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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The Effect of Pigment Type and Concentration on the Mechanical and Thermal Properties of Injection Moulded Polypropylene
Polypropylene (iPP) is increasingly being used in products for elevated temperature applications. The morphological development during processing of this semi-crystalline polymer is known to be dependent on processing conditions and the presence of nucleating agents such as pigments, influencing both mechanical and thermal properties. A range of injection moulded samples was manufactured from iPP containing 0.1 - 2.0% pigment loadings of different pigment types, using different mould cooling conditions. DSC, tensile and thermal analysis of the various samples showed significant increase in both crystallinity and tensile modulus with a decrease in impact strength for both increased pigment loadings and mould temperatures.
The Effect of Polypropylene MFI on the Rheological, Morphological and Mechanical Properties of Polypropylene/Polyethylene-Octene Copolymer Blends
Blends of polypropylene (PP) of MFIs 4 and 25 g/10 min with up to 30 wt. % ethylene-octene copolymer (EOC) were prepared using a Killion compounding extruder fitted with a barrier design screw. Rheological characterisation of these blends was studied over the shear rate range of 300 to 2000 sec-1. The apparent viscosity at temperatures 197 to 237 °C was shown to be dependent primarily on the MFI of the PP rather than the EOC concentration of the blend. The MFI had a significant effect on the mechanical and phase morphology properties of the various blends. Dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry analysis (DSC) would tend to indicate some degree of polymer miscibility especially at the higher EOC concentrations, with slight decreases in crystallinity and the phase transition temperature of EOC.
The Effect of Processing Conditions on the Appearance of Flow Lines in Injection Molded Articles Incorporating Pearlescent Pigments
The purpose of this study was to evaluate the effects of injection molding conditions on the appearance of a weld line/flow line in injection molded parts incorporating pearlescent pigments. In this study, a general-purpose grade polypropylene was the carrier resin used. Three different pearlescent pigments were mixed into the polypropylene at concentrations by weight of 0.5%, 1.0% and 2.0% and injection molded. The appearance of a flow line for each of the concentrations was characterized by a transmitted light intensity method for various settings of the main molding parameters, melt temperature, mold temperature, holding pressure and injection speed.Overall, the experimental results indicated that melt temperature and injection speed most significantly affected flow line appearance. The mold temperature had a less significant effect, and the holding pressure did not have significant effect on the appearance on the flow line.
Effect of Processing Conditions on the Development of Morphology in Clay Nanoparticle Filled Nylon 6 Fibers
Nylon 6/montmorillonite nanocomposites were melt-spun at extrusion temperatures of 230º, 240º and 250ºC. The resulting fibers display interesting features in differential scanning calorimetry scans: an exothermic peak just below the melting region and at least three melting peaks depending on the spinning temperature. The presence of nanoparticles was found to limit spinning speeds due to premature fiber breakup. Increasing melting temperature from 230º to 250ºC alleviated this problem. The spun fibers were found to possess ? crystal form. At higher take-up speeds ?-crystals begin to appear in the mixture. The orientation levels in crystalline regions were found to be quite substantial due to the presence of nanoparticles that increases the overall viscosity and the spinline tension.
Effect of Pulsed Tool Cooling on the Injection Moulding Process
Experimental studies have been carried out to assess the effect of using an advanced tool temperature management system for injection moulding, compared to conventional tool heating and cooling techniques. A highly instrumented 75 tonne servo-hydraulic moulding machine was used, moulding tensile test specimens from HDPE. Tool temperature was monitored at high frequency (50 Hz) during each cycle, as was nozzle melt pressure, temperature and screw position. Conventional tool temperature control was employed using a water heater/chiller to control temperature in both halves of the tool by controlling water temperature. The effect of tool temperature control on start-up times, process and part repeatability has been examined.
The Effect of Sealing Parameters on the Fracture Mechanism and Peel Properties of Medical Packaging Materials
This paper assesses the effect of sealing parameters, (time, temperature and pressure) on the peel properties and fracture mechanism of medical packaging materials. A design of experiment (DOE) methodology was adopted to conduct the trials and analyze the results; the materials studied were a heat-sealable coated Tyvek® bonded to film (of the types used to manufacture pouches).The properties of the peelable seal were characterized in terms of peel strength parameters and fracture mechanism. A novel method to quantify fracture mechanism, by measuring the amount of adhesive transfer with predictive capability is presented. A window of seal time, temperature and pressure exists which results in the optimum peel properties and fracture mode.
Effect of Surface Treatment on the Interfacial Interactions and Impact Properties of Calcium Carbonate Filled Polypropylene Composites
The present study investigated the effects of surface treatment on the surface properties of calcium carbonate and on the interfacial interaction between filler and matrix. An extensive comparison was made on the efficacy of the surface treatment between stearic acid, a non-reactive surfactant, and LICA 12, a reactive coupling agent. The change in surface properties due to surface treatment was characterized through inverse gas chromatography (IGC) at infinite dilution. The stearic acid treated filler showed lower dispersive and polar components of the surface energy than LICA 12 treated system for completely coated CaCO3 fillers. Infrared analysis demonstrated that stearic acid reacted extensively with the filler surface to produce organic salt compound. Izod impact strength was measured on sharp-notched samples. It was found that stearic acid treated composites exhibited greater impact strength than LICA 12 treated systems.
