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

PREPARATION OF MICROCELLULAR POLY(ETHYLENE-CO-OCTENE) RUBBER FOAM USING SUPERCRITICAL CO2 TECHNOLOGY

Wentao Zhai , Siu N. Leung , Hani E. Naguib , Chul B. Park, May 2010

In the past three decades there has been great advancement in preparing microcellular thermoplastic polymer foam. However little attention is paid to thermoplastic elastomer. In this study microcellular poly(ethylene-co-octene) (PEOc) rubber foams with a cell density of 2.9×1010 cells/cm3 and cell size of 1.9 ?m are successfully prepared by using CO2 as the physical blowing agent with a batch foaming process. Microcellular PEOc foams exhibit a well defined closed cell structure uniform cell size distribution and formation of unfoamed skin at low foaming temperatures. Their difference from thermoplastic foam is the foam shrinkage in the atmosphere due to the elasticity of polymer matrix. The effect of melt flow rates on the cell growth process is investigated by changing the foaming conditions.

PREPARATION OF MICROCELLULAR POLY(ETHYLENE-CO-OCTENE) RUBBER FOAM USING SUPERCRITICAL CO2 TECHNOLOGY

Wentao Zhai , Siu N. Leung , Hani E. Naguib , Chul B. Park, May 2010

In the past three decades, there has been great advancement in preparing microcellular thermoplastic polymer foam. However, little attention is paid to thermoplastic elastomer. In this study, microcellular poly(ethylene-co-octene) (PEOc) rubber foams with a cell density of 2.9??1010 cells/cm3 and cell size of 1.9 ?¬m are successfully prepared by using CO2 as the physical blowing agent with a batch foaming process. Microcellular PEOc foams exhibit a well defined closed cell structure, uniform cell size distribution, and formation of unfoamed skin at low foaming temperatures. Their difference from thermoplastic foam is the foam shrinkage in the atmosphere due to the elasticity of polymer matrix. The effect of melt flow rates on the cell growth process is investigated by changing the foaming conditions.

STIFF, HIGHLY DAMPING THERMOPLASTIC POLYURETHANE NANOCOMPOSITES VIA SIMPLE, SCALABLE PROCESSING

Erik Dunkerley , Daniel F. Schmidt, May 2010

Nanocomposites comprising a high percentage of inorganic layers and a low percentage of organic binder have been reported to exhibit remarkable physical properties due to high levels of organization, connectivity and phase morphology. We report the preparation and characterization of a system of this type consisting of montmorillonite layers and thermoplastic polyurethane (TPU) binder. Transparent sheets were prepared and characterized via SEM for structure, TGA and DSC for thermal properties, and DMA for mechanical response. These materials are stable, robust, and exhibit interesting combinations of stiffness and damping capacity.

MONITORING THE EFFECT OF OPERATING CONDITIONS ON MELT TEMPERATURE HOMOGENEITY IN SINGLE-SCREW EXTRUSION

C. Abeykoon, M. McAfee, K. Li, A. L. Kelly, E. C. Brown, May 2010

Delivery of a melt which is homogenous in composition and temperature is paramount for achieving high quality extruded products. However, melting stability can be difficult to determine via typical melt pressure and thermocouple instrumentation. This can result in inefficient operation through non-optimized operating conditions or extruder screw geometry. In this work, melt temperature homogeneity in a single screw extruder is investigated experimentally using a thermocouple mesh technique. The effect of barrel temperature settings and screw speed on die melt temperature homogeneity is investigated. Inferential methods of determining melting stability in-process are investigated with the aim of developing modeling and control techniques to improve process quality and efficiency.

PS FOAMS BLOWN FROM HFC-134a/HFC-32 BLENDS: PROCESSING BEHAVIOR

Michel F. Champagne , Richard Gendron , Jacques Tatibouët, May 2010

Manufacturing of extruded polystyrene (XPS) foam insulation boards is currently based on weak ozone depleting gases. Mixtures of blowing agents are actually seen as one of the most promising solutions to ozonedepleting substances phase-out. This paper investigates various blowing agent formulations based on mixtures of hydrofluorocarbons HFC-134a (1,1,1,2-tetrafluoroethane) and HFC-32 (difluoromethane). The study focuses on the rheological (plasticization) and degassing (solubility) behaviors of the formulations, as measured on-line during foam extrusion. Rules of mixing for such blends of HFCs are proposed based on the relative contribution of each component to the overall processing behavior.

