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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Degradation of Rubber Networks during the Ultrasonic Treatment
The ultrasonic treatment of vulcanized rubbers under controllable conditions softens the rubber and creates a considerable amount of sol that makes possible a further reprocessing of the rubber. This paper demonstrates that a unified approach can be applied to analyze the numerous experimental data on structure of various unfilled and filled rubber vulcanizates ultrasonically treated under the continuous (with flow) and static (no flow) conditions. This approach is based on a model, which describes degradation of rubber network as a random scission of crosslinks and main chains due to the thermo-mechanical action of ultrasound.
Alternatives to Coatings for Automotive Plastics
Coatings or paints are generally pigmented polymeric dispersions or powders that are usually applied as a secondary process step to form a layer on the substrate. Eliminating coatings can drastically reduce the cost of the part as well as provide environmental advantages. In recent years there have been major advances in alternatives to coatings for automotive plastic parts. These advances are categorized into two main areas, material development and process development. From a materials perspective, new colorants and modifiers have been developed as additives to plastic resins that provide the aesthetic and physical and chemical properties required. From a process perspective, advances in process technology in areas of extrusion, co extrusion, injection molding, laminating films, and thermoforming of multiplayer sheets have been developed. This paper will examine these different alternatives to coatings for automotive plastic applications.
Structural Analysis of Components Molded Using Microcellular Foam Molding Process
It is known that microcellular foam molding process is viable process in reducing product cost, process cost and improvement of dimensional stability. Reducing the part weight negatively effects certain properties of the material. Specific effect on the property will determine applicability of such process for a given part design. In order to determine the applicability of such process it is important to use Finite Element Analysis (FEA) to verify designs before making any prototypes. The traditional FEA is used for solid materials to predict component performance. There is little understanding of how traditional Finite Elemental approach will work using microcellular foam material properties.The traditional solid plastic material is tested and correlated through testing and simulation. The same components molded using microcellular foam process will be tested and simulation method will be applied to understand if the same correlation can be obtained.
Abrasion Resistance Requirements for Automotive Interior Soft Skin Materials
Interior automotive applications such as instrument panel (IP) topper pads, door trim, arm rests, and seats require soft skin materials that have good abrasion resistance. With the OEM’s move towards a polyvinyl chloride (PVC) free interior, materials such as thermoplastic polyolefin (TPO), thermoplastic polyurethane (TPU), thermoplastic elastomers (TPE), and polyurethanes have replaced PVC. The new materials have to meet the original equipment manufacturer (OEM’s) abrasion resistance requirements. This paper examines the OEM’s abrasion requirements for soft skin materials used in automotive interior applications and reveals the concern suppliers have with these requirements.
Characterizing Scratch and Mar Performance of Molded-In-Color Engineered Polyolefins for the Automotive Industry
Various new and modified test methods are proposed to characterize the scratch and mar performance of molded-in-color [MIC] engineered polyolefins [EPO] for the automotive industry. Mar is characterized by gloss retention after abrasion in a crockmeter. Scratch is usually characterized by the Ford 5-Finger Scratch Test. However, scratch can also be characterized by the instrumented microscratcher. A method to quantify chip resistance is proposed. These test methods are illustrated by a comparison of the performance of a new MIC EPO [INDURE™] against that of conventional TPOs.
Peroxide Initiated Grafting of Alkoxysilanes from Poly(Isobutylene-Co-Para-Methylstyrene) Utilizing a Co-Rotating Twin Screw Extruder
Reactive processing of various alkoxysilanes with poly(isobutylene-co-para-methylstyrene) copolymers in a co-rotating, intermeshing twin-screw extruder produced novel, curable, grafted elastomers with excellent barrier properties. One of these polymers is currently used as a coating in a commercial application. The effect of formulation, screw design, and processing conditions upon polymer properties, economics, and side reactions were studied. Also investigated was how grafting level and efficiency are influenced by a number of inhibitor additives.
Achievable Weld Strengths for Various Thermoplastics Using the Clearweld® Process
The ability to join thermoplastics using traditional welding techniques has been studied extensively. Clearweld® is a relatively new through-transmission laser welding technique for welding infrared transmissive plastics. The range of plastics that are weldable using the Clearweld process has not been well documented.Various thermoplastics, including polycarbonate, PMMA, polysulfone, PETG, LDPE, and PVC, were welded using the Clearweld process to determine the capabilities and limitations of the process. The evaluation was based on tensile strengths of welded butt joints. The effect of material properties and quality of the welded parts was also evaluated to enable the engineer to design joints for maximum strength welds.
