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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EFFECT OF MICRO-VISCOSITY AND WALL SLIP ON POLYMER MELT RHEOLOGY INSIDE MICRO-CHANNEL
The rheological model for polymer melt flow in micro-channels is vital for the accurate simulation of micro-injection molding. In this study, the governing equations for mlet flow in micro-channel were in terms of viscous, incompressible 1D flow. The simulated rheological difference between macro model and micro model becomes significant when the micro channel is smaller than 100?¬m, and increases with the diameter decrease. The simulated results indicate the combined micro-viscosity and wall slip model can improve the simulating precision.
STRUCTURAL BONDING ALTERNATIVES FOR PLASTICS
Plastics have become an integral part of everyday life. It would be difficult to identify a manufacturing process which does not use plastics in one from or another. Plastics have achieved widespread acceptance due to the virtually limitless combinations of plastic types, fillers, and additives which can be compounded at relatively low costs and processed by a wide variety of methods. When designing assemblies made from or including plastics, it is often critical to structurally hold assemblies together with a reliable mechanism. Plastics can be reliably fastened to a wide variety of substrates using an engineered adhesive solution.
RESEARCH ON ELECTROMAGNETIC SHIELDING PERFORMANCE OF SISAL FIBER / CARBON BLACK /PP COMPOSITES
A novel conducting filler was introduced to prepare Sisal Fiber /Carbon Black/PP composites. NaOH and Silane were adopted to treat natural sisal fiber (SF) in order to help SF adsorb carbon black as SF/CB conducting filler, and then SF/CB/PP composites with varied compositions were prepared by extrusion mixing and hot compression mold technique. The effects of fiber length and SF/CB content on electrical conductivity and shielding effectiveness(SE) have been investigated in frequency range 100MHz-1GHz. The experimental results showed that at the same content of CB, the SE of SF/CB/PP composites were remarkably improved when compared with those of CB/PP composites.
POLY(ARYLENE ETHER)-POLYSILOXANE MULTIBLOCK COPOLYMERS
This study focuses on the evaluation of novel, linear, poly(arylene ether)-polysiloxane (PPE-Siloxane) multiblock copolymers prepared by the reaction of a hydroxyl terminated oligomeric bifunctional poly(arylene ether), a hydroxyl terminated telechelic bifunctional polysiloxane, and an aromatic diacid chloride. The resulting copolymer chains had multi (greater than or equal to 2) siloxane blocks and multi arylene-ether blocks. The overall siloxane incorporations were varied and at high levels (>60 wt %) yielding flexible compositions with improved flow, ductility, flame retardancy and low smoke generation during burn.
EVALUATION OF FOAMING OF PHARMACEUTICAL POLYMERS BY CO2 and N2 TO ENABLE DRUG PRODUCTS
Gas mediated foaming of extrudate is of interest to the pharmaceutical industry as a method to improve milling performance, to increase surface area for dissolution of molded parts, and to increase the processing window of thermally labile active ingredients via gas-assist extrusion. Pharmaceutical polymers were characterized via rheology and gas solubility measurements for their ability to support a foamed architecture. Finally, batch foaming studies were conducted and the materials characterized for density and cell size.
THERMAL & FIRE RETARDANCY STUDIES OF RICE HUSK FILLED AMINOPOLYMER
Rice husk (RH), a naturally occurring biomass consists mainly of ligno celluloses and silica. With different weight percentage of 10, 30 and 50, this was reinforced into thio urea formaldehyde polymer matrix. FTIR and X-ray diffraction studies of these biopolymer composites showed the presence of silica. Due to high silica content in RH, their addition to synthetic polymer has a marked effect on the fire retardancy of the resultant composites. The thermo gravimetric analysis shows that the biocomposites undergo three stages of decomposition and the composite with 50% biomass was found to be more thermally stable than other composites.
PLASTIC SURFACE MODIFICATION: CLEANING, ADHESION AND FUNCTIONALIZATION
It is well-documented that plastics surface modification techniques can improve the acceptance of a wide variety of paints, coatings, adhesives and inks for improved decoration, painting and adhesive assembly. By increasing the hydrophilic characteristics and surface-free energy of plastics, bond strengths can be improved dramatically. This paper examines the surface modification mechanisms that promote adhesion on plastics and shares experimental data which reveal correlations between specific surface modification effects and adhesions of paints, inks, coatings and adhesives. The latest application-specific protocols will also be shared with regard to the use of atmospheric plasma technologies to promote surface adhesion to plastics.
