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.
The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?
Conference Proceedings
Forward to Better Understanding of Optical Characterization and Development of Colored Polyamides for the Infra-Red/Laser Welding: Part I-Efficiency of Polyamides for Infra-Red Welding
Val Kagan, Robert Bray, Al Chambers, May 2001
The influence of a wide range of the infrared (IR) wavelengths (from 830 to 1,064 nm) on the optical properties of welded thermoplastics was evaluated for unfilled, filled and reinforced polyamide 6, 66 and amorphous grades. Presented results and developed recommendations will help, designers, technologists and materials scientists in welded parts design, materials selection and new materials development for various laser welding (LW) applications.
Ethylene Styrene Interpolymers for Injection Molded Toys
Dane Chang, Y. Wilson Cheung, May 2001
Due to increasing regulatory pressure, the toy industry has found itself being challenged to find suitable replacements for flexible PVC in flexible injection molded toys. Plasticized PVC is typically used for flexible toys where design requires painting of the molded toy. A new family of compounds suitable for such toy applications has been developed. These compounds are based on ethylene styrene interpolymers and exhibit short cycle time, high tensile strength, and excellent paintability.
Rheology as a Tool for the Polymer Scientist
Montgomery T. Shaw, May 2001
Rheology is a discipline that has applications both for analysis of polymer structure and for correlation and prediction of processing behavior. As such, rheology has impact over the entire development of a commercial resin. Described are several projects in the areas of polymer blending, aging and fabrication that illustrate the important role that rheology has played in their execution.
Processing Ignition-Resistant Polystyrene Resins in Injection Molding Machines
Mark A. Spalding, Robert G. Nelb, James A. Patterson, Chris Youngson, Melissa J. Zawisza, May 2001
The demand for ignition-resistant polystyrene resins (IRPS) continues to increase. Moreover, economics at the molder are requiring that these materials cycle faster and still produce high-quality parts. A new high-flow IRPS resin was developed to meet these needs, and this paper describes a plasticating screw design and the process conditions for enhanced performance and improved economics for this resin.
The Effect of a Worn Feed Casing on Plasticating Extrusion
Mark A. Spalding, Kevin R. Hughes, John L. Sugden, Phillip A. Wagner, Kun Sup Hyun, May 2001
With continued use, a worn feed casing can cause severe rate reductions and unstable operation of plasticating extruders. This paper will present the performance of a commercial extruder with a worn feed casing, and laboratory experiments that show the factors that affect plasticating performance.
Influencing the Foam Structure of CO2-Blown Polypropylene Sheets
Robert Heinz, Walter Michaeli, May 2001
An investigation has been conducted to analyze the influence of different process parameters as well as material properties on the structure of CO2-foamed polypropylene sheets. The use of a linear and a branched polypropylene shows the influence of the rheological melt properties on the foam density and the structure. Using the branched polypropylene, densities down to 140 kg/m3 have been achieved. These samples also show a finer and more homogeneous foam structure than the samples made with the linear polypropylene.
Control of Morphology of Polypropylene and Noryl Blend via Melt Mixing
Yanmei Li, Hung-Jue Sue, Brian Coleman, May 2001
Morphological development of polypropylene/Noryl blends as a function of composition and processing conditions is studied. Effects of processing conditions such as screw speed and residence time, on the morphology and mechanical properties of PP/Noryl blends are investigated. The processing-morphology-property relationship in PP blends is discussed.
Application of Fused Deposition Modelling in Spray Metal Tooling for Injection Moulding
S.H. Masood, M. Bahri, I. Harianton, May 2001
This paper presents a modified spray metal tooling procedure based on FDM rapid prototyping process, where parting lines were defined in the design stage to simplify and accelerate the spray metal tooling. Core and cavity inserts for injection moulding of a gas turbine blade were created using the modified procedure and successfully injected using LDPE. The procedure significantly shortens and simplifies the tool fabrication process, particularly for complex shapes, when manual parting lines establishment is too complicated and time consuming.
The Effect of Crystallinity on Oxygen and Carbon Dioxide Gas Barrier Properties of PET
Jun Lin, Sergei Shenogin, Sergei Nazarenko, D.A. Schiraldi, May 2001
Gas barrier of cold crystallized poly(ethylene terephthalate) (PET) was studied as a function of crystallinity. Changes of permeability and solubility versus crystallinity showed complex behavior, which can not be understood in terms of traditional two-phase approach. The data, however, were amenable to interpretation by three-phase model where, in addition to regular amorphous and crystalline phase, the rigid" amorphous phase with density lower than the density of regular amorphous phase was considered."
Viscoelastic Material Characterization at Large Deformation
Karel Kouba, Petr Novotny, Armin Kech, May 2001
New method was developed for measuring stress-strain at large deformation typical for thermoforming. Method is similar to plug assisted forming with both large strain and high strain rate. Numerical method was developed to get use of reverse engineering for fitting of non-linear parameters of suitable viscoelastic model. The aim of the method is providing reliable data for computer simulation of thermoforming.
Predictive Control of Cavity Pressure during Injection Filling
Rickey Dubay, May 2001
Cavity pressure is a good indicator during injection molding for achieving high part quality and maintaining consistent part weight and overall dimensions. Its trajectory during the filling phase of injection is highly dependent on other molding variables. The repeatable control of cavity pressure is therefore vital for producing parts with tight tolerances. A predictive controller for cavity pressure control during cavity filling was developed and implemented. The controller was able to provide cavity pressure ramp rates ranging from 10 to 35 KPa/ms under high injection speeds.
