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
MEASURING DISTINCTNESS OF IMAGE OF HIGH GLOSS SURFACES
Human eye-apparatus notices varying distinctness of
image (DOI) of glossy surfaces very accurately. Therefore
high resolving measuring techniques are required. This
paper aims on presenting the Intensity Profile Analysis
(IPA) a novel methodology for the measurement of
distinctness of surface reflected images. IPA enables
measuring fine detail reproduction of glossy surfaces with
good correlation to standard DOI measurements while
featuring considerably enhanced preciseness. IPA is a
non-contact technique and therefore applicable for
uncured or hot surfaces.
AN ASSESSMENT ON OPTICAL QUALITY OF MOLDED BACKLITE COMPARED
TO THERMOFORMED BACKLITE
Injection molding and thermoforming are common
processes in both plastics and automotive industry. A
preliminary study was made comparing the quality of
large complex transparent and optical rear window parts
(automotive backlite prototypes) produced from an
injection-compression molding process and a vacuuming
thermoforming process. Optical quality on the parts was
evaluated in terms of optical clarity (only the haze is
discussed in this paper) optical distortion birefringence
and stress shape and dimension. It was demonstrated that
overall the molded backlites had much better optical
quality than the vacuum thermoformed backlites based on
the same shape and dimensions. Process recommendation
quality control and improvement for large complex optical
application of plastic products such as automotive
polycarbonate (PC) glazing are given during the
discussion.
AN ASSESSMENT ON OPTICAL QUALITY OF MOLDED BACKLITE COMPARED
Injection molding and thermoforming are commonprocesses in both plastics and automotive industry. Apreliminary study was made comparing the quality oflarge, complex, transparent, and optical rear window parts(automotive backlite prototypes) produced from aninjection-compression molding process and a vacuumingthermoforming process. Optical quality on the parts wasevaluated in terms of optical clarity (only the haze isdiscussed in this paper), optical distortion, birefringenceand stress, shape and dimension. It was demonstrated thatoverall the molded backlites had much better opticalquality than the vacuum thermoformed backlites based onthe same shape and dimensions. Process recommendation,quality control and improvement for large complex opticalapplication of plastic products, such as automotivepolycarbonate (PC) glazing, are given during thediscussion.
MELT FRACTURE OF LINEAR POLYETHYLENES: MOLECULAR STRUCTURE
AND DIE GEOMETRY EFFECTS
The melt fracture polymer extrusion instabilities are
studied primarily as functions of the geometrical details
of die (cylindrical slit and annular) and molecular
structure of polymers. Experimental observations
concerning the flow curves the critical wall
shear/extensional stresses for the onset of the instabilities
and the effects of geometry and operating conditions are
presented for two linear polyethylenes mainly highdensity
polyethylenes (HDPEs). It is found that
sharkskin and other melt fracture phenomena are
sensitive to details of the molecular weight distribution
(MWD). It is also found that critical conditions for the
onset of various melt fracture phenomena depend
significantly on the type of die used for their study. For
example sharkskin melt fracture in slit and capillary
extrusion was obtained at much smaller critical shear
stress values compared to those found in annular
extrusion. Such observations explain the lack of
correlation between experimental results from the
laboratory and the full scale process.
MELT FRACTURE OF LINEAR POLYETHYLENES: MOLECULAR STRUCTURE
AND DIE GEOMETRY EFFECTS
The melt fracture polymer extrusion instabilities are studied primarily as functions of the geometrical details of die (cylindrical, slit and annular) and molecular structure of polymers. Experimental observations concerning the flow curves, the critical wall shear/extensional stresses for the onset of the instabilities and the effects of geometry, and operating conditions are presented for two linear polyethylenes, mainly highdensity polyethylenes (HDPEs). It is found that sharkskin and other melt fracture phenomena are sensitive to details of the molecular weight distribution (MWD). It is also found that critical conditions for the onset of various melt fracture phenomena depend significantly on the type of die used for their study. For example, sharkskin melt fracture in slit and capillary extrusion was obtained at much smaller critical shear stress values compared to those found in annular extrusion. Such observations explain the lack of correlation between experimental results from the laboratory and the full scale process.
