SPE Library
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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Recycling
Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Evolution of Structural Hierarchy in Uniaxially Deformed Branched Poly Lactic Acid Films as Followed by Spectral Birefringence Technique and Others
Over the past two decades, the lactic acid homo and copolymers have been extensively investigated for a variety of medical and pharmaceutical applications; including wound closure1, dental repairs2, fracture fixation (bone plates, screws, pins, and splits)3, ligament reconstruction, vascular grafts4, nerve repairs5 and drug delivery6,7. They are also extensively used in controlled drug release area6-8. With the recent developments in the technologies for purification of the raw materials, the large scale usage of these lactic acid based polymers became quite feasible. This, in turn, is opening the door for application particularly in the biodegradable packaging.
Towards Design Guidelines for Injection Molded Biodegradable Plastics Products
Specimens of two semicrystalline biodegradable thermoplastics, polyester-amide and polyhydroxybutyrate, injection molded at various settings, have been tensile tested. Upper limits to wall thicknesses with respect to surface appearance were found less severe than for traditional plastics. Molding settings appeared important for mechanical behavior. A higher degree of crystallization was obtained for polyhydroxybutyrate when the cooling rate was decreased. The lowest possible mold fill pressures appeared preferable, increasing ductility for both materials.
Wasteless Distribution Medium: A New Development for the Resin Infusion Process
The typical resin infusion processes like SCRIMP (Seemann Composite Resin Infusion Molding Process) require the use of a distribution medium or system to increase the impregnation speed in large parts. Normally, a substantial amount of surplus resin remains in the distribution medium and has to be disposed with the medium or remains on the part as resin rich domains. A new patented type of resin infusion process is presented, which does not produce any surplus resin waste.
Improved Organotin Stabilizers: Continuing Health and Environmental Research
Years of experience and significant research support using organotin mercaptides as PVC stabilizers. Safe use of organotin stabilizers involves following Material Safety Data Sheet instructions and using adequate engineering controls and/or personal protective equipment. Modifications of stabilizers to develop more efficient formulations continue. Product stewardship includes continued development of data to improve our understanding of the effects of materials. An overview of stabilizer trends in the industry, existing data, and planned health/ environmental research is presented.
Investigative Analysis of the Influence Reprocessing Has on the CIEL*a*b* Tristimulus Color Values of Special Effect Thermochromic Polypropylene
The intent of this investigation is to determine the feasibility of achieving optimal color quality when reprocessing special effect" thermochromic polypropylene. The investigation involves blending extruding and molding samples of virgin and reprocessed "special effect" thermochromic polypropylene. All samples undergo visual as well as CIEL*a*b* Tristimulus color value testing. Analysis of the visual and numeric data will determine whether the color values of the reprocessed material remain within the color space established by the standard. If the investigation proves that the color values are within the acceptable color range then recycling of the material would be both economically and environmentally beneficial."
Linearity and Non-Linearity of Mechanical Properties in Blends of Virgin and Recycled HDPE's
This paper investigates the behaviour of blends of Recycled Milk Bottle Resin (R-MBR) with Injection Moulding or Film Blowing grade HDPEs (IM-HDPE or FB-HDPE). This was done by measuring changes in mechanical and rheological properties as a function of blend composition and compounding intensity. There were three categories of compounding: bag mixing (BM), single pass single screw extrusion (EBx1) and double pass single screw extrusion (EBx2). The results were examined for linear and non-linear trends, and relationships between morphology, mechanical properties and molecular weights were proposed.
Measurements and Modeling of Rheological Properties of Biodegradable PBS/CO2 Solutions
The purpose of this research is to study the pressure drop profiles of biodegradable polybutylene succinate (PBS)/CO2 solutions in a slit die and to measure the rheological properties of the solutions as a function of the blowing agent concentration. A slit die with four pressure transducers has been designed to describe the effects of shear rate, temperature, pressure, and gas content on the shear viscosity and extensional viscosity of the flowing PBS/CO2 solutions. The low shear rate viscosity of the pure polymer was measured using a cone and plate rheometer. Extensive experiments were conducted to investigate the polymer/gas solution viscosities at five different shear rates, three temperatures and five gas contents. Cross-Carreau model and generalized Arrhenius equation were used to describe the shear-viscosity behaviors of PBS/CO2 solutions. The extensional viscosity of solution was modeled based on Cogswell's equation.
Mechanical Properties of Starch Filled Poly(hydroxy ester ether) Biodegradable Composites
The mechanical properties of starch filled biodegradable composites have been investigated. The strength was found to be independent of the filler content below 10 vol% and above approximately 30 vol%. This behavior is due to the failure mechanism operating in these composites. The matrix, poly(hydroxy ester ether) (PHEE), adheres well to starch and as a result the granules do not dewet during deformation. Instead the composites behave as a quasi-homogeneous material with increased brittleness as the filler content increases. The deformation mechanism was investigated by acoustic emission analysis and by a post-mortem examination of the fracture surfaces.