Effect of Thermoplastic Elastomer Material Properties on Mold Filling Imbalances
Significant shear induced filling differences are commonly seen between cavities in multi-cavity injection molds. These filling variations can be particularly important when over-molding TPEs on delicate plastic inserts. This paper compares the amount of imbalance detected when molding different grades of TPEs. It then evaluates the relationship of the materials shear, temperature, and viscosity indexes on the magnitude of shear-induced mold filling imbalances to determine which factors most directly influence this imbalance. This understanding will help a molder more readily predict and address the problem. Furthermore, the study evaluates the use of melt rotation technology (1) to minimize the imbalances.
Effect of Viscosity on Low Density Foaming of Poly(Ethylene-Co-Octene) Resins
Foaming of low density poly(ethylene-co-octene) resins by injection molding is the result of various reactions occurring during the process. This includes simultaneous decomposition of the chemical blowing agent and cross-linking of the polymer matrix during curing in the mold, followed by foaming after mold opening. Dynamic rheology as well as elongational viscosity were investigated for compounds prepared from resins with different MFIs and various cross-linking agent levels, and these results were linked to the morphology and density of the corresponding foams. Rheological requirements were finally defined quantitatively for this set of conditions.
Effect of Viscosity Ratio on Co-Continuity for Ethylene-Propylene-Diene Terpolymer/Polypropylene Blends
Blends of ethylene-propylene-diene terpolymer (EPDM) and polypropylene (PP) of significantly different viscosity (torque) ratio (T.R.) were prepared in an internal mixer (Haake) over the entire range of composition. The torque of the blends as well as the torque of the pure materials were noted and compared.For the 0.7 viscosity ratio blend, SEM micrographs showed very fine dispersed particles of EPDM of size 50 to 200 nm in the low composition range of EPDM. For the 10.0 viscosity ratio blends the particle size ranged from a few hundred nanometers to a few hundred micrometers at low compositions of EPDM.Also according to solvent gravimetric data and SEM micrographs we find that, the 0.7 viscosity ratio blend demonstrates the onset of percolation at a composition of 30% EPDM and reaches 100% continuity at 60% EPDM. In contrast, the 10.0 viscosity ratio blend showed no continuity at 20% EPDM and attained 100% continuity at a composition of 30% EPDM.
Effects of a Diamond-Like Nano-Composite Coating on an Injection Blow-Molding Machine Core Rod
The study being conducted tests the effects of a coating on a core rod for an injection blow-molding machine. The coating is different than the standard chrome plating. The coating on the core rod is the ART Dylyn® R, which is a diamond-like nano-composite material. Through this study, we will determine the effect this coating will have upon friction and thermodynamic properties of the core rod. The significance of this experimentation is to find advantages and disadvantages of the coating. Our goal is to find the effects it will have on the overall part quality. We ran a Design Of Experiments (DOE) on both the coated core rod and the standard core, on an injection blow-molding machine. Following the experiments, analysis of the data, which includes, wall thickness, force, and pressure, will be interpreted.
The Effects Colorant Particle Size on the Mechanical Properties of Polycarbonate Resin
Polycarbonate resins are utilized in many engineering applications that require stable mechanical properties in a wide range of colors. The colorant itself may have an effect on the outcome of the mechanical properties of the final resin compound. If the particles that make up the colorant additive vary in size, this could possibly cause a variation in the mechanical properties of parts molded from the resin, much like the effects of molecular weight distribution in a polymer.This research studied the effects of the mean particle size distribution of the colorant to determine if the particle size does indeed have an affect on the resins mechanical properties.
The Effects of Compounding Conditions on the Properties of a Polypropylene/Polyamide-6 Blend
This study examined the effects of compatibilizer type, screw design, screw speed, melt temperature, and water content on the properties of TPO/polyamide-6 blends compounded on a co-rotating twin-screw extruder. Temperature had the greatest influence on the mechanical properties of the resultant blends with higher temperature causing a severe reduction in properties. Higher screw speeds also decreased properties due to shorter extruder residence time. The effect of screw design depended on the strength of the compatibilizer. For this system, a polysiloxane compatibilizer provided more effective dispersion than maleated polypropylene, but was sensitive to moisture content in the polyamide-6.
Effects of Conductive Particles onthe Strength of Adhesion between Conductive and Non-Conductive Polymer Compounds
Articles with surface conductive layers molded onto virgin polymers provide mechanical strength of virgin polymers and sufficient surface conductivity with small amounts of conductive particles, thus obviating the needs of molding the whole articles from conductive polymer compounds. Multi-layer molding methods, such as co-extrusion, injection-compression, compression molding, etc. can be used provided the adhesion between conductive and non-conductive layers is strong.This paper describe the effects of particle concentration and polymer molecular weight on the strength of adhesion in carbon black-filled polypropylene as measured by peel test and from changes in complex shear modulus of conductive/non-conductive sandwich compounds.
