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

Devolatilization of Polymers by Diffusion and Foaming
Ingo Gestring, Dieter Mewes, May 2000

Devolatilization is a key-step in polymer processing. Low-molecular-weight components are removed from a polymeric system. The transport of these components takes place by diffusion and in some cases by foaming. In this study the different transport phenomena are investigated independently from each other in a special designed apparatus. The transport in thin films and rotating pools with surface renewal is measured for different parameters. For the diffusive transport a high surface renewal rate and thick films enhance the mass transfer. For foam devolatilization the conditions for bubble nucleation and foam formation are investigated. The bubble nucleation takes place in the rotating pool in the area of high shear velocity.

Wonder Injection Molding with Momentary Mold Surface Heating Process (MsSH Process)
Myung-Ho Kang, Dong-Hak Kim, Y.H. Chun, May 2000

Momentary Mold Surface Heated Process is a invention which heats only the mold surface over 400°C in few seconds with gas flame and cool it down very quickly again. Practically it was tried to produce a shiny surface of 98% light reflecting of the injection molded article of 30% glass fiber reinforced Polycarbonate. And it was carried out successfully with a simple attached equipment and specially designed mold so called MmSH Mold which is to supply the gas fuel and air between the two parts of mold. The results and method of wonder injection molding with MmSH Process was reviewed in this paper.

Design of an Injection Mold with Removable Plates Using CAE
S. Villarroel, R.A. Morales, H. Rojas, May 2000

The objective of this work was to design a mold of normalized test specimen to evaluate mechanical polymer properties with removable plates to inject each specimen independently using computed-aided engineering (CAE). The design was validated through simulation program of the injection process C-MOLD. Four cooling systems, the position of the entrance and the percentage of shrinkage were evaluated. There were no differences between the cooling systems studied. The maximum shrinkage was less than 2% and no part warpage was observed

Design of an Injection Mold Using C-MOLD Software
H.B. León, R.A. Morales, O. González, May 2000

The purpose of this paper was to design a security cap and its injection mold using CAD/CAE tools. C-MOLD and Pro/ENGINEER softwares and the Concurrent Engineering Method were applied. The part and its mold were successfully designed in only 20 weeks.

Dynamic Rheological Properties of HDPE/Ethylene-Alpha-Olefin Copolymer Blends
R.A. Morales, J.J. Sánchez, A.J. Müller, May 2000

The blends of linear and branched polyethylenes have received much attention in recent years. Many studies have been carried out to evaluate the miscibility of these mixtures and its influence on the final properties. There still some degree of controversy on the issue of melt miscibility even though partial co-crystallization has been demonstrated for some of these systems.

Surface Delamination of an Injection Molded Medical Device Using Flexible PVC
Tahua Yang, Sherwin Shang, John Booras, Michael T.K. Ling, Henk Blom, Lecon Woo, Ho-Seon Jin, Dan Marcquenski, May 2000

An autoclavable medical device was designed using flexible PVC. The device was injection molded and subsequently was exposed to steam autoclaving. Surface delamination was observed in the adjacent area of the gate. Investigations on material properties, pigment dispersion, and residual stresses were conducted. It appeared that by simply controlling the molded-in stresses, the defect could be minimized. In a Design of Experiment (DOE) study, the key molding parameters were identified.

Constitutive Analysis of the Nonlinear Shear Rheology of Flour Suspensions Obtained from Different Botanical Sources
C.J. Carriere, A.J. Thomas, G.E. Inglett, May 2000

The evaluation and development of validated models for the nonlinear viscoelastic (VE) behavior of materials is an important area of research which has impact on a number of industrial processes including those in the food industry. Various nonlinear VE models have been developed over the years and evaluated for petroleum-based polymers; however, our understanding of the nonlinear VE behavior of biopolymers of industrial import lags our understanding of synthetic polymers. In the work reported herein, the nonlinear VE behavior of suspensions (20 % by weight in deionized water) of defatted oat flour, oat bran, barley flour, and oat flour were investigated. The rheological properties were measured using a Rheometrics Series IV controlled-strain rheometer equipped with a cone and plate fixture. The measurements were conducted at 23 ± 0.1°C. The rheological data were interpreted using a strain separable K-BKZ type (Wagner) model. The K-BKZ model was found to provide an accurate description of the rheological behavior of the four flour suspensions.