SOFT POLYURETHANE FOAMS AS CARTILAGE REPLACEMENT: PROCESSING BEHAVIOR AND BIOCOMPATIBILITY

Michel F. Champagne , Sashka Dimitrievska , Richard Gendron , Martin N. Bureau, May 2010

Massively invasive surgery is often the only cure for the worst cases of cartilage-related diseases. In an effort to physiologically mimic human joints, 4 biomedical thermoplastic polyurethanes (TPU) differing in glass transition temperature, modulus and wettability were foamed using a CO2-based solid-state process. Human cartilage mechanical behavior was closely matched by low density foams of the softest TPU investigated. In vitro osteoblastic studies showed improved cell differentiation, activity and proliferation; all suggestive of TPU foans potential osteointegration. The superior bioactivity and cartilage-matching mechanics make the TPU foam a promising cartilage replacement.

INFLUENCE OF PROCESSING CONDITIONS AND POLYMER CHARACTERISTICS ON SURFACE TOPOGRAPHY OF SMALL BORE TUBES

Peng Xiang-fang, Peng Jun, Xie Xiao-li, Turng Lih-Sheng, May 2010

The topography of the inner surface of small bore extruded tubes used in fluid handling applications can affect flow rates, fluid turbulence and biofilm adherence. Quantitative surface roughness analysis of tubes manufactured from different polymers has shown that the inner surface topography is related to the polymer molecular variables, rheological properties and extrusion processing conditions. Surface energy analysis of these surfaces has also been shown to be related to polymer type as well as surface roughness.

EFFECT OF ORGANOCLAY ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIORS OF INJECTION-MOLDED PP/ ABS/ MONTMORILLONITE NANOCOMPOSITES

Peng Xiang-fang , Peng Jun , Xie Xiao-li, May 2010

The mechanical properties and crystallization behaviors of PP/acrylonitrile-butadiene-styrene/organic montmorillonite nanocomposites (PP/ABS/OMMT) were studied. It was shown that compatilizer PP-g-MAH not only improved the compatibility of PP/ABS but also promoted the dispersity of OMMT particles in continuous phase PP and dispersed phase ABS. In addition PP was reinforced and toughened by both layered silicate OMMT nanoparticles and ABS. The blend weight ratio of PP/ABS/OMMT which was 85/15/2 wt % had a concerted effect on toughening. OMMT nanoparticles also increased crystallization temperature and crystallinity.

EFFECT OF ORGANOCLAY ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIORS OF INJECTION-MOLDED PP/ ABS/MONTMORILLONITE NANOCOMPOSITES

Peng Xiang-fang , Peng Jun , Xie Xiao-li , Turng Lih-Sheng, May 2010

The mechanical properties and crystallization behaviors of PP/acrylonitrile-butadiene-styrene/organic montmorillonite nanocomposites (PP/ABS/OMMT) were studied. It was shown that, compatilizer PP-g-MAH not only improved the compatibility of PP/ABS, but also promoted the dispersity of OMMT particles in continuous phase PP and dispersed phase ABS. In addition, PP was reinforced and toughened by both layered silicate OMMT nanoparticles and ABS.The blend weight ratio of PP/ABS/OMMT, which was 85/15/2 wt %, had a concerted effect on toughening.OMMT nanoparticles also increased crystallization temperature and crystallinity.

AUTOMATED OPTIMIZATION OF INJECTION MOLD COOLING CIRCUIT WITH OPTIMIZATION TOOL PIANO

Brian P. Grady, May 2010

In order to assure the part quality in the part design step, it is desirable to optimize the cooling circuit prior to the mold design step. In the environment of frequent design changes, a way to optimize automatically the cooling circuit in a short period of time is necessary. In this work, an automated optimization of the cooling circuit was examined with a commercial optimization tool, PIAnO. The optimization technique is useful largely for large parts such as instrument panels and bumpers. The objective function is the deviation of temperature difference from a target mold surface temperature.

