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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Impact Stregnth as a Function of Foam Density
Structural high density polyethylene foam is commonly used in many household applications. Is has been accepted by the industry that foaming creates internal space in an injection molded article and therefore allows the part to absorb impacts without initiating cracks. This paper seeks to determine the relationship between the density of a structurally foam molded article and the impact strength.
The Effect of Extrusion Processing Conditions on the Water Vapour Transmission Rates of Polyolefin and Polyamide Packaging Film
The water vapour transmission rate (WVTR) of polymer films is critical in flexible food packaging applications. The WVTR of a series of polyolefin and co-extruded polyethylene/polyamide films were shown to be affected by density, orientation and crystallinity, as well as the cooling process from cast and blown extruded films.
Novel Immiscible Blends for Membrane Applications
Following our earlier work on PP/PS immiscible blends, the morphologies of blends and microporous membranes of hydrophobic poly(4-methyl-1- pentene)(TPX)/ hydrophilic polyethylene vinyl alcohol copolymer(EVOH) immiscible blend systems prepared in continuous extruders are investigated. The EVOH can form a well-distributed minor phase with domains having dimensions around 1~5?m by adding compatibilizing copolymer Lotarder®AX8950. The immiscible blend systems are extruded through a sheet die and then stretched to make flat, solvent-resistant microporous membranes suitable for ultrafiltration applications.
Morphology and Rheology of Polycaprolactone/Thermoplastic Starch Blends
Polycaprolactone (PCL)/thermoplastic starch (TPS) biodegradable blends were prepared via a one-step extrusion system over the entire range of composition at different viscosity ratios. A detailed morphology analysis of the PCL/TPS blends was investigated by electron microscopy after selective extraction. Through a judicious combination of concentration control and processing conditions, the volume average diameter of TPS droplets can be closely controlled from 0.5 to 16?m. The rheological behavior of these blends is also examined in depth.
The Effect of Uni-Axial Stretching on the Gas Permeation Properties of LDPE/LLDPE Silage Wrap Films
This work investigates the effect of uni-axial stretching on the gas permeation properties of LLDPE/LDPE films. The results show improved gas barrier properties with increasing uni-axial stretch as a result of increasing film crystallinity and molecular orientation.
A Study on Nalidixic Acid/Polycaprolactone Blends for Medical Device Applications
The incorporation of an antibacterial agent within the polymeric matrix can prevent bacterial colonisation on the surface of implanted medical devices. In this study, nalidixic acid was melt blended with polycaprolactone at different concentrations. Its effect on the processability, crystallisation, mechanical properties and drug release were investigated.
Dielectric Properties of Self-Reinforced Polymers
The dielectric constants of two compositions of a new class of rigid rod polymers (Parmax® Self Reinforced Polymers (SRPs)) were measured and demonstrate potential for use in multiple electronic applications. Dielectric measurements were made over a range of frequencies using a Hewlett Packard 4192A LF Impedance Analyzer. At 1MHz the two samples displayed very low dielectric constants of 2.31 and 1.96.
The Optimal Parameters of the Water Assisted Injection Molding Process with ABS Material
In this paper, the Water Assisted Injection Molding (WAIM) technology is applied to the design of a new mold. Two kinds of the ABS materials are utilized to undertake tests for the above new designed mold. Good results for the great decrease in the deformation as well as Warpage of the ABS products can be obtained. Finally, the Taguchi Method and Grey Theory are applied to finding the optimal parameters of injection molding process.
Branched Modifiers for High Melt Strength Applications
Poly(?-olefin) elastomers (POEs) are used to modify the performance of polypropylene (PP). All the POE modifiers were found to enhance both the room and subambient temperature impact performance. However, POEs containing high levels of long chain branching improved the melt elasticity of the PP. Thus, giving an increase the melt strength of the PP making it more suitable for applications such as thermoforming and blow molding.
Synthesis of Elastomeric Nanoparticles via Microemulsion Polymerization
Copolymerization of buyl acrylate with dimethyl meta-isopropenyl benzyl isocyanate (TMI) was carried out at 40°C in microemulsions stabilized with a mixture of sodium dodecyl sulfate / sodium bis (2-ethylhexyl) sulfosuccinate (3/1 w/w). The mixture of monomers was dosed during the polymerization. An inverse dependence of particle diameter (DP) on dosing rate of monomers and TMI concentration was found. Polymer content close to 25 wt. % and DP between 30 and 40 nm were obtained.
