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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
TRACKING PHASE SEPARATION KINETICS OF BLOCK COPOLYMER SOLUTIONS USING DYNAMIC MECHANICAL MEASUREMENTS
Rheology is used to track the phase separation
kinetics of block copolymer solutions during processing
and then modeled using the Avrami equation. Previous
studies dealt explicitly with disorder-order transitions
following shallow temperature quenches. To make this
work applicable to the processing of solution-cast films,
styrenic block copolymers in solvents of varying
selectivity are cast as thin, dilute samples and dried
isothermally so that various constant-concentration
kinetics can be tracked. Rheology proves to be useful in
tracking both rapid and slow kinetics of diblock and
triblock styrenic copolymers in toluene. It is found that
the diblock copolymer undergoes faster ordering than a
triblock copolymer of comparable molecular weight. A
competition between thermodynamic driving forces and
kinetic suppression of the phase separation exists as
concentration changes. AFM images are provided to
confirm the kinetic data and to understand the meaning
of the Avrami exponent values determined for the
different systems studied.
INFLUENCE OF THE INJECTION MOULDING PROCESSING PARAMETERS
TO THE MECHANICAL PROPERTIES OF MICROCELLULAR FOAMED
POLYCARBONATE
Since many years microcellular foamed materials have
been produced. The advantages are all well known but to
improve the properties of the material it is necessary to
understand the interrelationship between the morphology
and the mechanical properties. Furthermore it is
important to know how the processing parameters
influence the morphology and the properties of the
produced part. By understanding the relation between
processing parameters and the consequential properties it
becomes possible to create microcellular foamed parts
with exactly defined properties. Equations by means of
linear regression were created and the main influence
processing parameters extracted. Out of this it is possible
to define a processing window which leads to best
mechanical properties for each specific load type.
INFLUENCE OF THE INJECTION MOULDING PROCESSING PARAMETERS TO THE MECHANICAL PROPERTIES OF MICROCELLULAR FOAMED POLYCARBONATE
Since many years microcellular foamed materials have been produced. The advantages are all well known, but to improve the properties of the material it is necessary to understand the interrelationship between the morphology and the mechanical properties. Furthermore, it is important to know how the processing parameters influence the morphology and the properties of the produced part. By understanding the relation between processing parameters and the consequential properties, it becomes possible to create microcellular foamed parts with exactly defined properties. Equations by means of linear regression were created and the main influence processing parameters extracted. Out of this it is possible to define a processing window which leads to best mechanical properties for each specific load type.
APPLICATION OF TAGUCHI METHOD ON NYLON6 NANOCOMPOSITES THIN WALL IN MOLD DECORATION MOLDING
Nylon6 and Nylon6 nanocomposites (addition of 2.0
wt% and 4.0 wt% Montmorillonite) were used as molding
material for in mold decoration (IMD) molding (square
plate specimen with thickness of 1.0mm). The Taguchi
method with orthogonal arrays was used to determine
important factors affecting ink washout in thin wall IMD
molding. It was found that the significant contributing
factors in the descending order were injection speed
(29.30%), nanocomposites additives (21.62%) and film
type (15.26%); moreover, higher melt temperature, higher
mold temperature and lower injection would increase
moldability for Nylon6 nanocomposites (4.0 wt%)
combined with 0.125 mm thick PC film.
EFFECT OF CLAY ON THE MECHANICAL / THERMAL PROPERTIES OF MICROCELLULAR INJECTION MOLDED LOW DENSITY POLYETHYLENE NANOCOMPOSITES
In this study, the effect of MMT content on the mechanical/thermal properties of low density polyethylene (LDPE) was studied. Maleated LDPE was compounded in a kneader with different montmorillonite (MMT) loadings.The maleic anhydride(MA)-grafted LDPE (LDPEgMA) nanocomposites were then molded by conventional and microcellular injection molding process. The effect of MMT content on the mechanical/thermal properties was investigated.The results showed that LDPEgMA nanocomposites (up to 5 wt.% MMT loading) have better tensile strength and wear resistance than their neat counterparts, using either the conventional or microcellular injection molding process. In addition to the mechanical properties, the LDPEgMA nanocomposites also have better foaming property (i.e., cell size and cell density) than their neat counterparts. The thermal stability of the LDPE material is also improved by the addition of MMT.
