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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Effects of Residual Fiber Length on the Mechanical Properties of Long Fiber Reinforced Polypropylene from Various Processes
Residual fiber lengths of long fiber thermoplastic (LFT) polypropylene (PP) composites made by injection molding (IM) or extrusion compression molding (ECM) were correlated with tensile modulus, strength, and impact energy. IM retained substantially lower fiber lengths than ECM, but neither strength nor stiffness was reduced. Impact properties, however, increased 4 fold as the length increased from 0.6 to 10 mm, and only ECM preserved fibers long enough to significantly improve impact resistance.
Lifetime and Safety Assessment of Pe Pressure Pipes Based on Fracture Mechanics Fatigue Tests
The present paper describes the main elements of a novel concept for lifetime and safety assessment of PE pressure pipes for arbitrary installation conditions based on modern methods of fracture mechanics. At the core of the proposed concept is the accelerated generation of so-called synthetic" crack growth curves and corresponding material laws for crack growth initiation and slow crack growth for service-near temperature conditions without the use of stress cracking liquids."
A Composite Model for Solid Conveying, Melting, Pressure, Temperatures and Fill Factor in a Metered Fed Closely Intermeshing Counter-Rotating Twin Screw Extruder
A composite model of solids conveying, melting and melt flow in a closely intermeshing counter-rotating twin-screw extruder of modular design has been developed. This is based on combining melt conveying models with new melting and solids conveying models. Computations are made for axial fill factor, pressure, temperature, and melting profiles. The results are compared with experiment.
Mechanism of Action of Ester Thiols as Stabilizers for PVC
Organic thiols containing at least one carboxylate ester group (ester thiols) are excellent heat stabilizers for both rigid and plasticized PVC. Their mechanism of action is now shown to involve the deactivation of unstable structural defects by nucleophilic chloride displacement, the retardation and removal of coloration through thiol additions to polyene double bonds, and the prevention of autoacceleration during thermal dehydrochlorination through polyene shortening reactions and the scavenging of free radicals formed from polyenes and HCl.
The Role of Analytical and Physical Methods in Plastics Failure Analysis
Without analytical and physical methods, many cases of plastics failure would be unsolved or solved incorrectly. Some methods require costly instrumentation and technical expertise. Others have little cost and are easy to learn. Accuracy and reliability are essential for correct conclusions about failure cause. Knowledge of the science and technology of polymeric materials helps in interpretation of analytical and test data.
Characterization of Crosslinked, Heat-Shrinkable Packaging Films
The shrinkage characteristics of polyolefin films that have been irradiation crosslinked prior to and after orientation have been studied using two types of tests: free shrink and shrink force tests. The shrink behavior can be described using various graphical tools generated from these tests in the term of tendency of shrink (shrinkage stress) and extent of shrink (unconstrained recoverable elastic strain). Finally, the residue energy calculated from the synthesized stress-strain plots provides insight into the mechanism of heat shrinkable films.
Effect of Hyperdispersants in Polyethylene Masterbatch and Rigid Polyvinylchloride Compound
Effect of addition of a dispersion aid or a hyperdispersant on the color strength, surface defects and processing characteristics of PE (Polyethylene) pigment masterbatch and rigid PVC (Polyvinylchloride) compound is investigated using pressure filter blocking test, cast film extrusion, torque rheometer and microscopy. Various hyperdispersants were tested at varying loadings to understand the optimum usage levels and their effect on throughput and melt viscosity.
Absorbance Control Welding by Laser
This paper discusses the method that enables laser welding of plastics using identical molding materials. For this purpose, we have synthesized colorants and controlled their absorbance. This method makes three-dimensional welding possible. This paper describes butt welding using un-reinforced nylon 66. Results indicate that it is important to control absorbance of the colorant and to adjust jig pressure for stable welding.
Structural, Thermal, and Mechanical Properties of Miscanthusderived Biocomposites
Miscanthus, a high yield, fast growing perennial grass with low mineral content, was put under a microscope to explore its potential as a source of natural and environmentally friendly fibers and polymers for composite manufacturing. The manipulation of miscanthus’ structural and thermal properties at 25°C < T < 550°C, as probed by SEM, DSC, TGA, and in situ diffuse reflectance-FTIR, suggested that composites with flexural strength as high as ~ 65 MPa could be formulated without the addition of external polymers.
Orientation Structure and Properties of a Propylene-Based Elastomer
An orientation process to enhance the elastic recovery and stiffness of propylene-based elastomers is described. Elastomers fabricated during this process have virtually complete elastic recovery, and are up to ten times stiffer than unoriented controls. The structural development during orientation is explored with WAXS. A relationship between crystal structure, strain recovery, and modulus is described.
