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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OBSERVATION AND MODELING OF THE TENSILE BEHAVIOR OF RUBBER TOUGHENED POLYPROPYLENE
Impact modified polypropylene, which is a blend of polypropylene with an impact modifier such as ethylene propylene rubber, ethylene alpha olefin elastomers or styrenic based rubber, is commonly used for applications with impact resistant requirements. In addition to the shape, amount and size distribution of rubber particles, crazes give additional deformation after elastic deformation until the necking process. In this study, a quantitative modeling of tensile behavior of impact modified polypropylene based on a micromechanical model of crazing initiated from rubber particles is presented. An accurate prediction of the stress-strain relationship until necking is possible based on the proposed model.
MULTIVARIATE FAULT DETECTION FOR THE EXTRUSION PROCESS
Multivariate modeling methods such as Principle Components Analysis (PCA) and Projection of Latent Structures (PLS) are increasingly used for process control. A design of experiments was performed on an instrumented tubing extrusion process. Results were used to develop 14 unique PLS and PCA models. A blind validation was performed to evaluate the model sensitivity to 18 imposed process faults. Results indicate that multivariate techniques are well suited for detecting faults in the extrusion process, and that PLS models slightly outperformed PCA models. Identifying the root cause of the process fault was quite challenging and requires careful instrumentation and data analysis.
DEVELOPMENT OF POLYMER FOAMS - TRENDS AND SUSTAINABILITY
Fueled by global megatrends such as energy efficiency, the demand for enhanced heat insulation and light weight solutions is steadily increasing. Due to their unique properties, polymer foams are regarded as an ideal candidate for tackling these challenges. At a minimum of raw material consumption, cellular polymers are tailor-made, cost-efficient, sustainable solutions. Despite the already high performance of today's foams, their innovation potential is still far from being tapped. Novel materials and processes provide a pathway to superior products for existing and new applications. In this paper, BASF's approach of innovative and sustainable particle foam products will be presented.
EFFECT OF POLYMER MATERIAL AND GRADE WHEN INJECTION MOLDING MICROFEATURES ON A SINGLE PLATFORM
Injection molding offers high-rate production of microstructured polymer surfaces, but very few studies have investigated the effect of material properties on microfeature replication. In this work, three grades of three commercially-available polymers were used to investigate the effect of flow characteristics and transition temperatures on replication of microfeatures with complex geometries. The results showed no correlation between replication and melt viscosity, but suggested that solidification time and interfacial effects influenced replication even with microscale features.
UNDERSTANDING THE AFFINITY BETWEEN COMPONENTS OF WOOD-PLASTIC COMPOSITES FROM A SURFACE ENERGY PERSPECTIVE
To evaluate surface compatibility in wood-plastic composites (WPCs), the dispersion and acid-base components of surface energy of various thermoplastic resins (matrices) and several wood-based reinforcing materials were determined using inverse gas chromatography (IGC). The corresponding surface energy, work of adhesion, and work of cohesion were calculated based on the van Oss-Chaudhury-Good approach. Composite performance was analyzed by measuring tensile and flexural strengths according to ASTM standards. The results indicated that for the same type of filler, the mechanical properties of the composites increased when the ratio of the work of adhesion to the work of cohesion increased.
DETERMINATION OF FLOW PROPERTIES OF THERMOPLASTICS AT HIGH SHEAR RATES BY INSTRUMENTED INJECTION MOLD
The knowledge of real viscosity of polymer melt in the processing is one of the most important properties. During the flow in nozzle, runner system and in thin walled cavities of injection molding machines, both shear and elongation deformation processes are carrying out. An injection molding slit rheometer was designed with a series of slit and orifice dies. A shear and elongational viscosity calculation method has been developed. The temperature and pressure effect were investigated. The measured viscosity curves were compared with ones given by Gttfert and HAAKE equipments.
A POST-PROCESSING METHOD TO IMPROVE THE MECHANICAL PROPERTIES OF CARBON NANOTUBE/THERMOPLASTIC FIBERS
This research studies the effects of multi-walled carbon nanotubes (MWNT) on the mechanical properties of thermoplastic fibers. The primary materials investigated are Graphistrength C M1-20 masterbatch and polyamide 12 (Rilsan PA12 from Arkema). Fibers were melt spun with MWNT contents of 1.0 wt%, 2.0 wt% and 5.0 wt%. Tensile tests were performed with an Instron 5548 Microtester machine. Following those results, fiber samples were submitted to a post-drawing under different conditions of temperature, drawing speed and final elongation with a Br¬ckner biaxial stretching machine. Increase of at least 400% in the strength and Young's modulus of the fibers was observed.
