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.
The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?
Conference Proceedings
CHARACTERIZATION OF PE RESISTANCE TO RAPID CRACK PROPAGATION
Chunxia Costeux, Joseph Dooley, May 2010
A small-scale test methodology for the determination of plastic pipe resistance to rapid crack propagation (RCP) is proposed. Like the full-scale and S4 tests, this test determines the critical pressure (pc) and transition temperature (Tc) of RCP. At the same time it is an inexpensive and safe small-scale alternative to the standard tests. The internal pressure in the proposed test is kept constant with practically no decompression. Therefore the pressure and crack length involved in the evaluation of dynamic toughness of material are directly measured at the crack arrest. Thus it allows for the evaluation of the material resistance to RCP (dynamic toughness) in terms of the energy release rate (ERR) at crack arrest, in addition to the determination of pc and Tc. Applications of the proposed characterization of the RCP resistance for PE-100 are discussed.
NUMERICAL PREDICTION OF THE FLOW OF COEXTRUDED POLYMERS IN A TUBE
Chunxia Costeux , Joseph Dooley, May 2010
An analytical solution has been developed to predict the flow of ƒ??Nƒ?layer coextruded encapsulated polymers through a round tube such as interface positions and pressure gradients. The predictions show fairly good agreement with the experimental measurements for two layer coextrusion with an equal flow rate in each layer.The effects of flow ratio total flow rate and layer composition on the interface position within the die and on the pressure gradient are examined. The knowledge of interface position and pressure gradient is important for die design and process optimization.
TEMPERATURE EFFECTS ON SLOW CRACK GROWTH IN PIPE GRADE PE
Alberto Naranjo, Walter Michaeli, May 2010
Temperature strongly affects the mechanical properties of pipe grade polyethylene (PGPE), such as strength and toughness. It is observed in this study that the temperature also affects the mechanisms of slow crack growth (SCG). A change in the mechanism of SCG is observed at certain temperature, named Crack Growth Transition Temperature (CGTT). The CGTT of the cold drawn (oriented) PGPE appears to be significantly higher than room temperature. At the temperature above CGTT the crack propagates discontinuously, stepwise, whereas at the temperature below CGTT the crack grows continuously. The slope of crack growth rate vs. stress intensity factor (SIF) is also noticeably different for temperatures above and below CGTT. The existence of CGTT implies certain limitations for commonly used extrapolation of SCG and lifetime data from the elevate temperature of an accelerated testing to the room temperature across CGTT.
NEW MODEL AND METHOD FOR THE DETERMINATION OF THE THERMAL DIFFUSIVITY IN SEMICRYSTALLINE POLYMERS UNDER DIFFERENT PROCESSING CONDITIONS IN INJECTION MOLDING
Alberto Naranjo , Walter Michaeli, May 2010
The most recent results for the measurements and modeling of thermal diffusivity of thermoplastics under injection molding conditions are presented. The method is based on the inverse numerical solution of the differential equation that describes the cooling process of the injected part. The effect on the thermal diffusivity of different cooling rates across the thickness of the injection part the cavity pressure the thickness of the part the wall temperature of the mold and the melt temperature were investigated and included as parameters in the improved mathematical model for the description of the thermal diffusivity. The model was validated for polypropylene in a wide processing window.
CLOSED LOOP CONTROL IN LASER WELDING OF PLASTIC COMPONENTS
Rick Davis , Chul Lee, May 2010
A new laser welding process that uses a real time closed loop control system of the process by monitoring thermal emissions directly from the weld region. These emissions are captured, measured, interpolated, and thus correlated to a known temperature. The process has been applied on laser welding a test box molded from thermoplastic PBT material, Ultradur B4300G6.Robustness of the process and the quality of the weld joint is evaluated by performing burst testing of the welded boxes, after welding the box samples at various surface temperatures. The experiment has identified optimum surface temperature regime for laser welding a material for a given weld section design. Microscopy study shows microstructure of good weld joint and poor weld joints
IMPACT OF CRIMS DATA ON THE ACCURACY OF MOLDFLOW WARPAGE PREDICTION
Venkatesh Aungadu Kuppuswamy , Stephen L. Spanoudis , Marian Petrescu , Ben Nagaraj, May 2010
This paper evaluates several simulation approaches in Moldflow, including the use of CRIMS (Corrected Residual In-Mold Stress) data, to better predict warpage in injection-molded parts. The evaluation includes a simulation matrix in which warpage is predicted by part geometry, process conditions, material and simulation method. In addition, selected injection-molded parts are scanned at high resolution to gather actual 3-D warpage data. The paper additionally describes novel methods for making comparisons between the predicted and actual data sets within an interactive CAV environment to determine the effectiveness of CRIMS.