EXTRUSION-ASSISTED DIRECT-FOAMING ROTATIONAL MOLDING PROCESS
This paper focuses on the evolution and experimental
validation of the novel patent-pending Extrusion-Assisted
Rotational Foam Molding (EARFM) process intended for
the fabrication of high quality integral-skin fine-celled
foamed-core polyolefin moldings. The process
innovatively conjoins the traditional rotational foam
molding technology with extrusion melt compounding in
a deliberate attempt to reduce the principal intrinsic
disadvantages associated with rotational foam molding
i.e. the energy intensive and very lengthy processing
cycles. A lab-scale custom-made heavy-duty
experimental setup along with three mold shape variations
(cylindrical flat plate and container-like) have been
designed and built. It was used for conducting a
comparative experimental process validation by using all
three mold designs for processing integral-skin foamed
core polyethylene (PE) parts. The process control
optimization included resin formulation optimization
direct foaming concept implementation for process
simplification and mold venting system re-design. The
thereby modified process resulted in even shorter
processing cycle times lower energy consumption and
improved foam morphologies.
EXTRUSION-ASSISTED DIRECT-FOAMING ROTATIONAL MOLDING PROCESS
This paper focuses on the evolution and experimental validation of the novel patent-pending Extrusion-Assisted Rotational Foam Molding (EARFM) process intended for the fabrication of high quality integral-skin fine-celled foamed-core polyolefin moldings. The process innovatively conjoins the traditional rotational foam molding technology with extrusion melt compounding in a deliberate attempt to reduce the principal intrinsic disadvantages associated with rotational foam molding, i.e., the energy intensive and very lengthy processing cycles. A lab-scale custom-made heavy-duty experimental setup along with three mold shape variations (cylindrical, flat plate and container-like) have been designed and built. It was used for conducting a comparative experimental process validation by using all three mold designs for processing integral-skin foamed core polyethylene (PE) parts. The process control optimization included resin formulation optimization, direct foaming concept implementation for process simplification, and mold venting system re-design. The thereby modified process resulted in even shorter processing cycle times, lower energy consumption, and improved foam morphologies.
MORPHOLOGICAL AND MECHANICAL CHARACTERISTICS OF RIGID
POLYURETHANE FOAMS
Cellular materials are formed by solid cells in a
gaseous core. They exhibit good strength to mass ratio and
they are used as insulators and as a core in sandwich
composite manufacture. This work describes an extensive
study on the structure and physical-mechanical properties
of rigid polyurethane (PU) foams. The effect of
composition and processing conditions on the mechanical
properties were studied. Morphology specific strength
and density were evaluated to determine the optimal levels
of processing for a required application. Foam
morphology was characterized using stereoscopy and
optical microscopy. A basic mechanical property as
compression strength was measured in the plateau zone.
MORPHOLOGICAL AND MECHANICAL CHARACTERISTICS OF RIGID POLYURETHANE FOAMS
Cellular materials are formed by solid cells in a gaseous core. They exhibit good strength to mass ratio and they are used as insulators and as a core in sandwich composite manufacture. This work describes an extensive study on the structure and physical-mechanical properties of rigid polyurethane (PU) foams. The effect of composition and processing conditions on the mechanical properties were studied. Morphology, specific strength and density were evaluated to determine the optimal levels of processing for a required application. Foam morphology was characterized using stereoscopy and optical microscopy. A basic mechanical property as compression strength was measured in the plateau zone.
NOVEL NANOBIOCOMPOSITES WITH ANTIMICROBIAL AND BARRIER PROPERTIES OF INTEREST IN ACTIVE PACKAGING APPLICATIONS
It is well-known that the nanocomposites technology can significantly enhance among others the thermal mechanical and barrier properties of plastics. It is also known that most bioplastics including the thermoplastic biopolymers have lower than desired levels for certain properties which makes their use in certain packaging applications problematic. The combination of active technologies such as antimicrobials and nanotechnologies such as nanocomposites can synergistically lead to bioplastic formulations with balanced properties and functionalities for their implementation in packaging applications. The present work presents the development and characterization of novel nanocomposites of polycaprolactone (PCL) with enhanced barrier properties and with controlled-release of biocide natural extracts.The antimicrobial nanocomposites of biodegradable materials were prepared in solution by a casting method.The morphology of the biocomposites was visualized by transmission electron microscopy (TEM) and by Atomic Force microscopy (AFM) the thermal properties were investigated by differential scanning calorimetry (DSC) and the solubility and kinetics of released biocide were determined by Attenuated Total Reflection Fourier Transformed Infrared (ATR-FTIR) spectroscopy. Water and limonene barrier properties were also enhanced in the biocomposites.
