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
IMPROVING THE FEEDING ZONE OF SINGLE SCREW EXTRUDERS AT HIGH ROTATION SPEED BY USING THE DISCRETE ELEMENT METHOD
Increasing screw speed is a possible approach to improve the performance of a single screw extruder but it challenges the processing technology and the material processed. Apart from difficult melting, the feeding of the screw with granules is complicated. This results in partially filled screw channels. In the following, the resin transfer depending on the screw speed is investigated and analyzed by means of the simulation program EDEM, which is based on the Discrete Element Method.
THE APPLICATIONS OF MULTIVARIATE STATISTICAL METHODS IN INJECTION MOLDING PROCESS MONITORING
In recent years, a series of multivariate statistical methods have been developed for batch process modeling and online monitoring, which take important batch process characteristics into consideration, such as, multiphase, batch dynamics and so on. As a typical batch process, injection molding is a suitable object to employ these methods. In this paper, the potential applications of these methods in industry are shown by monitoring and fault diagnosis results of the injection molding process.
PROPERTIES AND THERMOFORMING OF EASTMAN TRITAN™ COPOLYESTER FOR SIGNS
Tritan™ copolyester is a new high temperature
polymer developed by Eastman Chemical Company.
Tritan™ has many property attributes suitable for outdoor
sign applications including excellent color and clarity a
high heat distortion temperature and excellent toughness.
In addition TritanTM exhibits advantageous
thermoforming performance at low temperatures so that
(1) sheet can be formed without blistering due to absorbed
moisture eliminating the need to pre-dry the sheet and (2)
sheet pre-decorated with vinyl film can be thermoformed
without damaging the vinyl.
PROPERTIES AND THERMOFORMING OF EASTMAN TRITAN™ COPOLYESTER FOR SIGNS
Tritan' copolyester is a new high temperature polymer developed by Eastman Chemical Company. Tritan' has many property attributes suitable for outdoor sign applications including excellent color and clarity, a high heat distortion temperature, and excellent toughness. In addition, TritanTM exhibits advantageous thermoforming performance at low temperatures so that (1) sheet can be formed without blistering due to absorbed moisture eliminating the need to pre-dry the sheet and (2) sheet pre-decorated with vinyl film can be thermoformed without damaging the vinyl.
MELT COMPOUNDING OF POLY(ETHYLENE TEREPHTHALATE)/CLAY NANOCOMPOSITES: COMPARISON OF DIFFERENT ORGANOCLAYS
PET-clay nanocomposites were prepared by melt compounding using several organoclays. A new approach was used to overcome some of the problems associated with the thermal degradation of ammonium surfactants during melt processing at high temperature. The dispersion and performance characteristics of the new nanocomposite systems are compared to those obtained for systems employing ammonium or phosphonium surfactants.
ANALYSIS OF THERMOPLASTIC PROPERTIES AFTER CRYOGENIC TREATMENT AND NORMALIZATION
This study investigates tensile and impact property changes of polymers after cryogenic treatment and normalization to room temperature. Amorphous and crystalline specimens are subjected to multiple durations and cooling rates then reviewed for statistically significant shifts in properties. Statistical analysis of standard materials testing results show that the modulus of semi-crystalline materials tended to decrease after treatment and the ductility of HDPE and HIPS increased.
ANALYSIS OF THERMOPLASTIC PROPERTIES AFTER CRYOGENIC
TREATMENT AND NORMALIZATION
This study investigates tensile and impact property
changes of polymers after cryogenic treatment and
normalization to room temperature. Amorphous and
crystalline specimens are subjected to multiple durations
and cooling rates, then reviewed for statistically
significant shifts in properties. Statistical analysis of
standard materials testing results show that the modulus
of semi-crystalline materials tended to decrease after
treatment and the ductility of HDPE and HIPS increased.
FAILURE OF HUMAN BIOPOLYMERS
This paper looks at similarities and differences in chemical composition and in failure of synthetic polymers and human biopolymers. The 2 types share susceptibility to damage from free radicals, oxygen, UV and xray radiation, heat and stress. Biopolymers undergo changes in composition and structure by reaction with free radicals and by reaction of sugars with proteins, adversely affecting normal functioning.
INNER MELT PEAK PACK TEMPERATURE END PRESSURE SENSOR
A thermocouple profiling temperature and inner melt pressure flow from fill to peak pack is presented. The mold close processing cycle varies the melt cavity fill to peak pack volume. Mold
close starts the gas venting indicates injection start.
The heated melt front flow temperature and low
pressure encloses the sensor as melt flow
progresses to pack point. The static outer melt skin
and final inner melt pack pressure occurs at gate
seal. After inner melt packing stops the volume
shrink cure starts. The shrink rate is dependant on
final peak pack volume and melt temperature peak.
EFFECT OF FOUR STRESS CONCENTRATORS OVER THE MECHANICAL PROPERTIES OF INJECTED PLASTIC PARTS
The principal objective of this work was to study the influence of different stress concentrators (triangle rectangle medium circle and circle) over the mechanical properties of injected plastic parts. Simulations of the injection molding and the tensile test of plaques made of High Impact Polystyrene (HIPS) were made using CAD/CAE tools. The curves of stress concentrator (Kt) factor in relationship with the stress concentrator type and the geometric parameter d/D were made. The Kt factor is dependent of the geometric parameters and the stress concentrator used.