PREDICTION OF PE LONG-TERM CREEP PROPERTY AND LIFETIME IN DUCTILE FAILURE BASED ON SHORT-TERM TESTS
V. Schöppner, E. Enns, K. Anger, E. Giese, May 2010
A large number of different formulations of PE have been tested in load (creep) and displacement controlled (ramp) conditions. A certain symmetry (ƒ??mirror reflectionƒ?) between the stress ?Ÿ vs. log ?æ‹?? in ramp and creep tests and the stress ?Ÿ vs ductile failure tf in creep is observed. A procedure for prediction of PE long-term creep behavior and lifetime in ductile failure based on ramp and a short-term creep tests is formulated. The procedure employs Eyringƒ??s model for connecting stress, strain rate and temperature in yielding combined with the observed symmetry. A theoretical basis for the procedure and its experimental validation is presented.
A NEW MECHANISM FOR FLAME RETARDED, NON-HALOGEN WIRE AND CABLE COMPOUNDS
Feng Zhu , Yan Hu, May 2010
The use of mica as a filler to produce fire resistant tapes for the wire and cable industry is well known. Mica, which is a platelet inorganic filler, promotes the safety and integrity of electrical circuits under fire conditions by an exfoliation mechanism in which the cable is protected from the heat of the flame by the formation of an inorganic thermal insulation barrier. This insulating barrier is formed by the exfoliation or expansion of the mica filler under fire conditions.Unfortunately, mica can be difficult to process and is prone to premature exfoliation during extrusion wire coating.This paper presents the utilization in wire jacketing applications of a unique intumescent coating technology long used to protect steel beams during fire conditions. This technology uses organic components that intumesce and form a carbonaceous, non-flammable char in a fire environment. This char composition has sufficient physical integrity to prevent flaking off and provides thermal insulative protection. This new flame retardant technology is much easier to process than mica, is cost effective, and is efficient enough to formulate nonhalogen, flame retardant, polyolefin based jacketing compounds without sacrificing fire resistance performance
THERMAL STABILIZATION OF BIODEGRADABLE POLY-HYDROXYBUTYRATE (PHB) IN MELT EXTRUSION PART 1: POLY-OLIGOMERIC-SILSESQUIOXANE
Y. Shaked , H. Dodiuk , S. Kenig , C. Schwier , S. McCarthy, May 2010
Poly-Oligomeric-Silsesquioxane POSS nano modifier was examined as a thermal stabilizer for PHB.Melt compounding of Poly-Hydroxy-Butyrate PHB copolymers with different POSS moieties was performed.Reactive and non-reactive POSS nano modifiers were used. The effect of modification on PHB thermal stability was evaluated by changes in rheology and molecular weight. POSS modifiers with unique core-shell structures were found to significantly reduce the loss in molecular weight during melt mixing possibly by decreasing viscous-heating effects.
PREDICTION OF POLYPROPYLENE LONG-TERM CREEP BASED ON A SHORT-TERM TESTING
W. Zhou, A. Chudnovsky*, A. Doufas** and R. Andrekanic, May 2010
A method for prediction of polypropylene long-term creep behavior is proposed based on mirror symmetry between stress vs strain rate in ramp tests and stress vs. ductile-failure-time tf in creep. Such methodology has been previously proposed for polyethylene on the basis of power law creep behavior of polyethylene. Here we use more general approach based on Zhurkov-Eyring model that relates strain rate, stress and temperature with help of parameters having physical meaning such as activation energy of the process. The prediction of long-term creep of polypropylene is made based on the tensile ramp tests with variable strain rate and a short-term tensile creep testing. An analysis of the proposed methodology in view of the set of experimental data is presented. Validation of long-term creep predictions based on the short-term testing by comparison with conventional long-term creep data is discussed.
