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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New Developments in Unscrewing Molds
There are two new developments in unscrewing mold technology. The first development is an unscrewing system that is machine ejector actuated, eliminating the need for externally mounted hydraulic cylinders. This system was developed to suit clean-room applications for small diameter closures. The second development is a cavity-side unscrewing system utilizing a rotating cavity and is suitable for large diameter closures. This system was developed to suit multi-level stack molds.
Challenges in Characterizing Sealant
Sealant is one of the very few major consumer products valued primarily for its rheological and adhesive properties. While, these materials may appear to be simple elastic solids, upon further examination, their behavior can be extremely complex. In this research, reasonable simplifications are developed to model the non-linear viscoelastic properties of cured sealant. Also included are modifications of the traditional instrumental design to allow for high throughput evaluation of a cured sealant’s mechanical properties.
Rheological Properties of HDPE-Wood Composites
A comparison of the rheological properties of HDPE-wood composites as measured by both capillary and rotational rheometry was made. The blends studied ranged from 0% (pure HDPE) – 50% 40-mesh size maple wood flour. The elastic behavior of these materials was studied through the measurement of storage and loss moduli, creep data and Bagley correction factors. The Cox-Merz rule was found to be invalid for these HDPE-wood composites. The effect of processing behavior on the rheological properties was also investigated.
Yield Stress Measurements in Gels, Block Copolymer Systems and Suspensions
We will discuss a new slotted-plate device to directly measure static yield stresses of complex multiphase systems. Possible wall effects associated with our earlier yield-stress plate instrument have been minimized . Our new setup avoids the disadvantages of the vane instrument. Yield stress values on a variety of systems have been obtained and have been compared with the values obtained via a variety of other methods.
Dynamic Rheology of Amorphous Poly-Alpha-Olfeins (APAOs) as Hot Melt Adhesives
Amorphous poly-alpha-olefins based on propylene were characterized over a wide temperature range by dynamic rheology. The rheological characteristics were useful in correlating Brookfield viscosity, ring-and-ball softening point, needle penetration, and open time with molecular structure and comonomer content.
Using Diode Lasers For Welding Thin Polymer Films
Highly reliable high power diode lasers are now being increasingly employed in industry as alternatives to conventional techniques for welding of plastics. New laser sources that have been developed for other applications in completely different industries are becoming available to allow novel bonding techniques to be developed. This may include materials and material forms that are difficult to join using conventional techniques. Joining thin films and joining thin films to sheet materials is one new area application area that is covered here.
Effects of Friction Stir Welding on Polymer Microstructure
Friction Stir Welding (FSW) technology has shown great promise as a method of joining polymeric materials. Welds in several materials have achieved over 90% of base material tensile properties. Flexural strength has reached 90% of base material properties in PP. Research has shown a correlation between the process weld microstructure and mechanical properties. A study currently being performed establishes the relationships between the process parameters, material microstructure, and mechanical properties.
Diode Laser Welding of EPDM Based Elastomers
Contour transmission laser welding has been carried out on EPDM and on various grades of Santoprene welded to PP containing glass fiber filler. The effects of welding parameters on shear pull strength, and on the nature of failure has been examined, and analyzed with the help of finite element simulation.
Pyrometer Measurements during Laser Welding of Thermoplastic Elastomers to Polypropylene and of Nylon to Itself
Pyrometer measurements were collected during the contour through-transmission laser welding of thermoplastic elastomers to glass-filled polypropylene as well as of unfilled nylon to itself. The elastomer-to-polypropylene samples were in shear-lap configuration whereas the nylon welds were between a ribbed flange and a web, representing a modified T-weld. Trends observed in the pyrometer readings are reported for both of these cases.
Ultrasonic Twin Converter Technology For Welding Large Plastic Parts or Packages
Patented Ultrasonic Twin Converter technology as an alternative to other sealing methods for sealing larger injection molded parts, vacuum formed parts, blister packs or foils. Principle of Ultrasonic Twin Converter technology and the Weld Horn Array technology. Advantages, challenges, possibilities and limitations. Comparison to the generally used single horn technology. Typical applications with longer continuous joints or larger weld areas, circumferences.