PREDICTION OF GAP BRIDGING IN LASER TRANSMISSION WELDING OF AMORPHOUS POLYMERS
Gaps between joining partners can lead to defects in laser transmission welding of polymers. This paper presents a theoretical analysis of gap bridging during the laser transmission welding of polycarbonate. The model predicts the maximum allowable gap and maximum temperature as a function of carbon black level laser power and laser scan speed. The predictions agree with the experimental data. The model can help optimize material and process parameters for gap bridging in high speed contour welding of polymers.
DEMOLDING FORCES AND COEFFICIENTS OF FRICTION IN INJECTION MOLDING. A NEW PRACTICAL MEASUREMENT APPARATUS
The new measurement apparatus is a friction tester in an injection mold. It enables the comparative analysis of the influence parameters mold material and surface, polymer, and processing conditions, by determining the static coefficient of friction ?¬0. A plate-shaped, horizontaloriented molded part is first injected. A defined vertical force is applied then and the horizontal (demolding) force, required to open the mold, is measured, where ?¬0 corresponds to the adhesion-dependant force peak at the beginning.
CHARACTERIZE POLYURATHANE ACRYLATE BY HYPERDSC
Polyurethane acrylate can be cured by UV. There are two glass transiton temperatures due to the phase separated structure. After crosslinking, the glass transition temperature will be changed depending on the curing degree. Traditionally DSC is used to study the glass transition temperature. However in this case, the Tg is very weak so that conventional DSC can not detect the Tg easily. Now with the advance of fast scan DSC technology, the Tg of polyurethane acrylate can be readily detected at 200 ??C/min. Thus fast scan DSC can be used as a quality control tool for curing.
THERMAL AGEING OF CROSSLINKED ETHYLENE-VINYL SILANE
COPOLYMERS
This paper investigates the behavior and property
evolution of silane crosslinked polyethylene upon
thermal ageing. The work is focused mainly on
morphological mechanical property and chemical
changes in crosslinked and subsequently aged material.
The changes in polymer were followed by differential
scanning calorimetry infrared spectroscopy and standard
tensile testing.
THERMAL AGEING OF CROSSLINKED ETHYLENE-VINYL SILANE COPOLYMERS
This paper investigates the behavior and property evolution of silane crosslinked polyethylene upon thermal ageing. The work is focused mainly on morphological, mechanical property and chemical changes in crosslinked and subsequently aged material.The changes in polymer were followed by differential scanning calorimetry, infrared spectroscopy and standard tensile testing.
THE EFFECT OF LDPE CONTENT ON HIGH DENSITY POLYETHYLENE (HDPE) FILMS FOR STRETCHED FILM TAPES
A range of blown films were prepared by extruding blends of a commercial HDPE with two separate LDPEs with different densities. Narrow tapes of the films were then stretched at draw ratios of between 1:6 and 1:8 at elevated temperatures. The mechanical morphological and tensile recovery characteristics before and after drawing were investigated in order to determine optimum blend composition and drawing conditions for a range of polyolefin stretched tape applications.
NANOMECHANICAL MEASUREMENTS IN ULTRATHIN POLYMER FILMS: RECTANGULAR BUBBLE" INFLATION MEASUREMENTS"
Confinement effects on the mechanical properties of ultrathin polymer films (<100 nm) were investigated by a novel bubble inflation technique developed in our lab.Circular bubbles of different diameter were used in prior studies of ultrathin films of poly(vinyl acetate) (PVAc) and polystyrene (PS). Here we show early results from using a rectangular bubble geometry for measurements performed with ultrathin PVAc films. Results are compared with those for the circular bubbles.
IMPROVEMENT OF INTRINSIC VISCOSITY OF RECYCLED PET BY RADIO FREQUENCY HEATING
The improvement of Intrinsic Viscosity of recycled poly(ethylene terephthalate)(R-PET) pellets by an industrial radio frequency(RF) heating is described. RPET pellets are made from post-consumer PET bottles, degraded by hydrolysis during distribution process. Hence, intrinsic viscosity(IV) or molecular weight of RPET exhibits significant lower compared to virgin PET, caused from cleavages of chains. This study indicates thermal recycling method of solid phase polymerization to improve the IV values, namely molecular weight of RPET pellets.
VISCOELASTIC PROPERTIES AND ROTATIONAL MOLDABILITIES OF POLYOLEFINIC MATERIALS
We set up a uniaxial roto-molding system with a glass vessel to be able to directly observe the rolling motion of sample particles during roto-molding process in which adherence behavior of EMMA and LLDPE powders is investigated in-situ during molding. The adherence of powders on the glass vessel started above the relaxation temperature of crystalline phases. It was found that materials with a various types of morphology can be prepared by controlling temperature profile of roto-molding process.
COMPLEX VISCOSITY OF LIQUID N-HEXADECANE UNDER OSCILLATORY SHEAR USING NON-EQUILIBRIUM MOLECULAR DYNAMICS SIMULATIONS
Rheological computer experiments, involving small amplitude oscillatory shear flows for liquid n-hexadecane, are performed using non-equilibrium molecular dynamics methodology. In particular, the so-called Cox-Merz rule, which suggests that the magnitude of the complex viscosity with respect to frequency is equal to that of the steady shear viscosity with respect to shear rate, is validated. At different frequencies, the complex viscosity, including both dynamic and out-of-phase parts, varies significantly with respect to temperature.
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