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
GENERATING ALTERNATIVE TIME AND ENERGY SAVING PROCESSING
CONCEPTS FOR ROTATIONAL FOAM MOLDING
The nature of the rotational molding process is cyclic.
It requires the temperature of the rotating mold and the
plastic it is charged with to be elevated from room
temperature to beyond its melting temperature and then
cooled back to room temperature. Consequently,
rotational molding cycle times are lengthy, which is often
considered as the fundamental drawback of this plastic
fabrication process. The motivation and objectives of this
paper are twofold. First, the presently proposed research
focuses on developing an innovative processing
technology for the manufacture of integral-skin cellular
composite moldings having adjacent, but clearly distinct,
layers of non-cellular and cellular structures, consisting of
identical or compatible polyolefin grades. Its primary goal
is to significantly reduce the processing cycle time in
comparison with respective currently implemented
technologies.
CHARACTERISATION OF POLYETHYLENE POWDERS FOR ROTATIONAL MOULDING AND EFFECT OF POWDER SIZE AND SHAPE ON DENSIFICATION BEHAVIOUR
The particle size, shape and distribution of a range of rotational moulding polyethylenes (PEs) ground to powder was investigated using a novel visual data acquisition and analysis system (TP Picture??), developed by Total Petrochemicals. Differences in the individual particle shape factors of the powder samples were observed and correlations with the grinding conditions were determined. When heated, the bubble dissolution behaviour of the same powders was investigated and the shape factor correlated with densification rate, bubble size and bubble distribution.
EFFECT OF MACHINE DIRECTION ORIENTATION CONDITIONS ON STRUCTURE AND PROPERTIES OF HDPE FILMS
In this study, the effect of machine direction orientation (MDO) unit on the structure and performance of a high density polyethylene film are investigated. Both one step and two step stretching are used. The parameters studied are temperature, speed and draw ratio. Their effect on necking, row-nucleated lamellar structure, orientation as well as mechanical properties is investigated. The results showed a noticeable effect on orientation, crystalline lamellae characteristics and the mechanical properties along machine and transverse directions (MD and TD, respectively).
INFLUENCE OF RECYCLED ABS ADDED TO VIRGIN POLYMERS ON THE PHYSICAL PROPERTIES
Reuse of recycled polymers is steadily increasing. In this study, blends of varying proportions of ABS recycled resins (0~50%), obtained from the gate and runner materials of products, was added to virgin resin to investigate the effect of various compositions of virgin ABS and recycled polymers on the physical properties of the final blend. The results show that there is no obvious effect of recycled ABS percentage (by weight) on the tensile strength, elongation at yield, flexural strength, and flexural modulus. However, hardness, glass transition temperature, MFI, and heat conductivity of recycled ABS increase with as the percentage (by weight) of recycled material increases. The impact strength was also found to vary with the recycled ABS loading.
SMC REPLACEMENT WITH ENGINEERING THERMOPLASTICS IN HEAVY
COMMERCIAL VEHICLE BODY PANELS MARKET SPACE
Traditionally body panels of Heavy Commercial
Vehicles (HCV) are built in Sheet Molding Compound
(SMC) or metal. OEMs are looking for fuel-efficient
lightweight and greener technology solutions.
The specific gravity of Engineering Thermoplastic
(ETP) is much lower and offers significant weight
reduction opportunity over SMC/metal.
This paper presents limitations of SMC key
challenges in terms of aesthetics and high flow length to
thickness ratio in processing HCV body panels with ETP.
Show how these are solved through novel thickness
distribution feed system and process design.
It is highly essential to design with plastic friendly
concepts and to build the tool for balanced filling no
aesthetic defects minimum pressure and tonnage.
Predictive engineering is the best tool to use at the design
phase to achieve first time right.
