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

Morphology and Mechanical Behaviour of Polypropylene Hot Plate Welds
M.J. Oliveira, C.A. Bernardo, D.A. Hemsley, May 2000

Polypropylene tensile bars were hot plate welded and analyzed by microscopy and mechanical tests. The welding process originated deep modifications in the microstructure and shape of the bars at the weld zone. It was observed that the weld morphology was affected not only by the welding parameters but also by the thermal history of the components. The occurrence of oriented textures, coarse spherulites, voids or sharp notches at the beads are determinant morphological factors on the weld quality. The performance of the welds is dependent on the type of testing method used. The tensile impact test showed to be potentially good for quality control, as the fracture behavior was affected by the overall morphology.

Size and Confinement Effects on the Glass Transition
Gregory B. McKenna, May 2000

Since the first measurements of the reduction of the glass transition of small molecule liquids in nanometer pores, there has been an increasing number of studies of the effects of size and confinement on the glass transition of both small molecules and polymers. The measurements coming from different groups often give apparently conflicting results. This paper surveys the state of the field and provides insights into possible reasons for the apparent discrepancies that suggest paths for further investigation.

Computer Design and Screw Optimization
C.A. Thibodeau, P.G. Lafleur, May 2000

Screw design is often the main factor in polymer processing equipments to achieve better quality products or higher outputs. This work presents a new screw design tool based on the use of extrusion softwares and statistical methods that provides a reliable basis for screw design. This method is versatile, not time consuming, and can be applied to many cases in the plastic industry. A specific case in the field of PVC profile extrusion is discussed in detail. Experiments support the new screw design proposed for this application.

The Effect of LDPE-g-AA by a Reactive Extrusion Process
J.F. Kuan, W.H. Lin, H.F. Shen, J.M Huang, May 2000

Acrylic Acid (AA) was grafted onto LDPE to modify its properties by reactive extrusion process. In this study, a co-rotating twin screw extruder and Banbury were mainly used for the reactive grafting process. By changing the configuration of the screw elements, different degrees of shearing effects gave various degree of grafting. It was found that the ratio of LDPE/AA/DHBP=100/10/0.5 with a medium shearing in the extruder gave an optimal result, and the ratio of grafted AA was 4.7%, which was measured via a standard titration process.

Mechanical Performance of a Reinforced Unsaturated Polyester Resin Crosslinked with Divinyl Benzene/1,6 Hexanediol Diacrylate
C.F. Jasso, E. Rosas, R.J. Sanjuan, L.J. González, M.E. Hernández, May 2000

Searching for an advance in mechanical performance, two monomers of high functionality with different spatial structure, were used in this study to crosslink a general purpose reinforced unsaturated polyester resin. Varying the concentration of Divinyl benzene (DVB) and 1,6 Hexanediol diacrylate (HDDA), different crosslinking structures and properties are expected.

Designing a TPO Using ETP Modification Technology
David M. Dean, John A. Foltz, W. Michael Sanford, May 2000

Elastomeric Thermoplastic (ETP) is a patented alloying technology that utilizes ethylene copolymer resins to modify flexible thermoplastic polyolefin (TPO) systems. It is based on the reactive blending of a partially neutralized acid copolymer (ionomer), an epoxy functionalized ethylene copolymer, and a standard TPO. The reaction between the epoxy groups of the ethylene copolymer and the free acid groups of the ionomer results in a partially cross-linked system that forms an in-situ alloy with the TPO. This alloy imparts increased melt strength to the TPO, permitting significant increases in thermoforming performance and grain retention. By varying the amount and type of Surlyn® ionomer within the alloy, a desired mix of mechanical properties, forming performance, and hand can be obtained. As the automotive industry moves toward developing interior components based on thermoplastic polyolefins (TPOs), this ability to customize a TPO-based material for specific applications provides a key advantage for the design engineer. For example, instrument panel skins can now be produced with reduced weight, reduced fogging, and better resistance to heat and UV radiation relative to PVC/ABS, but yet possess the ability to undergo deep draws during thermoforming while maintaining grain definition. Alternatively, formulations have been developed specifically for molded-in-color injection-molded soft-touch surfaces, which require a different balance of melt behavior and physical properties. In this study, we report on the relationship between ionomer content and physical properties in ETP modified TPO systems. The effect of incorporating an ionomer containing a softening acrylate comonomer on the feel" of the modified TPO material as quantified by flexural modulus and durometer is also discussed."

