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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LASER WELDING OF THERMOPLASTIC URETHANE FILMS
Laser welding is increasingly becoming a technology of choice in the plastics joining industry. The use of infrared absorbers to laser weld thermoplastic materials, including thermoplastic elastomers, is also of interest to the plastics industry. Therefore, an investigation of the laser welding characteristics of four classes of thermoplastic urethanes using organic infrared absorbing materials was undertaken. In addition, the use of thermoplastic urethanes as intermediate layers with dissimilar plastics has also been examined. This paper reviews the results of these welding studies.
A COMPARISON OF STATISTICAL PROCESS CONTROL (SPC) AND PRINCIPLE COMPONENTS ANALYSIS (PCA)
The performance of statistical process control (SPC) compared to principal components analysis (PCA) for the purpose of quality control. Both methods used a nine run perturbation design of experiments to develop the initial model and control limits. Twelve molding faults were then imposed to characterize the performance of the two methods to identify process changes and molding defects. SPC identified 5 of the 12 process faults and 18 of the 24 molding defects. PCA identified 10 of the 12 process faults and 23 of the 24 molding defects.
RHEO-OPTICAL MEASUREMENTS IN MICROMOULDING
Flow visualisation has previously been used to study injection moulding. The smaller length scales associated with micro-moulding allow some additional measurements to be taken but pose new challenges due to the lower filling and cooling times. We have developed an experimental toolset for visual observation in micromoulding cavities via a sapphire window system that allows the study of mould filling post filling shrinkage of the polymer away from the cavity surface and determine the evolution of birefringence during solidification.
RHEO-OPTICAL MEASUREMENTS IN MICROMOULDING
Flow visualisation has previously been used to study injection moulding. The smaller length scales associated with micro-moulding allow some additional measurements to be taken, but pose new challenges due to the lower filling and cooling times. We have developed an experimental toolset for visual observation in micromoulding cavities via a sapphire window system that allows the study of mould filling, post filling shrinkage of the polymer away from the cavity surface, and determine the evolution of birefringence during solidification.
A PLASTICS MANUFACTURING SYSTEMS EDUCATION
Plastics manufacturing is an interdisciplinary endeavor crossing chemical, mechanical, and electrical engineering as well as other fields. In this paper, a systems approach is described for the decomposition and development of a plastics manufacturing system. The case study involves the design, implementation, and validation of a thermal imprint lithography machine used in an undergraduate process control course. Its development motivated systems thinking about open and closed loop control, variances between theory and practice, performance measurement, and process optimization.
SHEAR STRESS AND MELTING FLUX FOR POLYCARBONATE RESINS
Frictional forces (for temperatures less than the melting or devitrification temperature) and shear stresses are keys to the solids conveying and melting processes in plasticating single-screw extruders. For most processes the shear stress at the polymer-metal interface however is unknown. This paper presents shear stresses and melting fluxes for three polycarbonate (PC) resins with different melt flow rates. The data are related back to the extrusion process.
EVALUATION OF FATIGUE LIFE PREDICTION MODEL FOR GFRP COMPOSITE MATERIALS
A fatigue life prediction model for GFRP composites using the internal strain energy release rate as the damage metric for predicting fatigue life from a minimum of empirical data points has been proposed. This evaluation of the modelƒ??s accuracy demonstrates its simplicity and ability to model fatigue life for coupons and components. The model was able to fit fatigue data and predict fatigue life to within 5% log error with a high success rate.
LIFETIME PREDICTION OF PLASTIC PIPES FOR GAS DISTRIBUTION AND HOT WATER SUPPLY
This paper describes a comparison of the lifetime of polyethylene (PE) pipes between actual field failures and accelerated experimental failures for gas distribution. The results of deformation behavior of PE pipes are also indicated in differential settlements and earthquakes. The lifetime of plastic pipes for hot water supply and space heating were also evaluated by the stress rupture tests. A 30-year-or-more service life of the system for central heating will be guaranteed at 90 degrees C under an inner pressure of 0.25 MPa.
VISCOELASTIC PROPERTIES OF EPOXY AND VINYL ESTER NANOCOMPOSITES
The influence of different nanoparticles (nanoclay silicon carbide) concentrations on viscoelastic properties of vinyl ester and epoxy nanocomposites and nanofilled conventional fiber reinforced polymers were studied using Differential Mechanical Thermal Analysis (DMTA). The shift of the glass transition temperature with addition of nanoparticles was detected. The dependencies of storage and loss moduli on temperature on type of nanoparticles and on their concentrations are compared. Maximal tangent of mechanical loss angle was found changed with concentrations of nanoparticles.
