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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
Analyzing Air Gap Dynamics in Extrusion Coating by Means of Dimensional Analysis
Natti S. Rao, Günter Schumacher, Bruce W. Foster, May 2004
A number of experimental investigations in the past have dealt with the influence of various parameters such as melt temperature, air gap distance and coating thickness on the bonding strength between a primed film and the coating. By applying dimensional analysis to the data of the experimental results published in the literature novel equations were developed to predict the relationship between adhesion and the parameters mentioned.It was found that for a given temperature the shear history and the residence time of the melt in the air gap are of utmost importance to the adhesion between the film and the coating. The application of the formulas given, is explained by a number of practical, numerical examples.
The Rheological and Mechanical Performance of Commercial uPVC Formulations
W.C. Yap, A.C. Ruddy, K. Halliwell, G.M. McNally, W.R. Murphy, May 2004
Rheological and mechanical analysis of a range of virgin, recycled, and pigmented uPVC formulations used in extruded profiles for conservatory roofing applications is reported. The shear viscosity, tensile properties and dynamic mechanical thermal properties of the various formulations were shown to be dependent on stabiliser type, thermal processing history and pigment concentration. Lead stabilised uPVCs were shown to have better impact properties than Ca/Zn stabilised compounds and slight differences in Tgs, storage modulii (E’) were recorded for all formulations.
Analysis of Disproporationate Termination Effects in Free Radical Polymerization and Damped Oscillatory Kinetics of Simple Reactions in Circle
Kal Renganathan Sharma, May 2004
A system of reactions in circle is modeled using the methods of Laplace transforms and the method of Jacobian matrix. The conditions of reaction rate constants when the damped oscillatory kinetics may be observed are derived for the cases of three reactants, of four reactants, eight reactants and general case. For the case of Reactions in Circle with 3 reactants the kinetics will exhibit damped oscillatory behavior when k3 < k2 + k1 + 2sqrt(k2 k1 ) or when in any one of the rate constants is less than the square of the sum of the square root of the other two rate constants respectively. For the case of Reactions in Circle with 4 reactants the kinetics will exhibit damped oscillatory behavior when B3/27 + C2/4 > 0 where B = (? - ?2/3) and C = ? + 2?3/27 - ??/3 . In terms of the rate constants ? is given by the sum of all the four reaction rate constants and ? represents the sum of all the possible binary products of rate constants and ? is the sum of all the possible triple products of rate constants in the system in circle. For the general case the characteristic equation is written whose solution will determine the exact solution of the system. The cases where complex roots result will represent the conditions of the rate constants where damped oscillatory behavior can be expected.
Ethylene-Butyl Acrylate-Carbon Monoxide Terpolymer as a Replacement Plastcisier for Polyvinyl Chloride
D.C. McConnell, G.M. McNally, W.R. Murphy, Y. Romeo, B. Lahuerta, E. Rodriguez, May 2004
An ethylene-butyl acrylate-carbon monoxide terpolymer (EnBA-CO) was blended with two PVCs at various compositions. Several commercially available medical grade plasticised PVCs were also tested to assess the suitability of the PVC blends as replacements for the traditional PVCs. The results are also compared to previous work on effect of ethylene-vinyl acetatecarbon monoxide (EVA-CO) as the polymeric plasticiser for PVC. The tensile and flexural modulus of the blends decreased significantly with progressive increase in EnBA-CO, while maximum elongation at break and impact strength were recorded at 30-40% terpolymer content. A single glass transition temperature (Tg) between that of the PVC and EnBACO components was recorded (DMTA), indicating complete miscibility over the range of concentrations studied. Rheological analysis showed a decrease in shear viscosity with increasing EnBA-CO content. The properties of most of the PVC/EnBA-CO blends were similar to those of commercially available plasticised PVCs.