Design of Experiment (DOE) Procedures to Evaluate Ultrasonic Weldability of Materials
Joon Park, Jim Liddy, May 2000

Usage of Thermoplastic Olefin (TPO) is a common trend for automotive interior parts. TPO is a copolymer of Polypropylene (PP) and Polyethylene (PE) for rubber constituent and the TPO evaluated contains 20% of talc. Considering the facts that PP and PE are semi-crystalline thermoplastics with high molecular weight and that TPO contains rubber, talc, and reground material, weldability of the material has been always in question. Especially since the ultrasonic welding process deploys several tens of microns of vibration amplitude for welding, energy from ultrasonic vibration can be dissipated easily before effective heating of materials for welding. Therefore, evaluation of material weldability is an important requirement for material selection.

Effect of the Interaction Coefficient in the Prediction of the Fiber Orientation of Injection Molded Glass Fiber Reinforced Polycarbonate
N.M. Neves, A.J. Pontes, A.S. Pouzada, May 2000

The mechanical properties of injection molded parts in glass reinforced materials is sensitive to processing. A successful design requires a good estimate of performance before production. The product performance is strongly affected by the fiber orientation field. It is complex and varies tri-dimensionally in the moldings. Some commercial simulation programs already allow the prediction of the fiber orientation induced by the injection flow. However the simulations depend on the definition of the fiber interaction coefficient. C-Mold simulations were made to determine the best fit to experimental results varying the interaction coefficient between neighboring fibers in center gated circular flat discs.

New Technology for Dyeable Polypropylenes
Vicki Flaris, Joe Collier, Chris Henkee, May 2000

Approximately three billion pounds of polypropylene is consumed annually in fiber applications. Despite this success, one of the drawbacks to using polypropylene fiber remains its inherent lack of dyeability. In this paper we describe how a polypropylene resin can be modified via a blending process to produce a material that is readily dyeable and colorfast. In order to make the polypropylene dyeable, a reaction product of a maleated polypropylene and a polyether amine is blended into the fiber grade resin. The polypropylene portion of the maleated polypropylene co-crystallizes with the base resin, thus locking in the polyether portion of the molecule. This polyether molecule, with its high polarity, then allows the dyes to be absorbed. In these experiments fibers were spun using this modified material, fabrics were knitted, and dye testing was carried out. The results reveal that this modified polypropylene dyes several times better than the unmodified control.

Thermodynamic and Kinetic Analysis of Semicrystalline Recyclates by DSC
R. Bruce Cassel, Lin Li, May 2000

Pelletized curbside recyclate was analyzed using recently developed thermal analysis techniques. These techniques included stepwise DSC for accurate Cp determination even in the presence of difficult analytical conditions, rapid-scan crystallinity determination using the Gray-Mathot total enthalpy technique, and kinetics analysis of crystallization rates. These methods, which can be largely automated, offer a useful procedure for testing recyclate for possible processing, or end-use problems.

Modulus Properties of Triaxially Braided Carbon Fiber/Epoxy Spars
Stephen Petrie, John M. Veilleux, May 2000

Traditionally, masts for sailboats were manufactured using a trial and error approach. The object of this work was to fabricate these structures using a computer code for design. In order to verify the code, specimens were fabricated and tested. Experimental flexural test properties obtained from flat coupons and cylinders were found on an average to be thirty percent lower than code predictions. Conversely, tensile properties from flat coupon tests were ten percent higher than predicted.

Ultrasonic Absorption in Rubber Filled Epoxies
K. Gabriel, S. Petrie, May 2000

Mechanisms of sound absorption in rubber toughened epoxies were studied. The general mechanisms of sound absorption in plastics were reviewed. Design of experiment principles were used to develop an experimental regime to investigate the impact of density, glass transition temperature of the rubber phase, and volume percent loading of rubber particulate on sound absorption. It was found that maximum sound absorption occurred in materials with high loadings of low glass transition temperature, rubber particulate whose acoustic impedance was very different from the host matrix.

LCP Droplet Deformation in Fiber Spinning of Self-Reinforced Composites
C.H. Song, A.I. Isayev, May 2000

The development of morphology during fiber spinning of blends of polyesters (PET and PBT) with LCP (PET/HBA) was studied. The quantitative predictions of the blend morphologies under isothermal and non-isothermal conditions were obtained using a droplet deformation criteria based on the reduced capillary number and the affine deformation theory. The temperature, radius, velocity, and strain rate profiles of 60/40 polyester/LCP fibers along the spin line were calculated using Kase and Matsuo's theory for fiber spinning under the steady-state condition. Simulation of breakup of LCP phase during fiber spinning of the blend based on the dimensionless breakup time indicated the absence of their breakup. The flow curves of the blends at various temperatures required to carry out simulation were obtained. Initial and final sizes of LCP phase were examined by SEM and image analysis. The calculated diameters of LCP fibrils in the fibers were found to be in agreement with the measured values.

