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.
A new thermally conductive compound available in a variety of crystalline thermoplastic matrices can be used to improve material management in a variety of industrial and consumer applications, including heat sinks, thermostats, heat exchangers, and as radiant heating coils. Replacing heavy metal shrouds and non-recyclable metallized plastics, the new compounds are non-corrosive, can be processed on all conventional thermoplastic equipment, and can even be melt reprocessed for in-plant recycling. A variant on the technology also produces compounds that are simultaneously thermally and electrically conductive.
Unknown properties of recycles are the problem in the field of recycling thermoplastics. The off-line determination of selected properties (basicpolymer, colour and mechanical properties) is not sufficient to qualify recyclates. Important for the characterization is an almost complete knowledge of the material properties when producing recyclates that are supposed to be competitive as construction materials. Therefore the implementation of tools for the detection and assurance of material properties on-line during extrusion is a promising conception. This presentation shows and discusses the basic ideas of on-line property determination, the achieved results of material determination, and the resulting process control.
This paper is about upgrading tooling that has been built many years ago, or simply to make mouldings to suit our type of manufacturing operation. When these tools were built the techniques and technology used was the latest available to the polymer technologist designer, mould shop and toolmaker. Using tooling technologies as the starting point, I have added management, and more so Leader techniques to show how production can be changed and opportunities gained, by modernising; towards increasing production, saving money, material, and bringing about attitudinal changes. This paper will concentrate on the following topics, and show details where this revisiting process has changed tools and people to make them more motivated about competition, which will result in profitable, faster cycling and be better suited to today's fast operational needs.
PET foams of variable densities, (1 g/cc to 0.2 g/cc), based on virgin and recycled material were produced by extrusion with physical or chemical blowing agents and evaluated as low density core in sandwich panels having M/F impregnated paper or flame retardant mineral reinforced PET as skin faces. Flexural and shear stiffness of the laminates were determined by variable span three point bending. Panels were also tested for thermal and moisture stability and compared with competitive sandwich constructions based on PVC foam, flake board, particleboard and plywood. Potential applications of the PET based laminates in building and construction are presented.
The incompatibility of polypropylene (PP) and high density polyethylene (HDPE) is a source of industrial problems for recycling post-consumer polyolefins. Blends of PP and HDPE with peroxide and 3 vector fluid additives have been prepared in a co-rotating reactive twin-screw extruder. Compatibilization has been examined by stress-strain tests, impact tests and scanning electron microscopy (SEM). Molecular weight of the blends has been evaluated by gel permeation chromatography (GPC). An increase in elongation at break and impact resistance of some reactive blends compared to the mechanical blend was observed, with some links between the phases, as revealed by SEM.
Post-consumer high-density polyethylene is commonly used to make lumber products, but such products are substantially less stiff than wood lumber. Using a two factor full factorial experimental design, the effects on tensile, flexural and impact properties of adding ground recycled fiberglass composite in combination with wood flour to high density polyethylene were investigated. The addition of ground fiberglass composite was found to significantly increase tensile and flexural modulus, while decreasing impact strength. Ground fiberglass was found to have a greater stiffening effect than wood flour, but wood flour had no significant effect on impact strength.
Polycarbonate (PC) is used in computer and electronic housings, and here it was sought to reuse this polymer after having been separated from electronic shredder residue. The separated stream was not pure PC; there was some cross-contamination. The separated polymer was characterized by rheological, thermal and mechanical methods; the measured properties were only slightly inferior to those of comparable virgin materials. Recovered plastic and virgin polymer were blended using a TSE to determine the minimum virgin content needed to mask the effects of addition of recycled material on the rheological and mechanical properties of the blend. Differences in processing behavior and mechanical performance of the blends as a function of composition are discussed in relation to potential material recycling strategies.
Many outdoor products made from conventional lumber can be produced using wood flour filled polyethylene as a replacement material. In these applications the effect of ultraviolet radiation from the sun on the mechanical properties of these materials is important to understand prior to the design of any outdoor product. This study will examine the impact of long term ultraviolet exposure on the mechanical properties of wood flour filled high density polyethylene. An accelerated QUV testing apparatus will be used to simulate long term exposure to the sun. Impact strength, toughness, flexural modulus, and tensile strength will all be evaluated.