SMC REPLACEMENT WITH ENGINEERING THERMOPLASTICS IN HEAVY COMMERCIAL VEHICLE BODY PANELS MARKET SPACE
Traditionally body panels of Heavy Commercial Vehicles (HCV) are built in Sheet Molding Compound (SMC) or metal. OEMs are looking for fuel-efficient, lightweight and greener technology solutions.The specific gravity of Engineering Thermoplastic (ETP) is much lower and offers significant weight reduction opportunity over SMC/metal. This paper presents limitations of SMC, key challenges in terms of aesthetics and high flow length to thickness ratio in processing HCV body panels with ETP.Show how these are solved through novel thickness distribution, feed system and process design.It is highly essential to design with plastic friendly concepts and to build the tool for balanced filling, no aesthetic defects, minimum pressure and tonnage. Predictive engineering is the best tool to use at the design phase to achieve first time right.
NON-COVALENT FILLER-MATRIX INTERACTIONS IN POLY (METHYL METHACRYLATE)/CARBON NANOFIBER NANOCOMPOSITES
The non-covalent filler-matrix interactions in poly(methyl methacrylate) (PMMA) composites filled with carbon nanofiber (CNF) and oxidized carbon nanofiber (ox-CNF) were analyzed. Significantly improved state of filler dispersion was observed in composites containing ox-CNF. A direct evidence of hydrogen bonding between PMMA molecules and ox-CNF particles was obtained from the analysis of FT-IR spectra. Fluorescence emission spectroscopy did not reveal any insight on the filler-matrix interactions in composites, due to the lack of chromophores on PMMA and due to the presence of UV stabilizers.
FRICRIVETING: A NEW TECHNIQUE FOR JOINING THERMOPLASTICS TO LIGHTWEIGHT ALLOYS
The FricRiveting technique is a new alternative spot joining process developed for polymer-metal multimaterial structures. A cylindrical metallic rivet is used to join one or more thermoplastic-metal components by means of plasticizing and deforming the tip of the rotating rivet through frictional heating. Advantages of this new technique are short joining cycles minimal sample preparation and absence of environmental emissions.Fricriveted joints have enhanced mechanical performance.This study demonstrates with aid of a case study of polyetherimide to aluminum alloys the feasibility of FricRiveting.
EFFECT OF NORBORNENE CONTENT ON THE PHYSICAL PROPERTIES OF CYCLO OLEFIN COPOLYMERS
Cyclo olefin copolymer (COC) is one of the candidate materials for the flexible display substrate due to its unique combination in optical and thermal properties.Norbornene (NB) unit in COC prevents crystallization to obtain amorphous film and increases its glass transition temperature which is suitable for the inorganic (ITO) coating in the flexible substrate processing. In this study the effects of NB content on the physical properties of COC film were studied. NB content in COC was determined bysolid state 13C NMR. A tendency to an increase in glasstransition temperature with increasing NB was found. COC with higher NB shows lowering of melt process ability with high melt viscosity but it could be controlled by the NB content. In addition COC with higher NB content shows comparably low orientation behavior due to the rigidity of NB unit in COC.
THE INTERACTION OF NANOCLAY PLASTICIZER AND STABILIZER IN PVC WIRE AND CABLE FORMULATIONS WITH ENHANCED ACCEPTABILITY
We report the preparation of high-performance leadand phthalate-free PVC formulations for wire and cable applications. We describe the replacement of diisodecyl phthalate by epoxidized linseed oil and lead stabilizer by various non-lead stabilizers and the effects of nanoclay addition. Replacement of DIDP by ELO increases stiffness strength and degradation onset temperature(Tonset). Addition of nanoclay reduces ductility andthermal stability but enhances hardness and stiffness and improves fire properties (higher LOI lower PHRR).
CHARACTERIZING CO-CONTINUOUS MORPHOLOGY DEVELOPMENT IN MISCIBLE POLYLACTIC ACID / POLYVINYL ALCOHOL BIODEGRADABLE BLENDS
Targeted for tissue engineering scaffold applications, biodegradable polylactic acid (PLA) and water-soluble polyvinyl alcohol (PVA) resins were employed to produce miscible blends by means of melt blending in a thermokinetic mixer (K-mixer). Different volume fractions of PLA and PVA were melt mixed. After water leaching (extraction) of the sacrificial PVA domains, co-continuous morphology development of the blend systems was investigated via scanning electron microscopy (SEM). The dimensions of the voids occupied by PVA in the blends were measured using an image analysis tool. In addition, the miscibility of these blends was evaluated by thermal characteristic measurements using a differential scanning calorimeter (DSC). It was shown that the continuity development and microstructure features of PLA/PVA blends were dependent on the component composition and the miscibility.