Poly (Lactic-Glycolic Acid) and Funtional Hydrogels for Drug Delivery Applications
Hongyan He, L. James Lee, May 2004
Biodegradable polyesters like poly(lactide-coglycolide acid) (PLGA) and pH-sensitive hydrogels have been used increasingly for various medical and biological applications. The present work focused on the use of these functional polymers to design an assembled drug delivery system (DDS) that could integrate multiple functions in a single device and achieve different release patterns. For PLGA, The major concerns are the poor hydrophilicity, accumulated acidity during degradation, and bulk erosion characteristics. In this study, poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEOPPO- PEO) tri-block copolymer and a nano-clay Cloisite® 30B were utilized as modifiers to control the degradation behavior and hydrophilicity of PLGA. For comparison, a block copolymer, poly(lactic acid)/ poly(ethylene glycol) (PLA-co-PEG) was synthesized. A pH-sensitive hydrogel together with a poly(hydroxyethyl methacrylate) (HEMA) was used as a gate to control drug release. By using this bilayered self-folding design, the drug protection and selfregulated oscillatory release were demonstrated.
Performance of Polymeric Scaffolds in Tissue Engineering
A.M. Yousefi, C. Gauvin, P. Debergue, D. Laroche, R. DiRaddo, J. Fernandes, May 2004
Polymeric scaffolds in tissue engineering provide temporary mechanical support for tissue regeneration while shaping the in-growing tissues. The overall stiffness of the polymer-tissue constructs in bone/cartilage tissue engineering can affect the tissue in-growth by altering the local mechanical environment around the cells. This work deals with the influence of scaffold material properties on its load-bearing characteristics. Moreover, it demonstrates the role of scaffold porosity on the load dissipation through drag forces based on a biphasic model. The final goal of this work is to improve the performance of hybrid bone/cartilage polymeric scaffolds.
Biocomposites Based on Poly(L-lactic Acid) and a Functional Synthetic Filler
G. Chouzouri, S.H. Patel, M. Xanthos, May 2004
This work is a continuation of an earlier study on poly(Llactic acid)/hydrotalcite composites prepared by solution mixing. Two types of these synthetic magnesium/aluminum carbonate/hydroxide minerals, at 30wt% filler level, were used; surface coated and uncoated. Differential scanning calorimetric and thermogravimetric analysis of the unfilled polymer and its composites showed significant differences in structure and morphology through the addition of the filler. The composites were exposed to a phosphate buffer saline solution, at 37°C, to study the “in vitro” degradation of the polymer, and also to simulated physiological solution to detect bioactivity by the formation of an apatite type structure layer. The composites were analyzed before and after immersion for predetermined time periods in both solutions, by weight changes, SEM, EDX and RAMAN microscopy. Preliminary results suggest that these novel composites could have a potential use in tissue engineering applications.
Effect of the Mixing on the Mechanical and Thermal Behavior of HDPE/Hydroxyapatite Composites
C. Albano, A. Karam, G. González, N. Domínguez, Y. Sánchez, F. Manzo, C. Guzmán, J. González, M. Ichazo, P. Joskowicz, May 2004
In composite materials is important an adequate dispersion of the filler on the polymer due to the effect exerted on the material's behavior and as a consequence in its biomedical application. For this reason the objective of the present work is to analyze the thermal and tensil properties of HDPE composites with different hydroxyapatite compositions (10-30 wt.%) prepared by two different methods, extrusion and solution in decaline. The results showed that a better dispersion was reached and as a consequence, resistance at break and Young modulus increased for the composites prepared through solution.
Process Development for Molding a Medical Grade Silicone Elastomer via Rheological and Thermal Analysis Approach
Xiaoping Guo, May 2004
Both thermal analysis and rheological approaches were employed to study the cure behavior of a medical grade silicone elastomer. Isothermal cure experiments were conducted calorimetrically at temperatures from 80 to 100 °C and rheometrically at higher temperatures from 100 to 180 °C. Non-isothermal cure experiments were also performed at different heating rates from 5 to 50 °C/min. It has been observed that the glass transition temperatures for uncured and cured materials remain almost unchanged and that the rheometric measurements are more suitable for characterizing the process of curing, especially for the prolonged, later stages of cure. Based on the changes in dynamic viscoelastic properties measured under isothermal conditions, the characteristic times of cure, including the gelation and peak cure time were determined, and presented as functions of cure temperature. These results were used in an attempt to develop a robust and viable molding process. It has been found that the post-molding cure is essential for stabilizing and optimizing mechanical properties of molded silicone elastomers.
