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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EFFECT OF CRYSTALLIZATION AT FILM INTERFACE IN HEAT SEALING PROCESS
Heat sealing is a general technique used for joining polymer film. The mechanism was not clarified. Heat seal temperature at sealed film interface is an important factor to control heat seal properties. In this study temperature profile at sealed film interface in-situ heat seal process was precisely measured by a fine thermocouple. Molecular structure development at film interface was investigated by WAXD and DSC. In heating and cooling process temperature profiles were obtained. The heating and cooling rate depended on crystallization behavior in heat sealing process. We concluded that crystallization is a major factor to affect heat seal properties.
MANUFACTURING OF AGAROSE-BASED CHROMATOGRAPHIC ADSORBENTS WITH CONTROLLED PORE AND PARTICLE SIZES
The effect of ionic strength and quenching temperature on the mechanical properties and structure of agarose-based chromatographic adsorbents in micro-beads for bioseparation was investigated. The pore size/size distribution of the beads was measured by analysis of their AFM images. Their mechanical properties were determined by a micromanipulation technique based on compression of single micro-particles. It was found that the mean pore size and stiffness of agarose beads increase with ionic strength and slow cooling. These two parameters do not affect the particle size/size distribution.
THE PREDICTION OF INJECTION MOULDED PRODUCT MASS THROUGH PROCESS SIGNALS
The injection moulding process has a complicated set of process parameters and is subject to variations over time resulting from material, environmental and machine component changes. In order to maintain product quality it has been proven that monitoring the process signals is beneficial towards identifying possible changes in the moulded product. Here, the process signals (melt pressure, temperature and screw displacement) are utilised along with material pressure-specific volume-temperature (pvT) characteristics to estimate the moulded product mass. The successful validation of this method presented over a range of processing conditions.
THE EFFECT OF NANOTUBE FEEDING POSITION IN TWIN-SCREW EXTRUSION OF PP BASED NANOCOMPOSITES
The influence of feeding conditions of multiwalled carbon nanotubes (MWNT), namely Baytubes C150P and Nanocyl ›NC7000, into polypropylene (PP) was investigated with respect to achieve high electrical conductivity and suitable nanotube dispersion. Both MWNT types were fed at selected concentrations either in the hopper of the twin-screw extruder or using a side feeder under otherwise same conditions (rotation speed, throughput, temperature profile). The electrical resistivity was measured on pressed plates and injection moulded samples and the state of the filler dispersion was studied using transmission light microscopy (LM). Mechanical properties, like tensile and impact strength were characterised on injection moulded samples.
EFFECTS OF GAS AND D-LACTIC ACID CONTENTS ON THE STRUCTURE AND PROPERTIES OF MICROCELLULAR INJECTION MOLDED POLY (LACTIC ACID)
This paper investigated the effect of gas content on the tensile properties and microstructure of two grades of poly (lactic acid) (PLA) that differ in terms of D-lactic acid (D-LA) content. SCF Nitrogen (N2) was used as the physical blowing agent for molding microcellular PLA tensile bars. The properties of microcellular PLA were found to be dependent upon the D-LA content. Under the most favorable conditions, high cell density and small cell size was obtained. A high cell nucleation rate and a high degree of crystallinity with different levels of D-LA enhanced microcellular structure formation at higher levels of N2.
SIMULATION OF EPP BEAD MANUFACTURING IN BATCH FOAMING PROCESS THROUGH HIGH PRESSURE DIFFERENTIAL SCANNING CALORIMETER (HPDSC)
To simulate the evolution of the melting behavior of polypropylene (PP) during the manufacturing of expanded PP bead foams (EPP) through batch process, a high pressure differential scanning calorimeter (HP-DSC) machine was used. The EPP bead foam has two original melting peaks which are suitable for bead foams during the steam chest molding process to produce final products with well sintered beads and good firmness. The influence of various saturation temperatures, time, and pressure on the double crystal melting peak creation is investigated in this work. The results can bring an overestimation of the optimized parameters for the batch process.
EFFECTS OF PROCESS PARAMETERS ON ADDITIVE ASSISTED LASER SINTERING OF POLYETHERETHERKETONE
New approaches have been done to develop the selective laser sintering process and materials. Within this process a layer to layer fusion plays an important role to achieve good bonding and part properties. This paper deals with the additive assisted laser sintering of polymers, which allows an adjustable sintering depth and independency from the optical absorption behavior of the polymer. Within this study an approach is presented to correlate the observed sintering behavior of polyetheretherketone with process and material parameters. A statistical model has been used to describe a correlation and identify the important parameters and effects within the process.