Metallocene Catalyst Mixture for Propylene Polymerization
Mariana Poloponsky, Érica Gervasoni Chaves, Maria de Fátima V. Marques, May 2001
Metallocene mixtures have been used in order to design polymers with broader polydispersity, intending to improve polymer processing. In this work, the properties of isotactic polypropylene obtained by a mixture of (1) SiMe2(Ind)2HfCl2 and (2) SiMe2(Ind)2ZrCl2 , in different proportions, were investigated. The catalyst activities for the mixtures were lower compared to the individual complexes. We observed polymers showing broader molecular weight distribution, with a bimodal Gel Permeation Chromatography curve at 50/50 (1)/(2).
Syndiotactic Polypropylene from Metallocene Mixture
Érica Gervasoni Chaves, Mariana Poloponsky, Maria de Fátima V. Marques, May 2001
Considering the real interest in syndiotactic polypropylene (s-PP) and the possibility to design polymers with desired properties using metallocene catalyst mixtures, this work investigates the characteristics of s-PP produced by a mixture of (1) Et(Flu)(Cp)ZrCl2 and (2) Ph2C(Flu)(Cp)ZrCl2 in different proportions. By the results we observed that the polymers obtained from the mixed systems showed higher molecular weight and broader molecular weight distribution than the isolated polypropylenes.
Thermoset Filling Imbalances in Geometrically Balanced Runner Systems
David A. Hoffman, John P. Beaumont, May 2001
Shear induced variations created within runner systems dramatically affect the filling of the industry standard geometrically balanced runner systems. These variations not only cause imbalances in cavity filling, but may also impact the polymer curing properties and the mechanical properties of the molded product. This paper reveals the severity of the imbalance within thermosetting materials, its potential effect on the molded product, and a new technique used to solve the imbalances.
Spatially Resolved Studies of Polymer Film Dynamics
Boris B. Akhremitchev, Sabah Al-Maawali, Jason E. Bemis, Gilbert C. Walker, May 2001
We have developed several new scanning probe methods for analyzing polymers at surfaces. We present a technique for studying single polymer chains. We describe model for polymer dynamics on an AFM tip, and applications of the technique to analysis of polymer surface polydispersity and irreversible aspects of adhesion. We also describe developments in apertureless near field scanning infrared microscopy (ANSIM), to obtain IR spectra of surfaces at high spatial resolution.
Syndiotactic Polypropylene Using Different Supported Metallocene Catalyst
Queli C. Bastos, Simone C. Moreira, Juliana D. Rego, Maria de Fátima V. Marques, May 2001
Polymerizations of propylene were carried out with ?2C(Flu)(Cp)ZrCl2 catalyst supported on silica, sodic modernite (NaM) and ZSM-5. The molecular weight, molecular weight distribution, melting point and crystallinity of the obtained polymers and also catalytic activity were examined. The results report very high activities for the heterogeneous systems, specially with ZSM-5 as carrier. Higher melting point and crystallinity degree were presented in polypropylene synthesized with the catalyst supported on NaM.
Dimensional Stability of LDPE Foams: Modeling and Experiments
Chi-Tai Yang, Kevin L. Lee, S.-T. Lee, May 2001
The thickness change of extruded LDPE foam to the blowing agent and air counter diffusion during the post-extrusion aging process is modeled. The blowing agent and air counter diffusion equations are coupled with the viscoelastic equations to model the foam volume shrinkage and recovery processes in a closed-cellular low-density LDPE foam. The variables studied include polymer elastic and viscous constants, foam sheet thickness, cell count and foam density. The mathematical model is also compared with experimental data.
Failure Analysis Case Study - A Systems Solution
Michael P. Sepe, May 2001
Failure analysis typically employs a series of appropriate tests that result in a conclusion about the cause or causes of a product failure. Often the problem involves an interaction between the plastic part and other components in the product or between the plastic part and application conditions. Identifying these interactions is an important part of developing a solution that resolves the problem without unduly increasing costs. This paper outlines a case study in which a proper analysis of the failure mode and knowledge of commercial alternatives led to multiple options for a solution.
What Position on the Viscosity Curve Is the Most Repeatable with Respect to End of Fill Cavity PSI
Sean Mertes, Charley Carlson, John Bozzelli, Mike Groleau, May 2001
For many years, educators in the injection molding industry have suggested that higher injection speeds result in more stable processes when using 2-Stage processes. However, little data exists to verify this assertion. In this paper, injection speeds were varied on a 2-Stage process. Cavity pressure was measured at the end of the cavity to evaluate process stability in the face of several process perturbations. Results supported the claim that higher injection rates reduced overall process variation.
Toughening of Polypropylene with Calcium Carbonate Particles
W.C.J. Zuiderduin, C. Westzaan, H. Huetink, R.J. Gaymans, May 2001
In this paper the influence of precipitated calcium carbonate (PCC) particles on the toughening of polypropylene has been studied. It has been shown that the addition of the PCC particles increase the stiffness of the system and at the same time increase the impact resistance. The brittle-to-ductile transition temperature (TBD) was lowered considerably by increasing the calcium carbonate concentration. The debonding of the calcium carbonate particles prior to the yield stress is the dominating step in the toughening mechanism.
.jpg)
.jpg)
.jpg)
.jpg)