INFLUENCE OF SURFACE TEXTURE ON SCRATCH BEHAVIORS OF INJECTION INFLUENCE OF SURFACE TEXTURE ON SCRATCH BEHAVIORS OF INJECTION
A standard scratch test based on ISO19252 was conducted with injection molded plastics using a spherical shape scratch tip with a diameter of 5 mm. Effect of spherical patterns distance on scratch behavior was investigated. The spherical pattern size was 0.8 mm in diameter and the distance was varied in 0.5, 0.9 and 1.2 mm. The critical normal load for onset of pattern shape change decreased with increasing distance between spherical patterns, i.e. shorter distance led to higher scratch resistances. Polarizing optical microscope (POM) observation showed that yielded zone size in sub-surface increased as the distance between spherical patterns increased.
THE RELATIONSHIP BETWEEN TUBULAR LOW-DENSITY POLYETHYLENE (LDPE) BLOWN-FILM OPTICS AND MOLECULAR STRUCTURE
LDPE product development is accelerated by understanding the relationships between process, structure, rheology, fabrication, and end-use properties. This paper describes the data analysis of a large set of tubular LDPEs.Focus is put on film optics in relation to structure, including fabrication condition effects. It is found that haze, gloss, and clarity are largely independent in the good-optics range. Good optics is found to be related to narrow molecular weight distribution, whereas melt index and density play a secondary role. It is advised to use topology-generating models to further quantify structural features in relation to optics.
3D FORMING OF GENUINE WOOD VENEER AND IN-MOLD LAMINATION WITH WOOD-PLASTIC-COMPOSITES (WPC) IN ONE INJECTION MOLDING CYCLE
This paper covers the development of an innovative composite material together with a specialized process for 3D formed parts made of Wood-Plastic-Composites (WPC) with genuine wooden surface. Special preprocessed veneers are 3D formed and in-mold laminated with polypropylene-based WPC simultaneously. Questions relating to adhesive strength and warpage of the two components and the injection molding of WPC are analysed and discussed. Another key issue is the scientific derivation of the rheological behaviour of WPC, the optimization of the injection molding process for WPC and the analysis of the warpage between the two materials veneer and WPC
DEVELOPMENT OF AN ALTERNATIVE PROCESS TECHNOLOGY FOR MULTI-COMPONENT INJECTION MOULDING
Multi-component injection molding technology is increasingly developing into a key technology in polymer processing. A common problem encountered with the overmoulding process is that the aspired bond strength cannot be achieved. Based on consolidated findings from the fields of welding and refining of plastic parts, a number of different approaches will be investigated, particularly with regard to improving the process. The first step involves a higher temperature level inside the core than in the standard process. According to the theories of diffusion and adhesion, a higher temperature will improve the diffusion or wetting. The second step is a modified surface structure between the two components. Coated and eroded exchangeable disks have an influence on the peel stress. The results are shown in this paper.
RECENT ADVANCES IN JOINING OF POLYMER AND POLYMER-METAL HYBRID STRUCTURES BY FRICTION-BASED SPOT WELDING TECHNIQUES
Friction Stir Spot Welding (FSSW), Friction Spot Welding (FSpW) and Friction Spot Joining (FSpJ) are new joining technologies for lap joint connections. Due to the increasing importance of thermoplastics and lightweight alloys in industrial applications, such as for the automotive and aircraft industries, efforts have been made to develop new joining methods for similar and dissimilar polymer/metal structures. This study introduces these joining technologies and reports about recent developments with PMMA and PPS-GF / Mg hybrid joints. Good strength and improved microstructure were achieved in the joints. These positive characteristics illustrate the potential of these techniques as an alternative fabrication technology.
THE INTERPLAY BETWEEN POLYMER POLYDISPERSITY AND FILM GAUGE
IN HDPE BARRIER FILMS: HOW POLYDISPERSITY CONTROLS THE GAUGE
DEPENDENCE OF FILM BARRIER PROPERTIES
We studied the barrier properties of films produced from
eleven different HDPE resins as a function of film
thickness. The gauge-normalized water vapor
transmission rate (WVTR) and oxygen transmission rate
(OTR) depend on film thickness for samples with a larger
z-average molecular weight and the gauge-normalized
WVTR and OTR are independent of film thickness for
samples with a smaller z-average molecular weight. We
also find that WVTR tracks with the average degree of
crystallinity of the film as determined by DSC and that
the dependence of film crystallinity on film thickness
apparently accounts for the dependence of WVTR on film
thickness.