Due to the growing awareness of the necessity to protect the environment, the substitution of conventional plastic materials by biodegradable materials is gaining an ever increasing importance. An application that makes sense especially with regard to economic aspects is the processing of non-modified crop on plastics processing machines. This is made possible by the concept of a single-screw extruder equipped with a metering unit with which the total amount of energy required to plasticize the material is generated exploiting the friction occuring in the solid matter. As opposed to conventional extruder designs which exhibit separate areas for conveying the material and for plasticizing the same, these two tasks are united in one section of the extruder. The concept is based on specific geometries of screw and cylinder which secure that the entire mass flow passes a shear zone situated in the material conveying zone, warranting a very efficient transmutation of energy.
Hygrothermally decomposed polyurethane (HD-PUR) of polyester type has been used as a cost-efficient impact modifier in tri- and tetrafunctional epoxy (EP) resins. The PUR modifier was added between 5 and 80 wt.% to the EP prior its crosslinking with a diamine compound (Diaminodiphenylsulphone, DDS). The fracture toughness (Kc) and -energy (Gc) of the modified resins were determined on static loaded compact tension (CT) specimens at ambient temperature. The mean molecular weight between crosslinks (Mc) was determined from the rubbery plateau modulus of dynamic mechanical thermal analysis (DMTA) spectra. The change in the Kc and Gc as a function of Mc followed the prediction of the rubber elasticity theory. The efficiency of the PUR modifier was compared with that of a carbonyl terminated liquid nitrile rubber (CTBN). DMTA and fractographic inspection revealed that the PUR modifier was not only present in a dispersed phase of the EP matrix but participated in the build-up of the EP crosslinked network structure. Thus HD-PUR works as active diluent and phase separating additive at the same time. As HD-PUR can be regarded as an amine-functionalized rubber, it was used as hardener alone (by replacing DDS) in some EP formulations.
Fly ash is a by-product of the ground coal burning process used in power generation plants. Since fly ash primarily consists of inorganic materials, it is a potential filler substitute for conventional fillers in the plastic industry. In this work, the mechanical, physical, and thermal properties of fly ash filled polypropylene were determined and the effect of adding fly ash on the properties of the resin was studied. Driven by the economical potential and environmental aspect of the usage of fly ash, this study enabled us to determine the viability of coal fly ash to be used as a substitute filler in plastic resins.
Making an useful product from a nearly useless item is never an easy task. When it comes to combining rubber crumb from used tires to plastics - the task is even tougher.
The Valyi SFC molding process for surface finishing/compression molding (SFC) provides an economical route to molding and Class A finishing of large thermoplastic parts in one step. In the Valyi Process, decorative film or fabric is placed over a mold cavity in a press. Plastic melt is then deposited onto the film which subsequently heats the film to a formable temperature. Positive air pressure may be supplied to support the film/molten plastic. The press is then closed to form the final finished part. The process is similar to the textile back molding process. The Valyi Process uses much lower pressures than conventional injection molding. Molding (cavity) pressures for the Valyi Process are <<10 MPa (1450 psi) as compared to conventional injection molding which is typically >30 MPa (4350 psi). The in-mold lamination of paint film achieves the paint appearance and protection without the environmental and cost impact of conventional painting. Also, heating the film using the heat from the deposited melt eliminates the pre-heating step in the in-mold injection molding process. This paper describes the Valyi SFC Molding Process and reveals the advantages such as the mechanical performance of the part, reduction in cost and reduction in paint pollution, which can be achieved over the conventional injection molding - painting process.
Thermal properties are important parameters in both process and product design. In the case of plastics, the need for quick and accurate determination of thermal properties is gaining importance due to large variety of blends and recycled materials that are becoming available. A procedure based on an inverse method is presented for the determination of thermal conductivity and specific heat. The method makes use of transient temperature measurements. The temperature measurements are made in reference metal blocks and no temperature sensors are inserted in the plastic specimen. The method shows potential for obtaining the thermal properties over a wide range of materials and temperatures, and as a function of pressure. The method has been tested in simulation and results are presented.
A series of biodegradable polymer/clay nanocomposites have been prepared using two techniques: in-situ polymerization and twin screw extrusion. These samples containing 5-25% clay and polycaprolatone (PCL) were characterized with regard to processability, biodegradability, morphology, thermal behavior and mechanical properties. The processing at different screw speeds (20, 40, 60 rpm) did not alter the polymer/clay interactions. Biodegradation results in soil showed 50% mineralization of PCL/clay in 50 days as compared to 10% for the pure PCL film. X-ray diffraction patterns demonstrated that the polymer had different degrees of intercalation in the silicate layers of the clay. Dynamic mechanical analysis showed no change in the PCL glass transition temperature with the addition of clay.
