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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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.
Grafting Linear and Branched Architectures from an Ethylene-Acrylic Acid Copolymer Film Surface
Surface modification of polymer films is often necessary to enhance hydrophilicity or hydrophobicity without affecting bulk properties such as crystallinity. In this study the carboxylic acid functionality on the surface of ethylene-acrylic acid (EAA) copolymer film was activated by reacting with dicyclohexylcarbodiimide (DCC). This activated complex was then reacted with selected di- and tri-amine compounds to modify surface properties. The film surface resulting from each reaction step was analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and contact angle measurements.
Flow Induced Coating of Polymer Processing Additives: Development of Frustrated Total Internal Reflection Imaging
In the extrusion of polyethylene (PE), fluoropolymer-processing additives (PPA) are used to eliminate the surface defect known as “sharkskin” by coating the die wall and inducing slip at the PPA/PE interface. We describe a method to carry out in situ measurements of the coating kinetics by exploiting the optical phenomenon of frustrated total internal reflection (F-TIR). The estimated coating thickness was found to be significantly lower (60 to 350) nm than reported previously (5 to 15) ?m. The proposed coating mechanism may have origins at the die entrance.
Radiation Processing for Modification of Polymers
Radiation processing has been demonstrated on a large commercial scale to be a very effective means of improving end-use properties of various polymers. It is a well-established and economical method of precisely modifying the properties of bulk polymer resins and formed polymer components. The reactions of cross-linking, degradation and grafting on polymers initiated by radiation have found many useful applications in plastic and rubber materials. Important properties of polymer materials, such as mechanical properties, thermal stability, chemical resistance, melt flow, processability and surface properties can be significantly improved by radiation processing. Modern high energy, high-power electron accelerators have made industrial irradiation processes attractive with high throughput, low cost and other advantages over conventional chemical processes such as lower emissions of volatile organic compounds (VOCs), better energy utilization and precise process control. This paper provides a review of the basic principles of and main applications for radiation processing of polymers, as well as the prospects for new applications of this technology in the future.
An Experimental Study on the Effects of UV Absorbers Stabilization of Slip Agents in Water Bottle Closures
This investigation is an attempt to identify potential effects of the degradation of polymer slip agent additives on the organoleptics of bottled water. Specifically, research was done to evaluate the effects of UV light degradation on LDPE water bottle closures. The scope of this study was to determine if the addition of UV absorbers would eliminate potential UV degradation of the slip agent, which can have adverse effects on the taste and odor (organoleptic) properties of bottled water. Sample chips containing various loading levels of UV absorbers and slip additives were produced. Taste surveys were then used to characterize the performance of the manufactured test samples.
Evaluation of Antioxidant Performance of a Natural Product in Polyolefins
Mixed tocopherols were evaluated for antioxidant performance in polypropylene and polyethylene in combination with a phosphite secondary antioxidant utilizing a 2-factor central composite experimental design with oxidation induction time as the response. A commonly used phenolic antioxidant and synthetic vitamin E (?-tocopherol) were evaluated in comparison. Mixed tocopherols were found to have a greater antioxidant effect than the phenolic control and a similar to slightly greater effect than vitamin E in both polypropylene and polyethylene. No significant effects of the phosphite on oxidation induction times were observed for either of the tocopherol based antioxidants.
Process Aid Optimization in Uni-Modal HDPE Blown Film
The performance of several fluoropolymer process aids was evaluated in a high molecular weight, uni-modal HDPE. The process aids were tested for the ability to eliminate melt fracture during blown film extrusion as a function of process aid concentration. Results indicate that process aid performance varies widely; most effective are those designed to control the morphology of the fluoropolymer – HDPE blend delivered to the extruder die. Further evaluations using white (TiO2) and extended white (TiO2 + Calcium salt) pigments during film production show that extended white pigments can negatively interact with fluoropolymer process aids, although the degree of interaction differs between process aid types. The most effective process aid was scaled-up in a plant trial, and found to match or exceed the predictions from the lab evaluations.
Effect of Elevated Temperature on Erucamide Partitioning in Polyolefin Films
Erucamide is incorporated into polymer films to reduce their coefficient of friction (COF). However, the COF reduction may be influenced by a film’s exposure to elevated temperatures during storage or subsequent processing. At elevated temperatures, erucamide may be lost from the film surface to the surroundings, undergo chemical change or decomposition, and/or migrate back into the film. The major objective of this work was to investigate the fate of erucamide upon exposure to a higher temperature. Based on results from ATR-FTIR spectroscopy and solvent washing on one surface of the film it appeared that, upon exposure to the elevated temperature (55°C), the initial reduction in erucamide surface concentration was due to migration of erucamide back into the film. A subsequent slight reduction may be due to the decomposition of erucamide.
Study of Phlogopite Mica as Fillers for Polyethylene and Polypropylene
Phlogopite mica is an abundant micaseous mineral being experimented of its usage as reinforcement in plastics. In this study the mechanical and rheological modifications due to phlogopite mica as filler in polyethylene and polypropylene materials were determined. And relative comparison was made with the fillers: talc and calcium carbonate, which are currently standard fillers for plastics.The phlogopite mica filler showed better tensile strength, and flexural modulus properties than calcium carbonate but lower than talc as filler. The cost of this mineral is lower than talc and CaCO3 (calcium carbonate) depending on the purity and particle size of the mineral.Phlogopite mica is hygroscopic, nontoxic and even has nutritious value, has light brown color and due to its higher aspect ratio gives higher shear stress and apparent melt viscosity than other fillers at the same concentration.
Percolation Behavior of Thermoplastic Polymer Composite
Model thermoplastic composites containing both micro and nano filler particles were prepared and their melt flow behavior investigated near the physical gel point or percolation threshold loading levels. The threshold loading level was found to be strongly correlated with the particles size of the fillers and independent of the extrusion shear rate. Since the processing and compounding of high-surface-energy nano-particle filled polymers is very complex and not well understood, this study demonstrated the validity and adequacy of percolation study of such composites in steady-state pressure-drive flows using capillary melt rheometer.
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