THE INTERPLAY BETWEEN POLYMER POLYDISPERSITY AND FILM GAUGE
IN HDPE BARRIER FILMS: HOW POLYDISPERSITY CONTROLS THE GAUGE
DEPENDENCE OF FILM BARRIER PROPERTIES
We studied the barrier properties of films produced from eleven different HDPE resins as a function of film thickness. The gauge-normalized water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) depend on film thickness for samples with a larger z-average molecular weight, and the gauge-normalized WVTR and OTR are independent of film thickness for samples with a smaller z-average molecular weight. We also find that WVTR tracks with the average degree of crystallinity of the film as determined by DSC, and that the dependence of film crystallinity on film thickness apparently accounts for the dependence of WVTR on film thickness.
CHARACTERIZATION ON CARBON NANOTUBES DISPERSABILITY USING CENTRIFUGAL SEDIMENTATION ANALYSIS IN AQUEOUS SURFACTANT DISPERSIONS
This paper looks into the initial steps of the development of a self-optimizing hot-tool welding machine. By employing a new machine concept, it is possible to ensure displacement speeds counter to the direction of joining. This then allows the strength of the weld to be assessed while it is still in the molten state. To be able to use this data for self-optimization, it was necessary to establish a correlation between the short-time strength of the parts in the cooled state and their shorttime strength in the still molten state. Taking these correlations, a systematic approach can be worked out to allow the welding machine to find an optimum processing window with just a few test welds. The results show that the optimum of the joining displacement to the melt layer thickness ratio (sF/L0) can be established for the parameter setting by measuring the tear forces on the welding machine, even without knowing the short-time strength in the cooled state. The same applies for the ratio of the melt layer thicknesses to the wall thickness. Based on these results, the next steps are now to develop a means of selfoptimization and quality assurance during the running hottool welding process.
IN-LINE PROCESS OPTIMIZATION OF HOT-TOOL WELDING USING AN INNOVATIVE ACTUATION CONCEPT
This paper looks into the initial steps of the
development of a self-optimizing hot-tool welding
machine. By employing a new machine concept it is
possible to ensure displacement speeds counter to the
direction of joining. This then allows the strength of the
weld to be assessed while it is still in the molten state. To
be able to use this data for self-optimization it was
necessary to establish a correlation between the short-time
strength of the parts in the cooled state and their shorttime
strength in the still molten state. Taking these
correlations a systematic approach can be worked out to
allow the welding machine to find an optimum processing
window with just a few test welds. The results show that
the optimum of the joining displacement to the melt layer
thickness ratio (sF/L0) can be established for the parameter
setting by measuring the tear forces on the welding
machine even without knowing the short-time strength in
the cooled state. The same applies for the ratio of the melt
layer thicknesses to the wall thickness. Based on these
results the next steps are now to develop a means of selfoptimization
and quality assurance during the running hottool
welding process.
IN-LINE PROCESS OPTIMIZATION OF HOT-TOOL WELDING USING AN INNOVATIVE ACTUATION CONCEPT
This paper looks into the initial steps of thedevelopment of a self-optimizing hot-tool weldingmachine. By employing a new machine concept, it ispossible to ensure displacement speeds counter to thedirection of joining. This then allows the strength of theweld to be assessed while it is still in the molten state. Tobe able to use this data for self-optimization, it wasnecessary to establish a correlation between the short-timestrength of the parts in the cooled state and their shorttimestrength in the still molten state. Taking thesecorrelations, a systematic approach can be worked out toallow the welding machine to find an optimum processingwindow with just a few test welds. The results show thatthe optimum of the joining displacement to the melt layerthickness ratio (sF/L0) can be established for the parametersetting by measuring the tear forces on the weldingmachine, even without knowing the short-time strength inthe cooled state. The same applies for the ratio of the meltlayer thicknesses to the wall thickness. Based on theseresults, the next steps are now to develop a means of selfoptimizationand quality assurance during the running hottoolwelding process.
