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Conference Proceedings
A STUDY OF PROCESSING INDUCED PART FAILURES
Of the four pillars required for the successful
development of a plastic part; material selection, part
design, processing, and service environment, processing
is often assumed to be the most controllable. Even when
the service environment has been properly defined, the
best design principles implemented, and the appropriate
material selected, seemingly insignificant changes in
processing can grossly and adversely affect an otherwise
well developed product. This paper will explore case
studies where the failure of the part can be traced directly
back to improper processing and how shortcomings in
processing ultimately predisposed them to premature
failure.
REINFORCEMENT OF POLYPROPYLENE COMPOSITE SYSTEMS: EFFECT OF
FILLERS AND COMPATIBILIZERS
The purpose of this work is to compare the mechanical
properties of the different PP/ Filler composites. We
considered the effect of treatment of the filler on the
adhesion between the filler and the matrix .Modification of
polypropylene (PP) with different coated and uncoated
fillers is investigated in this paper. Six types of different
fillers are used for preparation of filled PP composites. The
composite samples were homogenized in a twin screw
extruder. The compatibility of PP and fillers focused in
this study and modified by using coupling agent.
The obtained values of composites were correlated with
mechanical properties.
REINFORCEMENT OF POLYPROPYLENE COMPOSITE SYSTEMS: EFFECT OF FILLERS AND COMPATIBILIZERS
The purpose of this work is to compare the mechanical properties of the different PP/ Filler composites. We considered the effect of treatment of the filler on the adhesion between the filler and the matrix .Modification of polypropylene (PP) with different coated and uncoated fillers is investigated in this paper. Six types of different fillers are used for preparation of filled PP composites. The composite samples were homogenized in a twin screw extruder. The compatibility of PP and fillers focused in this study and modified by using coupling agent.The obtained values of composites were correlated with mechanical properties.
POLYSTYRENE NANOCOMPOSITE MATERIALS BY IN SITU POLYMERIZATION INTO ZN AL LAYER DOUBLE HYDROXIDE STEARATE HEXADECANE STYRENE MONOMER INTERLAYER
Zn-Al Layered Double Hydroxides (LDHs) containing nitrate as the interlayer anion was prepared by coprecipitation. The resulting suspension was treated with deprotonated stearic acid (octadecanoic acid) to give an organo-modified hydrotalcite compound (Zn-Al LDHStearate).The prepared LDH-stearate was successfully delaminated in hexadecane resulting in a Zn-Al LDH stearate/hexadecane. In situ intercalative polymerization of styrene with the delaminated LDH (with different ratios) resulted in the formation of partially exfoliated polystyrene-based LDH-stearate/hexadecane nanocomposites (polymer/clay nanocomposites). The delaminated LDH nanosheets before and after introduction into the polystyrene matrix were confirmed by elemental analysis Atomic Absorption Spectroscopy (AAS) X-ray Diffraction Spectroscopy (XRD) and Thermogravimetric Analysis (TGA). X-ray diffraction confirmed exfoliation of the LDH through the disappearance of the basal (003) reflection.
NOVEL BIO-BASED THERMOSET RESINS FROM EPOXIDIZED VEGETABLE OILS FOR STRUCTURAL APPLICATIONS
Bio-derived thermosets were cured from inexpensive,
low-toxicity precursors. Epoxidized linseed oil (ELO) and
epoxidized soybean oil (ESO) were crosslinked with a
range of crosslinking agents: branched polyethyleneimine
(PEI) and triethylenetetramine (TETA). Curing conditions
were optimized through solvent uptake and soluble
fraction analysis. Properties may be varied from
elastomeric to rigid. Rigid bioepoxies, while not as stiff as
conventional materials, are expected to display better
toughness and may be promising for coatings and as
binders in engineered wood products.
ROOT CAUSE INVESTIGATION OF CRACKED POLYCARBONATE FOOD BLENDER JARS
Polycarbonates find applications in food
industries due to their clarity and ductility.
Sometimes failure of a polycarbonate part
occurs. In food blender jars molded from
polycarbonate, cracks were observed in the
sealed joint only a few days after assembly. The
root cause was investigated via microscopy,
FTIR and GC-MS analyses. It was determined
the cracks initiated and radially propagated from
the bottom raised lip of the part. The root cause
was a combination of a high stress in the lip
region due to molding and design, and
environmental chemical compounds, i.e., esters
from a melt nut used in the assembly. The
failure was typical environmental stress
cracking (ESC) problem.