POLYPHENYLENE ETHER MACROMONOMER: X. VINYL TERMINATED TELECHELIC MACROMERS
Unique low molecular weight polyphenylene ether telechelic copolymers (PPE-M) were designed for use in thermosetting resins. Indeed, PPE macromonomers have been heralded as a breakthrough in the search for materials that broadly enhanced performance of thermoset materials. For example, the phenolic terminated macromer gave broad enhancements of performance with epoxy resins and cyanate esters. Another important class of thermoset resins involves vinyl or unsaturated monomers. Therefore, various vinyl-terminated PPE macromonomers were prepared and their performance was quantified in vinyl-based thermoset resins. The vinyl groups were allyl, methacryl, allyl hydroxyl propyl, and vinyl benzyl.
INFLUENCE OF THE TOOL MATERIAL ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF PMMA LAP JOINTS WELDED BY FRICTION SPOT
The development of new polymer welding techniques is currently a key subject in the field of science and technology of joining. Industrial sectors such as the automotive, airspace and civil engineering are examples where polymer welding is largely applied. Recently, the feasibility of the friction spot welding process was demonstrated on thermoplastics. The objective of this work was to evaluate the influence of tool material on the properties of polymeric friction spot welds on poly (methyl-methacrilate). Microstructure, lap shear resistance and fracture mechanisms of single lap joints produced with stainless steel and titanium tool materials were investigated for this purpose.
GLASS FIBRE-REINFORCED POLYETHYLENE COMPOSITES IN ROTATIONAL MOULDING
Fibre-reinforced mouldings are of growing interest to the rotomoulding industry through their outstanding price/performance ratio. However, a particular problem that arises when using reinforcements in this process is low shear, good mixing of resin/reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcements segregating out of the powder to lay-up on the inner part surface. In this paper we report on studies to incorporate glass-fibres into rotomoulded parts. Results indicate that pre-compounding is necessary to gain performance enhancement and the single-layer part made from glass-reinforced, pre-compounded powder exhibited the highest tensile and flexural modulus.
EXPERIMENTAL STUDY OF THE EFFECT OF MOLDING AND COATING ON THE DURABILITY OF OPTICAL POLYCARBONATE PRODUCTS
Polycarbonate (PC) has become widespread in public transportation vehicles, lenses, as well as glazing due to its light weight, outstanding unique engineering properties, and extreme levels of toughness and ductility. PC is usually injection molded, or sometimes extruded and thermoformed, into desired 2D/3D complex shape, then applied with hardcoats to improve its weathering and abrasion resistance performance. The effect of molded-in stress on the brittleness and microcracking of silicone-based hardcoats during the coating process was quantified, and the impact resistance performance of weathered and aged polycarbonate samples was studied with different coating system.
TENSILE BEHAVIOR OF SYMMETRIC AND ASYMMETRIC STRUCTURAL COMPOSITE FOAMS
Structural composite foams were produced by enclosing a foamed core between two composite skins. The effect of layer thickness and composition was studied using different amounts of chemical blowing agent (1 and 1.5%) and flax fibres (0, 15, 30%). The samples were produced by compression molding and characterized in tension. Videos were also taken. The results show that for symmetric structures, both skins break simultaneously, whereas asymmetric foams present two consecutive skin breaks. As expected, increasing CBA content decreased all the properties, while increasing fibre content led to higher Young's modulus and lower strain at break.
IN-PROCESS MONITORING OF DRUG LOADING DURING TWIN SCREW EXTRUSION OF PHARMACEUTICAL POLYMER COMPOUNDS
Near infrared spectroscopy has been used to characterize a solid dispersion of the poorly soluble antidiabetic drug glipizide in a polyethylene oxide (PEO) matrix during twin screw extrusion. A range of drug loadings and extrusion temperatures were examined. All compounds exhibited a significantly improved rate and extent of drug dissolution compared to the pure drug and physical mixtures. NIR spectroscopy was found to provide a clear indication of drug loadings, highlighting the potential to incorporate the technique into a real-time quality control system.