Microfibrillar Composites with Ultimate Properties
In the past decade, numerous novel polymeric products were introduced, including polymer blends, for various applications in the automotive and electronic industry. Up to now a homopolymer as such has to be reinforced to meet the high demands on stiffness and strength in engineering applications and glass fibres were the major reinforcing element used in these materials. Microfibrillar reinforced composites based on polycondensates are new polymeric construction materials with ultimate properties. Such a composite has specific economical and ecological advantages since, upon recycling, a polymer blend is obtained which can be re-used to make again polymeric materials with specific properties.
Mid-Infrared Process Control Systems for Polymer Melts and Film
The applications of on-line mid-infrared analysis in the polymer field comprise the detection and quantification of additives in polymer melts; compositional analysis of copolymers and polymer blends; control of polymerization processes: end-group determination; network characterization: determination of degree of cross-linking; reaction monitoring: reaction profiling, curing processes, kinetics, end-point determination; in-situ spectroscopy of molecular interactions: fluid impregnation, diffusion, drying, dyeing and extraction; monitoring of extrusion processes; safety and environmental monitoring, gas analysis, This paper examines in particular the current prospects of on-line (multi component) additive analysis in the polymer melt by means of mid-infrared spectroscopy.
Modeling the In-Mold Coating Process of Thermoplastic Substrates
In-mold coating (IMC) is being successfully used as a primer IMC to cover surface defects such as porosity and sinks, for Sheet Molding Compound (SMC) compression molded automotive and truck exterior body panels. A new class of coating materials is being developed [1, 2] for thermoplastic substrates. The potential benefit of using In-mold coating (IMC) as a topcoat for thermoplastics is large. Painting is a very costly and a non-environmentally friendly operation. Key to optimizing the IMC process is to be able to predict the fill pattern, so as to locate the injection nozzle or nozzles, in locations where the potential for trapping air is minimized [3, 4]. CAD software is available [4] to predict the flow of IMC, when the substrate compressibility can be neglected. However, for SMC parts with large regions parallel to the mold closing direction (most truck parts) and in particular for thermoplastic parts, the substrate compressibility cannot be neglected. Our long-term research aims to develop a simulation package that predicts the flow of IMC when the substrate compressibility cannot be neglected. In this paper, a simple model to predict the pressures needed to inject the coating as a function of the substrate compressibility is presented. We will also show how the clamping force needed to prevent the mold deflection can be estimated.
Morphology/Property Relationships in Thermoplastic Starch/Poly(hydroxy ester ether) Biodegradable Blends
The effect of moisture level during processing on the mechanical properties of biodegradable blends of thermoplastic starch and poly (hydroxy ester ether) (PHEE) was studied. The morphology of the blends changed with the moisture content of starch. The dispersed phase was significantly deformed under high moisture conditions, leading to fibrillar and laminar types of morphologies at 50-80% starch level. A low moisture level produced a more dispersed morphology. Improved tensile properties were observed for the blends processed at high moisture levels due to the presence of elongated morphologies.
Municipal Plastic Waste: Alternatives for Recycling with Profit
The recovery and recycling with profit of municipal plastic waste (MPW) is still an unsolved problem. Only in the developed countries a small portion of their MPW is used with profit. The major part of the plastic residue is disposed of landfilling. This work analyses the existing methodologies for recycling and assesses their potential application to MPW. Also, a comparative study of incineration, in terms of energy saving and contamination risks, is performed. The energy required for recycling and the energy obtained for controlled incineration is calculated, and the maximum energy opportunity is obtained. On the other hand, the energy needed to recycle either commingled or separated plastic residues was compared, taking into account the final properties obtained and the compatibilization step.
Near-Infrared Spectroscopic Product and Process Control
The main applications of near-infrared spectroscopy relating to polymers are quality control, monitoring of textile fibers, remote identification/classification of polymeric materials (recycling), monitoring of polymer melts for additive and/or (co)polymer composition, and polymerization monitoring (of polyolefins, epoxies, nitrogen-containing polymers). Diffuse reflectance and transmission, transreflectance and reflectance modes are being used. Examples of the aforementioned applicational areas will be given with the main emphasis on the on-line (multicomponent) additive analysis in the polymer melt by means of near-infrared spectroscopy.
New Rapid Tooling Concepts
Within the scope of Rapid Tooling the IKV is working on the optimization of Soft Tooling techniques and on the development of Hard Tooling techniques. The aim is to get molds with a high mechanical strength and series-like cooling conditions. For that purpose the resin casting process is improved taking advantage of the sedimentation of a steel powder filler. Furthermore the metal injection molding (MIM) is analyzed with respect to its suitability for manufacturing steel molds or prototypes. The mold used in the MIM process is made by stereolithography. The results show the possibility to get steel powder contents as high as the bulk density with the resin casting. It is also feasible to manufacture green parts of steel molds or prototypes with MIM.
New Thermally Conductive Thermoplastics Offer Freedom of Design in Heat-Management Applications
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.
On-Line Material Characterization during Extrusion of Recyclates
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.
Profit from Recycling Tooling and Leadership Change
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.
Properties and Applications of Sandwich Panels Based on PET Foams
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.
Reactive Extrusion of Polyolefin Blends
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.
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