LOW SMOKE POLYPHENYLENE ETHER BLENDS
Flame retardance, low smoke generation and low smoke toxicity (often referred to as the FST properties) are among the critical requirements for polymeric materials used in building and construction as well as mass transit interior applications. Polyphenylene ether (PPE) is wellknown for its high char formation and low smoke toxicity when burned. Addition of a proprietary smoke suppressant 'LS-1' to a flame-retarded PPE blend results in low smoke density without significantly affecting smoke toxicity and flame-retardance, possibly owing to the formation of intumescent char. In addition to improved FST performance, various PPE compositions exhibit low specific gravity, wide colorability and good mechanical, thermal and electrical properties.
COMPRESSION INDUCED SOLIDIFICATION (CIS) . A NOVEL INJECTION MOLDING STRATEGY FOR HIGH PRECISION PARTS
During polymer processing the solidification is accompanied by local and temporarily varying temperature and pressure distributions. The simultaneous occurrence of the molten and solid state leads to the development of inhomogeneous shrinkage and dimensional instability.With a novel processing approach (CIS), the solidification is achieved by uniform compression over the entire part volume, which leads to an even shrinkage.In this paper, the fundamentals for this process were investigated. It was found that the specific volume is dependent on the pathway of compression. As main impact factors the pressure, temperature and compression speed were detected. Finally, the compression heating of the melt was measured and a relation to the volume change was found.
THREE DIMENSIONAL SIMULATION OF COEXTRUSION IN A COMPLEX PROFILE DIE
Mesh partitioning technique is used to simulate bilayer
coextrusion in a complex profile extrusion die. Mesh
partitioning technique allows coextrusion simulation
without changing the finite element mesh as the interface
between the adjacent polymer layers is changed during a
coextrusion simulation. Since the finite element mesh in
the die remains fixed during the simulation, the mesh
partitioning technique allows coextrusion simulation even
in highly complicated profile dies. Effect of polymer
viscosity on interface shape, velocity, pressure, shear rate,
and residence time distribution in a profile coextrusion die
is analyzed. It is found that polymer viscosity has
significant effect on the interface shape, velocity,
pressure, and shear rate, but only a minor effect on the
residence time distribution in the die.
MICRO INJECTION MOLDING OF LCP-MODIFIED PA66
Injection molded micro parts require accurate
replication of micro-scale features. This replication is
governed by complex mechanisms and its quality depend
on the plastic material properties the geometry of the
features and the process conditions The objective of this
paper is to improve the replication of the micro-scale
features by decreasing the polymer viscosity. The effects
of melt viscosity and molding conditions on replication of
microscopic features in injection molded parts were
examined for a PA66 blended with a LCP additive. The
replication was measured at different contents of LCP and
at different process conditions.
SELECTIVE LOCALIZATION AND MIGRATION OF MULTIWALLED CARBON NANOTUBES IN BLENDS OF POLYCARBONATE AND STYRENE-ACRYLONITRILE
The localization of multiwalled carbon nanotubes (MWNT) in immiscible polymer blends was discussed based on the aspect ratio of the filler particles and the wetting coefficient. As a model system, MWNT were introduced into compatible blends of polycarbonate (PC) and poly-styrene-acrylonitrile (SAN) by melt mixing in a microcompounder either by pre-compounding small amounts into PC or SAN or by mixing all three components together. In agreement with the presented theoretical considerations, in all blends, regardless of the way of introducing the nanotubes, the MWNT were exclusively located within the polycarbonate phase, inspite of the almost equal surface energies of the two blend phases.
MORPHOLOGY DEVELOPMENT OF POLYPROPYLENE/POLYAMIDE 6 BLEND MOLDED BY WATER-ASSISTED INJECTION MOLDING
Morphology development of polypropylene /polyamide 6 (PP/PA6) blend in water-assisted injection molded (WAIM) curved pipe was investigated. The blend morphology development was interpreted with the aid of stress and temperature fields within the mold cavity under melt filling and high-pressure water penetration during WAIM process. The results showed that the morphology developed at the position near the water inlet is induced mainly by the melt filling, whereas the morphology at the position near the end of water channel is mainly ascribed to the high-pressure water-assisted filling. Then the water pressure and melt temperature were investigated in terms of their effects on the morphology development of dispersed PA6 phase. It was demonstrated that higher water pressure result in more obvious deformation of the dispersed phase at the position near the end of water channel.
DIE DESIGN OPTIMIZATION FOR MONOLAYER AND COEXTRUSION PROCESSES
Multilayer materials offer benefits in terms of new materials for packaging and barrier applications. The ability to maintain layer stability as the material flows into different die designs is important for fabrication of these materials. This work investigated different die designs for use in fabricating multilayer films. Three dimensional analyses of different types of manifold designs have been applied to optimize the die design of a coat hanger die. For the horizontal multilayer systems, an elongated tear drop manifold design with a relatively sharp angle provided the most uniform flow and layer distribution. With the vertical multilayer system, however, a gradual change in the manifold geometry enabled more uniform flow. The vertical layered systems also consistently exhibited curving of the layer interfaces. The horizontal layers were not affected by the presence of a secondary manifold, but in vertical layered systems, the secondary manifold produced non-uniformities in the layers and instabilities in the flow.