Polypropylene (PP) and polysulfone (PSU) were successfully blended despite viscosity and processing temperature variations. These blends showed structure-property improvements with the addition of functional polyolefins. A series of membranes were made using an environmentally-friendly process.
Comparison of Block and Random Ethylene-Octene Copolymers Based on the Structure and Elastomeric Properties
The structure and elastomeric properties of the novel olefinic block copolymers (OBCs) were studied by DSC, WAXS, AFM combined with stress-strain, and strain recovery measurement. Their structure and properties were compared with the conventional statistical ethylene-octene (EO) copolymers. The OBCs showed higher strain recovery than the statistical EO copolymers, which is attributed to their unique crystalline morphology. AFM and WAXS studies revealed the elastic" spherulites in OBCs."
Miscibility of Novel Block Copolymers
The miscibility of novel olefinic block copolymers (OBCs) with random ethylene-octene (EO) copolymers was studied using blends of two homogeneous random EO copolymers as a model system. The critical comonomer content difference for miscibility between OBC and random EO blend was observed to be lower than that for the blend of two random EO copolymers. The OBC and random EO blend also exhibited a broader partial miscibility window. Interaction parameters for blends of two EO copolymers were extracted from partially miscible blends.
Crystallization Kinetics of Olefinic Block Copolymers
The effect of the blocky chain architecture on spherulite growth rate and bulk crystallization kinetics of novel ethylene-octene block copolymers is described. These copolymers form space-filling spherulites even when the crystallinity is as low as 7 %. Spherulite growth rates were analyzed by Lauritzen-Hoffman theory and the bulk crystallization kinetics were subjected to Avrami analysis. Comparison with random copolymers showed that the blocky architecture imparts a substantially higher crystallization rate.
Polyethylene Nanocomposites Based on High Thermal Stability Organoclays
In this work, alkyl pyridinium, imidazolium and phosphonium cationic surfactants were used to produce highly thermally stable organoclays. The volatile products issued from the thermal decomposition of those organoclays were analyzed by mass spectroscopy (MS). The organoclays were compounded with LLDPE and an appropriate compatibilizer. The micro- and nanodispersions were investigated through X-ray diffraction (XRD) and electron microscopy (SEM, TEM). The thermal stability of the nanocomposites was evaluated by thermogravimetric analysis (TGA).
Utilizing the Power of Three to Enhance Student Learning
Considering a class to comprise three parts: introduction of fundamental principles during the lecture; assignment of a practical problem, requiring application of these principles; provision of a detailed solution at the beginning of the subsequent class, student involvement and learning has been significantly improved.A typical polymer processing class would consist of deriving the equations for steady-state, pressure-driven flow of a Newtonian fluid through a circular cross-section, allowing assignment of a melt-spinning problem.
Study on Crystal Structures of Isotactic Polypropylene Processed by Injection Molding
The crystallinity and crystallite size of injection molded isotactic polypropylene was measured by wide angle X-ray diffraction(WAXD) and the distinct skin-core morphology was visible under a polarizing optical microscope. The results show that the crystal structures are dependent on the injection molding processing conditions. The crystallinity and crystallite size decreases with the distance from the gate. The skin layer thickness is thinner with the higher injection temperature.
In-Mold Part Shrinkage Rate Measurement
An on-line technique for quantifying part shrinkage rate in the mold has been developed. The technique consists of measuring post-hold cavity pressure decay rate inside the mold during the injection molding process. A comparison of the technique as applied to amorphous and semi-crystalline polymers will be presented.
Determination of Shear Viscosity and Shear Rate from Pressure Drop and Flow Rate Relationship in a Rectangular Channel
In this study, we present a unique approach to calculate the shear viscosity and shear rate with the pressure drop and flow rate data from a channel having a rectangular cross-section with a height-to-width ratio (H/W) of close to one. The derived equation was verified with experimental data from rectangular dies whose height-to-width ratio (H/W) ranges from 0.1 to 1. It was confirmed that the proposed approach is reliable for calculation of the shear viscosity and shear rate from the flow data in a rectangular channel.
Improvement of Transparency and Processing Properties of Hard TPU Materials
A statistical model is discussed which will help to understand the sequence length distribution of thermoplastic polyurethane block copolymers. Using this model processing range and transparency of some TPU materials were correlated to the theoretical segment length distribution.Considering this analysis some new Elastollan® 1200 materials (E 1200 materials) were developed. Due to the wide processing range and the high transparency of these new materials they are suitable to an increased number of applications.
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