The Study of the Novolac Type Phenolic Resins: Cure Characteristics and Mechanical Properties
Tae Ryong Hwang, Sang Min Lee, Yang Sun Song, Jae Wook Lee, May 2004
The phenolic resin system widely used, such as fiber reinforced composites, honeycomb panelling, electrical laminates, acid resistant coatings and wood panels and so on. phenolic resins like other thermoset resins demand analysis about cure behavior to enhance property of final products. Therefore, investigation of cure kinetics is very important to achieve the full cure state for the proper properties, not to pass vitrification states. The optimum contents of hardener, HMTA(Hexamethylenetetramine), were determined by measuring the heat of cure and mechanical property. And then we conducted the isothermal cure kinetics of novolac type phenolic resin by performing differential scanning calorimeter.
Effects of Free Phenol Contents and Cure Temperature upon the Cure of Phenolic Novolac Resins
Tae-Ryong Hwang, Sang-Min Lee, Yang-Sun Song, Jae Wook Lee, May 2004
The cure conditions as well as resin structure is the most important factors for coming up to possibilities of the hidden strength of the thermoset polymers like phenolic resin which are widely used for the industrial binder due to their excellent thermal and chemical properties. And it is very difficult to eliminate or minimize the unreacted phenol contents below ppm levels in the phenolic resins whereas the containing of phenol is definitely undesirable things especially for the electric/electronic applications and highly thermal resisted applications. In this work we studied the cure temperature effects on their cured properties, also quantitatively investigated the unreacted free phenol effects upon the cure behavior and cured properties of phenolic resins by performing the differential scanning calorimeter, dynamic mechanical analyzer, and izod impact tester. Thus we could figure out the higher temperature above 140? can not be recommended to reach the full cure state, and cure acceleration effects rather than the plasticizer effects of free phenol components on their thermal and mechanical properties when the resins were cured at high temperature which it could be easily reach the vitrified state.
Dimensional Analysis and Scaling Approach for Thin-Wall Injection Molding
Sylvana García, Alejandro Roldán, Juan P. Hernández, Tim Osswald, May 2004
In thin - wall injection molding processes, parts thinner than 1 mm are produced using high injection pressures and velocities. Modeling has not been successful in predicting process physics during molding. A dimensional analysis is performed, considering the most relevant variables of the process, the geometry and the non – linear material properties. Using similarity analysis with the material and process related dimensionless groups, the process is scaled by reducing the thickness. The scaled dimensionless groups are used to find relations between process conditions, material properties and other physical parameters, which lead to reasonable conclusions.
Time Scales of Coalescence in Processing Flows: Investigation of Flow through Runners and Strip Molds
Jairo E. Perilla, Sadhan C. Jana, May 2004
The time scales of coalescence in several processing flows were determined from a mechanistic model based on ballistic aproximation and drainage of partially mobile interfaces and compared with the characteristic times of flow through runners and filling of strip molds. It was found that coalescence takes place in a zone between the centerline and the walls of runner of circular cross-section and far away from the injection point in the filling of the strip mold. Qualitative agreement was found between model predictions and experiments carried out in a capillary die and in an injection mold.
Residual Orientation in Injection Molding: A SANS study
John Healy, Graham H. Edward, Robert B. Knott, May 2004
The orientation of polymer chains after Injection Molding is usually studied using techniques that measure the average orientation of a polymer segment. Small-angle neutron scattering (SANS) is a technique for measuring orientation at molecular scales and is very sensitive to molecular anisotropy. The residual orientation and conformation of polyethylene and polystyrene chains after injection micro-molding has been measured using SANS. We have found that, for micro-moldings, the residual orientation decreases with increasing injection speed and that the residual chain orientation at the molecular scale is not necessarily related to the average orientation of short chain segments.
New Method of Designing Runner System for Injection Mold using CAO Technique
Shinichi Nagaoka, Tomoo Hirota, Yoshiaki Togawa, May 2004
Today it is popular to evaluate injection molding process using computational analysis in advance. Designing runner system is important to control flow balance and weld positions for molds of large parts with multi gates. If designers use conventional injection molding analysis, they need to evaluate many runner systems by trial and error for obtaining solution, which is optimum only within the tried runner systems.In this paper, we propose an automatic method of designing runner system using Computer Aided Optimization (CAO) technique in order to control weld positions, and show an example of this method with Variable Complexity Model (VCM) approach to reduce optimization time maintaining accuracy of analysis.
