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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Resin Design for High Stiffness and High ESCR Performance in Rotational Molding Applications
This paper presents new developments in the design of ethylene copolymers for rotational molding applications with higher stiffness and ESCR requirements. The performance of novel ethylene copolymers is discussed based on phenomena fundamental to the rotomolding process and on the relative impact of the choice of comonomer, manufacturing technologies and resin design strategy.
Relating Polymer Viscoelastic Properties to Thermoforming Process: A Short Review
This paper reviews the relation between polymer viscoelastic properties and the plug-assist thermoforming process. One of the important attributes of polymers is their macromolecular interaction. Molecular interaction provides enhanced networks of molecules that contribute to minimizing polymer deformation at high temperatures. As a result, sheet sagging will be reduced during thermoforming. Additionally, molecular interaction could enhance the melt strength of the polymer by reducing its molecular mobility.
Upgrading the Capacity of an Existing Extrusion System
Several low-cost techniques are readily available to upgrade the capacity of an existing extrusion system. These techniques include upgrading a screw to restore the flight clearance due to wear, changes to the motor drive train system, and the use of high-performance screws. The technique used will depend on the rate limitation and the current process.
Troubleshooting and Mitigating Gels in Polyolefin Film Products
The term “gel” is commonly used to refer to any small defect that distorts a film product. Eliminating gel defects from extruded polyolefin film products can be difficult, time consuming, and expensive due to the complexity of the problem and the high levels of off specification product produced. This paper discusses the identification of gel types, the common root causes for gels, and the technical solutions for mitigating gels in film products produced using single-screw extruders.
Comparison Study of Talc and Nanosilica as Nucleating Agents for Low-Expansion Foaming Applications
This paper compares the effectiveness of talc and nanosilica as nucleating agents for generating polypropylene foams with high cell density and low expansion. Experiments were conducted in two stages: 1) In-situ foaming observation in a batch system; 2) Extrusion foaming. Nanosilica was more effective than talc in inducing cell nucleation under static conditions. However, in extrusion, their effectiveness in enhancing cell nucleation was similar due to the presence of extensional and shear stresses.
Characterization of iPP-PDMS Elastomers
An isotactic polypropylene-polydimethylsiloxane (iPP-PDMS) elastomer was prepared by reactive extrusion with tert-butyl peroxide. Rheology and thermomechanical analyzer (TMA) experiments demonstrate typical elastomeric behavior. Two complimentary techniques TMA and differential scanning calorimetry (DSC) were combined to estimate the density of iPP in the crystalline phase and to calculate the volume change associated with melting and crystallization thermal transitions. Further, the analysis confirmed the presence of crystalline iPP and amorphous PDMS phases in the elastomer
Fiber length and orientation distribution measurement of a charge for D-LFT compression Molding
Initial fiber orientation distribution (FOD) and fiber length distribution (FLD) of a fiber glass reinforced polypropylene charge for a D-LFT compression molded part were measured using image processing techniques. The FOD was measured from ?-CT scans using two different image processing approaches. These results are intended to be used in compression molding simulations.
Supercritical CO2 Improving Compatibilization of PP/PS Blend in Continuous Extrusion
Supercritical carbon dioxide (scCO2) was used in extrusion for the improvement of polymer blend properties. The compounding took place in two-single screw extruder. The morphologies of prepared blends were compared. Carbon dioxide was added at 3, 5wt% based on polymer melt flow rates. The experimental results indicate that the viscosity of PP and PS blends were reduced obviously and a sharp decrease in the size of the dispersed phase was observed. The impact strength of press molded 80/20 polypropylene /polystyrene blends increase by the addition of CO2.
Considerations regarding the EN13900-5:2005 determination by filter pressure value test
With the increasing demands on masterbatches the DIN EN13900-5 standard has been used as a more stringent and objective indicator of dispersion quality in a polymer matrix. Introduced within the last 7 years this method is being widely adopted in the industry. This paper will examine the history and the key components needed to assess the dispersion of a colorant in a masterbatch as well as equipment considerations.