MORPHOLOGY AND RHEOLOGICAL PROPERTIES OF POLY (BUTYLENE ADIPATE-CO-TEREPHTHALATE) AND POLY (LACTIC ACID)/CLAY COMPOSITES
This work studied Poly(butylene adipate-co-terephthalate) (PBAT) and polylactide (PLA) bends compounded with organically modified silicate layers. Compounds of 80% PBAT, 20% PLA and 3% organically modified silicate layers showed significantly improved modulus and enhanced thermomechanical performance compared to PBAT. Rheological analyses showed solid-like behavior for the melt, indicating formation of a network structure of the particles in the blend although the clay platelets were partially dispersed in PBAT matrix and a large portion of the platelets was located at the interface based on the electron microscopy analysis. Also the addition of organoclay reduced the dispersed phase domain size significantly.
HYBRIDIZATION OF THERMOPLASTIC POLY(LACTIC ACID) AND POLYOXYMETHYLENE COMPOSITES THROUGH MICRO-BRAIDING
Polymer melt blending would be difficult especially when two polymers are incompatible. Therefore, this study proposes a novel polymer blending technique by using the micro-braiding technology. Micro-braided yarns (MBY) were produced by continuously braiding resin yarns around a reinforcing jute yarn. These MBY were then wound around steel frames and compression molded to form unidirectional composites. The effect of braiding sequence on the blend homogeneity, fiber-matrix interfacial strength and mechanical performance of the composites was evaluated. It was found that hybridization technique through micro-braiding was effective in blending of the matrix resins and increased the mechanical properties.
BRAIDING PULTRUSION SYSTEM FOR CONTINUOUS FIBER REINFORCED THERMOPLASTIC COMPOSITE
In this study, thermoplastic composite beams with an L-shaped Cross-section were manufactured by the braid-trusion method. This continuous manufacturing process combines the braiding performing technique and the thermoplastic composite pultrusion process to fabricate constant cross-section products. The yarn precursor was a blend of carbon filaments and polyamide 66 filaments in a parallel hybrid arrangement. The filling is the ratio between the area of material pulled through the die and the internal area of the die. Pultrusion experiments were performed at different filling ratio by modifying the braid architecture and at different pulling speeds.
RHEOLOGICAL CHARACTERIZATION OF POLY(ETHYLENE TEREPHTHALATE) RESINS USED IN THE BOTTLING INDUSTRY
Poly(ethylene terephthalate) (PET) is extensively used as the packaging material for bottled beverages. Qualifying PET properties from different suppliers is an important way to ensure the performance of manufactured bottles. In this study, we used dynamic melt rheology to determine the zero shear viscosity and the molecular weight of the polymer. This rheological characterization aids in understanding the properties of each resin in the molten phase during processing. Finally, the performance of PET bottles made from different resins was evaluated through the top load capacity.
FURTHER UNDERSTANDING OF MECHANISM OF ANIONIC POLYMERIZATION THROUGH BULK POLYMERIZATION OF STYRENE AT HIGH TEMPERATURE
A self-designed device consisting of a tubular reactor and two precision metering pumps was used for investigating the kinetics of the anionic bulk polymerization of styrene (St) at high temperatures. The results confirmed that the inactive aggregation of n-butyllithium at a low temperature (<20§C) could be transformed into the active species and initiate the polymerization of St at a high temperature (60§C). The GPC results indicated the existence of aggregated active species containing 6 polystyryllithium molecules. The effects of polar regulator THF or temperature on the kinetics of anionic polymerization were also identified, which improves the understanding of polymerization mechanism.
MELT EXTRUSION - SHAPING PHARMACEUTICAL DOSAGE FORMS
Melt extrusion has been an established industrial manufacturing technology for over 50 years. Today, applications of melt extrusion for pharmaceutical production range from controlled release systems to oral bioavailability enhancement and show potential for small molecules and therapeutic peptides. The emergence of novel drug delivery systems and routes of administration have allowed for the expansion of melt extrusion applications within the pharmaceutical industry. This review presents an overview of the processing technology and also four major areas of application: bioavailability enhancement; oral controlled release; melt granulation; and the production of advanced controlled release dosage forms.