RECENT IMPROVEMENTS IN MECHANICAL PROPERTIES MEASUREMENTS AT THE NANOSCALE
Understanding the mechanical behavior of nanostructured polymers is of great academic and practical interest. We used Atomic Force Microscopy (AFM) nanoindentation to measure mechanical properties of such materials. While AFM is generally acknowledged as a high-resolution imaging tool, accurate quantification of AFM nanoindentation results is a challenge.We report significant accuracy improvements for modulus measurements of polymeric materials when special large end-radius tips are used for indentation and viscoelastic contact models are applied for data analysis. Using these tips results in only minor loss of imaging resolution so that very small regions of interest can be identified and indented for mechanical analysis. We show AFM results for nine polymers and two polymer blends and a comparison with instrumented indenter results.
ENHANCING PROPERTIES OF PP-IMPACT COPOLYMERS BY CHEMICAL MODIFICATION
Polypropylene impact copolymers are widely used in
automotive applications. They are required to comply
with many criteria. Customers demand high-performance
materials which also exhibit good aesthetical properties.
The challenge is to balance properties as high impact
strength, good flow ability and absence of surface defects,
like tiger stripes.
It is known that peroxide modification whilst
increasing the flow ability of polypropylene impact
copolymers deteriorates the basic mechanical and
aesthetical properties.
Work was performed in which a PP-impact
copolymer was subjected to peroxide aided chain-scission
under simultaneous presence of the co-agent 1,4-
butanedioldimethacrylate (1,4-BDDMA). Results show
that samples made with 1,4- BDDMA exhibit superior
cold impact resistance and tiger stripe performance
compared to the materials made with only peroxide. In
addition, morphology, molecular weight distribution, and
rheological behaviour of the continuous and dispersed
phases of the modified PP impact copolymer were
studied.
ENHANCING PROPERTIES OF PP-IMPACT COPOLYMERS BY CHEMICAL MODIFICATION
Polypropylene impact copolymers are widely used in automotive applications. They are required to comply with many criteria. Customers demand high-performance materials which also exhibit good aesthetical properties. The challenge is to balance properties as high impact strength, good flow ability and absence of surface defects, like tiger stripes. It is known that peroxide modification whilst increasing the flow ability of polypropylene impact copolymers deteriorates the basic mechanical and aesthetical properties. Work was performed in which a PP-impact copolymer was subjected to peroxide aided chain-scission under simultaneous presence of the co-agent 1,4-butanedioldimethacrylate (1,4-BDDMA). Results show that samples made with 1,4- BDDMA exhibit superior cold impact resistance and tiger stripe performance compared to the materials made with only peroxide. In addition, morphology, molecular weight distribution, and rheological behaviour of the continuous and dispersed phases of the modified PP impact copolymer were studied.
LOW SEAL INITIATION OF COMMODITY POLYPROPYLENE FILMS, USING NOVEL BLENDS OF TERPOLYMERS AND POLYBUTENES
Processors who process mono or multilayer films on blown or cast film plants need to optimize the performance in terms of Low Seal Initiation Temperature (SIT), Hot Tack Strength and Heat Seal Strength. Masterbatches of terpolymer & polybutene-1 were prepared and added to skin layers of three layer polypropylene cast film. The results indicate lower SIT and higher Heat Seal & Hot Tack Strength.
Polypropylene based terpolymers along with Polybutene-1 offer wider choice to film manufacturers to tailor-made films with properties. This paper will provide path for processors on tailor-making the properties as desired by end users.
IMPROVING THE EXFOLIATION OF LAYERED SILICATE IN A POLY(ETHYLENE TEREPHTHALATE) MATRIX USING SUPER CRITICAL CARBON DIOXIDE
A novel technique for improving the exfoliation of organically modified layered silicate (OMLS) in a PET matrix using super critical carbon dioxide (scCO2) is compared to traditional direct melt blending. The process relies on the rapid expansion of a sc-CO2/OMLS mixture into the second stage of a single screw extruder where it is subsequently melt blended with the PET matrix. The simple environmentally benign process results in a more highly exfoliated system than direct melt compounding.X-ray diffraction analysis and mechanical testing are used to reveal improved clay exfoliation and the resulting mechanical properties.
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