This paper will analyze the feasibility of using granulated polyvinyl chloride-coated fiberglass screen as a filler and/or reinforcement in injection molded plastic products. The screen, composed of the trim cuts from large rolls and defective sections, will be granulated and blended, in different weight ratios, with recycled high-density polyethylene and polypropylene. The resulting composites will be injection molded to produce ASTM D638 testing specimens. Also, one population of specimens will be produced from a composite of the granulated screen and commingled post-consumer recyclate. The process- ability of the composites and several mechanical properties will be observed and recorded. Statistical methods will be applied to the data, in order to predict the effect of adding different levels of filler/reinforcement on the mechanical properties of the composites.
For several years the Minnesota Legislature, guided by the MPCA (Minnesota Pollution Control Agency), has been evolving a law to significantly reduce heavy metal pigment use in the state. The finalized law takes CONEG (Coalition of Northeastern Governor's) guidelines to a higher level. CONEG was intended to reduce the amount of heavy metals in the consumer waste stream by limiting their use in disposable packaging materials. The Minnesota law applies CONEG limits of lead, cadmium, mercury and hexavalent chromium to all pigments, including plastic colorants. This paper will review the evolution of this law. What could this mean to the plastics industry if similar events occur in other states?
Modern municipal waste disposal strategies involve the development of integrated waste management systems in which the waste is disposed of in a safe, efficient, and cost effective manner. Such systems require alternative methods of collecting, handling, and processing solid waste according to the unique characteristics of the various fractions (ASTM, 1996). This includes composting of the biodegradable fraction of the organic waste including paper, food & yard waste, and new biodegradable" plastics. Indeed aerobic composting represents an attractive alternative to the disposal of solid wastes in landfills. Composting by biologically mediated oxidative decomposition produces highly stable organic matter that can be used for land applications or horticulture. However the degradation of plastics within a compost can affect the decomposition of materials enclosed in the plastic and the resulting composition and appearance of the composted material. From an environmental perspective biodegradable polymers offer an attractive alternative to traditional petroleum-based non-biodegradable polymers; i.e. they need not be landfilled will re-enter normal geochemical (natural) cycles with timeand many are derived from renewable (agricultural) resources. Nevertheless as a new generation of biodegradable products enters the marketplace questions regarding the long-term fate of these materials in the environment and their effects on the environment are being asked by industry government and consumer groups. In particular: how do specific materials degrade in different compost environments? and how well do standardized laboratory scale biodegradation tests predict a product's biodegradability in an actual full-scale compost environment?"
Modern municipal waste disposal strategies involve the development of integrated waste management systems in which the waste is disposed of in a safe, efficient, and cost effective manner. Such systems require alternative methods of collecting, handling, and processing solid waste according to the unique characteristics of the various fractions (ASTM, 1996). This includes composting of the biodegradable fraction of the organic waste including paper, food & yard waste, and new biodegradable" plastics. Indeed aerobic composting represents an attractive alternative to the disposal of solid wastes in landfills. Composting by biologically mediated oxidative decomposition produces highly stable organic matter that can be used for land applications or horticulture. However the degradation of plastics within a compost can affect the decomposition of materials enclosed in the plastic and the resulting composition and appearance of the composted material. From an environmental perspectivebiodegradable polymers offer an attractive alternative to traditional petroleum-based non-biodegradable polymers; i.e. they need not be landfilled will re-enter normal geochemical (natural) cycles with time and many are derived from renewable (agricultural) resources. Nevertheless as a new generation of biodegradable products enters the marketplacequestions regarding the long-term fate of these materials in the environment and their effects on the environment are being asked by industry governmentand consumer groups. In particular: how do specific materials degrade in different compost environments? and how well do standardized laboratory scale biodegradation tests predict a product's biodegradability in an actual full-scale compost environment?"
With an ever-present desire to increase the amount of plastics, being recycled, specifically PET and HDPE, a premium has been put on optimizing the whole recycling process. This process involves many steps including collection, sortation, cleaning and reuse. Each of these steps includes many stages with varying degrees of sophistication. In this paper we will look specifically at the cleaning process and the parameters effecting cleaner performance.
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