PLASTICS INDUSTRY INNOVATION: HOW TO SURVIVE AND THRIVE IN A RECESSION

Brian P. Grady, Abhijit Paul, Warren T. Ford, May 2010

In this paper, we will discuss several companies who have not seen recessions as a deterrent to innovation but an opportunity. Using a case study format, we will discuss four companies that have innovated in a recessionary environment. We will derive the lessons learned and offer some recommendations as to ƒ??how toƒ? look for the silver lining in an economic downturn. The objective of this paper is to present examples of companies that re-positioned for growth during an economic downturn. In two of the cases, an innovative business grew out of adversity. The third is a new company that was able to identify a technology developed earlier but eventually abandoned due to a lack of a market. The last invested while its competitors contracted. Due to the poor economy, most of us are experiencing a drop in our business and are looking for ways to reposition our businesses. Our businesses are down as much as 50% from prior years. We have cut our costs, reduced our payrollsƒ??what do we do nowƒ?? The following four companies are examples of what can be done to innovate in a recessionary environment. The following table shows the types of business segmentation opportunities.

POLYMER DYNAMICS IN SINGLE-WALLED CARBON NANOTUBE POLYMER COMPOSITES

Brian P. Grady , Abhijit Paul , Warren T. Ford, May 2010

A 100 000 g/mol polyethylene molecule has a crosssection of about 0.5 nm and a contour length of about 0.9 ?m. A typical single-walled carbon nanotube (SWCNT) has a cross-section of about 1 nm and a contour length of about 1 ?m. The critical difference from a physics perspective between these two molecules is that the persistence length of the former is about 0.6 nm and the persistence length of the latter is reported as ? 30 ?m.1 One can make a similar comparison between SWCNTs and liquid crystalline polymer molecules; in this case the key difference is that the length of the former is much larger than the length of the latter. This paper presents what is believed to be a synergistic type of behavior that is possibly related to the similarity in size of the two high aspect-ratio materials the fact that single-walled carbon nanotubes can increase the jump in heat capacity at the glass transition. Other measurements involving the behavior of fictive temperatures and activation energies measured from calorimetric studies are also given.

POLYMER DYNAMICS IN SINGLE-WALLED CARBON NANOTUBE POLYMER COMPOSITES

Brian P. Grady , Abhijit Paul , Warren T. Ford, May 2010

A 100,000 g/mol polyethylene molecule has a crosssection of about 0.5 nm and a contour length of about 0.9 ?¬m. A typical single-walled carbon nanotube (SWCNT) has a cross-section of about 1 nm and a contour length of about 1 ?¬m. The critical difference from a physics perspective between these two molecules is that the persistence length of the former is about 0.6 nm and the persistence length of the latter is reported as ƒ?? 30 ?¬m.1 One can make a similar comparison between SWCNTs and liquid crystalline polymer molecules; in this case the key difference is that the length of the former is much larger than the length of the latter. This paper presents what is believed to be a synergistic type of behavior that is possibly related to the similarity in size of the two high aspect-ratio materials, the fact that single-walled carbon nanotubes can increase the jump in heat capacity at the glass transition. Other measurements involving the behavior of fictive temperatures and activation energies measured from calorimetric studies are also given.

CONFORMAL COOLING CHANNEL DESIGNS TO REDUCE TEMPERATURE DEVIATION BY USING CONSTRUCTAL DESIGN

S.-H. Zhu, C. Tzoganakis, May 2010

Conformal cooling channel could make the temperature distribution in the mold uniform, reducing cycle time and improving part quality. However, design principle for the conformal cooling channel has not been established yet. In this study, a constructal design principle was tried with hexagonal cooling channel. The size and the depth of the hexagonal cooling channel were optimized to minimize the temperature deviation of the mold surface. Constraint was pressure drop through the cooling channel limited by the pumping capability. The CAE tool for mold cooling analysis was Moldflow Cool.

THE MORPHOLOGY AND MECHANICAL PROPERTIES OF TPU/PP TPE FROM EXTRUDED AND INJECTION-MOLDED SAMPLES

S.-H. Zhu , C. Tzoganakis, May 2010

A thermoplastic elastomer (TPE) blend of thermoplastic polyurethane (TPU) and polypropylene (PP) was sampled from extruded strands and injection molded plaques. Highly stretched strands of the PP phase are aligned parallel to each other along the extrusion direction in the extruded samples while in the injection-molded samples the PP phase is in ellipsoidal domains residing in the shear plane of the mold. Subjecting the samples to a tension load leads to rupture of the elongated strands, resulting in increased tensile set and reduced moduli. Annealing the extruded specimen at 150 oC for 30 min. can create cracks in the blend similar to those generated during tensile testing.