FLOW EFFECTS ON REPLICATION OF INJECTION MOLDED MICROCHANNELS
Injection molding is an attractive method of manufacturing of microfeature-enabled devices, but the effect of tooling design has yet to be fully explored. This work investigated the effects of flow direction on the replication quality of complex angled microchannels. The channel designs utilized two different angles and three line widths. The design and orientation of the microfeatures significantly affected the ability to fully replicate feature depth, but not the feature definition. Design and orientation, however, did not have as large an effect on replication quality as feature aspect ratio.
FRACTOGRAPHIC CHARACTERIZATION OF PIPE AND TUBING FAILURES
Plastic piping systems are an important commercial product used in a wide variety of applications. Because of the diversity of applications and wide range of material used to produce pipes, many different types of failures can result in service. Evaluating these failures through a systematic analysis program allows an assessment of how and why the pipes failed. An essential portion of the failure analysis process is the fractographic examination, which provides information about the crack origin location, and the crack initiation and extension modes. The focus of this investigation was to characterize the surfaces of intentionally cracked laboratory samples.
FRACTURE BEHAVIOR AND OPTICAL PROPERTIES OF MELT COMPOUNDED SEMI-TRANSPARENT POLYCARBONATE (PC)/ALUMINA NANOCOMPOSITES
Two different molecular weight SMA copolymers were employed to pre-treat and coat Al2O3 nanoparticles to facilitate dispersion in a PC matrix. Melt compounding was done using a K-mixer. The low MW SMA polymer coating produced better dispersion of nanoparticles in the PC nanocomposites, resulting in fairly high light transmittance even through 2 mm thick specimens. The addition of 1 wt% well-dispersed nanoparticles improved the impact strength during brittle fracture of the PC/alumina nanocomposites through the formation of multi-level microcrazes induced by the nanoparticles. However, further increasing the alumina nanoparticle content altered the energy dissipation behavior, resulting in less effective reinforcement.
AN ENGINEERING MODEL FOR INTERPRETING RCP TEST RESULTS FROM PLASTIC PIPE
Both of the standard methods used to test plastic pipe for resistance to rapid crack propagation (RCP) evolved primarily from experience with polyethylene pipe for gas distribution. Advocates of other pipe materials (e.g. polyamide) have questioned the applicability of these methods and of the supposedly material-independent correlation factor which correlates their results. Discussion is hampered by the complexity of gas-driven RCP and the unavailability of an accepted mathematical or computational model. Using a straightforward new engineering model, we present new results on the influence of backfill, of residual stress and of water pressurisation.
FIBER MOTION IN FOUNTAIN FLOW AND ITS RELATION TO FIBER FREE REGIONS AT THE SURFACE OF INJECTION MOLDED PARTS
Mold filling of short fiber reinforced plastics play a significant role on part quality. In injection molding the fountain flow dominates the mold filling process. In this work, a mechanistic fiber model is presented, which is coupled with a simulation of the fountain flow region using the Radial Basis Function technique. The results show how the fountain flow influences the fiber content in the outer surface of an injection molded part. Therefore it plays a major role on the final fiber position and on the fiber free region or skin at the surface of a part.
CHARACTERIZATION OF SINTERED POLYLACTIDE (PLA) SCAFFOLDS FOR BONE TISSUE ENGINEERING
This study represents preliminary work on characterizing powder-sintered porous polylactide (PLA) scaffolds intended for use in bone tissue engineering. PLA powder and sintered material were characterized by DSC and GPC. The morphology and mechanical properties of cylindrical scaffolds were determined by SEM and compression testing. Scaffolds of two average particles sizes were fabricated using six different processing conditions. Values of the apparent elastic modulus ranged from 25.9 ?ñ 3.08 MPa to 97.3 ?ñ 11.5 MPa, with the maximum occurring in samples sintered for 15 minutes at 170 C. The observed modulus correlates well with the stiffness of human cancellous bone.
IMPROVING THE ENERGY EFFICIENCY OF A BARREL HEATER - COOLER DESIGN FOR HIGH TEMPERATURE SINGLE SCREW EXTRUSION APPLICATIONS
The energy efficiencies of two different types of extruder barrel heater- cooler configurations for a single screw extruder were compared. A conventional air cooled, electrical heated system commonly used in many extrusion applications today was compared to a new energy efficient heater-cooler designed to reduce both radiant and convective heat losses. Each heater-cooler design was examined over a large operating range that simulated the performance of a single screw extrusion process. The new design was found to be significantly more energy efficient compared to the conventional design.
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