Coextrusion of High Barrier Films Containing Liquid Crystalline Polymers
S. Kenig, A. Ophir, F. Wiener, M. Omer, May 2000

Thermotropic Liquid Crystalline Polymers (TLCPs) possess the lowest oxygen and humidity permeabilities among commercial polymers. However, TLCPs are highly incompatible with conventional polymers (polyolefins, polyesters), due to their unique composition and morphology. To compatibilize TLCPs with conventional polymers, a variety of polymers were evaluated having various functional groups like maleic anhydride, epoxy, acrylic acid etc. Using Ethylene Glycidyl Metha Acrylate (EGMA), three and five layer films containing TLCPs were prepared by conventional coextrusion. Experimental results have shown that a 10 ?m TLCP layer with polypropylene or polyester, increased the barrier to oxygen by a factor of 120 compared to neat polypropylene and by a factor of 40 compared to neat polyester, respectively. Furthermore, five layer films demonstrated higher barrier and stiffness properties compared to three layers films having identical overall composition. These unique barrier properties of TLCPs containing multi-layer films can compete commercially with EVOH and PVDC containing coextruded films, and can be further shaped by thermoforming and blow molding for high barrier packaging applications.

Fracture Behavior of Polypropylene Modified with Metallocene Catalyzed Polyolefin
Laura A. Fasce, Patricia M. Frontini, Shing-Chung Wong, Yiu-Wing Mai, May 2000

The fracture and deformation behaviors in polypropylene homopolymer toughened by metallocene catalyzed poly-ethylene elastomer are unknown. It is desired to understand the fracture and deformation mechanisms of PP toughened by the elastomer using standard puncture tests, J-integral fracture initiation toughness and tensile dilatometry. Preliminary results show that impact toughness of PP homopolymer was greatly enhanced in the presence of the elastomer. Volumetric strains were measured to estimate the degree of dilatational deformation relative to volume-conserving shear yielding.

Free Volume and Molecular Mobility in a Styrene/n-Butyl Methacrylate Copolymer Series
George P. Simon, Charles L. Beatty, Stuart R. Andrews, Sara Shinton, Graham Williams, May 2000

In this work a wide series of copolymers of styrene and n-butyl methacrylate are investigated in terms of their physical and free volume properties. The study follows on from recently published work in which the relaxational and intermolecular coupling properties of this copolymer series was examined. It is found that even though the glass transition of polystyrene is higher than that of poly (n-butylmethacrylate), it has a lower density and higher molecular free volume fraction. The free volume fraction behaviour is complex, all copolymer values showing greater free volume fraction than the homopolymers. This correlates with a negative deviation over the Fox Tg behaviour of the copolymer. This is despite the moderately monotonic variation in the individual aspects of free volume (size and number of free volume pores). There are some dramatic changes in these properties at the extreme values of comonomer concentrations.

Nucleation in Foam Extrusion
S.T. Lee, May 2000

Nucleation results are presented for polyethylene sheet extrusion while using volatile carbon dioxide without any nucleating agent to study homogeneous nucleation. Since the extrusion pressure has to exceed the system pressure, mechanical superheat was calculated from the processing pressure. The experimental results show a different distribution from the conventional nucleation predictions, based on either chemical superheat or mechanical superheat. Also noted was the shear energy dependence. Various nucleation mechanisms are discussed to address the energy role played by shear in foam extrusion.

Modeling Flow-Induced Crystallization in Film Blowing
Antonios K. Doufas, Anthony J. McHugh, May 2000

A mathematical model was developed for the simulation of film blowing including the effects of flow-induced crystallization, viscoelasticity, and film cooling. The microstructural model is based on the formulation of Doufas et al. Our model predicts the location of the freezeline naturally as a result of crystallization and the stresses at the frost line, which are closely related to the mechanical and physical film properties. Depending on the processing conditions, our model predicts uniaxial or biaxial film stretching.

Process Monitoring Using UV-VIS Spectroscopy
J.C.J. Bart, May 2000

The paper describes process monitoring applications by spectroscopic methods for polymer/additive analysis, polymer melt analysis, additive quantitation, QA/QC purposes, on-line compositional polymer analysis, in-situ reaction monitoring (cure kinetics, polymerisation, color designation, molecular interactions, monitoring of extrusion processes, real-time measurements and use of fiber optics. In particular, the current status of on-line multicomponent additive analysis in the polymer melt by means of UV-VIS spectroscopy will be illustrated.

