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
Drawing of UHMWPE Fibers in the Presence of Supercritical CO2
Manuel Garcia-Leiner, John Song, Alan J. Lesser, May 2002
The drawing behavior of UHMWPE fibers in supercritical CO2 is compared to that in air at different temperatures. Temperature substantially influences the drawing properties in air, while in scCO2 a constant mechanical response is observed. DSC and WAXS results show that air-drawn samples crystallize during deformation in an internally constrained manner, promoting changes in their thermal behavior. In contrast, scCO2 allows crystals to grow without constraints through a possible crystal-crystal transformation, increasing the processing temperature to 110°C.
Solid Finite Elements for the Prediction of Complex Parison Distortions
D. Laroche, P. Debergue, May 2002
Significant developments in finite element modelling of the blow moulding process have been observed in the recent years. The large deformations occuring during parison formation, clamping and inflation have traditionally been modelled using membrane or shell type elements. In this paper, a 3D solid finite element approach for improving the part wall thickness predictions is proposed. A 27-node brick element with incompressibility constraint is presented for modelling large viscoelastic deformations of the parison in the consecutive stages of the process. Part wall thickness predictions using 3D simulations are compared to experimental measurements on two different blow moulding cases. The results are also compared to predictions from the membrane formulation.
Dynamic Mechanical and Rheological Properties of Ethylene/1-Octene Resins with Bimodal Structural Distributions
Colin Li Pi Shan, João B.P. Soares, Alexander Penlidis, May 2002
Ethylene/1-octene resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. Comparison of the dynamic mechanical (tensile) and rheological properties of these blends shows that increasing the fraction of copolymer in the reactor blend results in a decrease in its stiffness. However, the energy dampening properties of these blends benefit from the presence of the copolymer. It was confirmed that melt flow properties of polymers depend on their molecular weight distribution.
Dynamic Piston Speed Control during Low Shear Capillary Rheometer Measurements
Burke I. Nelson, May 2002
Pressure transients in a capillary rheometer can take hours to reach steady state during low shear rate measurements, causing problems with material degradation during the test. Instead of running the piston at constant speed and waiting for equilibrium, it is possible to use dynamic speed control of the piston to reach the steady state pressure more quickly.Models from literature suggest that the long pressure transients at low shear rates are due to changes in the material density as a function of pressure. These models are used to determine an optimum velocity profile for the capillary piston, reducing measuring times to a fraction of previous times and using less material per test point.
Dynamical Mechanical Study of Single Wall Nanotube Reinforced ABS Composite
Oziel Rios, Arturo A. Fuentes, Karen Lozano, Enrique V. Barrera, Franz R. Brotzen, May 2002
The dynamic mechanical properties of single wall nanotube (SWNT) reinforced polymer composites were studied. This paper analyzes preliminary results between the theoretical and experimental effect of SWNT concentration on anelasticity versus nanotube concentration. The theoretical model assumes that the assembly is a standard linear solid (SLS). The following assumptions were made: 1) the filler material is purely elastic, 2) the only time-deformation is that of the polymer matrix, and 3) the SLS unrelaxed elastic modulus varies linearly with the relative concentration of the filler material. The results indicated that the preliminary studies using the SLS model showed a good approximation to the experimental results within the chosen region.
Dynamics of a Slender Bubble in a Non-Newtonian Liquid in an Extensional Flow
Ramesh Raju Mudunuri, Moshe Favelukis, May 2002
Mass Transfer between a slender bubble and a non-Newtonian liquid in a simple extensional and creeping flow has been theoretically studied. Exact shapes of slender bubbles in power-law liquids are presented, along with analytical approximations. Steady-state mass transfer is studied assuming the thin concentration boundary layer approximation. The results indicate that the total mass transfer increases with n, the power-law parameter, due to larger surface areas in dilatant liquids compared to pseudoplastic liquids for a similar imposed flow. The relevance of this work to the processes of polymer melt devolatilization and the production of polymer foams is discussed.
Economic Value Added in the Plastic Processing Industry
Drahomira Pavelkova, Tomas Saha, J.G. Drobny, H.R. Skov, May 2002
The goal of the study has been to identify factors influencing the creation of the Economic Value Added (EVA) of companies in the plastics processing industry. EVA as an indicator of new created value for the owners of the company is an important criterion of success of the company‘s activities. The sources of the creation of EVA are being identified by comparing several plastics processing companies including some in different geographical regions. Some differences in the EVA in the investigated regions have been correlated to technological level, creativity of management and financial ratios. Data for the analysis were obtained mainly from companies´ annual reports.
The Effect of Additives on the Processing and Physical Properties of Recycled Polyethylene Terephthalate (RPET)
Mark Kegel, Igor Sbarski, Edward Kosior, Syed Masood, May 2002
This paper describes the effect of individual additives that are present in masterbatch formulations, and the role they play in modifying physical properties and processability of blends based on RPET. Additives such as titanium dioxide, carbon black, linear low-density polyethylene and polyethylene wax are often incorporated in masterbatch compositions. The blends based on these additives have been analysed for shifts in thermal transition points, levels of crystallinity and physical properties such as tensile and impact strength. The results show that at the addition rates used, some additives had significant effects on processability and crystallinity, negligible effects on physical properties and antagonistic effects were noted when additives were combined.
