SPE Library

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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Conference Proceedings

Effects of Conductive Particles onthe Strength of Adhesion between Conductive and Non-Conductive Polymer Compounds

Chang Min Hong, Sadhan C. Jana, May 2002

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

N. Callan, M.P. Kearns, M. Spencer, R.J. Crawford, May 2002

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

W.S. Jou, T.L. Wu, S.K. Chiu, May 2002

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

Robert M. Belz, Eric Lingle, May 2002

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

Cevdet Kaynak, Aslihan Arikan, Teoman Tincer, May 2002

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

Suel E. Vidotti, Luiz A. Pessan, May 2002

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

Nanying Jia, Howard A. Fraenkel, Val A. Kagan, May 2002

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.

The Effects of Multiple Heat Histories on the Mechanical Properties of High-Impact Polystyrene

Jonathan DeSousa, May 2002

The plastic materials that make up consumer items are most often discarded after use. However, thermoplastics can be subjected to several recycle histories before they are disposed of in a landfill. Many studies have shown that mechanical recycling can cause some level of degradation of polymer properties. However, few studies have looked at the effect of repeated recycle histories on the properties of plastics. In this study, the effects of multiple recycle histories on the mechanical properties of high-impact polystyrene were determined in an attempt to show that plastics can be quite recyclable even after a large number of recycle histories. In this study, the high-impact polystyrene was reprocessed a total of thirty (30) times. Melt flow rate, tensile properties, and impact properties were determined for these multiple recycle histories. In most cases, the change in properties was relatively small, even for the large number or recycle histories studied.

Effects of Oil Temperature Difference on Part Weight

Albert O. Lorya, May 2002

This project investigates the effects of oil temperature variations on the repeatability of the parts, based on part weight. Two different material types were used for this study: Polypropylene & ABS. These two materials were selected to represent the two types of plastics: semi-crystalline (PP) and amorphous (ABS).The study compared the weights of the parts at three different oil temperatures, and the parts were matched by cycle. The study reveals that the lower the oil temperature the heavier the parts. Also the lower the oil temperature the less the part weight variation was with one material. The findings are based on data collected from two machines.

The Effects of Power Ultrasonic Wave on In-Situ Polymerization and Formation of PMMA-Clay Nanocomposites

Joung Gul Ryu, Hyung Soo Kim, Jae Wook Lee, May 2002

Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character.In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various sonication times, sonication ratios, addition of initiator and different kinds of clay.It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM.

Effects of Processing Conditions on the Hollow Structure of Liquid Gas Assisted Injection-Molded Parts

Dong-Hak Kim, Kwansik Oh, May 2002

Gas-assisted injection molding (GAIM) offers many advantages such as design flexibility, dimensional stability, reduction of machine tonnages, and so on[1]. But, for thick parts such as handles, it is observed the surface defects including hesitation mark and gloss difference.Liquid gas-assisted injection molding (LGAIM) is a good alternative of conventional GAIM especially in manufacturing simple and very thick parts. We developed total system for LGAIM and applied to several parts[2-4].In this paper, we present experimental investigation on the effect of various processing parameters associated with LGAIM process. The processing parameters chosen for this study included shot size, liquid injection time, delay time, and injection molding machine conditions such as injection speed, injection pressure, and so on. From this study, we obtained the useful design guide for LGAIM process.

Effects of Processing Parameters on the Preparation of High Density Polyethylene / Layered Silicate Nanocomposites

Minhan Kwak, Minhee Lee, Bong-Keun Lee, May 2002

Effects of polyethylene-g-maleic anhydride, processing parameters and molecular weight of matrix polymer on the nanocomposite preparation are demonstrated in polyethylene / layered silicate system using a Haake batch mixer. XRD and TEM techniques are utilized for evaluating the degree of exfoliation. The d-spacing value of the layered silicate, Cloisite 6A, linearly increases with the amount of PE-MAH and the layered silicate is successfully exfoliated over 25wt% at a certain processing condition. Effects of major processing parameters, such as temperature, mixing time and mixing speed, on the intercalation or exfoliation behavior are also clarified in this study. In addition, some discussion about the shear stress and the diffusion of polymer is presented to figure out the exfoliation behavior based on phenomenological results observed in this experimental work.

The Effects of Processing Variables on the Weld-Line Strength of Plastics in Aggressive Environments: Part I Materials and Solvent Selection

Stephen Petrie, Mark D. Charbonneau, May 2002

In a lengthy study, three commercial materials {high density polyethylene (HDPE), nylon 6,6 (PA) and polycarbonate (PC)} and three common liquids {a synthetic non-ionic surfactant (Igepal CO-630), an alcohol (ethanol) and an n-alkane (heptane)} were used to investigate the affects of processing variables on weld-line strength in an aggressive medium. An experimental design was used to evaluate each of the processing parameters.There were five mechanical properties studied at the onset of testing, with the intent to examine exclusively the most sensitive. The breaking strength was calculated to have the largest normalized sensitivity.The screening design showed which processing parameters were most important. These significant variables were then investigated further with a factorial design. Processing alone increased the breaking strength by 30 percent.Analysis of the results, from the factorial design, gave mathematical models, which described the effect of the processing parameters on the breaking strengths of the PC and PA. Also no interactions were observed between the significant parameters, however curvature effects were most prevalent.

Effects of Supercritical CO2 on the Dispersed Phase Size and Cocontinuity of PS/LDPE Blends

Anle Xue, Costas Tzoganakis, May 2002

PS/LDPE blends were prepared in a twin-screw extruder over a wide range of composition with the aid of supercritical CO2 (scCO2). The effects of scCO2 on the dispersed phase size and the phase cocontinuity of these blends were studied by scanning electron microscopy and gravimetry after selective extraction. Supercritical CO2 was found to reduce the dispersed phase size and shift the region of cocontinuity. The morphology development along the twin-screw extruder was also studied by taking samples from both the vent and the die. The effects of scCO2 on the morphology were observed at the vent. However, the morphology at the die after CO2 venting was similar to that without CO2. Within the cocontinuous region, very fine morphologies with a special pattern were found during the foaming process with CO2.