EVALUATION OF ENVIRONMENTAL STRESS CRACKING RESISTANCE IN POLYETHYLENES: BENT STRIP VS. CONSTANTTENSILE- LOAD METHODS
Franco Guastaferro Preda , Delia de Jesús , Johan J. Sánchez, May 2010
For a group of 14 polyethylenes (PE) with different densities (0.924 to 0.966 g/cm3) and melt flow index MFI (0.38 to 42 dg/min) the Environmental Stress Cracking Resistance (ESCR) of each PE was determined by the typical method of bent strip or ESCR at constant strain. The results were compared with those obtained by the evaluations of ESCR by constant-tensile-load method. For both methods the effects of the density and MFI on ESCR were similar and in agreement with those reported in the literature. However the failure time spread measured in the ESCR at constant load is smaller although both methods lead to high experimental errors attributed to limitations or omissions in the experimental protocols described in the standards used for these measurements.
CALCULATION OF THE ACTIVATION ENERGY FOR SELF DIFFUSION
Mark D. Wetzel, May 2010
The bonding of semicrystalline polylactic acid (PLA) films was investigated for a broad range of temperatures and contact times above the glass transition temperature in a lap shear joint geometry using an impulse welding system. It was observed that interfacial strength was linearly dependent on the fourth root of welding time until it approached the bulk material strength. Using models based on reptation therories the interfacial strength of lap shear welds was estimated based on thermal histories. In more detail, the activation energy for interfacial healing and self diffusion coefficient were calculated based on shear strength measurements of samples welded with well defined thermal histories. The parameters were then used to predict interfacial strength with varying temperature histories.
INSTRUMENTATION AND CONTROLS INVENTIONS AND INNOVATIONS IMPACTING THE POLYMER PROCESSING INDUSTRY
Mark D. Wetzel, May 2010
The processes to compound and shape polymeric materials into a wide variety of products have made significant and prolonged global economic impacts and have provided enormous societal benefits. Since the advent of the plastics industry many key enabling inventions and innovations in instrumentation and control system technology have been made that engineers now may take for granted. This paper reviews the development and commercialization of several examples of sensing actuation and control methods that are critical in extrusion compounding and other polymer processing operations.
INSTRUMENTATION AND CONTROLS INVENTIONS AND INNOVATIONS IMPACTING THE POLYMER PROCESSING INDUSTRY
Mark D. Wetzel, May 2010
The processes to compound and shape polymeric materials into a wide variety of products have made significant and prolonged global economic impacts and have provided enormous societal benefits. Since the advent of the plastics industry, many key enabling inventions and innovations in instrumentation and control system technology have been made that engineers now may take for granted. This paper reviews the development and commercialization of several examples of sensing, actuation and control methods that are critical in extrusion, compounding and other polymer processing operations.
FOAMING PROCESS AND DAMPING CAPACITY OF BELL STRUCTURE
Minoru Shimbo , Shirei Koshida , Akihiro Misawa, May 2010
This study has examined the forming process and its characteristics of bell structures with the use of batch type foaming that the blowing agent of a supercritical fluid was used. In this study, various forming methods have been tried for bell structures together with a series of impact tests and acoustic tests of the structures, followed by evaluation of shock absorption and sound insulation for inclusion of particles. The trial succeeded in forming the bell structures including steel balls by means of batch type foaming. It was also verified that these bell structures exhibit required shock absorption and sound insulation performance.