Effect of Aging on Film Properties of Ethylene-Alpha Olefin Copolymers
H. Mavridis, May 2002
Film toughness of certain ethylene – alpha olefin copolymers of high impact strength, shows significant aging effects, decreasing with time. In this work we studied the time and temperature dependence of film aging of several copolymers of varying molecular structure. Film aging appears to be associated with the presence of highly branched polymer chains (>30 branches per 1000 carbon atoms). It is speculated that the thermally activated rearrangement of such branched species, over time and under film storage conditions, leads to film aging. Higher film storage temperatures lead to faster aging. It is possible to employ an “accelerated aging” testing protocol, so as to obtain longer-term aged data from a short-term test, which would be useful in an industrial production setting.
The Effect of Boron Nitride on the Rheological Properties and Processability of Polyethylene
Sang Myung Lee, Jae Wook Lee, May 2002
The processability of the polymer in capillary extrusion is closely related to the interface between the polymer melts and die wall, and wall surface energy affects the flow of polymer melts in extrusion dies. In this paper, when used Boron Nitride (BN) with low surface energy as the processing aid, we studied about changes of the rheological behavior and processability of metallocene polyethylene (m-LDPE). It also studied about the effect of the hot-pressed BN die on the instability of capillary flow. The equipment used includes a capillary rheometer with two kinds of dies, namely the tungsten carbide and hot-pressed BN dies. The rheological properties of resins with and without BN particles were analyzed by parallel-plate and capillary rheometers. Two types of BN powders with a different the agglomerated particle size and distribution, are tested at various contents. It was found that the BN powder has an influence on the processability of the polymer, depending on the BN content and particle size.Lastly, it must be underlined that it is possible to significantly delay or eliminate the melt fracture, by considering the polymer flow through the hot pressed BN die instead of the tungsten carbide die.
The Effect of Calcium Carbonate Size and Loading Level on the Impact Performance of Rigid PVC Compounds Containing Varying Amounts of Acrylic Impact Modifier
William S. Bryant, Henry E. Wiebking, May 2002
This study demonstrates how the impact performance of a rigid polyvinyl chloride (PVC) compound can be affected by the particle size of the calcium carbonate filler and its loading level. The test compounds contain 0 to 8phr of acrylic impact modifier and fillers ranging in size from 3 to 0.07 microns. By taking all three variables into consideration one can, not only optimize a compound's performance, but also lower its cost. Notched Izod and falling weight impact data will be reviewed. Flexural modulus and low temperature impact data are also included.
The Effect of Carbon Dioxide on the Viscoelastic Properties of an Epoxy Resin: CO2 Pressure Jumps
Francesco Briatico-Vangosa, Mataz Alcoutlabi, Gregory B. McKenna, May 2002
We report results from tensile creep tests performed on an epoxy resin in the presence of carbon dioxide pressure (Pco2) at a constant temperature below the glass transition temperature Tg. Time - Pco2 superposition was applied to the data to account for the plasticization effect due to the interaction between the carbon dioxide molecules and the polymer. In addition, physical aging of the epoxy films was investigated using sequential creep tests after carbon dioxide pressure down-jumps at constant temperature and also after temperature down-jumps at ambient carbon dioxide pressure. The isothermal pressure down-jump experiments showed physical aging responses similar to the isobaric temperature down-jump experiments. However, the aging rate for the CO2–jump was lower than that for the T-jump.
Effect of Chemical Modification on Polyolefin Crystalline Structures
N. Villarreal, J.M. Pastor, R. Perera, C. Rosales, J.C. Merino, May 2002
A thermal treatment of Successive Self-Nucleation and Annealing (SSA) of LDPE, LLDPE, PP, PP grafted with diethyl maleate and PP grafted with maleic anhydride were made. The study of these materials was combined using capillary rheometry, DSC measurements, FTIR and Low-Frequency Raman-Active Longitudinal Acoustical Mode (LAM). The results indicated that the grafting process mechanism in a co-rotating twin-screw extruder and their effects on the polyethylenes structures occur through secondary carbons. The SSA technique is a useful tool for the characterization of grafted PEs. However, more work is needed for the grafted MA polypropylenes.
The Effect of Cure Conditions on the Mechanical, Shore Hardness and Frictional Properties of Styrene Butadiene Rubber for Industrial Conveying Applications
G.M. Mc Nally, J.L. Clarke, C.M. Small, W.J. Skelto, V. Monroe, May 2002
A range of samples were prepared from a commercial styrene butadiene rubber (SBR), over a range of cure temperatures (140°C – 170°C) and cure times (30min – 120min), using a high temperature moulding press held at a constant pressure of 5000 psi. Mechanical analysis of the various samples showed considerable increase in modulus, shore hardness and break strength with progressive increase in cure temperature, especially at lower cure times. Dynamic frictional analysis under different loadings, of the SBR samples with HMWPE and 90 Shore A Polyurethane (PU), showed progressive decrease in frictional force with increase in SBR cure temperature and time. Some reversion of the SBR was shown to occur at higher temperatures and longer cure times.