The Suitability of Polyvinyl Chloride / Ethylene Vinyl Acetate-Carbon Monoxide Terpolymer Blends for Medical Devices
An ethylene vinyl acetate-carbon monoxide terpolymer (EVA-CO) (Elvaloy® by Du Pont) was blended with two PVCs at various compositions. Several commercially available medical grade plasticised PVCs were also tested to assess the suitability of the blends for the current market.Mechanical analysis showed that the tensile and flexural modulus of the blends decreased significantly with increasing EVA-CO content, with the impact strength greatly improved. DMTA showed a single glass transition temperature (Tg) between that of the PVC and EVA components indicating complete miscibility over the range of concentrations studied. Rheological analysis showed only slight changes in shear viscosity with increasing EVA-CO content. The properties of most of the PVC/EVA-CO blends were similar to those of commercially available plasticised PVCs.
Coextrusion of TPU and BaSO4 Filled Medical-Grade TPU
Coextruded products for the medical device industry, involving layers of filled and unfilled polymers, are difficult to fabricate, especially due to the various degradative processes taking place especially when various stabilizers are not included in the medical-grade formulations. Significant differences in the degradation behavior and the subsequent rheological behavior of unfilled and BaSO4 filled TPUs generally give rise to severe fluctuations at the interfaces and poor coextruded products. It is shown here that the shear viscosity values of the filled and unfilled TPU need to be matched under the extrusion conditions to obtain acceptable coextruded medical products.
Modification of Biodegradable Polyesters with Inorganic Fillers
Composites produced by solution mixing of a biodegradable thermoplastic polyester based on butylene adipate / succinate, as well as a commercial polylactic acid, with surface coated and uncoated hydrotalcite inorganic minerals were studied. Materials were also melt-mixed in a twin screw extruder for comparison. Significant structural and morphological differences were noted following characterization of the composites by DSC, TGA and melt rheology. Results varied depending on the materials and the processing methods. Biodegradability and biocompatibility were evaluated by performing tests “in vitro” in the presence of a phosphate buffered saline solution.
The Mechanical and Rheological Characterisation of Implantable Medical Devices Formulated from Binary Mixtures of Cellulose Derivatives
This study highlights the potential associated with utilising multi-component polymeric gels to formulate materials that possess unique rheological and mechanical properties. The synergistic effect* and interaction between hydroxyethylcellulose (HEC) and sodium carboxymethylcellulose (NaCMC), polymers which are commonly employed as drug delivery platforms for implantable medical devices, have been determined using dynamic, continuous shear and texture profile analysis. * The difference between the actual response of a binary mixture and the sum of the two components comprising the mixture.Increases in polymer concentration resulted in an increase in G’, G’’ and ?’ whereas tan ? decreased. Similarly, significant increases were also apparent in continuous shear and texture analysis. All binary mixtures showed positive synergy values which may suggest associative interaction between the two components.
Micromoulding: Consideration of Processing Effects on Medical Materials
New medical technologies are driving demand for smaller plastic components. In response, micro-injection moulding has evolved as a technology for the mass production of minute, intricate, polymer and composite components for medical and MEMS applications. There has been significant growth in the technology but little understanding of the effects of process dynamics on product properties. To address this knowledge gap a program of work with the objectives of enhancing the understanding of polymer processing-property interaction has been implemented in our laboratories. The impact of micro-scale processing on the rheological, mechanical and tribological properties of polymers and composites are being explored. Process conditions are potentially more severe on melts than those encountered in conventional moulding. This is especially pertinent when considering process sensitive biomaterials used in medical applications. A novel micro-injection compounding (MIC) machine has been developed minimising process stages and reducing material exposure to excessive residence times. This paper gives brief details of the effects of micromoulding process conditions on component surface morphology and mechanical properties measured using atomic force microscopy.
Medical Plastics Showing Bacteriostatic Properties
Medical device developers, manufacturers and users have long sought coatings or additives that instill bacteriostatic properties to their devices. The bacteriostatic properties sought include reducing or eliminating device-related infections, while not interfering with the normal function of the device and its surroundings. One such bacteriostatic agent tested in polyvinylchloride (PVC) is an organic acid metal salt. This agent was compounded into PVC resin and subsequently melt processed into components for a urinary collection device. These components have been tested against pathogens most commonly associated with device-related urinary tract infection (UTI) via zone of inhibition (ZOI) and bacterial adherence tests. The components were also evaluated for interference with normal urine culture and urinalysis testing. Additionally, the normal processing, assembly and operation of the components and final device were evaluated for any type of interference from the bacteriostatic agent.