Polymer Welding of Powder Injection Molded Ceramics and Metals
Ceramic or metal-filled plastics are increasingly being used for the production of sintered parts today, with the function of the plastic being to ensure that the compounds can be processed on the standard types of injection molding machines currently in use.In this way, it is also possible to use the plastic matrix to join individual components and produce material composites of mold steel/structural steel, for example, before sending the joined parts to be debound and sintered.
Novel Foam Composite Having Thick Skin and Core-Stiffening Dividers
Using a conventional RM process, we have developed various types of foam composites having a hard skin and a foamed core which is finely separated in divisions by solid walls. One type has characteristics of light weight and good mechanical properties, and another of excellent thermal insulation.This report describes the production method and some properties of novel foam composites.
Rotational Molding of Micropelletized Polypropylene-Based Copolymers
Deficiencies in grinding performance of polypropylene homo- and copolymers have restricted their use for rotationally molded articles. This paper will demonstrate that micropelletization overcomes these deficiencies, allowing these resins to be processed into rotationally molded articles. Four different propylene-based copolymers were molded under varying conditions. Low temperature impact strengths, tensile and flex properties and oxidative induction times were determined. Results will be compared to commercial LLDPE products.
Optimization of a Rotationally Molded Pressure Vessel
Optimization software is used to optimize the structure of a rotationally molded pressure vessel by suggesting a shape that maximizes strength and minimizes material investment while incorporating the manufacturing constraints. A previous design is utilized as a starting point that will be the basis for comparison of strength, material, and cost.
Rotomoldability of Cyclic Polybutyleneterephthalate
This study investigates the rotomoldability of a new and innovative plastics technology called Cyclics thermoplastics. It outlines the general guidelines for successful rotomolding of this material as well as, establish the (as rotomolded) Impact and tensile properties of cyclic Polybutyleneterephthalate (CPBT). This material has several features that make it attractive the rotomolding industry.
Particle Size Distributions in Rotomolded Parts
This study quantifies how different sized particles distribute themselves in bi-axially rotationally molded parts. The paper will demonstrate that within normal particle size distributions found in rotational molding, that it is difficult to obtain well-sorted layers in the final molded part. This paper compliments recent papers on powder characteristic in rotational molding.
Filling Pattern of Underfill and Particle Distribution
Underfills can improve flip chip reliability. However, the fillers used in some underfills to enhance coefficient of thermal expansion (CTE) properties can be dispersed unevenly, causing less than optimal reliability. In this study, underfill dispensing was conducted using various fill patterns. Experimental results show that particle migration is a secondary mechanism, which causes uneven filler distribution. Particle settling mainly occurred during the curing process, rather than during dispensing, and was affected by the surface tension.
Three-Dimensional Simulation of Wire Sweep during Semiconductor-Chip Encapsulation
In this paper, numerical methods to analyze the wire sweep during semiconductor-chip encapsulation are presented. The flow simulation necessary for wire-sweep analysis is based on a three-dimensional model. Different methods to calculate the force on the wire from the flow simulation results have been investigated. The calculation methods have been applied to typical semiconductor-chip encapsulation cases. The comparison between numerical and experimental results in terms of wire-sweep values shows reasonable agreement.
Interactions between Reactive Impact Modifiers and Carbon Black in Copolyesters
Conductive fillers are frequently added to thermoplastics such as polyesters to impart electrical conductivity; however, the addition of these fillers can be detrimental to the impact properties of the plastic. Reactive impact modifiers such as ethylene-methyl acrylate-glycidyl methacrylate copolymers (E/MA/GMA) are effective for toughening polyesters, but they can also interact with carbon black making it ineffective for imparting conductivity. Copolyester formulations exhibiting conductivity and good impact strength are realized by varying the GMA level.
Characterization of Structural Changes in Polypropylene Nanocomposites by Infrared Thermal Wave Imaging
Thermal wave imaging (TWI) technique using an infrared thermal camera has been used to follow the mechanical deformation of polypropylene nanocomposites. Images were acquired real-time during fracture toughness testing. TWI proved to be a useful tool to identify the differences in deformation mechanisms as well as to distinguish the plastic contribution in each of the specimens. Calculations of surface energy were done using data obtained from the thermal images.
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