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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Influence of Curing Systems and Irradiation on Woodflour Filled EPDM Compounds
Rheological and mechanical behavior of EPDM rubber filled with woodflour was studied based on blend ratio and curing systems. Irradiation was also studied as an alternative crosslinking method. Results indicate that woodflour accelerates rubber vulcanization. When comparing curing systems, final overall vulcanizates properties did not deteriorate with the efficient system. Concerning irradiation, an optimum dose of 110 kGy was found, since lower doses do not promote crosslinking and higher doses tend to decrease overall properties.
The Dynamic Rheological Behaviors of PP Melt during Pulsatile Extruding Processing
A novel dynamic capillary rheometer (DCR) was designed to investigate the viscoelastic characteristic of polypropylene melt. The pulsatile flow of polymer melt could be got by parallel superposition of oscillation on steady shear flow in this novel DCR. The vibration frequency-dependent behavior of the phase angle and the shear stress vs. shear rate loops can be determined during pulsatile extruding processing. With the increase of the vibration frequency, the elastic characteristic of PP melt becomes more apparent.
3D Numerical Simulation of Flip-Chip Underfill Encapsulation
The analysis of encapsulant flow during under-fill encapsulation would be discussed in this work. With solving the melt-front positions based on 3D Finite Volume Method, we get better predictions than 2.5D simulation. For the surface effects among encapsulant, bumps and substrate, the results illustrate that the variations of contact angle influence filling time greatly. Moreover, by applying approximated parameters of dynamic contact angle model, we can simulate the influence of different processing conditions on filling time predictions.
Molding of Polycarbonate / ABS Parts for Chrome Electroplating
Electroplating PC/ABS requires the plastic be conditioned through “etching” where metal is interlocked into the part. This only occurs when the part has a butadiene-rich surface. Not achieving this condition results in costly unrecoverable plated scrap. In this study, the injection molding process effect on plating scrap was studied where it was learned that the slower the injection rate provides less plating scrap, contrary to traditional molding efficiency.
Slender Bubbles: Inertial Effects and Stability
The influence of inertia on the deformation and breakup of a slender bubble embedded in a Newtonian liquid in an axisymmetric extensional flow has been theoretically studied. The steady-state problem is governed by two dimensionless parameters: The capillary number and the Reynolds number for the external flow. The calculated stationary deformation reveals the existence of multiple solutions. A stability analysis of these results is used to distinguish between stable and unstable solutions and to establish the break-up point.
Effect of Process Aids on Interfacial Instabilities in Coextrusion
New slip model based on ‘effective continuum methods’ for the description of slip was developed and used for investigation of process aids effect on the zigzag type of interfacial instabilities in coextrusion flow.
Design of PVC Pipes for Shock Resistance
One of the major difficulty in designing extruded structures consists in understanding and managing their driving parameters like: material structure;process characteristics;their system effects; which influence the shock resistance. Thus, it is proposed to identify these relationships within the context of redesigning the PVC pipes for sewer systems.
Carbon Assisted Laser Sintering of Thermoplastic Polymers
Selective laser sintering (SLS) with CO2 lasers is only used commercially with polyamide (PA) and polystyrene (PS). This is because only these polymers absorb enough energy to melt properly in the SLS process.In a new approach, carbon black is added to the thermoplastic polymer powder. Carbon is sensitive to the wave length of Nd:YAG lasers and can absorb enough energy that adjacent polymer melts.In this paper a feasibility study of this new method is presented. As an example the sintering behaviour of the high temperature resistant polymer polyether ketone (PEK) is shown.
Evaluating Flow through Grill-Like Features Using Width-To-Thickness Ratio in an Adjustable Mold
Using a mold specifically designed for the purpose of studying Width-to-Thickness Ratios in grill shaped geometry, parts are molded at each of four different width-to- thickness ratio settings using a control ratio of 10:1 in each setting. Semi-crystalline and amorphous behavior is investigated.
Experimental and Numerical Investigation of the Elongational Viscosity Effects in a Coat-Hanger Die
The flow in a flat die is simulated using the axisymmetric and planar elongational viscosities of a low-density polyethylene (LDPE) resin. Elongational viscosity is found to have only a limited effect on the velocity distribution at the die exit. However, the predicted pressure drop in the die increased when the effect of elongational viscosity is included in the simulation. Predicted pressure drop is compared with the corresponding experimental data.