Effect of DCP Crosslinking on the Mechanical and Electrical Properties of LDPE
M. Rafizadeh, S. Mohseni, May 2002
The good electrical and mechanical properties of low density polyethylene (LDPE) make it an ideal insulation for the electric cables. The main draw back of polyethylene is its softening temperature. Crosslinking of polyethylene improves its properties.The effect of dicumyl peroxide (DCP) on mechanical, thermal and electrical properties of crosslinked polyethylene (XLPE) have been investigated. Crosslinking of LDPE improves its mechanical properties and, to some extent, improves its thermal degradation. DCP increases dielectric breakdown voltage, elongation at break, tensile strength and gel-content of XLPE, but decreases young modulus, crystallinity, heat of fusion and melting point of XLPE.According to the results, an optimized amount of DCP is determined. In this study, the LDPE (POLIRAN LF0200) was used to produce insulators for medium and high-voltage electrical cables.
The Effect of Extrusion Processing Conditions and Polyisobutylene Concentration on the Properties of Polyethylene for Stretch and Cling Film Applications
C.M. Small, G.M. Mc Nally, A. Marks, W.R. Murphy, May 2002
A range of LLDPE films with polyisobutylene (PIB) content from 2%-8% was manufactured using a Killion blown film extrusion system and a cast film extrusion system. The films were aged at 25, 35 and 45°C for up 28 days, to enable tack (cling) development. The results show that tack, in both blown and cast films, improved significantly with ageing, at increased storage temperatures and at higher film blow up ratios. DSC analysis showed only a slight decrease in film crystallinity with increasing PIB concentration. The film tensile modulus, elongation and tear properties in both MD and TD were not significantly affected by increase in PIB concentration.
The Effect of Extrusion Processing Conditions on the Thermal and Mechanical Performance of Extrusion Cast Metallocene Polyethylene Films
B.G. Millar, G.M. Mc Nally, W.R. Murphy, May 2002
Cast extruded films were prepared from a range of mPE resins with various co-monomer types (hexene, octene), using different chill roll temperatures from 30 to 60°C. Mechanical analysis showed that the tensile modulus of the films increased with progressive increase in chill roll temperature. DSC analysis showed increases in crystallinity with increasing quench temperature and decreasing MFI. Rheological and molecular weight distribution analysis showed that activation energies of flow for mPE (18-28kJ/mol) were low, this is attributable to the narrower polydispersity of mPE (2.1-3.1) compared to the wider distribution of conventional polyethylenes (4.0-5.0).
Effect of Fluoropolymer Processing Aids on the Processibility of an Octene LLDPE
Kasinath Nayak, Mohan Gownder, Glen Giacoletto, May 2002
Polymer processing additives (PPA) have found their niche in the extrusion and processing of polyolefins, especially to improve their processing characteristics. It has been known that PPA can be used in the range of 100 – 1000 ppm to eliminate surface defects including melt fracture and gels, as well as to reduce die build up. The main focus of this paper is to determine the effect of various fluoropolymer processing aids in the elimination of melt fracture of an octene linear low density polyethylene. Also the influences of both antiblocking agent and slip additive on the performance of PPA are assessed.
Effect of Functionalized Polyolefin Coupling Agent Types on the Mechanical Properties of HDPE/Wood-Flour Composites
Qingxiu Li, Laurent M. Matuana, May 2002
The performance of fiber reinforced thermoplastic composites strongly depends on solid fiber-matrix adhesion to allow stress transfer between the phases. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and the polymer. This study investigated the effects of coupling agent's functional monomer (acrylic acid vs. maleic anhydride) and base resin (polyethylene vs. polypropylene) types on the on the tensile and flexural properties of high-density polyethylene (HDPE)/wood-flour composites. The experimental results indicate that the types of functional monomer and base resin are important factors determining the effectiveness of functionalized coupling agents for HDPE/wood-flour composites. Maleic anhydride-functionalized polyolefins perform better than acrylic acid counterparts whereas polyethylene-based maleated coupling agents are more effective than polypropylene-base counterparts in improving the mechanical properties of HDPE/wood-flour composites.
Effect of Gamma-Irradiation on the Mechanical Behavior of PS/PP Blends
C. Albano, J. Reyes, M. Ichazo, J. González, M. Hernández, M. Rodríguez, May 2002
The effect of Gamma-irradiation on the tensile behavior of PS/PP blends (80/20) and its mathematical analysis indicates that the blend presents a high radiation resistance to low doses (80-70 kGy), since mechanical properties present no significant changes; this is due to the presence of the aromatic ring in the PS structure, factor which was confirmed by the lineal mathematical adjustment. On the other hand, at high doses of irradiation (70-1300 kGy), a dramatic change on the mechanical properties was observed and the mathematical adjustment showed a third order polynomial behavior, which indicates a competition between crosslinking and degradation mechanisms, being the latter predominant.
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