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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TROUBLESHOOTING THE CO ROTATING TWIN SCREW EXTRUDER
Twin screw extrusion technology originated in the early 20th century and it revolutionized material compounding. The technology is used in the polymer, chemical, food, and recently in the pharmaceutical industries. Considering the numerous materials twin screw extrusion can operate with, it is evident that each process behaves uniquely. The problems that occur during these unique processes can be solved or prevented using similar guidelines and strategies. The following paper provides a strategy on successfully troubleshooting the co-rotating twin screw extruder and it offers possible solutions to several problematic scenarios that frequently are experienced.
IMPROVING SURFACE QUALITITY OF FOAMED POLYCARBONATE (PC) PARTS USING WATER AS THE PHYSICAL BLOWING AGENT
This paper presents a new process for producing microcellular injection molded plastic parts using water as the physical blowing agent and micro-scaled particles as the cell nucleating agents. Distilled water with dissolved salt were fed through the hopper of an injection molding machine and mixed with polycarbonate (PC) in the machine barrel. Dog-bone bars were molded with different shot volumes, water/salt solution feed rates, and salt concentrations. The resulting surface roughness and microstructure were compared with conventional solid and microcellular injection molded parts.
MECHANICAL PROPERTIES OF CYCLOALIPHATIC TEREPHTHALATE CO-POLYESTER CLAY NANOCOMPOSITES
Polymer nanocomposites have been studied extensively and can provide many benefits, including enhanced mechanical, barrier and fire properties. This paper studies the effect of montmorillonite nanoclay in a primarily amorphous cycloaliphatic terephthalate co-polyester system. The measured tensile properties show increased stiffness coupled with retention of ductility (elongation at break) at low nanoclay loadings, contrary to expected trends. The morphology of these materials was analyzed in an attempt to understand the unusual effects of the nanoclay in this case.
GENIOPLAST® PELLET S - PERFORMANCE ADDITIVE FOR AUTOMOTIVE INTERIOR COMPOUNDS
Amongst the performance additives for property enhancement and improved processing for polyolefins, scratch resistant additives, especially for the automotive interiors have become very attractive. Increased amounts of polyolefins are being used in different components in cars, and while the general performance is good, there are ever more stringent requirements that need to be met. This paper is going to present testing data of a commercially available silicone-based pellet, GENIOPLAST® Pellet S in comparison to reference samples, as well as other silicone and organic materials currently used in these applications.
STUDY ON ENVIRONMENTAL STRESS CRACKING BEHAVIOR OF INJECTION MOLDED POLYCARBONATE PARTS UNDER DIFFERENT PROCESSING CONDITIONS
The environmental stress cracking (ESC) behavior of injection molded polycarbonate (PC) plates in carbon tetrachloride (CCL4) was investigated. Molecular orientation was determined by birefringence measurement, which was used to study the effect of microstructure on crack development. It has been found that crack occurred in the edge surface of the molded PC plates after immersed in CCL4. The crack formation and location was correlated with molecular orientation and residual stresses of the parts. The effects of processing conditions on ESC behavior of molded PC parts were also elucidated in terms of microstructural analyses.
AN INVESTIGATION ON THE EFFECT OF SURFACE CHARACTERISTICS ON ADHESION BETWEEN POLYMER MELTS AND REPLICATION TOOLS
Understanding interfacial characteristics between a polymer and its associated tool surface is critical to successful optimization of processes such as injection moulding, embossing and extrusion used to produce polymer parts. One of the factors characterizing the strength of the polymer-tool interaction is the adhesion energy and it is specific for a particular polymer-tool pair. Its magnitude depends upon the tool material, tool coating and surface contamination, where relevant, polymer chemical structure, processing conditions and the surface roughness of the tool substrate. This paper presents the results of an experimental study aimed at determining the effect of selected tool surface characteristics on the work of adhesion, by measuring contact angles of polymer droplets on the surfaces. The experimental set-up, selection of test parameters and main challenges faced to date are described and experimental results presented.
NEW TECHNOLOGY FOR ANTI-YELLOWING AND WEATHER RESISTANT PEARLESCENT WHITE MICA BASED PIGMENTS
This Paper will review the newest Anti-Yellowing and Weather Resistant WHITE Pearlescent Pigment based on Mica. This NEW AY-W (anti-yellowing and Weather resistant) pigment will be called experiment #1 AY-W , for ease of reference . This New pigment consists of a mica platelet coated with titanium dioxide (TiO2). It is just this TiO2 coating that can contribute to yellowing under certain conditions. Through a revolutionary technology, a new product that has encapsulated the TiO2 surface with an additional coating to make it less reactive. Now your plastic and print applications can maintain a long-lasting silver-white appearance.
