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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Compounding and Characterisation of Long Fibre Reinforced Composites Based on Flax and Polypropylene
The compounding of long fibre reinforced composites based on flax and a polypropylene matrix has been implemented by a co-rotating, close-intermeshing twin-screw extruder. Extensive experiments have been carried out to optimise the fibre/matrix adhesion and the screw concept. Only short fibre structures could be achieved by the use of conventional screw elements, like kneading blocks or turbine mixing elements. Applying newly developed special screw elements long fibre structures as well as an optimum fibre dispersion could be reached.
Considerations in the Roughness of the Molds Surface and the Molded Parts Utilized in Injection Molding
The methodology of this work is based in the performance of tests to study the influence of the process parameters on the final properties of molded parts (roughness, Ra and Rz).First of all it was necessary to design and manufacture a mold to observe the roughness of different surfaces. EDM and turning were chosen as typical processes for injection mold machining.Finally some preliminary results are included, illustrating the dependence of the average roughness of the molded parts with respect to the machining process and injection molding conditions.
Control of Gas Direction in Gas Assisted Injection Molding; Definition of Resistance to Velocity
Resistance to velocity, rV , should be used as a criterion in the prediction of gas direction in gas assisted injection molding. In addition, melt resin velocity is also used in the prediction. Comparison of the velocity of fluid is especially important for more complex situations. These methods predict the gas flow direction from the knowledge of process variables such as resin flow length, cross section area of cavity, melt temperature, and short shot.
Controlling the 'Color' of Electrochromic and Electroluminescent Polymers and Devices
This lecture provides an overview of a group effort on NIR electroluminescence along with visible and IR electrochromism. Significant advances continue to be made in developing visible light emitting PLED’s and electrochromic polymers with visible color responses. Less effort has been directed to longer wavelengths.
Coprecipitates of Dibasic Lead Phthalate and Tribasic Lead Sulfate
Coprecipitates of dibasic lead phthalate and tribasic lead sulfate tend to crystallize with the latter forming the core of a core/shell structure. The reactivity of this structure towards hydrolysis of ester plasticizers is considerably lower than that of physical blends of the basic lead salts.
Correlations between Orientation and Some Properties of Polymer Films and Sheets
The orientation of biaxially stretched polystyrene (PS) sheets and polyethylene (PE) blown films were investigated. The study mainly focused on the relationships between orientation of amorphous PS and semi-crystalline PE and their shrinkage, tensile properties and tear resistance. For low orientations, it is found that the stress and strain (shrinkage in films) can be simply related to birefringence for both PS and PE. For tear properties of PE films, better correlations were observed with crystalline orientation factors.
Decisions, Judgment and Uncertainty: Psychology and Intuitive Probability
Most decisions in business (and life) are made on the basis of incomplete or estimated information. A wide range of psychological studies conducted over the past thirty years have shown that when forced to deal with uncertainty people fall back on rules of thumb that more often than not violate basic rules of probability and lead to flawed results. By understanding the types of mistakes people typically make, one can avoid these traps and improve the quality of the decisions. This paper discusses several of these, including regression towards the mean, ignoring base rates, and linked events.
Design of an Integrated Crash Energy Absorber for Compression Molded Bumper Beams
Due to upcoming demands from insurance companies, there is an increasing need for bumper beams that take care of minimum repair costs after collision. The compression molding technique offers excellent possibilities to integrate crash absorbers into the bumper beam design. Experiments were carried out on six types of reinforced polypropylene cans. The difference in crush energy absorption of these materials was studied. The tests were carried out at crosshead speeds of 50 and 2000 mm/min.
Design, Material and Processing Effects on the Tensile Properties of Filled Polypropylene
A statistical evaluation was performed to evaluate the effects of design, material and processing conditions on the tensile properties of a filled polypropylene. Coupons were machined from injection molded plaques at different orientations and evaluated using the common tensile test. The results were compared using an analysis of variance (ANOVA). The following effects were found to be of significance in decreasing order: the type of filler, the level of filler and orientation.
Designing Runners to Control Gas Distribution in Gas-Assist Injection Molding
This paper presents a study about the ways in which shear, developed in the perimeter of the runner, affects the distribution of gas in gas-assisted injection molding. High-shear regions in the perimeter of the runner can be traced and followed into a part-forming cavity. The high-shear regions create variations in the melt viscosity within the cavity. Once gas is injected, the gas flow is significantly influenced by these viscosity variations. A method is investigated which controls the position of these high-shear laminates and thereby the distribution of gas within the mold.
