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
EXPERIMENTAL VERIFICATIONS OF CAE PREDICTIONSONBIREFRINGENCE OF INJECTION MOLDED LENSES
Injection-molded lenses have been widely employed for portable consumer products nowadays. A 3D CAE flow analysis program coupled with Generalized Newtonian Fluid (GNF) models based upon polymer melts and measurements of residual birefringence have been conducted for investigation on effects of prominent processing conditions. Furthermore experimental verifications of the predictions on residual stresses are investigated with two example cases of plastic lenses molded by cyclic-olefin-copolymers. Final results have shown that frozen-in shear stresses in terms of residual birefringence levels are mainly contributed by melt temperature and injection speed during the filling stage.The predictions agree well to the experimental measurements.
SIMULATION OF MULTIFILAMENT FIBER SPINNING
We present a nonisothermal multifilament spinning model applied to a variety of polymer and process conditions.The model combines the flow-enhanced crystallization fiber spinning model of McHugh et al. with a generalization of Dutta's multifilament model. The model predicts fiber and quench air properties throughout the fiber bundle. The McHugh FEC model for a single fiber which includes effects of viscoelastic flow and crystallization has been experimentally validated. We compare the multifilament simulation results to experimental measurements. A secondary goal of the current effort is to develop a model which can be executed on a desktop in 2 to 3 hours or lesscontinuing work.
THE EFFECT OF SCREW DESIGN ON THE QUALITY
OF INJECTION MOLDING PRODUCTS
The melt quality and its effect on the final
product quality is one of the least studied
subjects in the process of injection molding.
Consequently the present study is aimed at
investigating the plastification stage in injection
molding. A general-purpose screw and a barrier
type screw were studied with respect to the effect
of melt temperature back pressure and screw
rotation speed on product quality. Results
indicated that the melt temperature and the back
pressure are the decisive factor in the case of the
general-purpose screw and the barrier screw
respectively. Due to the longer residence times in
barrier type screws lower temperatures should
be used to avoid melt degradation and inferior
mechanical properties.
THE EFFECT OF SCREW DESIGN ON THE QUALITY OF INJECTION MOLDING PRODUCTS
The melt quality and its effect on the final product quality is one of the least studied subjects in the process of injection molding. Consequently, the present study is aimed at investigating the plastification stage in injection molding. A general-purpose screw and a barrier type screw were studied with respect to the effect of melt temperature, back pressure and screw rotation speed on product quality. Results indicated that the melt temperature and the back pressure are the decisive factor in the case of the general-purpose screw and the barrier screw, respectively. Due to the longer residence times in barrier type screws, lower temperatures should be used to avoid melt degradation and inferior mechanical properties.
AN EVALUATION OF DIFFERENT INJECTION MOLDING SCREW DESIGNS AND
THEIR EFFECT ON MIXING QUALITY USING AN INLINE MELT CAMERA (I.M.C)
Improved color mixing for injection molding can be
improved by different variables. Screw speed melt
temperature back pressure barrel temperature profiles
screw design dispersion discs etc. can all influence color
dispersion. The mixing ability of an injection molding
screw is an important element in the finished part quality
of a part which is why screw design is the focus of this
study. An I.M.C will allow examination of the molten
melt stream prior to exiting the die to give a quantitative
comparison of different injection molding screw designs.
AN EVALUATION OF DIFFERENT INJECTION MOLDING SCREW DESIGNS AND THEIR EFFECT ON MIXING QUALITY USING AN INLINE MELT CAMERA (I.M.C)
Improved color mixing for injection molding can be improved by different variables. Screw speed, melt temperature, back pressure, barrel temperature profiles, screw design, dispersion discs, etc. can all influence color dispersion. The mixing ability of an injection molding screw is an important element in the finished part quality of a part, which is why screw design is the focus of this study. An I.M.C will allow examination of the molten melt stream prior to exiting the die to give a quantitative comparison of different injection molding screw designs.
PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS
A new method concerning with the simultaneous
reinforcing and toughening of polypropylene (PP)
was reported. Dynamical cure of the epoxy resin
was successfully applied in the PP/maleic
anhydride-grafted styrene-ethylene
butylenes-styrene (MAH-g-SEBS) triblock
copolymer and the obtained blends named as
dynamically cured PP/MAH-g-SEBS/epoxy blends.
The stiffness and toughness of the blends are in a
good balance and MAH-g-SEBS was acted as not
only an impact modifier but also a compatibilizer.
The structure of the dynamically cured
PP/MAH-g-SEBS/epoxy blends is the embedding
of the epoxy particles by the MAH-g-SEBS.
PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS
A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene-ethylene butylenes-styrene (MAH-g-SEBS) triblock copolymer, and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends.The stiffness and toughness of the blends are in a good balance, and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer.The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-g-SEBS.
VVARIABLE MOLD TEMPERATURE FOR IMPROVING SURFACE QUALITY OF MICROCELLULAR INJECTION MOLDED PARTS USING INDUCTION HEATING TECHNOLOGY
In this study a variable mold temperature method via induction heating combined with water cooling was used to improve surface quality of microcellular parts. It was found that the surface roughness can decreases from 25?¬m to 6.5?¬m when mold surface temperature increases from 100?øC to 160?øC. The flow marks of gas bubbles on the part surface can be removed completely at mold temperature of 160?øC. When the mold temperature over a critical value about 180?øC the surface roughness can reach a saturated value about 5?¬m. Compared to conventional water heating with initial In 60?øC mold temperature surface roughness can be greatly improved by about 80% without a significant increase in cycle time.
EVALUATION OF MOLECULAR ORIENTATION IN POLYSTYRENE BY LASER RAMAN SPECTROSCOPY
Molecular orientation in injection molded polystyrene was investigated by polarized laser-Raman spectroscopy. The relative intensity ratio of two specific peaks in a spectrum was determined as Orientation Index Ior in accordance with an earlier report. Two kinds of orientation peak along the depthwise direction were found in a section of the molded specimen. This result is qualitatively consistent with the orientation model presented by Tadmor. Polarized laser-Raman spectroscopy was applied to a weldline region in which molecular orientation is supposed to be one of main factors to reduce its mechanical properties. The degree of molecular orientation increased along the flow direction in the case of adjacent flow weldline occurring behind an obstructive pin in the flow channel. This means that the orientation along the weldline in the area near the pin is relatively low. The tensile strength of the area nearest to the pin was higher than that of the downstream area despite the fact that the surface V-notch was deepest. This fact insists that the molecular orientation affects significantly to the mechanical properties of weldline in injection moldings.
EFFECTS OF SOLVENT-CASTING CONDITIONS ON THE MORPHOLOGY AND PROPERTIES OF DISULFONATED POLY (ARYLENE ETHER SULFONE) COPOLYMER FILMS FOR POLYMER ELECTROLYTE MEMBRANES
Disulfonated poly(arylene ether sulfone) (BPSH) copolymers have been shown to be potentially useful in the generation of polymer electrolyte membranes (PEMs) in fuel cells. In our work we find that solvent-casting conditions such as solvent type drying temperature and initial polymer concentration significantly affects the morphology and properties of PEMs produced by means of film casting. The design of the solvent removal process requires a knowledge of the kinetics of phase separation which occurs during the drying process. Block copolymers are found to be much more sensitive to drying conditions than the random copolymers.
THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM
The purpose of this research is to investigate the
effect of vibration on cell morphology of PC foam. In this
study foamed PC was produced using a dynamic
simulation foaming setup designed by ourselves with
supercritical CO2 as foaming agent. Cell morphology was
compared as vibration frequency varied from 2.5Hz to
10Hz and vibration amplitude varied from 25? m to 100
? m respectively under the same condition. The cell
morphology of foamed samples was characterized by
using SEM. It was found that foamed samples with better
cell morphology could be obtained as vibration frequency
increased?foamed samples with better cell morphology
could be obtained as vibration amplitude increased to 75
? m then cell morphology became worse with further
increase of vibration amplitude.
THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM
The purpose of this research is to investigate the effect of vibration on cell morphology of PC foam. In this study, foamed PC was produced using a dynamic simulation foaming setup designed by ourselves, with supercritical CO2 as foaming agent. Cell morphology was compared as vibration frequency varied from 2.5Hz to 10Hz and vibration amplitude varied from 25?¬ m to 100 ?¬ m respectively under the same condition. The cell morphology of foamed samples was characterized by using SEM. It was found that foamed samples with better cell morphology could be obtained as vibration frequency increased‹¬?foamed samples with better cell morphology could be obtained as vibration amplitude increased to 75 ?¬ m, then cell morphology became worse with further increase of vibration amplitude.
CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS
Blend films of acrylic acid grafted polycaprolactone
(PCLgAA) and chitosan (CS) with different
compositions were prepared from aqueous acetic acid
solution. DSC measurements showed that the melting
temperatures and enthalpies of the blends decreased
with increasing CS content. From FTIR results it can
be seen that the amino groups of CS form covalent
bonds with the carboxylic groups of PCLgAA in
addition to hydrogen bonds between these components
in the blends. Though the crystal structure of the
PCLgAA component was not changed as proved by
WAXD results blending CS suppressed the
crystallinity of the blends. Furthermore the ductility
of CS was increased during tensile testing in
PCLgAA/CS blends due to enhanced affinity between
the two components. However PCLgAA/CS blends
showed greater resistance than PCL/CS blends to
biodegradation in an enzymatic environment.
CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS
Blend films of acrylic acid grafted polycaprolactone (PCLgAA) and chitosan (CS) with different compositions were prepared from aqueous acetic acid solution. DSC measurements showed that the melting temperatures and enthalpies of the blends decreased with increasing CS content. From FTIR results it can be seen that the amino groups of CS form covalent bonds with the carboxylic groups of PCLgAA in addition to hydrogen bonds between these components in the blends. Though the crystal structure of the PCLgAA component was not changed, as proved by WAXD results, blending CS suppressed the crystallinity of the blends. Furthermore, the ductility of CS was increased during tensile testing in PCLgAA/CS blends due to enhanced affinity between the two components. However, PCLgAA/CS blends showed greater resistance than PCL/CS blends to biodegradation in an enzymatic environment.
STUDY ON THE RIB-DESIGNED PART SURFACE QUALITY MOLDED BY EXTERNAL GAS-ASSISTED INJECTION
This study investigates the surface quality of parts molded by external gas assisted injection. A flat ABS part was constructed 100 mm long 50 mm wide and 1.5 mm thick (designated T) with four different thicknesses of rib: 0.6T 0.8T 1T and 1.2T. Under external gas assisted molding process the sink mark for 1.2T rib design can be reduced from 26.88?¬m under conventional injection molding to 3.47?¬m. Combined with process condition optimization of parameters such as mold temperature gas pressure and packing time the sink mark can be further reduced (below 1?¬m). Increased cavity surface smoothness created by various polishing techniques also improves sink marks.
RHEOLOGICAL PROPETIES OF BRANCHED POLYSTYRENE PREPARED BY AN ULTRASOUND ASSISTED INTENSIVE MIXER
By combining ultrasonic energy which can cause chain scission of polymer molecules and a multifunctional agent (MFA) having double bonds at its ends we were able to modify the molecular structure of polystyrene (PS) from linear to a branched structure during melt processing. The three double bonds in chain ends of MFA were expected to act as sites for trapping macroradicals of PS during the course of ultrasound- assisted mixing process. The transformation of molecular structure of PS was confirmed by the measurements of rheological properties of the modified PS. After the ultrasonic irradiation of PS together with MFA increase in complex viscosities and shear-thinning behavior were observed. The Cole-Cole plot revealed the characteristic features of branched structure.