INFLUENCE OF PROCESSING PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF A POLYETHERIMIDE JOINED BY FRICRIVETING: INVESTIGATION OF ROTATIONAL SPEED
Sergio T. Amancio Filho , Jorge F. dos Santos, May 2010
FricRiveting is a new and promising spot joining technique for polymer-metal structures recently introduced at ANTEC 08. It is well known that processing in joining technology plays a central role in dictating joint properties and so understanding it is important for producing reliable connections. Rotational speed is an important controlling parameter in FricRiveting. This study experimentally determines the influence of rotational speed on FricRiveting’s joint microstructure local and global strength and thermal history for a thermoplastic polyetherimide joined by threaded aluminum rivets.
INFLUENCE OF PROCESSING PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF A POLYETHERIMIDE JOINED BY FRICRIVETING: INVESTIGATION OF ROTATIONAL SPEED
Sergio T. Amancio Filho , Jorge F. dos Santos, May 2010
FricRiveting is a new and promising spot joining technique for polymer-metal structures, recently introduced at ANTEC 08. It is well known that processing in joining technology plays a central role in dictating joint properties and so understanding it is important forproducing reliable connections. Rotational speed is an important controlling parameter in FricRiveting. This study experimentally determines the influence of rotational speed on FricRiveting's joint microstructure,local and global strength, and thermal history for a thermoplastic polyetherimide joined by threaded aluminum rivets.
CURE KINETICS OF POLY (PHENYLENE ETHER)/EPOXY RESIN SYSTEM
Yu Pin Tsai, , Chi Feng Hsu, Ray Quen Hsu, May 2010
The cure kinetics of poly(phenylene ether)/epoxy resin (PPE/EP) cure system was investigated by using an advanced isoconvensional method (AICM). The curing experiments of PPE/EP cure system with different PPE/EP ratios were carried out by means of nonisothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20 oC/min. From the DSC curves it can be shown that the curing mechanism of PPE/ER is so complicated that PPE content effects most cure kinetic parameters. A variation of the effective activation energy with the extent of conversion was obtained by AICM and analysized.
STUDY ON THE IN-MOLD PUNCHING OF THE THERMOPLASTIC INJECTION MOLDING
Yu.Pin Tsai , Chi Feng Hsu , Ray Quen Hsu, May 2010
An in-mold punch device was designed; the shear break mechanism was installed in the position of the holes of the product. The surface of the product is integrated during the plastic injection forming process; therefore, no appearance defect like weld lines will occur. Experimental results showed that lower processing temperature and faster shear velocity are helpful to reduce the difference between the punch dimension and the hole dimension. The shorter cooling time is advantageous for the product shrink; while if the point is the smoothness of the circular hole; the correct way is to enhance the punch velocity and prolong the cooling time.
COMPONENT MICRO - INJECTION MOLDING TECHNOLOGY FOR MANUFACTURING OF HIGH PRECISION MICRO PARTS: A SYSTEMATIC PROJECT APPROACH
R.A. Morales, M. V. Candal, May 2010
The project set itself the goal of the new possibilities of micro-injection molding of shotweight-optimized two component micro parts in regards of quality, flexibility and cost, including in-line measurement and testing with the stages of assembly, handling and logistics in the territory of the production of micro-optical systems. Based on the new machine concept of a two-component micro ƒ?? injection machine (2C-?¬IMM) a flexible and compact example of supply chain for the production of reliable optical systems were developed. The process chain contains the technologies of high precision micro injection molding technology, quality-control by optical control and geometric dimension and shape measurement, separation procedures of the runner and further assembly steps. A process-handling technology with special grippers combines and automates the individual process steps. An optoelectronic sensor, and an application with microfluidic functions for Biotechnology (so called Demonstrators) were selected to test the developed system. In both cases, all stages of product development from product design to be included on replication by injection molding, assembly and integration of handling opereations of the components had to be evaluated. The development of a scalable manufacturing technology for both examples is essential, and will be pursued as a priority. The project provides a variety of results: A novel, multiflexible manufacturing plant for the production of future-oriented products, innovative individual modules, new and improved production methods and advanced microoptic products.
.jpg)
.jpg)
.jpg)
.jpg)