Determining Cause of Failure in Plastic Parts through Microscopic Analysis
A critical first step in analyzing a plastic part failure is the examination of the cracking and the fracture surfaces. Important clues in understanding the failure mechanism are revealed by the recognition of distinctive crack pattern and characteristic fracture surface features. Several actual field failure case histories are described to illustrate the microscopic techniques and how the interaction of mechanical stresses and service environment produce unexpected failures.
Developing a Method for Rapid Design and Manufacture of Tooling
Following is the development of a method for the rapid design of bridge or short production tooling for injection molding. Starting with a product definition, part was modeled in a solid modeler. The part model was analyzed by the finite element method for performance under load and by flow analysis software to determine molding characteristics.Once the design was proven, NC code was generated to cut the cavity and runner system. The mold was commissioned and the mold cycle parameters were verified.
Developing Coaches and Mentors in Your Organizations
Increasingly, companies are looking for leaders and not managers. Inherent in this move is the necessity for skills to motivate and develop employees. One way to cultivate leaders, as opposed to managers, and to drive positive change in an organization is to implement a coaching and mentoring system for employee development and day to day management. The next logical questions is how do you develop coaches and mentors?" This paper will provide some insight into this question and possible solutions that may work for your organization."
Development of a Data Acquisition and Control Software for an Extrusion Process
This paper describes the development of a system control and data acquisition (SCADA) system for a Killion KTS-100 extruder. At the heart of this computer based system is LabVIEW software that facilitates the various operational requirements. Particular attention is given to the human-machine interface that allows the operator to observe the extruder's operational conditions and permit necessary operational changes to the process.
Development of a New Elastomeric Homopolymer Polypropylene
A new elastomeric homopolymer polypropylene has recently been developed. Its unique properties are caused by the introduction of a controlled level of stereo-errors into the PP chain. This new-to-the-world material has the possibility to replace existing polymers at low cost such as thermoplastic elastomers (TPEs), flexible PVC, rubbers and other high performance polymers with the additional benefit that the polymer is completely recyclable (the only building blocks are propene!).
Development of Blends of HIPS/SB Copolymers with Superhigh Impact Properties
Synergistic blends of HIPS and SB block copolymer have been prepared with exceptional toughness. Notched Izod values for the blends vary from 240J/m to 470 J/m depending on the composition and type of SB copolymer. The neat experimental HIPS is characterized by either a bimodal or broad unimodal rubber particle size distribution. It is shown that the rubber particle size and distribution not only affect the impact properties of HIPS but also affect the blend effectiveness of HIPS with SB block copolymers. Comparisons with blends of commercial HIPS/SB block co-polymers are made.
Development of New-Type Glass Fiber Reinforced Thermoplastics
A new type glass fibers which are coated by thermoplastic resin, PA resin in this paper was used as reinforcements of PP injection molding materials. This fibers and surface the aments created thick interphase and also interdiffusion occurred PA and PP resin. The residual fiber length pellet was longer and interfacial shear strength was larger. Accordingly not only high tensile strength but also high impact strength injection moldings could be achieved by this new type glass fiber.
Direct Sheet Extrusion and Thermoforming of TPO Compounds
This research explores the development of thermoplastic olefin compounds through direct sheet extrusion and their thermoforming characteristics. A number of high rubber content formulations were compounded on a twin-screw extruder and formed directly into sheets via a gear pump. Sheets produced by direct sheet extrusion were thermoformed using a several thermoforming techniques, and the effect of material properties on thermoformability was evaluated for high draw applications. A thermoforming process window was developed for each compound and processing method.
Dispersed Solids Melting Model in Single Screw Extrusion
In opposite to most screw designs the geometry of some single screw concepts lead to a break-up of the so called solid bed. Therefore the well known Tadmor-Model is not capable to describe this melting behavior. First approaches for such a model were already made by several scientists. Unfortunately these models assuming some simplifications having a strong effect on the accuracy. Thus a new dispersed solids melting model was developed assuming less simplifications. It shows good agreement with experimental results.
Drawing of UHMWPE Fibers in the Presence of Supercritical CO2
The drawing behavior of UHMWPE fibers in supercritical CO2 is compared to that in air at different temperatures. Temperature substantially influences the drawing properties in air, while in scCO2 a constant mechanical response is observed. DSC and WAXS results show that air-drawn samples crystallize during deformation in an internally constrained manner, promoting changes in their thermal behavior. In contrast, scCO2 allows crystals to grow without constraints through a possible crystal-crystal transformation, increasing the processing temperature to 110°C.
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