A STUDY ON THE BLENDS OF HDPE AND LLDPE FOR ROTOMOLDING APPLICATIONS
This paper examines the technical feasibility of using blends of high-density polyethylene (HDPE) with linear-low density polyethylene (LLDPE) for rotational molded underground water tanks application. Various blending ratios were investigated to determine the most optimum stiffness reasonable toughness and low warpage properties required in underground water tanks. Mechanical properties were characterized and determination of miscibility by different methods including zero shear viscosity study DSC analysis and Crystallization rate measurement were done in order to find the suitable ratio of blending. Rotomoldability was checked for this ratio to using vacuum tests. It was found that HDPE/LLDPE blends are miscible in all compositions and that the ratio 70:30 (HDPE:LLDPE) has the most optimum mechanical properties for underground water tanks and also for any load-bearing applications. The resulting warpage after vacuum tests confirmed mechanical characterization. The grade 70:30 with LLDPE MI 1 (g/10 min) can be used for underground water tank applications to increase mechanical properties and to reduce warpage.
HHEATING AND COOLING TECHNOLOGIES FOR INJECTION MOLDING TO IMPROVE PRODUCTS QUALITY
Temperature is one of the most important processing parameters in injection molding which has effects on products quality and production efficiency. The relatively assistant heating and cooling technologies to adjust mold and resin temperature during the injection molding processing were discussed including heated water electric heater induction heating and chill water. Firstly the heating/cooling effects on the uniformity of mold temperature field and the time consumption to obtain the ideal processing temperature were considered by experiments. Then the appearance quality of molded parts (surface roughness) produced by the heating/cooling technologies were measured. The residual stress distribution of transparent PC parts made by different cooling rate was examined by photoelastic instruments.Compared with traditional processing it is found that microcellular injection molded specimens average surfaceroughness was reduced from 26 ??m to minimum 5.1 ??mwhen mold temperature above 18 ?? oC ?? From a series ofmulticolored band or fringe pattern it shows that whenmold temperature increase 20 oC ?? ?? ??he stress strip reducedfrom 6 to 2 which meant less residual stress.
HEATING AND COOLING TECHNOLOGIES FOR INJECTION MOLDING TO IMPROVE PRODUCTS QUALITY
Temperature is one of the most important processing
parameters in injection molding which has effects on
products quality and production efficiency. The relatively
assistant heating and cooling technologies to adjust mold
and resin temperature during the injection molding
processing were discussed, including heated water,
electric heater, induction heating and chill water. Firstly,
the heating/cooling effects on the uniformity of mold
temperature field and the time consumption to obtain the
ideal processing temperature were considered by
experiments. Then the appearance quality of molded parts
(surface roughness) produced by the heating/cooling
technologies were measured. The residual stress
distribution of transparent PC parts made by different
cooling rate was examined by photoelastic instruments.
Compared with traditional processing, it is found that
microcellular injection molded specimens average surface
roughness was reduced from 26?m to minimum 5.1?m
when mold temperature above 18? oC? From a series of
multicolored band or fringe pattern, it shows that when
mold temperature increase 20 oC???he stress strip reduced
from 6 to 2, which meant less residual stress.
SOLID STATE SHEAR PULVERIZATION AND CHEMICAL RECYCLING OF POLYMERS
Solid state shear pulverization is a novel technology in polymer processing for production of new polymeric materials. By implementation of this technology various processes such as polymer recycling compounding and improving of mechanical-chemical properties of polymers can be enhanced. This is a continuous and one-stage process with low energy consumption. During this process polymers are subject to high pressure and shear forces. In this paper this technology and its applications to polymer processing is perused. At the end recycling of PET wastes by this technology is presented that have higher efficiency in comparison with existing methods.
