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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The Simulation of Residual Stresses of Injection Molded Crystalline Polymers
Based on the theoretical analysis about the morphology and the effect of crystallinity on the development of residual stresses for injection molded crystalline polymers, the residual stresses have been simulated by means of a new four elements viscoelastic mechanical model. Considering the crystalline orientation of injection molded parts, we view the parts as orthotropic solids to simulate the development of residual stresses in both longitudinal and transverse directions of the parts.
A Study on the Preparation of Irradiation Crosslinked Silicone Rubber Foam and its Mechanical Properties
A silicone rubber foam was prepared through crosslinking with electron beam irradiation and foaming by the decomposing of blowing agent in hot air. The effects of irradiation dose, silicon dioxide content and the amount of blowing agents on the physical and mechanical properties of silicone rubber foam were studied in this paper in order to control and optimize the physical and mechanical properties of the silicone rubber foam.
Determining the Processability of Multilayer Coextruded Structures
Multilayer coextrusion is a process in which two or more polymers are extruded and joined together in a feedblock or die to form a single structure with multiple layers. This paper will discuss techniques for measuring experimental rheology data for monolayer and multilayer structures and how that data can be used for determining the processability of multilayer coextruded structures.
Polycarbonate Copolymers with Improved Heat and Hydrolytic Resistance
Polycarbonate homopolymer when exposed to heat and humidity, under some conditions may suffer a reduction in the mechanical properties. This paper discusses significantly improved heat and hydrolytic resistance of copolymers of Polycarbonate with Polysiloxane. Retention of transparency coupled with good mechanical properties upon heat and hydrolytic aging makes these new materials excellent candidates for hot and humid engineering thermoplastic applications.
Improvement of the Mechanical Properties of Soy Protein Isolate Based Plastics
Biodegradable plastics based on soy protein were prepared with glycerol as a plasticizer and compounded with different additives such as: polycaprolactone and zinc stearate as well as heat treated at various temperatures after the injection molding process in order to characterize base material strength and the effect of water absorption. The results indicated that the polycaprolactone and, respectively a medium to high heat treatment enhanced the tensile strength and decreased the water absorption significantly.
Effects of Molding Process on Residual Fiber Length of Long Fiber Polypropylene Composites
Fiber length distributions were determined for long fiber polypropylene composites reinforced with carbon, glass or glass-organic fibers from pultruded pellets, chopped fiber, or in-line roving, and molded by multiple long fiber thermoplastic injection (LFT-IM) or extrusion-compression molding (LFT-ECM) processes. All processes degraded the fiber length significantly. Injection molding processes reduced fiber length by up to 90%, much more than LFT-ECM, which produced broad, asymmetrical residual length distributions, with substantial amounts of much longer fibers.
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.
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