Grafting of 12-Aminododecanamide to EAA Copolymer Film to Reduce COF
Ning Luo, Amol V. Janorkar, Scott M. Husson, Douglas E. Hirt, May 2004
The effect of covalently bound 12- aminododecanamide on the surface coefficient of friction (COF) of ethylene-acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12- aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15~0.18. Repetitive COF testing revealed that amide-modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness.
Selection of Process and Design Variable Settings under Multiple Performance Measures in Injection Molding
Carlos E. Castro, Mauricio Cabrera Ríos, Blaine Lilly, José M. Castro, May 2004
Injection molding (IM) is one of the most prominent processes for mass-producing plastic products. Selecting the proper settings for an IM process is crucial because the behavior of the polymeric material during shaping is highly influenced by the process variables. Consequently, the process variables govern the quality of the part produced. In order to obtain the variable settings that result in the best balances between key quality performance measures, Data Envelopment Analysis (DEA) was used to solve the respective multiple objective criteria problem using empirical models as surrogates. In addition, a DEA modification is explained here with the objective to further screen efficient solutions. Finally, practical cases containing only a subset of performance measures were analyzed to illustrate customized analysis and to illustrate how to identify robust process settings.
Thermal Stability Characterization of Plasticized PVC Compounds Using Calcium and Zinc Stearates
M. Guadalupe Rodríguez-Serrano, Saúl Gallegos Castillo, Martin Arellano, Luis J. González-Ortiz, May 2004
Thermal stability of plasticized PVC compounds (50 phr di(2-ethyl hexyl) phthalate and 0 or 5 phr of epoxidized soybean oil) was studied. The effect of Ca/Zn stearate ratio (0.0/1.0, 0.2/0.8, 0.4/0.6, 0.6/0.4, 0.2/0.8 and 1.0/0.0) and total amount of stearates (0.25, 0.5, 1.0 and 2.0 phr) was considered. The effect of presence of epoxidized soybean oil was evaluated only in formulations containing 2.0 phr of stearates. Degradation behavior was followed by color evolution (yellow index and L a b color coordinates), measurement of gel content, total amount of HCl and polyene produced and mass loss rate.
Added Value for Long-Fiber Reinforced Thermoplastic Components by In-Line-Compounding in the LFT-D-ILC Process
Stefan Troester, Oliver Geiger, Frank Henning, Peter Eyerer, May 2004
The relevance of long fiber reinforced thermoplastics in the automotive sector has grown significantly during the last years. State of the art technologies are processing of semi-finished products like glass mat reinforced thermoplastics (GMT) and long fiber granulates (LFTG). However, the so called long fiber direct process technologies (LFT-D) are about to gain growing market shares. These technologies enable manufacturers to produce components based on the raw materials glass fibers, thermoplastic resin and additives by using a compression molding technique.An important characteristic of long-fiber reinforced composites is the effect of fiber-orientation and thus anisotropic material properties within the components. The implementation of a new characterization procedure, the analysis of circular tensile specimen (so called “Zugronden”) to obtain the integral fiber-orientation will be introduced.The second focus of this paper is the presentation of some selected results of the material development related to the LFT-D-ILC process technology. The interaction between the different material components polymer, fibers and additives were well-investigated to achieve fundamental understanding of the LFT-D-ILC-Process. This enables optimised material compositions for specific applications.
Injection Molding Short Air Ducts Using TPVs
Sigenori Sasaki, Daniel J. Collins, Brendan Chase, May 2004
This paper presents comparisons between three primary process methods for the production of short air ducts for the automotive air induction market with a focus on thermoplastic vulcanizates (TPVs). Cost comparisons between rubber injection molding, extrusion blow molding and thermoplastic injection molding are presented. Injection molded short air ducts using TPVs offer recyclability and a lower air duct weight when compared to a thermoset rubber (TSR) air duct. Additionally, TPV injection molded short air ducts offer a lower cost alternative to blow molding by allowing simplified part consolidation and reduced finishing cost. Part design and process recommendations for injection molded TPV short air ducts are discussed.


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