MORPHOLOGY, MECHANICAL, AND RHEOLOGICAL BEHAVIOR OF MICROCELLULAR INJECTION MOLDED EVA-CLAY NANOCOMPOSITES
Ethylene Vinylacetate (EVA)/montmorillonite (MMT) nanocomposites diluted from master batch (50 wt%) with EVA and EVAgMA was used in this study. The organoclay EVA nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content and high/low MA grafted EVA on the mechanical, rheological properties of the EVA-clay nanocomposites was investigated. The results showed that the mechanical properties (tensile and impact) increased as the clay content increased. The high MA grafted EVA nanocomposites had better mechanical properties than that of low MA grafted EVA nanocomposites.
GATE LOCATION OPTIMIZATION IN INJECTION MOLDING BASED ON FEASIBLE SPACE
A methodology is presented in this paper to find the optimum gate location to achieve balanced flow so that a good quality part can be produced. The objective function is expressed in terms of injection pressure from the point of view of energy consumption. The coordinates of the gate location are chosen as design variables. A method is also proposed to determine the possible feasible space for gate location. The resulting optimization is solved by iterative search in the constrained space based on sequential linear programming algorithm. Examples are given to demonstrate the effect of the proposed method.
UV CURABLE COATINGS FOR CONTAINERS AND CLOSURES
The containers and closures market utilizes numerous decorating techniques on a variety of plastic and glass substrates. These decorating methods need to be functional as well as aesthetically pleasing. UV curable coatings can offer value to this market by providing high performance decorative coatings that are cost effective, easy to process and environmentally friendly. This paper will discuss the benefits of using UV curable coatings as an alternative to other ways of decorating containers, some challenges encountered in formulating coatings to meet all specifications of the containers and closures market, and typical performance and processing requirements.
THE ENVIRONMENTAL STRESS CRACKING RESISTANCE OF POLY-CARBONATE AS AN RESULT OF PROCESSING CONDITIONS AND INNER PROPERTIES
Environmental stress cracking is the most common failure reason of plastic parts. The influence of the processing conditions e.g. of the injection molding process on the environmental stress cracking resistance has not been investigated yet. Therefore several tests are carried out at the IKV. Test specimens are injection molded with different parameters for melt temperature, mold temperature and injection rate. These parameter variations cause variable inner properties of the molded parts. The environmental stress cracking resistance of specimens with different inner properties differs in a wide range. The results are discussed in detail.
BONDING POLYOLEFINS: WHAT ARE MY OPTIONS?
Since the first industrial production of polyethylene in the 1930's, polyolefin based plastics have become inescapable in our daily lives and indispensable to the production of modern industrial products. Although polyolefin based plastics such as Polyethylene and Polypropylene have proven useful in innumerable applications they have also proven difficult to bond to with adhesives. Advances in the field of bonding to polyolefin plastics have been made by the introduction of various surface pre-treatment methods and adhesives based on polyolefins themselves. Today we have new developments in the field of polyolefin bonding without the need for these cumbersome pre-treatment procedures.
DIFFERENTIAL INJECTION MOLDING METHOD FOR MULTI MICROPLASTIC PRODUCTS
In order to control metering accuracy and homogeneity of the very small quantities of melt in micro-injection molding process, and combine the advantages of micro-injection molding with conventional injection molding, differential injection molding method that uses conventional injection molding systems with a separate differential unit have been developed. The novel method can realize production of multi microplastic products. By using conventional injection molding with reciprocating screw injection systems, better plastication effect and mixing performance can be achieved. A planetary gear pump was employed as the differential unit, high metering accuracy could be achieved.
THE MECHANISM OF SKIN LAYER FORMATION WITHIN EPP PRODUCT PREPARED BY STEAM CHEST MOLDING AND ITS EFFECT ON INTER-BEAD BONDING ACROSS EPP PRODUCTS
Bead boundaries are potential fracture paths when a polymeric bead foam product is broken into pieces by force; the inter-bead bonding between beads tends to determine the mechanical properties of bead product. In our previous study, the formation mechanism of the inter-bead bonding in expanded polypropylene (EPP) bead foam processing with the steam chest molding process was proposed based on DSC simulation as well as tensile strength tests of products. In this study, the effect of skin layer on the density and tensile strength variations are assessed, and the mechanism of skin layer formation is proposed.