Effects of Cooling Rate on the Mechanical Properties of Rotationally Moulded Polyethylene Parts
It is well known that the rate of cooling has a major effect of the dimensions and shape of rotomoulded plastic parts. There is also qualitative evidence that the mechanical properties are affected by the cooling method. This paper will quantify the effects of the cooling rate on the microstructure and mechanical properties of rotationally moulded polyethylene parts. A variety of cooling profiles were used, including external forced air, water-cooling and internal part air-cooling. Differential Scanning Calorimetry was used to measure the degree of crystallinity throughout the cross-section of the mouldings and this information is correlated with the toughness of the mouldings as measured by falling weight impact tests.
Effects of Fiber Orientation upon the Electromagnetic Shielding of Injection Molded Liquid Crystal Polymers
The shielding effectiveness (SE) of liquid crystal polymers (LCP) composites with longitudinal fiber orientation is higher than that with random fiber orientation under the same weight percentage of carbon fibers filled because that longitudinal fiber orientation is parallel to the electric field of incident EM wave. The fiber orientation was controlled by two kinds of gate locations and the samples were injection molded. The shielding effectiveness of 20% conductive carbon fiber filled liquid crystal polymers composites were measured to be 50 dB at frequency of 0.3 GHz and 53 dB at 1 GHz.
Effects of Hygroscopic Properties on Weld Line Integrety of Tensile Specimens of High Temperature Glass Reinforced Nylon
Weld lines are present in many plastic components throughout the world. Avoiding weld lines is almost impossible, so knowing the effect they have on the physical properties of plastic structures is extremely important. Combining this with the hygroscopic properties of polyamide yields vital information about the integrity of the molded nylon.Single and double gated specimens were obtained and saturated under controlled conditions to determine the rate of water absorption into the molecular structure of the nylon. Based on this, controlled groups of single and double gated samples were saturated at 10% increase by weight increments and sealed. Finally the change in maximum tensile strength was measured, documented, and analyzed.
Effects of Liquid Rubber Modification on the Flexibility of Fiber Reinforced Epoxy Composites
The purpose of this study was to improve flexibility of short glass fiber reinforced epoxy composites by using a liquid rubber modifier. For this purpose, diglycidyl ether of bisphenol-A (DGEBA) based epoxy resin matrix of the composite specimens were modified with hydroxyl terminated polybutadiene (HTPB) liquid rubber. A silane coupling agent (SCA) was also used to improve the interfacial adhesion between glass fibers and epoxy matrix. In specimen preparations, hardener and HTPB were premixed and left at room temperature for an hour before epoxy addition to allow possible reactions to occur. The flexibility of the specimens was evaluated by 3-point bending tests. It was observed that HTPB modification resulted in formation of relatively round rubber domains in the epoxy matrix increasing the flexibility.
Effects of Low Molar Mass Additives on the Molecular Mobility and Transport Properties of Polysulfone
The aim of this work was to study the effects of the incorporation of low molar mass additives into polysulfone (PSF) to improve its water vapor barrier properties. The additives N-phenyl-2-naphthylamine (PNA) at the concentration of 10, 18 and 30% by weight and 2,6-di-terc-butyl p-cresol (BHT) at the concentration of 5, 10, 15 and 20% by weight were incorporated into PSF. The incorporation of these additives resulted in changes on molecular mobility and transport properties of the glassy matrix associated with the antiplasticization phenomena. The effects observed due to the incorporation of the additives were reduction in glass transition temperature, reduction in the magnitude of the secondary loss transition peak and changes in secondary loss transition peak for higher temperatures. The properties of the systems were determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The changes in molecular mobility of PSF were accompanied by reductions in its water vapor permeation. The mixtures PSF-PNA showed a reduction on the water vapor permeation of up to 95% for 30% of additive incorporated and up to 81% for mixtures PSF-BHT with 20% of additive.
Effects of Moisture Conditioning Methods on Mechanical Properties of Injection Molded Nylon 6
The influence of various standard (ASTM, ISO) and experimental moisture conditioning methods on mechanical performance of injection molded nylon 6 is discussed as a result of an in-depth, comprehensive investigation.The analyzed methods covered a wide range of two basic process parameters for conditioning: temperature (from 23 to 100°C) and relative humidity (from 50% RH to water immersion). The variation of these parameters may result in significantly different moisture absorption rates, equilibrium levels and mechanical properties. The kinetic of mechanical performance and microstructure were evaluated prior to tests and during conditioning in this comprehensive analysis.The results from this investigation may provide comprehensive, up-to-date information and recommendations concerning accelerated nylon conditioning methods for test specimens and various molded parts, pre-selection of nylon based plastic for design, and prediction and optimization of mechanical performance.
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