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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Foam Extrusion of Linear Polyolefins by Lightly Cross-linking
Linear polyolefin resins, which are difficult to foam by extrusion, have been successfully expanded to good-quality foams by lightly crosslinking the resins with an azido-functional silane or peroxide.
Drop Test of Mouse Housing - Simulation and Experimental Verification
In this paper, explicit 3D finite element procedures were employed to simulate a mouse housing with sophisticated features. Effects of geometrical simplification were investigated and assessed via deviation of total mass and responses of stress and acceleration. Compared with the result of a patented drop test platform, it was shown that simplification is allowable to have 3% deviation in total mass. The stress and acceleration distribution within molded mouse housing upon impact were well understood with the aid of both simulation and physical drop test.
Orientation on Polyimide Sliding Surfaces Studied by Raman Spectroscopy
Small-scale tribological tests are performed on sintered polyimides in the temperature range between 80°C and 260°C. A transition towards low friction is observed at 180°C corresponding to stabilisation in wear rates. This characteristic is further related to an endothermal reaction in the polymer bulk as revealed by TGA/DTA and reorientation of C=O and C-N-C bonds as studied by Raman spectroscopy.
Model Based 100% Quality Documetation System Suitalbe for Small Lot Sizes in Injection Molding
The production of high precision injection molded parts for medical or safety technology usually requires 100% quality control and documentation. This quality inspection is made in the majority of cases manually and is therefore expensive. A new method has been developed for using quality prediction models based on multiple linear regressions also for small batch size products. Experiments show the applicability of this concept even if the process is disturbed by variation of process parameters or raw material properties.
The Effect of Preparation Method on Mechanical Behaviour of Chitosan Composites
This work investigated the addition of Polycaprolactone (PCl) and Sodium Tripolyphosphate (TPP) to the biodegradable polymer chitosan, via the preparation method of dry blending, followed by compression. The improvement in mechanical properties and suitability for biomedical applications were determined through the changes in surface characteristics, crystallinity and mechanical properties. It was found that the differences in melting temperature, contact angle and phase transition temperatures (tan ?) were highly dependent on the ratio of PCl and chitosan in each blend.
Monitoring Polymerization in Microfluidic Flow Channels Using Spectroscopy Methods
A micro-fluidic device, designed as a high throughput system for characterizing polymerizations over a range of solvent, monomer, initiator and temperature conditions, was instrumented with a fluorescence spectrometer. A fluorescent dye, incorporated into the monomer at very low concentration, was used as a molecular viscosity probe to monitor changes in viscosity during the polymerization of acrylic polymers. The measurement provides information about the extent of polymerization.
Magnetic Rotor Encapsulation
Magnetic rotors are used in bearingless pumps for wet processes in the semiconductor industry. These rotors must be encapsulated so that they resist corrosion from the aggressive chemical environment and do not permit permeation of the metallic ions from the rotor to the outer fluid. This paper describes our approach to evaluating fluorinated materials and processing techniques to produce encapsulated prototypes. Eighteen prototypes were manufactured and evaluated for testing. Details regarding this work are presented.
Cavity Temperature Control in Injection Molding Machine
A new approach for controlling part cooling in plastic injection molding is developed using a PI controller and coolant flow rate as the manipulated variable. The method uses an average part surface temperature within the mold as the setpoint parameter. A mechatronic system was developed for providing variable coolant flow rates. The control strategy was simulated using plant models, and then implemented and tested on a 50 tonne injection molding machine with good closed loop responses.
Injection Molding of a High Heat Polyetherimide Sulfone with Tg of ? 250°C
An injection moldable thermoplastic Polyetherimide Sulfone resin with Tg of ? 250°C (482°F) was developed for advanced automotive lighting systems and other applications requiring thermal capabilities greater than those currently achieved with Polyetherimide. With a +30°C higher Tg than Polyetherimide, the resin can still be melt processed using standard injection molding machine equipment by increasing melt temperature to 385-415°C and mold temperatures of 150- 175°C. The injection molding processibility of the resin and its properties are presented and compared with Polyetherimide.
Effects of Vibrating Injection on Structure and Property of Polymer Produce
A novel Vibration Injection Molding (VIM) Machine was introduced. Under factual manufacture conditions in a VIM machine, the effects of the vibration parameters on the structures and mechanical properties of HDPE, PP and HIPS materials were researched. It was discovered that vibrating injection can obviously improve the micro-structures and mechanical properties through optimizing vibration frequency and amplitude conditions of injection screw.