A NOVEL 3-D BLOW MOLDING METHOD AND ITS PART
THICKNESS CONTROL STRATEGY
In this study, a novel air traction 3-D blow molding machine was presented. Distinct from conventional blow molding machine, this 3-D blow molding machine utilized compressed air to draw the extruded parison through the closed mold. The results showed that the new 3-D molding machine was low flash waste and high molding quality. To further improve the performance of the 3-D blow molded product, a control strategy based on fuzzy iterative learning control algorithm was designed and implemented to control the wall thickness of blow molded part. The results showed that after five times iterations, the average axial thickness of 3-D bend pipe converged to the object area of thickness.
BIAXIAL CONSTITUTIVE RESPONSE OF PET DURING HOT DRAWING: EXPERIMENTAL STUDY AND NEW IMPLICATIONS FOR CONSTITUTIVE MODELLING
A study was made of hot drawing of an
amorphous isotropic poly(ethylene terephthalate) (PET)
under biaxial stress in the temperature and strain rate
regime prevalent in injection stretch blow molding and
biaxial film drawing. The constitutive response was
mapped out more thoroughly than hitherto as functions
of temperature and strain rate for constant width and
equi-biaxial drawing. The data suggest multiple Eyring
type flow activation volumes at lower drawing
temperatures. Also the flow activation volume appears
to decrease with increasing strain level possibly
attributed to entanglement slippage and intrinsic
anisotropy of the flow process. The former observation
would have a significant implication for current
constitutive modelling approaches based on single shear
and pressure activation volumes. The implications for
refinement of the model are discussed.
BIAXIAL CONSTITUTIVE RESPONSE OF PET DURING HOT DRAWING: EXPERIMENTAL STUDY AND NEW IMPLICATIONS FOR CONSTITUTIVE MODELLING
A study was made of hot drawing of an
amorphous isotropic poly(ethylene terephthalate) (PET)
under biaxial stress, in the temperature and strain rate
regime prevalent in injection stretch blow molding and
biaxial film drawing. The constitutive response was
mapped out more thoroughly than hitherto, as functions
of temperature and strain rate, for constant width and
equi-biaxial drawing. The data suggest multiple Eyring
type flow activation volumes at lower drawing
temperatures. Also the flow activation volume appears
to decrease with increasing strain level, possibly
attributed to entanglement slippage and intrinsic
anisotropy of the flow process. The former observation
would have a significant implication for current
constitutive modelling approaches based on single shear
and pressure activation volumes. The implications for
refinement of the model are discussed.
STRUCTURE-PROPERTY RELATIONSHIPS OF LDPE
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.
FACTORS CONSIDERED IN DARK COLORED WINDOWS AND SIDING - PART II - ACHIEVING SUFFICIENT VINYL STIFFNESS IN THE SUN
Successful dark colored windows and siding require several properties discussed in Part I of a companion paper. Two important factors are low coefficient of linear thermal expansion for low thermal stresses and sufficient glass transition temperature to maintain stiffness at maximum solar heating for several decades of time. This work estimates properties for 25 years with additive formulations containing fillers, polymers, polymer blends, and chlorinated PVC. Two promising materials to provide successful properties are a blend of PVC with poly-?ñ-methylstyrene/acrylonitrile/styrene and chlorinated PVC, both filled with talc.
IMPROVING ADHESION PERFORMANCE BETWEEN LOW SURFACE TENSION COMPOSITE AND DISSIMILAR SUBSTRATES
The growing demand for high performance plastic components for automobile aerospace medical and electronic applications has made the job of formulating paints adhesives and coatings more challenging. Composite plastics having low surface energies but which deliver high-strength low-weight performance are becoming more prevalent. Adhesion to the surfaces of these composites as well as between dissimilar high performance materials is being solved by atmospheric pretreatment technologies. This paper links specific atmospheric surface pretreatment improvements in adhesion to an array of composite and dissimilar materials.
EVALUATION OF GATE GEOMETRY AND PROCESSING VARIABLES EFFECTS
ON GATE FREEZING TIME BY CFD METHOD
The aim of the present work was to study the effects
of gate geometry and processing parameter on the gate
freezing time and quality of the injection molding by
using CFD method. The simulation was performed on two
different gate geometries Pin and Fan gate for polyacetal.
The gate freezing time was predicted on the basis of
solidified fraction as a function of time. In the
experimental works the gate freezing time was taken as
the time which the weight of moldings remained
unchanged. From the predicted results it was found that
at equal gate cross-section the freezing time of fan gate
was shorter than that of the Pin gate. A good agreement
was found between the predicted and experimental
results.
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