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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Injection Molding by Direct Compounding
Direct compounding has long since been eastablished in sheet-, profile- and pipe-extrusion, where the high cost-advantages of single-stage article production are appreciated . Compared to extrusion applications, direct compounding of injection molded articles is comparitively unknown territory. The IMC-process (Injection Molding Compounding) enables filled or reinforced plastics to be direct-compounded immediately before injection molding. This offers two advantages to the molder: his material costs are reduced and he gains in flexibility.
Spatial Variation of Structural Hierarchy in Injection Molded Polypropylene
The structural hierarchies in injection molded isotactic polypropylene are mapped at two different mold temperatures and injection speeds in order to quantitatively understand their spatial variation. The mechanisms of formation of structure in various locations of three-dimensional objects and their quantitative representations are addressed at different levels of size hierarchy (superstructure, lamellar, and unit cell) using Optical Microscopy, Hot Stage Video Microscopy, SALS, SAXS, and Microbeam WAXD. A structural model describing the overall behavior is presented.
Motors and Drives for Extrusion Applications
There are many choices and options available for motors and drives for extruders and other machinery used in extrusion lines. This paper provides an in-depth explanation of DC, AC Vector, Servo, Brushless DC, and other common drive and motor technologies. It covers how they work, their major differences, their pros and cons, and some guidelines in how best to apply them. This knowledge should help plastics engineers in the selection of extrusion equipment.
Velocity Distributions in the Nip and Translational Regions of a Co-Rotating Twin-Screw Extruder
The positive displacement characteristics of a twin-screw extruder are often attributed to the intermesh of the two screws. Our objective was to measure velocity distributions in the nip and the translational regions of a co-rotating twin-screw extruder. The variation of axial and tangential velocity with screw rotation changed significantly from the translational to the nip region. Much higher axial velocity values were measured in the nip when compared with those measured in the translational region.
Effect of Thermal Degradation on the Impact Properties of PVC Compounds
Instrumented drop weight impact test was used to study the effect of thermal degradation on the impact properties of PVC compounds. The impact resistance of the aged compounds related well with their weight loss and hence thermal degradation. Each compound showed a specific weight loss percentage that correlates with a 50% loss in its impact properties (failure point) irrespective of the aging temperature. The results were also used to estimate a thermal index (TI) of each compound in a rapid and reliable way.
Immersion Study of Composite Poly(Propylene) on DMTA
Dynamic Mechanical Thermal Analyzer (DMTA) tests were conducted while samples were immersed in a chemical solution at various temperatures. Time Temperature Superposition (TTS) was used to create the MasterCurve of strain(t) and creep modulus over extended time. The effect of strain(t) before and after immersion was be studied.
New Polyolefin-Based Thermoplastic Vulcanizates
This paper describes the formulation and generation of novel types of thermoplastic vulcanizates based on PP/EP-and TPU/EVA-compositions. In both concepts the elastomeric phase is dynamically crosslinked and embedded in a microdisperse distribution in a continuous thermoplastic matrix. As a result of blend composition, preparation and morphology formation concepts, two-phase polymers with outstanding thermomechanical and physical properties were generated, highly appreciated in automotive, rubber and furniture industry.
Compounding of Long Glass Fiber Reinforced PP (DIF-LFT) on a Single-Screw Extruder
This contribution introduces an economical process technology to generate long glass fiber reinforced polypropylene on a single-screw extruder. The technology can work both as a single-stage or as a two-stage process. The innovative material enlarges the use of fiber reinforced thermoplastics (LFT and GMT), for example large-scale productions in the automotive industry. Besides the plant development it is necessary to evolve a polymer formulation and its optimization. The mechanical profile of the new material DIF-LFT30 is presented and discussed.
Translating Failure into Success - Lessons Learned from Product Failure Analysis
Analyses of hundreds of failed plastic products have revealed some interesting trends and recurrent themes. Designers and manufacturers can reduce failures by examining the lessons learned from product failure analysis. Case studies are presented with emphasis on operating environment and loads, working stresses, computer modeling, compatibility with metallic materials, end-use testing and performance tracking. A set of simple guidelines is discussed that, if considered early in the product cycle, may help in reducing product failures.
Dipolar Dynamics in Miscible Polymer Blends
The reorientational dynamics of dipoles in PVDF/PMMA blends were investigated by dielectric relaxation spectroscopy (DRS). Various relaxation processes associated with different morphological regions were identified. Phase separation during crystallization was monitored in-situ by DRS. In addition to the relaxation related to the glass transition, a relaxation which cannot be attributed exclusively to the crystal-amorphous interphase is found in the blends. An interpretation of experimental observations is based on cooperativity and morphological considerations.