FAILURE OF HUMAN BIOPOLYMERS
Failure of Human Biopolymers was introduced to the SPE Failure Analysis and Prevention Special Interest Group at the 2009 ANTEC. It broadens failure of synthetic polymers (plastics) to include biopolymers that control human life. It is a vast field in which synthetic polymers and human biopolymers intersect. Both polymer types share susceptibility to failure by oxygen, free radicals, UV and X-ray radiation, heat and stress. Combining each type with the other benefits both. The basics will be reviewed briefly and other aspects of the subject will be presented.
A STUDY OF THERMALLY AND FLOW INDUCED RESIDUAL STRESSES IN INJECTION MOLDING
During the injection molding process mold filling may introduce residual stresses. And the sequential cooling process may result in thermal stresses. Some cases show flow induced residual stresses dominate the final stresses. Sequential multi-component molding is one of good examples of thermal stresses. On the other hand in the higher speed injection molding cases higher shear stresses may be the major contribution to final residual stresses.
EFFECTS OF STEAM EXPLOSION CONDITIONS ON THE MECHANICAL PROPERTIES OF LDPE/COTTON BAST COMPOSITES
The effects of cotton bast (CB) content and steam explosion parameters (including steam pressure, holdup time, and moisture content) on the mechanical properties of low density polyethylene (LDPE)/CB composites were investigated. The results show that LDPE/steam exploded cotton bast (SECB) composites show superior tensile and flexural properties compared with pure LDPE and LDPE/unmodified CB composites. The superficial area of CB is increased by steam explosion pretreatment, thus enhancing the mechanical properties of composites.
ELECTRICAL, THERMAL, AND TENSILE BEHAVIOR OF CARBON NANOTUBE/POLYCARBONATE COMPOSITES
Carbon nanotubes (CNT) are effective at increasing the electrical conductivity of polymers at low loading levels without compromising the resulting composite's mechanical properties. In this study, varying amounts (2 to 8 wt%) CNT were added to polycarbonate and the resulting composites were tested for electrical, thermal, and tensile behavior. The percolation threshold was < 1.4 vol % CNT. The addition of CNT to polycarbonate increased the composite electrical and thermal conductivity and tensile modulus.
SLIDING WEAR OF POLYMERS: REVIEW OF MECHANISMS TEST METHODS AND EXPERIMENTAL DESIGN
An overview of sliding wear testing of polymers is presented. The primary wear mechanisms for polymers are reviewed. Common wear test methods and other experimental design considerations are discussed. In addition metrics for comparing the wear performance of materials and their advantages and disadvantages are discussed. Since the results of wear testing depend on many different variables careful experimentation is required to obtain meaningful data.
NUMERICAL PREDICTION OF THE FLOW OF COEXTRUDED POLYMERS IN A TUBE
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.
DYNAMIC TEMPERATURE MEASUREMENT IN POLYMER PROCESSING
The use of a fast responding infrared thermometer enables to measure the mass temperature inside the screw channel and the resultant profile over the screw length during the plasticizing process. With a response time of 10 milliseconds this IR-Thermometer is more than 1000 times faster than conventional thermometers.
INSTRUMENTATION AND CONTROLS INVENTIONS AND INNOVATIONS IMPACTING THE POLYMER PROCESSING INDUSTRY
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.
BEYOND THE BLING: THE DEVELOPMENT OF DECORATIVE PVD/UV COATING SYSTEMS
Several market and technological developments occuring at the same time are resulting in a surge of interest and development of systems that utilize both decorative physical vapor deposition (PVD) and coatings that utilize ultraviolet light curing mechanisms.
REBUILDING A PLASTIC ENGINEERING CAREER IN YOUR FOURTH DECADE
Downsizing is affecting technical employees in mature industries, such as plastics. This paper examines the statistical probability of being impacted by these organizational changes. Strategies are presented to plan for the financial, professional and emotional impacts. If properly planned, rebuilding a technical career can be a rewarding experience.
PROCESSING COSTS AND ENVIRONMENTAL IMPACT OF BIO-PLASTICS
This work studied bio-plastics such as polylactic acid (PLA) and protein based plastics form corn and compared to petroleum based plastics such polyethylene (PE) and polystyrene in terms of their ecological as well as economical performance from a 'Cradle to Grave' perspective. This study included energy input, emissions output of green house gases and costs from their life cycle steps of raw material acquisition to the final product disposal. It was found that products manufactured from bio-based feedstocks were relatively higher in cost, they resulted in less green house gas emissions.
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