THERMAL MODIFICATION OF SEMI-CRYSTALLINE THERMOPLASTIC POLYMERS USING
POLYFUNCTIONAL ADDITIVES
Traditionally the upper application temperature
of semi-crystalline polymers is improved by increasing the
modulus at temperature by simple addition of glass fiber or
manipulation of the crystalline behavior. In the current
study the heat distortion temperature (HDT) of LDPE was
increased by as much as 11oC by blending with high Tg
thermally stable amorphous styrene maleic anhydride
(SMA) copolymers. Microdomains of SMA prevented
LDPE chains from conforming to the applied load at
temperature. The HDT of PBT was shown to increase by
up to 13oC by a proposed reaction with the end groups
yielding a homogenized single phase. In PA6/6 the HDT
was found to increase by as much as 18oC by reaction with
the amine groups yielding a crosslinked structure.
Although the mechanism was different for each polymeric
system the net effect on the crystallization behavior was
negligible.
THERMAL MODIFICATION OF SEMI-CRYSTALLINE THERMOPLASTIC POLYMERS USING POLYFUNCTIONAL ADDITIVES
Traditionally, the upper application temperature of semi-crystalline polymers is improved by increasing the modulus at temperature by simple addition of glass fiber or manipulation of the crystalline behavior. In the current study, the heat distortion temperature (HDT) of LDPE was increased by as much as 11oC by blending with high Tg thermally stable amorphous styrene maleic anhydride (SMA) copolymers. Microdomains of SMA prevented LDPE chains from conforming to the applied load at temperature. The HDT of PBT was shown to increase by up to 13oC by a proposed reaction with the end groups yielding a homogenized single phase. In PA6/6 the HDT was found to increase by as much as 18oC by reaction with the amine groups yielding a crosslinked structure. Although the mechanism was different for each polymeric system, the net effect on the crystallization behavior was negligible.
Improved adhesion between chemically sized glass fiber and PP, PBT and PA6/6 was achieved using SMA, hydroxyl terminated epoxidized polybutadiene, and maleic anhydride grafted polybutadiene. Gains in modulus were reflected in increases in HDT in both PP and PA6/6.In the case of PA6/6, the HDT was shifted to the melting point of the base polymer. PBT did not observe an increase in HDT despite demonstrating improved interfacial adhesion. The inherent Tg of the coupling agent was not found to be influential on HDT improvements.
QUANTIFICATION OF NANOCLAY DISPERSION AND EXFOLIATION IN POLYMER COMPOSITES
Over the past two decades lot research has been devoted to making polymer nano-composites, mainly because of unique property profiles like optical, mechanical, electrical, barrier, etc., they can generate. The benefits of nano-composites derive primarily from the exceptionally large amounts of particle surface area that can be achieved by a small addition of particles (typically 1-5 wt%)
As the performance of polymer layered silicate nanocomposites strongly depends on achieving a uniform dispersion of silicate platelets having high aspect ratio, quantification of the degree of dispersion and inter-layer spacing is needed to establish the structure-property relationships. In this work, we have developed a methodology combining XRD (using the modified Warren-Averbach method) and TEM to calculate the mean platelet stack thickness distribution and diameter to yield the aspect ratio of the partially exfoliated layered silicates. Results from this calculation have been used successfully in micro mechanical modeling to predict mechanical and barrier properties.
EFFECT OF PROCESS CONDITIONS ON THE CRYSTAL STRUCTURE AND PROPERTIES OF
POLYPROPYLENE CAST FILMS
Cast films of a high molecular weight linear polypropylene (L-PP) were prepared by extrusion followed by stretching using a chill roll. An air knife was employed to supply air to the film surface right at the exit of the die. The effects of air cooling conditions, chill roll temperature, and draw ratio on the row-nucleated lamellar crystallization and mechanical properties of the PP cast films were investigated. The results showed that air cooling and cast roll temperature have crucial roles on the orientation and lamellae formation as well as on the mechanical and tear properties of the cast films.