The Effects of Weld Geometry and Glass-Fiber Orientation on the Mechanical Performance of Joints Part I: Weld Design Issues

Val A. Kagan, Christopher Roth, May 2002

The mechanical performance of injection molded glass-fiber reinforced [thermo]plastic components is anisotropic and depends on the fiber orientation and distribution. The purpose of this comprehensive analysis is to show the relationship between short-fiber orientation at the pre-welded bead and wall areas, and the mechanical performance of welded butt-joints that have various geometry and thickness, namely straight" and "T-type" welds.Findings on the mechanical performance of these two different types of butt-joints by the design and geometry butt-joints will help designers and technologists with material selection welding processing and design optimization. In a subsequent paper (Part II)1 we related these findings to the kinetics of glass-fiber re-orientation and micro-structural changes and how they influence part and weld design."

Efficiency of Clear-Welding Technology for Polyamides

Val A. Kagan, Nicole M. Woosman, May 2002

Many industrial applications require optically transparent thermoplastic components, and structural joints almost invisible to the human vision. Traditional transmission laser welding of plastics joining is limited by the process conditions when one thermoplastic is optically transparent and the second absorbing laser energy. Advanced Clear-Weld™ (clear-welding)1 laser technology may satisfy these specific requirements in joining various similar and dissimilar optically transparent thermoplastics. These innovative design-joining technology considerations require the following conditions at the interface between the joined surfaces: 1) laser absorbing material; 2) optimized laser energy for heat generation between joined thermoplastics.The analysis of representative test results shows that clear-welding technology is highly efficient also for use with various transparent nylon grades. The tensile strength of the clear-weld butt joint is similar to the results achieved for nylon with other advanced plastics joining methods such as linear, orbital, hot plate and regular infrared (laser through-transmission) technologies. The developed comprehensive recommendations will help designers and technologists with welded parts design, material(s) and process selection and optimization for laser welding applications when the joined thermoplastic part requires optical transparency, as well as flash and particle free conditions.

Electrical Conductivity Changes of Silicone or Polyurethane Rubber/Carbon Black Composites during Cyclic Pressure Deformation

J. Vilcakova, A. Lengalova, P. Saha, O. Quadrat, T. Kitano, May 2002

Elastic composites consisting of a non-conductive matrix and conductive filler change their electrical properties under deformation, which enables them to be used as pressure sensors. For this purpose change in electrical conductivity of carbon black/silicone or polyurethane rubber composites during cyclic pressure deformation has been studied. The findings revealed that the character of conductivity changes depends on the filler concentration. While below the percolation threshold the conductivity decreases with the pressure deformation, above this critical filler content conductivity increases. This behaviour is explained as a result of the different space structure of conducting particles in the composite matrix. Cyclic pressure experiments showed that even a small deformation causes irreversible changes in the composite structure and, consequently, non-reproducibility of the repeated loadings.

Electrical Conductivity of a Graphite Based Composite as Affected by the Degree of Mixedness of Graphite in the Elastomeric Matrix

Dilhan M. Kalyon, Elvan Birinci, May 2002

The development of the electrical properties of composites as a function of the degree of mixedness of graphite distributed into a plasticized thermoplastic elastomer (Kraton with mineral oil plasticizer) is investigated. A wide-angle x-ray diffraction (WAXD) based quantitative phase analysis method was used to characterize the variations of the concentrations of the elastomer and the graphite particles around their mean values as a function of mixing time in an intensive batch mixer. Increasing the specific energy input during the mixing process results in a more homogeneous spatial distribution of graphite in the elastomer. The increasing specific energy input alters the rheology of the composite suggesting that significant structural changes do occur. Indeed the degree of mixedness of the graphite in the matrix is quantitatively determined to be improved, generally resulting in better coating of the individual graphite particles. This improved coating effectiveness in turn results in a decrease of the volume conductivity of the composite.

Energy Absorption and Damage Mechanisms in Rubber Modified Systems Tested in Multi-Axial Stress States

S. Ramaswamy, Alan J. Lesser, May 2002

The toughening mechanisms in three different systems namely, acrylonitrile-butadiene-styrene (ABS), methacrylate-butadiene-styrene (MBS) modified poly (vinyl chloride) (PVC) and styrene-butadiene-styrene (Kraton D) have been investigated. Samples were tested over a range of biaxial stress states followed by analysis of damage using confocal microscopy and scanning electron microscopy. In a certain range of biaxial stress states, the damage in these systems was in the form of cracks propagating perpendicular to the direction of the maximum applied tensile principal stress. The cracks appear to be arranged in more or less a periodic manner that would result in stress reduction at the crack tips. Similar patterns have also been found to occur in several other polymeric systems. Since materials themselves fashion these patterns, it is speculated that they are energetically favorable.

Engineering and Specialty Plastics in the World 2000-2010

Françoise Pardos, May 2002

Out of total world plastics consumption currently over 150 million tons, engineering plastics amount to 6 million tons, specialty plastics to 200 000 tons. Overall value figures are much higher compared to volume figures.Engineering and specialty plastics have common characteristics:Higher performance properties than commodity plastics, higher temperature performancesConcentration of few world suppliers.Main applications in the car and electrical industriesFaster growth than commodity plasticsCompetition between commodity and engineering plastics.Some engineering plastics might achieve commodity volumes by 2010