EVALUATION OF CHEMICAL RESISTANCE OF POLYMETHYLMETHACRYLATE TO AUTOMOTIVE WINDSHIELD WASHER FLUID
Polymethylmethacrylate material (PMMA) is used in several automotive exterior applications such as exterior appliques and lighting lenses. There are different grades of PMMA that are commonly used for automotive exterior applications. This paper examines the chemical resistance of different grades of PMMA that are commonly used in automotive exterior applications to automotive windshield washer fluid under different strains. The exterior automotive parts are subjected to harsh environments. The parts are exposed to a range of environmental elements such as chemicals, sunlight, rain, snow, cold and hot temperatures. This study focuses on the chemical exposure of PMMA to windshield washer fluid.
HOT PLATE WELDING OF WOOD PLASTIC COMPOSITES BASED ON POLYVINYLCHLORIDE AND POLYPROPYLENE
In this work fundamental investigations of the weldability of wood-plastic composites (WPCs) with high proportions of fillers were conducted at the Sueddeutsches Kunststoff-Zentrum (SKZ) using a hot plate welding process. The objectives of this research work were not only to obtain investigations about suitable welding parameters and possible process optimisations in relation to the welding apparatus and the weld strength, but also to determine the achievable weld quality regarding the lack of standards and guidelines worldwide on this field. A welding apparatus for the welding of WPC parts was designed and optimized for this purpose.
UNDERSTANDING THE EXISTENCE AND MAGNITUDE OF FLOW INDUCED SHEAR IMBALANCES IN LIQUID SILICONE RUBBERS
The intent of this study is to investigate the existence of shear imbalances when using Liquid Silicone Rubbers (LSRs) in Injection Molding. This study will compare the effects of both intra-cavity and inter-cavity shear imbalances through the use of an 8-cavity mold with a geometrically balanced runner system. A simple bar was used as the test part to investigate the existence of variation in filling patterns due to shear imbalances. The study showed through the determination of flow groups and comparison of the part weights from these groups that shear imbalances exist in geometrically balanced runners with LSR.
INVESTIGATING THE FOAMABILITY OF LOW MELT STRENGTH HOMOPOLYMER LINEAR PP AND COUPLING AGENT BY USING NANOCLAY
In this work, the feasibility of producing microcellular foam by using linear polypropylene and different nanoclay contents has been investigated. A twin-screw extruder was used for nanocomposite compounding. An X-ray diffraction machine was utilized to observe the dispersion of nanoclay within the matrix. Shear viscosity of the samples was measured as well. Also, a single screw extruder was used for foaming by using 5% supercritical CO2 in various die temperatures. SEM was utilized to explore the morphology of the foamed samples and foams with high expansion ratios of about 20 and high cell density of about 108-9 cells/cm3 were achieved.
EFFECT OF THE PROCESSING VARIABLES ON THE MECHANICAL PROPETIES AND MORPHOLOGY OF PP/MODIFIED CLAY NANOCOMPOSITES
In this work, the screw speed and the feeding rate of Polypropylene/clay nanocomposites was investigated. The nanocomposites were prepared in a co-rotating twin screw extruder under different processing conditions, and characterized by X-Ray Diffraction, mechanical properties, Optical Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy. The results showed that the Brazilian sodic bentonite clay was successfully modified with the surfactant. Higher screw speed and shear rate promoted the most favorable condition, where it was possible to obtain clay lamellae exfoliation. The mechanical properties were not influenced by the change in the processing conditions (screw speed and feeding rate).
POLY(LACTIC ACID) ADDED WITH TOCOPHEROL AND RESVERATROL. I. OPTICAL, PHYSICAL, THERMAL AND MECHANICAL PROPERTIES
Poly(lactic acid) (PLA) films containing two natural antioxidants, ñ-tocopherol (ñ-TOC) and Resveratrol with various concentrations were fabricated by melt compounding and compression molding processes. The influence of the antioxidants on the optical, color and UV-VIS light transmission properties of the films was analyzed. Thermal and physical properties of films were also assessed. Films with two antioxidants showed a yellowish brown color, and the lightness was influenced by the presence of the antioxidants. Thermal properties were also significantly changed with addition of antioxidants.
MODELING OF ANISOTROPIC POLYMERS DURING EXTRUSION
It is known that a liquid crystal polymer (LCP) melt aligns in the direction of the shear flow when it passes through an extrusion die. This alignment causes thin films of the anisotropic LCP material to display different properties in different directions. To overcome this problem, many complex die design technologies have been developed that involve moving surfaces. However, there is a clear need to develop a method of predicting crystal orientation (alignment) to aid in die design. This paper investigates different modeling methods, and develops a numerical modeling technique using FLUENT.
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