On-Line Rheological Measurements
John M. Dealy, May 2000

Rheometers are being used increasingly as sensors for process control. This is because of the sensitivity of rheological properties to polymer characteristics such as molecular weight. The process rheometers now being used are mostly of the on-line, pressure flow type, in which a gear pump feeds a capillary or slit, and the pressure drop is measured. For process control applications, the signal delay associated with the flow of melt from the main flow to the capillary or slit slows the system response, and this problem has been addressed by the use of a larger sampling line together with a bypass around the rheometer. Other recent advances are aimed at providing a more extensive characterization of the melt.

A New Generation of High-Performance PVC Alloys
Dexi Weng, John Andries, Keith Saunders, John Macaluso, Robert Brookman, May 2000

Newly developed alloys of flexible poly(vinyl chloride) [PVC] and polyolefin elastomers have been shown to exhibit improved physical properties compared to conventional flexible PVC control compounds. In particular the new alloys display enhanced electrical properties, better high temperature stability, greater low temperature flexibility, and superior gas barrier properties. In addition, the following study demonstrated that PVC/polyolefin rubber alloys have potential utility in many applications where conventional flexible vinyl compounds do not meet certain end-use performance requirements.

Mid-Infrared Process Control Systems for Polymer Melts and Film
J.C.J. Bart, May 2000

The applications of on-line mid-infrared analysis in the polymer field comprise the detection and quantification of additives in polymer melts; compositional analysis of copolymers and polymer blends; control of polymerization processes: end-group determination; network characterization: determination of degree of cross-linking; reaction monitoring: reaction profiling, curing processes, kinetics, end-point determination; in-situ spectroscopy of molecular interactions: fluid impregnation, diffusion, drying, dyeing and extraction; monitoring of extrusion processes; safety and environmental monitoring, gas analysis, This paper examines in particular the current prospects of on-line (multi component) additive analysis in the polymer melt by means of mid-infrared spectroscopy.

Multilayer Films Using PP/PPgAA Blends
S. Flores-Gallardo, S. Sánchez-Valdes, L.F. Ramos de Valle, May 2000

Blends of polypropylene (PP) with 0 to 100% wt of Polypropylene grafted with Acrylic Acid (PP-gAA) were prepared by melt mixing and then coextruded as external layers with a central layer of nylon-6 on three layer coextruded flat films The effect of the modified polymer content and its molecular weight on interfacial adhesion between PP and nylon was determined by T-peel strength measurements. The effect of melt temperature and contact time during coextrusion on peel strength was determined. The observed increase on T-peel strength of the films when using 10% and higher levels of functionalized PP in the blend, suggest good interfacial adhesion between layers. Besides PPgAA content, its molecular weight has a notorious effect on interfacial adhesion between PP and nylon-6 (PA6).

Effects of Magnesium Hydroxides on the Physical Properties of a Semirigid PVC Used in Wire Coating
Jeffrey A. Torone, Stephen Petrie, May 2000

This is a study of ductility and smoke generation of Polyvinylchloride (PVC) with different smoke suppressants (SS). These smoke suppressants consisted of Magnesium Hydroxide (Mg(OH)2) and Alumina Trihydrate (ATH). It was found that the amount of smoke generated (SG) during the tests, decreased when the outer layer of the test samples were removed. The smoke generation and physical properties were analyzed to determine which smoke suppressant was best. No chemical versus physical correlations were found.

Simulation of CaCO3 Dispersion in a PP Matrix during Twin Screw Extrusion
Pierre G. Lafleur, Françoise Berzin, Miroslav Grmela, Bruno Vergnes, Sebastien R. Tremblay, May 2000

Compounding of highly filled minerals in polymeric matrix has never been an easy task. This work deals with the simulation of CaCO3 (25 and 50 % wt.) dispersion in a PP matrix during twin screw extrusion. Based on a kinetic model of agglomeration/breakup of the filler, we were able to pin point the effect of twin-screw operating conditions on dispersion. Experimental work has been done to validate the model and evaluate kinetics constants.

Analysis of Polypropylene Behavior at Constant Load below the Elastic Limit
Alejandro Hernandez-Luna, Nandika A. D'Souza, May 2000

Polypropylene dog-bone samples have been tested using creep-recovery analysis at different stress values in order to determine the behavior of the material in the elastic region. It has been found non-linear behavior in the sample at values under the elastic modulus at the elastic region. It has been also found, by means of calorimetric analysis, that creep test affected the material, promoting changes in crystallinity in the tested samples. These effects are important in the performance of the material in time.

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