EFFECT OF COMPRESSED CO2 ON THE NON-ISOTHERMAL AND ISOTHERMAL CRYSTALLIZATION BEHAVIORS OF PLA AND PLA/TALC COMPOSITES
In this study, a regular and high pressure DSC were used to quantificationally assess the crystallinity development of PLA resin during the non-isothermal and isothermal crystallization processes. It is found that the plasticization effect of compressed CO2 could decrease linearly the Tg, and the increased chain mobility enhanced the crystallization dynamic of PLA at lower temperatures, while suppressed it at higher temperatures. Talc is one kind of nucleating agent and is often used in the polymeric foaming process. Its effect on the crystallization dynamic of PLA resin at various gas pressures was also investigated.
NANO-SILICA ADDITION IMPROVING CELL MORPHOLOGY AND EXPANSION RATIO OF PP COPOLYMER FOAMS BLOWN IN CONTINUOUS EXTRUSION
In this study, a block PP (BPP) copolymer with linear structure was selected and the nano-silica was used to challenge the fabrication of PP foam with uniform cell structure, high cell density and high expansion ratio . BPP foam exhibited poor cell morphology and low cell density at different die temperatures. An introduction of small amount of nanosilica dramatically improved the foaming behavior of BPP. Furthermore, the presence of nanosilica broadened the foaming window of BPP obviously. The effect of foaming on the dispersion of nanosilica in BPP matrix was also investigated in this study.
IMPROVING FLOW UNIFORMITY FROM A FILM DIE BY GEOMETRY MODIFICATION USING A THREE DIMENSIONAL FINITE ELEMENT OPTIMIZATION TECHNIQUE
This study shows how the flow uniformity from a film die can be improved by modifying the geometry of the die using a 3-D FEM optimization technique. A DOE is constructed based on the number of adjustable geometric parameters, and FEM simulations are run for the DOE cases. A response surface model is then created based on the DOE results, and is used to optimize the geometry to meet the desired objectives of uniform flow and minimal pressure drop. FEM simulations using the optimized geometry predict a more uniform flow at the die exit than simulations using the baseline geometry.
PERFORMANCE IMPROVEMENT ON ARAMID/POLYPROPYLENE COMPOSITE FOR HIGH VELOCITY IMPACTS
The aim of this work is to analyze the effect of adding a polymeric matrix to a weaved aramid textile for general applications in a bullet proof shield. Resistance to frontal impact with high speed projectiles was compared in two arrangements; woven aramid fibers and another composite made of the same fibers with a polypropylene matrix. The methodology for this comparison consisted in establishing a fixed impact energy (93 Joules) using an arrangement of Kevlar?? 129 with and without thermoplastic matrix, in order to find the corresponding configuration to its ballistic limit at that energy.
CRYSTALLIZATION OF HIGH-DENSITY POLYETHYLENE: THE EFFECT OF SHEAR & UNIAXIAL EXTENSION FLOWS
In this paper, the effects of shearing, uniaxial extension and temperature on the flow induced crystallization of a high-density polyethylene (HDPE) are examined using rheometry. Extensional flow found to be a stronger stimulus for polymer crystallization compared with that of simple shear. Generally, strain and strain rate found to enhance crystallization in both simple shear and elongation at temperatures around the meting point. At temperatures well above the melting point, polymer crystallized under elongational flow while there was no crystallization under simple shear flows.
MORPHOLOGY AND PROPERTIES OF POLYLACTIDE AND POLYCARBONATE BLENDS
PLA was melt-blended with polycarbonate (PC) modified with high molecular weight bisphenol A type modifier. Both the mechanical properties and the thermal properties were investigated. The blends showed two distinct glass transition behaviors. Glass transition temperatures of the PLA phase were literally not changed. On the other hand, the glass transition temperature of the PC phase moved toward Tg of PLA with the addition of the modifiers, suggesting some degree of interactions. Microscopic observations revealed non-uniformly dispersed PC inclusions in the PLA matrix, confirming that phase separation has occurred.
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