Comparative Performance and Barrier Properties of Biodegradable Thermoplastics and Nanobiocomposites vs. PET for Food Packaging Applications
This paper reports about the comparative behaviour, regarding PET, of biodegradable biopolymers such as PCL, PLA and PHBcoV and their nanobiocomposites, in terms of thermal and retorting resistance (thermal humid processes) and oxygen, water vapour and aroma barrier by means of time-resolved synchrotron radiation, FT-IR and permeation methods.
Drawing Forces and Film Properties in Semi Sequentially Stretched Polypropylene
The relationship between biaxial stretching kinematics and oriented polypropylene film properties was studied. Initially only transverse direction (TD) speed was varied while areal draw ratio and machine direction (MD) speed were held constant. Slow TD speeds increased final TD drawing force and produced anisotropic film shrinkage. Tensile properties were primarily a function of draw ratios. Using different MD and TD draws allowed tensile properties to be changed while holding film shrinkage nearly constant.
Melt Fracture Analysis Using an In-Line Camera
A low melt flow rate metallocene isotactic polypropylene homopolymer was cast into film with and without melt fracture. Using an in-line camera, melt fracture was quantitatively described using real-time measurements of film defects. Melt fracture caused more variation in light transmittance, leading to a higher defect count. This measure of film optics was more sensitive to melt fracture than haze or gloss.
Effect of Flow Behavior on Internal Structure of PC/ABS Injection Moldings
Effect of flow behavior on internal structure of PC/ABS injection moldings was investigated. The cross sections in flow direction of etched specimens were observed, and the thicknesses of the cavities (ABS rich region) through thickness direction were measured. Subsequently, the flow field was calculated by using CAE software and the relationship between the flow behavior and internal structure was examined. As a result, it was found that the maximum shear stress and solidification time of the resin was important in determining the final morphological properties.
The Effect of Molecular Weight on the Interfacial Properties of GF/PP Ingection Molded Composite
The interfacial shear strength of glass fiber(GF)/polypropylene(PP) injection moldings were investigated by using the Kelly-Tyson formula. PP was grafted with maleic anhydride for compatibilization purpose. The weight - average molecular weight of PP was also varied. As a result, it was found that the interfacial shear strength of GF/PP can be influenced by changing weight - average molecular weight of PP. Smaller weight - average molecular weight of PP would yield higher interfacial adhesive strength between the glass fiber and PP.
Scratching Behaviors in Injection Molded Products
Scratch behaviors of injection molded products, such as PS, HIPS, ABS, PC/ABS, were investigated. From the observation by optical microscopy of scratch, the damages generated were understood. They depended on the types of polymers and the structure near the surface generated during the injection molding. The scratch behaviors would be affected by friction between the polymers and scratch tip and modulus, yield strength, fracture toughness of the polymers.
Fast Simulation Methodology and its Application in Injection Molding
The injection molding is a popular technique of polymer processing, which multiple parts with tight tolerances and complex shape can be produced in a single operation. Through studying the flow behavior of melt in cavity and runner system, a fast flow simulation method is developed based on the introduction of the equivalent flow length concept. The optimization algorithms and fast flow simulation technology are integrated to optimize gate design.
Mechanical Properties of Polyoxymethylene Copolymer Injection Moldings
Polyoxymethylene (POM) copolymer using dioxysolane (DOL) with polyethyleneglycol (PEG) was fabricated by injection molding. The DOL and PEG contents were varied, and the effects of them on morphology and mechanical properties were discussed. Small particles were observed in the case of PEG 1-5wt%, and the number and diameter increased with increasing PEG content. The charpy impact strength increased with increasing PEG content. Such morphology with particles resulted in the improvement of the impact strength.
Morphology of PC/ABS Blend Systems Fabricated by Injection Moldings
Morphology of PC/ABS injection moldings was observed by TEM in parallel to flow direction and transverse. The thin films, which thickness was less than 100 m, of PC and ABS were observed near the surface with regardless of injection speed, while ABS was in fibrous shape at the center. The geometry of butadiene rubber domains creating salami occluding SAN was a focus. It is confirmed that they elongated in flow directions.
An Approach to Gradation Mesh Generation in Injection Molding Simulation
Based on advancing-front method and Delaunay triangulation concept, a new interior point generation scheme is proposed. The longest edge at the current advancing-front is always chosen to create a new triangle element by using Delaunay triangle’s property, so that a high-quality graded mesh is obtained and a smooth transition in element size is maintained. The high-quality mesh can make plastics injection molding computer simulation more precise.
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