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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.
Molecular-Scale Reinforcement of Glassy Networks
Improvements in mechanical and thermal properties of glassy networks have been made through the use of a unique class of molecules that reinforce the network at the molecular scale, commonly referred to as fortifiers. In our studies, fortifiers are incorporated either as an additive or as a reactive monomer in the network. Each approach provides different benefits in properties. Several mechanisms of fortification are discussed and correlated to the observed improvements in properties.
Effect[GTLim1] of Slip Agent and Talc Surface Treatment on the Scratch Behavior of TPOs
A set of model TPO systems, with and without slip agent and talc surface treatment, was investigated using a linear load increase scratch test methodology. Our findings suggest that both the presence of slip agent and surface treatment of talc fillers[GTLim2] can greatly reduce scratch visibility. The underlying mechanisms are discussed.
Synthesis of Uniform ZnO Nanorods via Wet Chemistry Approach
ZnO nanords were synthesized using spherical ZnO nanoparticle precursor solution. Our unique wet chemistry approach can produce uniform ZnO nanorods at a much lower concentration than expected. We used transmission electron microscopy to characterize the rodlike shape evolution of ZnO quantum dots. The underlying mechanisms for the formation of ZnO nanorods are described and discussed.
Creep Behavior of Sisal Reinforced Starch Based Blends
Creep measurements were carried out on starch based blend reinforced with sisal short fibers. The selected matrices were MaterBi-Y (cellulose acetate) and MaterBi-Z (polycaprolactone). The studied temperatures were higher than Tg for MaterBi-Z and lower of Tg for MaterBi-Y and as expected, the behavior was different. Different models were applied and allowed the comparison with other materials.
Geometry Influence in Cavity Pressure Curves Registration
The geometric factors influence of injected pieces on the cavity pressure curves behavior during the injection process was studied. Mold cavity sensors were placing in the most critical areas in the pieces. The geometries were evaluated using an injection process simulator program. Substantial changes in the cavity pressure curves in pieces with different thickness were obtained. The shape factor is an important geometric factor that showed smaller variation in the cavity pressure registrations in pieces of small length.
Investigation of Molecular Entities Present in Maleated Polypropylene Using LSM
Maleated polypropylene (mPP) is often used as an adhesion promoter in polypropylene composites. Poly (maleic anhydride) (PMA) or oligomers of maleic anhydride are often present in maleated polypropylene, but they do not contribute to the adhesion of polypropylene to glass fiber reinforcements. PMA can be detected by confocal laser scanning microscopy.
Failure Analysis of a PEX Piping Crimp System
Premature failures have occurred in some PEX piping systems that utilized a stainless steel crimp ring to attach the PEX pipe to copper or brass fittings. Leaks in these systems were traced to a non-uniform crimping of the PEX tubing around the circumference of the fittings. Some leaks were also due to cracking of the crimp rings as a result of the crimping process and corrosion of the rings.
Flow Field Simulation of the Modular VCR in Continuous Mixer
VCR (Various clearance rotor) is a new type of continuous mixer’s modular rotor. The flow field of different configurations flow field of VCR has been simulated in this paper. According to the simulation result, the pressure, velocity and viscosity field are obtained. The average shear stress, shear rate and shear degree in deferent configurations are calculated by post-process program. Meanwhile, the mixing ability of different configurations flow field is compared.
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