A REACTION-DIFFUSION MODEL DESCRIBING ANTIOXIDANT DEPLETION IN PE-CLAY NANOCOMPOSITES UNDER THERMAL AGING
Antioxidants can increase durability of polyethylene, and clay nanoparticles can improve the mechanical properties of polyethylene. This paper describes models that predict oxygen and antioxidant diffusion and reaction with free radicals in thick polyethylene and its clay nanocomposites. Predicted antioxidant degradation is compared to experimental antioxidant profiles measured by oxidative induction time. To achieve qualitative agreement between model and experimental results, the initial free radical concentration in nanocomposite has to be higher than in polyethylene.
HYDROLYTIC DEPOLYMERIZATION OF PET DURING EXTRUSION
Depolymerization of PET to high molecular weight oligomers could introduce opportunities to re-use PET waste via chemical recycling. Hydrolysis of PET in the presence of water/steam was carried out in a twin screw extruder, at barrel temperatures of 265°C and 300°C with screw speeds of 20, 60 and 200 rpm. The extruded products were characterized to determine intrinsic viscosity (IV) of samples as well as thermal properties (DSC) and rheological behavior. Proton nuclear magnetic resonance (HNMR) analysis was used to estimate carboxyl end group content. The results showed that the average molecular weight (Mw) of extruded polymer was reduced to less than 10,000 g/mol
A NEW IMPROVED FLOW HIGH STRENGTH POM COPOLYMER
POM or polyoxymethylene is an engineering resin used primarily for injection molded parts that replace metal. POM’s usefulness is derived from the combination of strength, stiffness, toughness, creep resistance, and lubricity. POM homopolymer and copolymer compete in this market space. Homopolymer grades have some mechanical advantages while copolymer grades have better thermal and chemical stability. In 2010 Ticona introduced a new high strength, high viscosity POM copolymer with the mechanical properties of a typical homopolymer, while maintaining copolymer stability. This paper introduces an improved flow, high strength POM copolymer, its property profile, salient features and potential applications.
ADDING VALUE TO PRODUCT DESIGNS: THE CONVERGENCE OF DESIGN PATENTS AND TRADE DRESS
Securing the right form of intellectual property protection is sometimes overlooked during the development of a new product. However, intellectual property protection should not be ignored. The right combination of patent and trademark protection can give a company long-term control over its invention. For lifetime protection of product designs, companies should consider using design patents and trademarks together. Design patents can initially be used to exclude others from copying the design. This will provide a company time to develop consumer recognition in the design so that it can continue to be protected as a trademark even after the patent expires.
BENEFITS OF SERVO ULTRASONIC WELDERS TO MEDICAL INDUSTRY- A CASE HISTORY
The introduction of servo-driven ultrasonic technology, with Dukane’s iQ Series Servo system, provides a new level of control to an already fast and flexible welding method. This breakthrough has allowed greater consistency than ever before possible with ultrasonic welding, one of the most widely used processes for bonding polymers. In the medical industry, there is a great need for reliable weld results in production. Some of the most forward thinking manufacturers of medical parts have already benefitted from servo-driven ultrasonic equipment. One of these manufacturers, Value Plastics, A Nordson Company, a leader in the design and manufacture of plastic tube fittings and connectors, began working with Dukane's servo-driven ultrasonic welder in the second quarter of 2010. Already, they have used the servo welder in full production projects and are completing the research and development phase for additional jobs. Every one of these projects has shown improved weld consistency over the previously employed pneumatic welders.
KINETIC MODEL OF GLASS FIBER BREAKUP IN COROTATING TWIN SCREW EXTRUDER
The damage of glass fibers at various conditions was investigated by varying viscosity, screw speed, screw configuration and glass fiber length and diameter. Increasing screw speed, melt matrix viscosity and glass fiber concentration were found to increase the extent of fiber breakage. Based on our experimental data and Euler buckling theory the composite modular kinetic model to describe glass fiber damage was developed. Regions of major and minor fiber breakage in co-rotating twin screw extruder were established. The simulation program based on experimental data and kinetic constants was developed. Comparisons were made between simulated results and experimental data.