Reliable Damping Parameters for Simulating Flow of High Molecular Weight HDPE
Determination of damping parameters from uniaxial extensional flow data per K-BKZ/PSM model are evaluated for high molecular weight HDPE resins. It was found that the damping properties depend on strain rate. The strain dependence, however, cannot be represented reproducibly as the relaxation mode-dependent ?k per Luo-Tanner from SER data. More efficient description of the strain dependency remains to be further explored.
Laser Transmission Welding for Medical Devices
Laser transmission welding is a well established joining technique for molecular diagnostic devices such as lab on a chip. This paper provides an overview about the effects of the injection molding parameters and the joining process parameters on weld strength. Design of experiments was used to maximize the weld strength. Additional optical and microscopic tests are required to validate the process for medical devices.
Die Design Effect on Internal Die Drool Phenomenon
n this work, the effect of die exit design on the internal die drool phenomenon occuring during extrusion of HDPE has been experimentaly investigated. It has been revealed, that firstly, the effect of flared length and die exit angle on the internal die drool intensity during extrusion of HDPE has non- monotonic character and secondly, flared dies are more stabilizing in comparison with chamfered dies.
Influence of the Endgroup Nature on the Rheological Behavior of Branched Polycarbonate Resins
Branched polymer rheology represents a very active field of research with important challenges, both from the scientific and technological point of view. A study of the rheological properties of branched polycarbonate resins is presented. The effect of the endgroup nature on the polymer melt viscosity was investigated.
A New Rheometer Concept Extending the Capabilities of Rotational Rheometer
A new rheometer concept based on two air bearing supported motors is introduced. The combination of two motors into one rheometer system offers increased sensitivity and new testing capabilities not possible before. Three completely different testing modes such as combined motor transducer, separate motor transducer and counter rotation are available in one single rheometer system. The aim of the paper is to describe the new technologies involved and to outline applications.
Cavity-Integrated Injection Molded Accoustic Foams
An injection molding machine enhanced with gas counter-pressure was used to produce cavity integrated acoustic foams using mold opening technique. The cell morphology of the produced foams in different mold opening lengths was studied. An automated perforating system was developed to perforate acoustic foams. Acoustic behavior of the produced foams with and without perforation was studied.
Reliability of Weld Join Under Fatigue Conditions
This paper focuses on reliability of glass-reinforced polyamide (PA) vibration welded joints with respect to fatigue. It presents a statistical extension of the thermodynamic model of lifetime under creep into reliability model under creep and fatigue. The paper also presents in detail a method of obtaining Weibull distribution parameters employed in the model. The proposed reliability analysis can be easily implemented for weld joint design.
Processing and Characterization of High Speed Extruder for Nanocomposite Formulations
Ethylene Co-Vinyl-Alcohol (EVOH) blends were compounded on a high speed extruder, with kaolinite loading levels at 0, 3.0, and 7.5%. Extruded samples were processed with varying screw speeds (0 to 3000rpm) and feeder rates, and then characterized for dispersion, thermal, and mechanical properties.
Modeling polyurethane foam flow in a mold with constricted vents
A computational flow model has been developed that accounts for the volume expansion and viscosity behavior of thermosetting polyurethane foam with water as the blowing agent in pour molding of polyurethane foam. This model was then used to investigate the effects of (a) varying pour distribution and (b) restricted air flow through vents on the merging of expanding flow fronts and air pocket formation in a vented rectangular mold cavity with a rigid rectangular insert.
Basic Day-Night Laser Ablation
Lasers have been used for over 10 years to ablate paint layers in day-night applications. Over this time, there has been a lot of confusion over how laser systems are set up to perform this application. This paper will address different variables that effect how lasers interact with paint and why each variable is important to the process.
Study on the Effect of Material Elasticity on Acoustic Performance and Rheological Properties of Bio-Based PLA and PHA Blend Foams
In this study, open cell foams were fabricated from blends of bio-based polymers to be used as sound absorbers. Different blends of Polylactide (PLA) with two grades of Polyhydroxyalkanoates (PHA) where foamed and characterized based on acoustic and mechanical performance. Rheological properties of pure polymers as well as their blends were studied to investigate the effect of material elasticity on the acoustic absorption of the resulting foams.
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