Effects of Processing Conditions on Extruded Polystyrene Sheet Feedstock Quality
Kolapo P. Adewale, Robert Roberts, May 2000

This work investigates the influence of various extrusion parameters on the physical properties of rubber modified polystyrene sheets. The extrusion parameters under consideration are melt temperature, chill-roll temperature, line speed and sheet thickness. Optimum extrusion conditions for producing polystyrene sheet feedstock are discussed.

Intelligent Guidance of the Melt Front in Injection Molding Machines
Athanasios Bikas, Nikos Pantelelis, Andreas Kanarachos, May 2000

In the present paper the numerical simulation software 'NASPLAN' is presented allowing the intelligent guidance of the flow at the filling stage in an injection machine. NASPLAN allows the guidance of melt flow through prescribed p-q Time profiles. Especially the use of negative pressure is proved to be of great importance for the guidance of the Melt Front Advancement. This procedure leads to balance flow for complex geometry parts and multi-cavity molds. The primary objective of NASLAN compared to the conventional software is the improved part quality, by minimizing the flow defects (such as warpage, non-uniform shrinkage, sink marks). Additionally, the filling stage is completed in less time with the need of lower injection pressure. A simple part is adapted as a test case in order to visualize the effects of the above procedure.

Polyblends of Polyphenylene Ether with Styrene-Ethylene/Butylene-Styrene Block Copolymer
Rudolph D. Deanin, Paul Lunn, May 2000

Polyphenylene ether (PPE) and styrene-ethylene /butylene-styrene block copolymer (SEBS) were melt blended in ratios from 100/0 to 50/50. Balancing the molecular rigidity of PPE vs. the molecular flexibility of SEBS produced the expected qualitative effects on properties. Quantitatively, tensile modulus and tensile and flexural strengths gave monotonic curves for properties vs. polyblend ratio. All other properties - melt index, flexural modulus, ultimate elongation, impact strength, and heat deflection temperature - gave more complex curves. Practically, addition of SEBS produced significant increases in melt index, ultimate elongation, and impact strength, along with decreases in rigid properties.

Survey of Plastics Education in U. S. Colleges and Universities
Rudolph D. Deanin, May 2000

Inquiries to 234 schools found 66 which offered courses in plastics, for a total of 2492 credit hours. Classifying these by subject matter showed 768 credits in polymer science, 324 in plastics in general, 125 in plastic materials, 238 in structure and properties, 568 in processing, 170 in product design, and 299 in other applications of polymers. The plastics industry began in 1868 (1) reached commodity status in the 1940’s (2), and has been growing in size and diversity ever since. The earliest plastics entrepreneurs came from other fields, and educated themselves. With the continuing and expanding growth in numbers of materials and processes, and in the intensity of polymer science and engineering, the need for higher education specifically in polymers and plastics has also grown exponentially.

Make Flat Sheet Using Contrabend Rolls
Richard Palmer, May 2000

Most plastic sheet produced today is made using a typical three-roll sheet stack. Material is passed through a preset gap between the rolls to form the final thickness of the sheet. The variation in this gap is related to the bending of the chill roll, which is a major factor in the gage variation of the sheet. Producing flat sheet" has always been the goal of the sheet producer. Until recently there has been little advancement in cooling roll construction as it relates to bending in the cross line direction. The Contrabend Reverse Bending Roll has been developed to greatly reduce the effect of roll deflection on sheet thickness variation. This work will explore the Contrabend concept and compare the bending to standard chill rolls."

Bubble Growth in a Solvent-Polymer Solution
Vivek Pai, Moshe Favelukis, May 2000

A model for the growth of a non-ideal gas spherical bubble in a quiescent viscous liquid is presented. The growth of the bubble in the solvent-polymer solution is assumed to be controlled by momentum, heat, and mass transfer. Using the integral method, the differential transport equations were transformed into ordinary differential equations, which were numerically solved. The numerical results show that the pressure inside the bubble can increase to extremely high values before it decreases to a value close to the ambient pressure. It was also found that at low solvent concentrations heat transfer is not important, and the usual isothermal assumption can be applied. The relevance of this work to the process of polymer melt devolatilization is discussed.

Design for Rotational Molding
Jordan I. Rotheiser, May 2000

This paper will cover the details of piece part design particular to the rotational molding process. Ribs, bosses, wall thicknesses, parallel walls, internal and external corners, openings, draft angles and undercuts will be discussed. Joining features, such as inserts, hinges and molded-in threads, will also be reviewed.










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