STUDY ON DYNAMIC MOULD OF PMMA MICROCELLULAR FOAM WITH VARIOUS SHEARING FIELD

Oludolapo Shobanjo, Stuart Blackburn, Owen Draper, Richard Greenwood, May 2010

The foaming process of PMMA in specially designed rotor system with screws and previously designed rotor system without screw was studied respectively. In this study, with supercritical carbon dioxide (ScCO2) as a blowing agent, microcellular foam of PMMA was made in traditional steady process and dynamic vibration field respectively by using the isobarical feeding equipment of supercritical carbon dioxide and microcellular foaming simulator. The effects of processing parameters such as pressure, time of saturation, shear stress were investigated, in order to study and analyze the effects of processing conditions on PMMA microcellular plastics. Foamed samples with the cell density of 78.7??107 cell/cm3, average cell size of 12.6 ?¬m have been produced by using the screw system.

INFLUENCE OF MECHANICALLY BLENDED INVESTMENT CASTING WAX FORMULATIONS ON QUALITY OF INJECTION MOULDED PARTS

Oludolapo Shobanjo , Stuart Blackburn , Owen Draper , Richard Greenwood, May 2010

Wax formulations prepared using paraffin wax (PW) and hydrogenated resin (HR) were studied to identify effects of temperature and composition on phase homogeneity. A phase diagram was constructed showing regions of PW/HR miscibility and tracking changes in PW crystallisation as HR is added. Polarised optical microscopy identified changes in nucleation and crystal growth mechanisms of the PW semi-crystalline phase promoted by HR. A simplified wax injection system was used to investigate conditions for defect formation. Results, to be validated using a ProCAST model, showed defects occurred by injecting blend compositions corresponding to regions of PW/HR phase separation as shown by the phase diagram.

THE FOAMING PROCESS OF PMMA IN SPECIALLY COMPOUNDS UNDER HIGH PRESSURE, VELOCITY AND TEMPERATURE CONDITIONS

Reema Sinha, Sangita Nandi, Arun Sikder, Radha Kamalakaran, Susanta Mitra and Edward Kung*, May 2010

In the present study, the friction and wear properties of high temperature resistant polymers, Polyetherimide (PEI) and Polyetheretherketone (PEEK), have been investigated at specific combinations of high pressure, velocity and temperature against smooth steel counterparts. The effects of internal lubricant, polytetrafluoroethylene (PTFE) and PTFE with short fiber reinforcements (carbon fiber) are outlined. The tests were performed on a thrustwasher testing machine under dry sliding conditions. Different analytical techniques were employed to study the correlation between the transfer layer and friction properties. Lubricated and lubricated-reinforced compounds showed excellent wear resistance compared to pristine resins.

RESEARCHES ON MECHANICAL PROPERTIES AND MICRO-STRUTURES OF SBS/AS TOUGHENED HIPS

Han-Xiong Huang, Kun Li, Sha Li, May 2010

The mechanical properties and misconstrues of high impact polystyrene (HIPS) toughened by styrenebutadiene-styrene (SBS) were studied to find the Brittle-Ductile Transition Point. At the Brittle-Ductile Transition point, HIPS and SBS alloys were prepared using melt intercalation technique by blending HIPS and SBS while used acrylonitrile-styrene (AS) powder, gaining higher impact and tensile strength. Their microstructures near the Transition Point were characterized by scanning electron microscope (SEM) to investigate the toughening mechanism of HIPS/SBS/AS composites. The toughening mechanism is similar to the mechanism of RIF toughening rather than the cold-drawing theory which applied to ductile matrixes toughed by rigid organic filler (ROF).

EFFECTS OF PROCESSING PARAMETERS ON SHRINKAGE UNIFORMITY OF INJECTION-COMPRESSION MOLDED PART

Han-Xiong Huang , Kun Li , Sha Li, May 2010

Both polypropylene (PP) and polystyrene (PS) parts were molded by injection-compression molding. The Taguchi method was utilized to investigate the effects of six processing parameters including mold temperature compression speed compression time compression distance delay time and compression force on part shrinkage uniformity. Analyses of means and variance showed that the compression force is the most important parameter for part shrinkage uniformity of both parts. The compression distance is the second most significant parameter on shrinkage uniformity of PS part but not significant parameter on PP part. The optimal processing parameters for improving the shrinkage uniformity of both parts are found and verified experimentally.