A Novel Seal/Peel System for Medical Packaging Applications
Films with peelable sealant layers are well known in the packaging industry, and have been in widespread use for some time. This paper serves to highlight a further evolution in seal/peel technology made possible by the coextrusion of novel materials to produce a system with a very wide sealing window and narrow range of peel strengths upon opening. This is achieved by separating the sealing and peeling functions by assigning them to different layers of a multilayer polymeric structure. The use of separate layers for the sealing and peeling functions allows for the development of specialized systems that can provide significant advantages to the end user. This paper describes the seal/peel system and highlights some of the advantages it brings to medical packaging applications.
Investigating the High-Temperature Peel Properties of Medical Packaging Materials
This paper proposes a novel measurement method, for investigating the high temperature peel properties of medical packaging materials using a modified tensile testing machine. This technique provides information on the temperature dependence of peel strength. High temperature peel strength is an important parameter during pouch manufacture, sterilization and also in service.A link exists between high temperature peel and hot tack. A bond with superior high temperature peel should also rapidly form a reliable bond after sealing, reducing the chance of failure during the pouch manufacture process. Sufficient peel strength at evaluated temperature is also necessary for Eto (Ethylene Oxide) sterilization. In addition, medical packaging materials may be subjected to high ambient temperatures during shipping, which can weaken the seal and lead to failure.The high temperature peel strengths of two grades of wax/polymer type adhesive coated Tyvek® were compared. The peel strength was found to decline with increasing temperature in a linear manner.
Investigation of Phenomenological Differences of Impulse Heat Sealing and Constant Heat Sealing in Ziegler Natta and Metallocene Polyolefin Blends
Experimental and theoretical discussion of differences in heat sealing behaviour of several Polyolefins films during impulse and constant heat sealing process is presented. The study included films prepared with blends of LDPE, C4-LLDPE, C8-LLDPE, metallocenic LLDPE and Polyethylene plastomers (m- PE). A complementary correlation of DSC data and heat sealing was performed.Although some differences in the maximum seal strength were observed, the impulse heat sealing process is more sensitive to process parameters and configuration changes in sealing equipment than to film composition changes. On the contrary, significant changes in the heat sealing curves were measured in the constant heat sealing process due to film composition changes.
Structured Product Definition: The First Step to a Successful New Product
Successful New Product Development (NPD) is the lifeblood for many organizations. The first step in any endeavor is always the most important as it sets the direction. For NPD projects this first step is defining what the product should be.Structured Product Definition (SPD) is a revolutionary new method that provides a customer-focused and measurable product definition, while focusing on team-building and unambiguous communications.SPD pulls together the customer knowledge that already exists within the organization.SPD focuses on team and consensus building to foster an alignment with project and corporate goals.SPD uses databases and structured reports to help the team accomplish their goal and to provide the ability to monitor their progress.Compared to the Japanese developed Quality Function Deployment (QFD), SPD is quicker, more flexible, and less expensive. Its team-based approach is cognitive of our Western culture and works with the culture, instead of trying to alter the culture. Its database and report methodology is easier to use and monitor than the complex “House of Quality” graphics. Typically the process is 1/3 to 1/10 the cost of QFD.
Nylon Polymers Industry Undergoing Major Changes
Since the discovery of nylon 66 and 6 polymers in the 1930s, the largest end use for nylon polymers has been textile fibers. Usage of nylons as engineering thermoplastics took nearly another two decades to attain commercial importance. The nylon fibers industry is now showing signs of having reached maturity, with important economic implications for the engineering plastics sector. In addition, nylon 6 is growing faster than nylon 66, driven by both by cost differences and changes in marketing philosophies. The rapid scaleup of nylon capacity in China is bringing about a significant regional shift in consumption patterns. What might this mean for the future structure of the nylon polymers industry?
A Reliability Function Based Approach to the Analysis of Weathering Data
A methodology is proposed for estimating the lifetime of a polymer material under conditions of UV exposure from measurements on physical properties during weathering. The method entails calculating a probability distribution function for failure at each weathering interval based on physical data and a definition of a failure criterion. By fitting the distribution function to a reliability model, specifically a Gaussian distribution, a lifetime can be estimated. This method is to be contrasted with classical" methods for estimating lifetimes which average physical properties over a given interval and look for a failure criterion for the averaged result."
High-Throughput Methods for Evaluation of Process Degradation of Polymer Formulations
Polymeric materials exhibit complex degradation mechanisms during their processing and end use. High-throughput (HT) development of new polymer formulations requires new methods for material preparation and measurements of properties. We are exploring various approaches to increase the throughput and decrease the sample size for evaluating the relative effectiveness of process stabilizers for polypropylene (PP). In this paper, several measurement methods for rank ordering stabilizer effectiveness in PP are introduced that have the potential for use in HT systems for rapid identification of high performance stabilizers.
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