt temperature of the polypropylene inorganic composite material. This experimental investigation has now been extended to consider cavitation around particulates within the composite material during the die drawing process using macroscopic and microscopic finite element models validated via image analysis and density measurements of actual drawn components. Within this paper we demonstrate the modelling route to achieve micro-scale predictions of cavitation based on a macroscopic analysis of the complete component through a technique known as submodelling.
A STUDY OF USING FILLED PLASTIC BOTTLES AS CRASH BARRIERS
This paper presents an experimental investigation on the capability of using commercially available plastic bottles as energy absorbing devices for safety crash barrier applications. The compression tests are conducted in vertical and horizontal orientations with bottles of various sizes and with a variety of filler materials such as air water foam sand and paper pulp and also with mixture of such fillers. Results are compared in terms of varying plastic bottle size bottle orientation and filler types.Results show that commercially available plastic bottles with proper orientation and appropriate filler materials are capable of absorbing significant amounts of crash energy.
DISPERSION OF FUNCTIONALIZED CARBON NANOFIBERS
IN THERMOPLASTIC POLYURETHANES
Carbon nanofibers - as received oxidized and functionalized with polyol - were mixed with thermoplastic polyurethanes (TPU) at the time of in situ synthesis in a chaotic mixer. The TPU was synthesized from polypropylene glycol butanediol and 4 4'-diphenylmethane diiocyanate. The degree of nanofiber dispersion was analyzed using hard segment hydrogen bonding. It was found that functionalized carbon nanofibers showed more interactions with hard and soft segments in TU. Consequently these fibers dispersed well promoted mixing between the hard and soft segment phases and prompted an increase of glass transition temperature.
FOAM INJECTION MOLDING OF CELLULOSE FIBER REINFORCED
POLYPROPYLENE COMPOSITES
This paper investigates the effects of the fiber content
and the processing conditions such as the shot size and
the injection speed on the foaming behavior of injection
molded composite foams made from cellulose fiber
reinforced polypropylene. Composites are injection
molded by using an advanced structural foam molding
machine with a physical blowing agent N2. Foamed
specimens are prepared with different injection speeds and
void fractions while the mold pressure profile void
fraction and foam morphology are characterized. The
results suggest that there is an optimum fiber content for
the cell morphology of injection molded composite foams
made of cellulose fiber reinforced polypropylene.
FOAM INJECTION MOLDING OF CELLULOSE FIBER REINFORCED POLYPROPYLENE COMPOSITES
This paper investigates the effects of the fiber content and the processing conditions, such as the shot size and the injection speed, on the foaming behavior of injection molded composite foams made from cellulose fiber reinforced polypropylene. Composites are injection molded by using an advanced structural foam molding machine with a physical blowing agent, N2. Foamed specimens are prepared with different injection speeds and void fractions while the mold pressure profile, void fraction and foam morphology are characterized. The results suggest that there is an optimum fiber content for the cell morphology of injection molded composite foams made of cellulose fiber reinforced polypropylene.
EXPERIMENTAL STUDY OF EXTRUSION AND SURFACE TREATMENT OF ORGANO CLAY WITH PET NANOCOMPOSITES
The use of organoclay in polymers is expected to increase on average annually by about 5 percent. This paper describes melt blending techniques using PET nanocomposites containing commercially available organoclays with different percentage of surfactant coatings. This paper will also evaluate the morphology and mechanical properties of the composites using a range of techniques like scanning electron microscope melt rheology andthermal analysis. Comparisons will be made between properties of amorphous and semi crystalline films in terms of surfactant used and material properties. It will be demonstrated that the quantity of surfactant used with the organoclays can significantly affect dispersion and properties of composites produced.
THE EFFECT OF RESIDUAL STRESSES ON BIOLINKER PROTEIN G
ADHESION TO PMMA
The ability to manufacture micro-scale features on
polymers with good optical properties has proven to
be useful in biomedical applications such as
microelectromechanical systems (Bio-MEMS). High
rate manufacturing of such Bio-MEMS could be
accomplished through the injection molding process.
A drawback to the injection molding process is the
occurrence of residual stresses as a result of flow
induced orientation. In bio-MEMS applications the
directed adsorption of bio sensing molecules like
antibodies to the surface is critical. A patented
PMMA bacterial Protein G antibody orientation
method previously reported termed ALYGNSA can be
used to achieve such adsorption. The bacterial protein
G linker protein is used in part on two residual
stressed (high and low) injection molded micro-fluidic
patterned PMMA discs. Results indicate low residual
stress may aid the adsorption of Protein G and
enhancement of antibody orientation.
THE EFFECT OF RESIDUAL STRESSES ON BIOLINKER PROTEIN G ADHESION TO PMMA
The ability to manufacture micro-scale features on polymers with good optical properties has proven to be useful in biomedical applications such as microelectromechanical systems (Bio-MEMS). High rate manufacturing of such Bio-MEMS could be accomplished through the injection molding process. A drawback to the injection molding process is the occurrence of residual stresses as a result of flow induced orientation. In Bio-MEMS applications the directed adsorption of bio sensing molecules, like antibodies, to the surface is critical. A patented PMMA, bacterial Protein G antibody orientation method previously reported termed ALYGNSA can be used to achieve such adsorption. The bacterial protein G linker protein is used in part on two residual stressed (high and low) injection molded micro-fluidic patterned PMMA discs. Results indicate low residual stress may aid the adsorption of Protein G and enhancement of antibody orientation.
DEVELOPMENTS ON PROPYLENE-ETHYLENE COPOLYMERS BLENDS WITH
STYRENE BLOCK COPOLYMERS
Thermoplastic Elastomers (TPEs) based on
styrene block copolymers such as SBS and
SEBS still draw technological and scientific
interest because their low cost formulations
combine the entropy-elasticity of elastomers with
the processability of thermoplastics. This class of
material plays an important role in replacing
many traditional thermo-set rubber applications.
Metallocene catalysts provided a broad range of
new olefin based copolymers. Among them the
propylene a-olefin copolymers had a fast growth
in TPE scenario as modifier in polymer blends
because of their properties. In a previous paper
we discussed the use of metallocene based
ethylene-octene copolymers in blends with
SBCs. They provide the right balance of costperformance
when used as an elastomeric
extender.
In this study we demonstrate the effect of
different metallocene based propylene -olefins
copolymers (PAO) in blends with SBCs.
The results achieved for the PAO containing
compounds indicate that such family of materials
can be tailored to yield new TPEs with a
combination of desirable softness and
mechanical properties with improved processing.
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