INSTRUMENTAL INVESTIGATIONS OF PHYSICAL GUMMIINESS OF
A MEDICAL GRADE EPOXY-AMINE ADHESIVE AFTER CURING
Various factors that might interfere with reaction
stoichiometry and result in physical gumminess of the
cured mass were investigated for a medical grade
epoxy-amine adhesive system. Dynamic rheometry
was used to probe the evolution of dynamic mechanical
properties in the adhesive during isothermal curing
and a Fourier-transform infrared spectrometer (FT-IR)
was utilized to measure the degree of chemical
conversion after curing. It has been found that physical
gumminess of the adhesive cured under a selected
normal curing condition was primarily due to the
presences of excessive hardener and also liquid
residuals of an industrial cleaner containing hydroxyl
and amine functional groups while the presence of
excessive epoxy resin at a moderate level arising from
non-stoichiometric mixing is unlikely to cause physical
gumminess of the cured adhesive mass. Accordingly
it is considered that the selection of a proper cleaner
and improvement of stoichiometric adhesive mixing
prior to adhesive dispensing is of vital importance to
developing reliable and strong adhesive bondlines.
INSTRUMENTAL INVESTIGATIONS OF PHYSICAL GUMMIINESS OF A MEDICAL GRADE EPOXY-AMINE ADHESIVE AFTER CURING
Various factors that might interfere with reaction stoichiometry and result in physical gumminess of the cured mass were investigated for a medical grade epoxy-amine adhesive system. Dynamic rheometry was used to probe the evolution of dynamic mechanical properties in the adhesive during isothermal curing, and a Fourier-transform infrared spectrometer (FT-IR) was utilized to measure the degree of chemical conversion after curing. It has been found that physical gumminess of the adhesive cured under a selected, normal curing condition was primarily due to the presences of excessive hardener and also liquid residuals of an industrial cleaner containing hydroxyl and amine functional groups, while the presence of excessive epoxy resin at a moderate level arising from non-stoichiometric mixing is unlikely to cause physical gumminess of the cured adhesive mass. Accordingly, it is considered that the selection of a proper cleaner and improvement of stoichiometric adhesive mixing prior to adhesive dispensing is of vital importance to developing reliable and strong adhesive bondlines.
BREAKTHROUGH MATERIAL FOR LOW GLOSS AND ABRASION RESISTANCE WITH MOLDED-IN-COLOR AUTOMOTIVE INTERIOR COMPONENTS
The luxury impression of a vehicle’s interior is
strongly determined by the surface quality of the plastic
interior trim parts. In higher level vehicles this is achieved
by covering the plastic surfaces with Polyvinyl Chloride
(PVC) or Thermoplastic Olefin (TPO) skins fabrics or
paint. However in the majority of cases cost constraints
dictate the use of unpainted molded-in-color plastic parts.
The critical factors that determine the quality of unpainted
interior part surfaces are low gloss appearance along with
good scratch and abrasion resistance. The typical
materials currently in use for molded-in-color parts are
Polypropylene talc-filled Polypropylene (TF-PP) talcfilled
Thermoplastic Olefin (TF-TPO) Acrylonitrile
Butadiene Styrene (ABS) Polyamide/ABS (PA/ABS)
and Polycarbonate/ABS (PC/ABS). Through extensive
development efforts over the past several years the
performance of these materials has significantly improved
with respect to scratch resistance and low gloss aesthetic
appearance. However a significant gap in surface quality
and robustness in comparison to the painted solution is
still present. A development project aiming to reduce
these specific deficiencies resulted in new innovative
material formulations which provide breakthrough
improvements in low gloss appearance with excellent
scratch and mar resistance. The resulting new material
family makes use of the latest advancements in elastomer
technologies from Dow Automotive. Velvex™ an
Advanced Reinforced Elastomer will enable the
automotive OEM to realize significant cost savings
through the elimination of paint in higher segment vehicle
interiors or with aesthetically more demanding
applications.
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