STUDY ON THE ELECTRICAL CONDUCTIVITY OF BIPOLAR PLATE WITH DIFFERENT MOLDING PROCESSES USED FOR FUEL CELL
Bipolar plates of Polyphenylene Sulphide (PPS) with 50 wt% carbon-fibers (CF) were molded by injection molding (IM) and injection-compression molding (ICM) with an assistance of induction heating (IH) and gas heating (GH) for mold temperature control. In-plane conductivity (IPC) was measured by four point probe, while through-plane resistance (TPR) was measured by the contact resistance method. Carbon fiber orientation was examined by Scanning Electrical Micrograph (SEM). ICM reduces TPR by 15% and increases IPC by 35%. TPR and IPC can be further improved by 19% and 40%, respectively, using IH whereas GH improves TPR and IPC by 23% and 91%, correspondingly. Optimum values of IPC and TPR are 155 S/cm and 1.56 ??.
DISCONTINUOUS-THICKNESS-VARIATION TO MINIMIZE WARPAGE OF PLASTICS PARTS INJECTION MOLDED UNDER UNBALANCED MOLD COOLING
Discontinuous variations of part thickness (From 10% to 40%) in a pitched manner were designed to match with various mold temperature difference between the mold core and cavity sides. Their effects on part warpage were investigated. Results show that part warpage will reach max value when there is unbalanced mold temperature of 30?øC with a 40% local thickness variation. In unbalanced cooling, the neutral axis will deviate from the gap center toward the mold wall of the higher temperature. Using variations in thickness and different mold temperatures we can control the part warpage value and location.
WEATHERING PERFORMANCE ADVANTAGES OF MOLD-IN-COLOR ACRYLIC VERSUS COATED PLASTICS FOR EXTERIOR TRIM APPLICATIONS
This paper will explore the actual outdoor weathering performance of multiple plastic technologies used for exterior trim including various approaches to coatings and the use of molded in color acrylic. For each technology, actual 5-year old parts were obtained and then photographed along side new parts to visualize change in appearance. Next the specimens are analyzed for change in color and gloss.Finally the parts are analyzed for surface chemistry changes via infrared spectroscopy. Changes in surface chemistry and appearance after weathering are associated with the chemical nature of each polymer. While the weatherable mold-in-color PMMA does not change, it is concluded that many of the coating technologies used to protect plastics that are not weatherable deteriorate after 5 years of outdoor usage and that degradation of the plastic still occurs.
ABS+PA INNOVATION FOR AUTOMOTIVE INTERIORS
The need for automotive interior molded-in-color (MIC) low gloss, rigid plastic components with good scratch and mar resistance is well known. Typical interior product gloss targets of automotive Original Equipment Manufacturers (OEMs) now range from 1.5 - 2.5 units for sixty degree Gardner gloss. Interior scratch objectives require a scratch width of less then four tenths of a millimeter with slight whitening when a 15 Newton load is applied via a one millimeter hemispherical tip.Strength and rigidity requirements now range from 1.0mm to 3.0mm max deflection on high touch interior areas when subjected to an arm or finger loading.Recent advancements in the field of Acrylonitrile- Butadiene-Styrene + Polyamide (ABS+PA) blends by BASF Corporation have allowed for such a copolymer that with the proper design and tooling considerations allows one to meet these specifications.
USING PULSED COOLING TO REDUCE CYCLE TIME AND IMPROVE PART WARPAGE
Pulsed cooling enables proper high mold temperature within a given molding period and is a convenient way to carry out dynamic mold temperature control. In this study, we compare the effects of the cooling efficiency of conventional cooling and pulsed cooling under different conditions of mold temperature, coolant temperature, melt temperature, and flow rate. It was found that pulsed cooling can improve cooling efficiency from 0.288?øC/s to 0.631?øC/s, compared to conventional cooling, and improve warpage by 20% as well. To reach the same level of warpage as that of conventional cooling, cooling time for pulsed cooling can be reduced roughly 30%.
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