SOFT THERMOPLASTIC POLYURETHANES
The synthesis and physical properties of soft
plasticizer-free thermoplastic polyurethanes (TPUs )
exhibiting durometers below 70A on the Shore scale
have been investigated. The TPUs have been further
characterized in terms of their thermal and tensile
characteristics set and tear properties as well as density.
By employing hydrocarbon polyols along with suitable
chain extenders aromatic TPU with specific gravity less
than 1.0 that exhibit acceptable physical properties and
exhibit low compression set characteristics have been
prepared. Furthermore these TPUs are hydrophobic an
unusual characteristic for a TPU which suggests that
they could be useful for applications where TPUs would
not normally be considered e.g. water barriers.
SOFT THERMOPLASTIC POLYURETHANES
The synthesis and physical properties of soft plasticizer-free thermoplastic polyurethanes (TPUs ) exhibiting durometers below 70A on the Shore scale have been investigated. The TPUs have been further characterized in terms of their thermal and tensile characteristics, set and tear properties as well as density. By employing hydrocarbon polyols along with suitable chain extenders, aromatic TPU with specific gravity less than 1.0, that exhibit acceptable physical properties and exhibit low compression set characteristics, have been prepared. Furthermore, these TPUs are hydrophobic, an unusual characteristic for a TPU, which suggests that they could be useful for applications where TPUs would not normally be considered, e.g., water barriers.
EVALUATION OF MULTI-SAMPLE MICRO-CAPILLARY RHEOMETER
We present a Multi-sample Micro-capillary Rheometer (MMR) which is capable of measurements over a broad range of temperatures viscosities and shear rates. The instrument is simple as the flow is generated by external gas pressure and the shear rate is measured optically. We test the MMR against two National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) three low viscosity standards and one commercial polymer (Polydimethlysiloxane Polyisobutylene solution Oils and Polystyrene) and report a high level of accuracy and precision. This instrument will be particularly useful as a combinatorial method and in cases of limited material quantity (typical sample size 20 ?¬L). The dynamic range of the instrument is eightorders of magnitude in viscosity and four orders of magnitude in shear rate.
IMPROVED PROPERTIES AND COST EFFICIENCIES OF CYCLIC
OLEFIN COPOLYMER ENHANCED FORMING FILMS
Cyclic olefin copolymers (COC) can provide film
producers and packaging converters with an opportunity to
create thermoforming films. COCs are amorphous
thermoplastics with excellent moisture barrier high
temperature stability and stiffness. Mono- and multi-layer
examples of LLDPE-based forming films compared
against commercially available products clearly
demonstrate how well the addition of COC improves
physical properties thermoforming and packaging
performance. COC improves material distribution of
LLDPE formed trays. These improvements enable the
formed tray to withstand higher crushing force. Enhanced
performance permits possibility of down gauging.
APPLICATION OF THE HAMMETT ACIDITY FUNCTION FOR THE EVALUATION OF RESINS RESISTANCE
Chemical resistance of resins determines the lifetime of plastic materials. Chemically stable resins with ester groups undergo the hydrolysis in acidic environment.This hydrolysis is catalyzed by hydronium ions.The Hammett acidity function determines the concentration of hydronium ions in concentrated acids and their mixtures.This function can be used for material evaluations in laboratory testing and specific industrial environments.We used this approach to evaluate the chemical resistance of Dion 9100 (epoxyvinylester based resin) and Polilate 250 (unsaturated isophtalicpolyester based resin).
ADVANCED COMPATIBILITY MATRICES BY MULTI-COMPONENT INJECTION MOLDING PROCESS
The principles of materials compatibility for joining of plastics using multi-component injection molding have been investigated. In order to expand compatibility matrices the influence of processing transient and pretreatment parameters on the bonding strength has been identified. The Experimental approach has included the determination of the influences of in-line-plasmapretreatment melt temperature on the contact zone and the surface contamination. Electron spectroscopy surface tension electron microscopy and IR-temperaturemeasurements have been used to analyze the contact surface.
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