EFFECT OF VARIOUS ADDITIVES (TALC, NANOCLAY, AND NANOSILICA) ON EXTRUSION FOAMING OF PLA THROUGH CRYSTALLIZATION
The dependency of PLA extrusion foaming on three different fillers (nanoclay, nanosilica, and talc) and their impact on crystallization has been investigated. PLA with nanofillers showed smaller cells due to more nucleation sites, whereas talc showed bigger cells. Nucleated crystals can be a secondary reason for the increase of cell density for all cases. However, increasing the filler content decreased the cell size in the case of talc due to the higher crystallization rate, which creates bigger nucleation sites with bigger cells
RELATIONSHIP BETWEEN RESIDUAL STRESS AND FLAME RESISTANCE OF POLYCARBONATE
There are growing interests in the area of flame retardant (FR) thermoplastic materials, especially in thin wall applications. Consistency in flame rating measurement is critical in FR resin development and commercialization. However, flame performances are difficult to assess due to a multiplicity of factors that influence the material behavior, such as, molding conditions, operator training and orientation of specimen during testing. In this study we have investigated the role of ? mold/barrel temperatures ? injection speed ? switch point ? holding pressure on flame properties of a Lexan* grade of polycarbonate so that we can eliminate/ reduce the effects of molding parameters during flame testing This was done by first investigating the effect of post molding residual stress on flame properties. It was observed that the such properties of are influenced by the post- molding residual stress profile built-in the bars and that such profile is in-turn influenced by the processing conditions.
FRACTURE TOUGHNESS AND SCRATCH BEHAVIOR OF POLYMERIC THIN FILMS
Two recent efforts on mechanical characterization of ductile polymeric thin films are presented. One is on fracture toughness determination of polyolefin thin films and the other is on scratch deformation study of laminated films for food packaging applications. Characterization of fracture toughness of ductile polymer thin films is nontrivial. It requires extreme care in sample preparation to avoid premature film damage, in fixture design to minimize out of plane film rotation, and in meaningful analysis to establish structure-property relationship. The essential work of fracture approach has been chosen for quantifying fracture toughness of ductile polyolefin films. Issues related to sample preparation, data generation and interpretation are discussed. Possible correlation between the fracture toughness and other industrial practices is also made. In the case of scratch test, it is found that the scratch performance correlates well with the field performance of the films. The usefulness of the scratch test for evaluating film structural integrity, adhesive strength between film layers, and laminate structural design optimization is discussed.
STRATEGIES FOR ACHIEVING HIGH EXPANSION FOAMS OF CROSSLINKED ETHYLENE-VINYL ACETATE (EVA) USING A CHEMICAL BLOWING AGENT
This paper investigates the foaming behaviour of crosslinked Ethyl-vinyl acetate (EVA) using a chemical blowing agent (CBA). In this study, foaming experiments were conducted using the chemically crosslinked polyolefin foamed BUN process, with the help of a compression molding machine. It was found that an optimum degree of crosslinking was needed to produce high quality EVA foams with high expansion ratios. A mountain-shape curve can be used to describe the relationship between the expansion ratio of the EVA foams and the crosslinking content. Furthermore, with more blowing agent used in the foaming process, the value of the optimum crosslinking content at the expansion ratio peak increases.
MECHANICAL PROPERTIES AND INTERACTION OF INDIVIDUAL NANOTUBES AND NANOPLATELETS IN EPOXY
We have investigated epoxy/MWCNT nanocomposites and propose that the primary role of the nanoparticles is to reduce stress concentrations at internal defect sites. This leads to improvement in ductility and tensile strength without affecting modulus. The shielding of internal defects may also allow synergistic interaction with secondary particles. This behavior is reported to promote improved fracture toughness in the presence of pre-formed thermoplastic particles, and substantially enhanced modulus and strength when coupled with exfoliated nanoplatelets.
THERMAL AND THERMOMECHANICAL BEHAVIOUR OF INJECTION MOLDED SOLID AND MICROCELLULAR POLYLACTIC ACID (PLA)/POLYHYDROXYBUTYRATE-VALERATE (PHBV) BLENDS
This paper investigated the thermal and dynamic mechanical properties of solid and microcellular injection molded PLA/ PHBV blends of different weight ratios. The properties were characterized by DSC and DMA. The results showed that when the content of PHBV exceeded 45% it could significantly affect the crystallinity of the PHBV and improve the G' for both solid and microcellular components. It was also found the Tg of the PLA phase decreased with increasing PHBV content.
ESTER FUNCTIONALIZATION AND STRUCTURAL MODIFICATION OF POLYPROPYLENE VIA SOLID-STATE SHEAR PULVERIZATION
Using solid-state shear pulverization, we have identified the potential to functionalize polypropylene by taking advantage of near ambient temperature reactions. Polypropylene was pulverized in the presence of benzoyl peroxide; under these temperature conditions the decomposition of benzoyl peroxide results in the formation of benzoyloxy radicals that react with the polypropylene chain, introducing ester functional groups onto the chain. Fourier transform infrared spectroscopy indicates that such functionality cannot be obtained using conventional high temperature processing methods.
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