Structure-Property Relationship and Processing of Nanocomposites
Exfoliated organophilic clays dispersed in a polymeric matrix such as polyolefin, epoxy or polyamide form nanocomposites that exhibit improved mechanical, thermal, flame resistance and barrier properties. The effect of the organoclay’s chemical structure, its polarity and surface chemistry and how it is dispersed in the polymeric matrix determine the properties of the nanocomposite. Various characterization techniques are discussed as well as the effect of processing parameters on the properties of the nanocomposite.
Continous Processing Long Range Order in Sebs Block Copolymer Thermoplastic Elastomers
Ultra-long range order has been obtained in styrene-b-ethylene-co-butylene-b-styrene (SEBS) triblock copolymers with simple continuous extrusion processes. The effects of extrusion processing conditions like temperature and shear rate on the long-range order have been investigated using small angle x-ray scattering and rheometric techniques. Also, comparison has been made to long-range order obtained by different processes. Mechanical properties of these systems have been characterized and compared to isotropic un-oriented systems.
Polymer Degradation and Filling Incompletion Monitoring for Micromolding Using Ultrasound
Polymer degradation was successfully probed by measuring the ultrasonic velocity in the polymer at the barrel and mold insert of a micromolding machine with ultrasonic pulse-echo technique. Filling incompletion of the mold cavity was also detected by monitoring the ultrasonic energy variation transmitted into the part at different points along the melt flow length. The presented ultrasonic sensors and technique enable optimizing the micromolding process to improve quality of the molded parts.
The True Cost of Snaps
Snap fit assembly has many advantages over non-integral fastener techniques. Snaps can improve product cost by part reduction and reduced assembly labor. However, the cost and time for engineering and tooling for snaps probably are increased. While the piece part and assembly cost may be reduced by snaps, the up front time and costs may wipe out this gain unless the manufacturing volumes are very high.
Antioxidant Performance of Mixed Tocopherols in Styrenic Block Copolymers
Mixed tocopherols containing a predominance of ?- tocopherol were evaluated for antioxidant performance in polybutadiene and polyisoprene based styrenic block copolymers using oxidative induction time as a measure of antioxidant performance. A conventional hindered phenolic antioxidant and ?-tocopherol (vitamin E) were evaluated in comparison. Mixed tocopherols exhibited significantly higher performance than the controls in both SIS and SBS polymers.
Benefits of Using Secondary Guide Rod with Lifter Core Assembly
Reactionary forces and bending moments within conventional lifter core rods require smaller rod angles, which can increase mold die height and foot print. A new approach to designing lifter cores utilizes a second guide rod that is parallel to the lifter rod. The resulting parallelogram results in the elimination of the bending moment seen in conventional single-rod lifter configurations. This approach allows for a greater lifter angle, reducing the necessary die height and mold footprint.
Experimental Measurements of Degree of Fill in a Co-Rotating Twin Screw Extruder
Degree of fill is a key factor in extruders because it can affect pressure profiles, residence time distributions, and mixing performance. In this paper, the fully filled length and pressure profiles in a co-rotating twin screw extruder were measured experimentally. The fully filled length in a conveying section prior to a kneading block shows a linear relationship with specific throughput. We also explored the effect of the kneading disk configurations (staggering angles and thickness) on the fully filled length.
Structure and Properties of Elastomeric Propylene-Based Fibers and Film
The solid state structure and mechanical properties of fibers and oriented films made from a new class of propylene based elastomers (PBE) are investigated. The effect of processing conditions on the solid state structure is probed with density, WAXS, DSC and OM birefringence measurements. Relationships between fiber and film process conditions, solid state structure, and mechanical behavior are described.
Improved Solvent Stress Testing for Polycarbonate
Solvent stress testing has proven to be an effective method for identifying areas of elevated stress in parts and assemblies made from polycarbonate. Dilutions of various stress-cracking agents have been developed to quantify the levels of molded-in and/or applied stresses. Unfortunately, there has not been good correlation between the various test solutions. Calibration tests were performed for this study to develop guidelines to improve the resolution and accuracy of solvent stress testing, particularly at low stress levels.
Controlling Intra-Cavity Melt Flow and Weld Strength through New Runner Design Technology
The development of high sheared laminates are shown to have a significant effect on filling pattern. New methods are shown to manage these hotter high sheared laminates to control filling pattern and position them so as to increase weld line strength.
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