Trouble Shooting Cavity to Cavity Variations in Muticavity Injection Molds
Significant differences are commonly seen between parts molded in multicavity injection molds. The elimination of these variations is complicated by the large number of variables existing within the mold, the injection molding process and the material. This paper presents a means of isolating and quantifying the primary causes of these variations. By isolating the causes the molder can more effectively and efficiently address the differences between parts molded in different cavities and thereby maximize productivity.
Flow Fields of Polymer Melt Flowing through Wedge Converging Channel
Simple formulae are proposed for the velocity and extensional strain rate profiles for a power-law fluid in a converging wedge channel. Trajectory images are obtained of a colored strand in the high density polyethylene melt flowing through a tapered slit die. The theoretically predicted trajectories are in reasonable agreement with the experimental results. The varying trends of the extensional strain rate with the radial and angular positions in the converging channel are then theoretically revealed.
Case Studies of Plastics Failure Related to Improper Formulation
Troubleshooting of plastics failures often requires chemical analysis to determine if the formulation is a contributing factor. Examples of failures in product performance or development associated with incorrect or improper chemical composition of formulations include (1) adhesive problem due to improper order of films in a multilayer system; (2) hardener left out of an adhesive; (3) delamination of tin coating from copper due to adhesive tape wrap; (4) stiffening of grease lubricating a moveable screw in a servo motor; (5) unintentional color in a portion of an electrical cable.
Isomers and Isomerization Processes in Poly-Anilines
The extraordinarily important potential role of isomers in determining the electronic, magnetic, optical, structural and mechanical properties of poly-anilines, including polyaniline is presented. Positional and cis/trans isomers and isomerism processes, some of which occur relatively slowly even at room temperature in solution are reported for the phenyl/phenyl end-capped dimer and the phenyl/amino end-capped tetramer (emeraldine oxidation states).
Kinetics of Non-Isothermal Crystallization of Syndiotactic Polypropylene: Avrami, Ozawa, and Kissinger Approaches
The kinetics of non-isothermal crystallization of syndiotactic polypropylene was investigated using a differential scanning calorimeter (DSC). Analysis of the data was carried out using the well known Avrami and Ozawa equations. The activation energy for molecular transport based on non-isothermal melt crystallization was calculated using the Kissinger method.
Performance of Rubber-Modified Cyanate Ester Matrices
Cyanate ester resins were modified with epoxy-terminated butadiene acrylonitrile rubber (ETBN) and impregnated into woven glass fabric. Mode I and mode II interlaminar fracture toughness of the cured laminates were evaluated as a function of rubber concentration. Mode I fracture toughness increased almost twice that of the unmodified system, while mode II fracture toughness remained essentially unchanged. Composite samples were subjected to aging experiments in water and the absorption behavior and thermal performance were characterized.
Thermally Conductive Thermoplastic Materials
Thermoplastics have made steady gains in the replacement of metals in a wide variety of applications. One of the last areas in which thermoplastics have not been effective in replacing metals has been in applications where thermal conductivity is required. Central to the development of these materials is an understanding of the heat transfer requirements in these applications. A simple model will be presented in which the heat transfer requirements for thermally conductive materials can be understood. Through the use of various filler systems, materials have been developed with thermal conductivities from 1 to 10 W/m°K.
Instrumenting the Elmendorf Tear Test
The Elmendorf tear test is widely used to evaluate tear strength of blown and cast films. Yet, the tear strength value does not directly relate to toughness, energy, or, indeed, any other true material property. Development of structure-property relationships are very difficult when the property one attempts to measure is so ill-defined. Furthermore, the Elmendorf value does not differentiate between initiation and propagation events. In this paper we describe a setup for instrumenting the Elmendorf tear test so that the information that one derives from the test is analogous to an instrumented impact test.
Plastic Part Design - Lessons Learned
Five different parts and assemblies that seemed to have been designed well but failed to meet the functional requirements after production are analyzed for the reasons of the failure. These are compatibility of materials, long term stress cracking, and effect of tool design on the part properties. The theory behind the failures is discussed briefly. Finally the solution to alleviate these problems is discussed.
Metal-Polymer Interfaces in Polymer-Based Electronic Devices
A number of degradation mechanisms in polymer-based light emitting devices have been studied. It was found that interfacial chemistry occurs between indium tin oxide (ITO) and precursor poly(p-phenylene-vinylene) (PPV) forming InCl3, which enhances the rate of conversion to PPV but leaves the polymer slightly p-doped. Electron flux on/through PPV films damages mainly the vinyl linkage, probably causing scission with subsequent cross-linking or bond formation with oxygen species.
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