Advances in Understanding the Cure and Properties of Thermosetting Systems in the Laboratory of Professor John K. Gillham during His Career
Premise of Research: (a) Properties vs. gelation and vitrification. (Vitrification occurs when Tg = Tcure); (b) Isothermal properties at T vs. conversion as a consequence of rising transition temperatures (e.g., modulus and density at T vs. T? and Tg); (c) Effect of isothermal aging in the localization of subsequent properties vs. temperature. Results in Graphical Form: (a) TTT Diagram: Isothermal Time-Temperature- Transformation Cure Diagram; (b) CHT Diagram: Continuous Heating TTT Diagram; (c) Property- Temperature-Conversion Diagram.
Experimental Investigation of PET and PP Film Casting
In film casting, a polymer melt is extruded through a die before rapid cooling on a chill roll. The process stretches the material and induces some orientation in the film. In this paper, we study experimentally the effects of processing variables such as the draw ratio and the die temperature on film formation. The temperature, width and velocity profiles in the air gap are measured for films produced using polypropylene and polyethylene terephthalate.
Weatherability and Physical Properties of Opaque Injection Moldable Lexan* SLX Resins
New opaque blends and copolymers based on resorcinol phthalates have excellent weatherability and polycarbonate-like physical properties. The unique weatherability of these resins comes as a result of a photogenerated UV absorber (UVA) on the surface of a part. The gloss retention of these resins can be varied through proper selection of the resorcinol phthalate content and color package.
Transparent Injection Moldable Lexan* Slx Resins
New copolymers based on resorcinol phthalates have excellent weatherability and polycarbonate-like physical properties. The excellent retention of optical and mechanical properties on weathering of these resins is the result of the polymer’s ability to form a UV absorber at the surface of a part.
Extruded Open-Cell Foams Using Two Semi-Crystalline Polymers with Different Crystallization Temperatures
This paper presents an extrusion-based open-cell foaming process with polypropylene (PP)/metallocene polyethylene (mPE) and PP/low-density polyethylene (LDPE) blends. The basic strategy for achieving a high open-cell content is to induce a hard/soft melt structure using two semi-crystalline polymers with distinctively different crystallization temperatures (Tc), and to foam this non-homogeneous melt structure with supercritical CO2. The effects of polymer blending, die geometry, and temperature on cell opening were investigated in this study.
New Non-Hygroscopic Thermoplastic Vulcanizates with Improved Colorability and Weatherability
A new line of non-hygroscopic thermoplastic vulcanizates (TPVs) has been developed for applications requiring both color and photo-oxidative stability. These products span the hardness range from 20A to 50D and offer superior oil resistance and compression set. In this paper, we will discuss the properties of the new TPVs, including non-hygroscopicity, oil resistance, compression set, color consistency, colorability and weatherability.
Development of Damping Machine Augmented Composite Materials
This work investigates energy dissipation in machine augmented composite (MAC) materials consisting of small machines in a matrix. The machines are fluid-filled tubes, and the tube cross-sectional geometry causes fluid flow when deformed. Dimensional analysis identifies the ratio of solid moduli to the product of driving frequency and fluid viscosity as an important parameter. Finite element models predict the performance of the MAC lamina. The highest energy dissipation predicted is 0.8 out of 1.0.
Processing and Properties Optimization of Dynamic Injection-Molded PP
With the Taguchi method, the process parameters of dynamic injection molding are optimized and the relationship between processing conditions and the physical properties of isotactic polypropylene is explored. The results show that vibration frequency and vibration amplitude have greater influences on mechanical properties of isotactic polypropylene than injection velocity and packing pressure in most of our experiments. The samples’ impact strength could be improved by about 40% with optimum parameters. The morphology and crystallinity are also explored with DSC and WAXD.
Active Polymer Composite for MEMS Applications
Finite element analysis (FEA) simulated the performance of an active polymer-matrix-composite material. Microscale muscle elements actuate the material. The muscle element contracts longitudinally, expands transversely, and twists when pressurized. A coupled elastic/piezoelectric element provided the response of the muscles to actuation and 3D elastic coupling of the lamina. The contractions of isolated elements and of a lamina were approximately the same; elastic coupling of elements within the lamina produced novel out of plane deformation.
Increasing the End-Use Temperature of TPU Products
TPU products are well known for their mechanical properties and wear resistance. However, in comparison to vulcanized rubber TPU materials have a lower softening point (limited end use temperature) and a limited elasticity (elongation set) preventing the use of TPU in some interesting applications. Here we introduce a family of new cross-linking agents and how they can improve these properties. Application examples are shown to demonstrate how these improvements can be utilized.
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