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

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.

Near-Infrared Spectroscopic Product and Process Control

J.C.J. Bart, May 2000

The main applications of near-infrared spectroscopy relating to polymers are quality control, monitoring of textile fibers, remote identification/classification of polymeric materials (recycling), monitoring of polymer melts for additive and/or (co)polymer composition, and polymerization monitoring (of polyolefins, epoxies, nitrogen-containing polymers). Diffuse reflectance and transmission, transreflectance and reflectance modes are being used. Examples of the aforementioned applicational areas will be given with the main emphasis on the on-line (multicomponent) additive analysis in the polymer melt by means of near-infrared spectroscopy.

Polymer Rheology-Challenges for the 21st Century

John M. Dealy, May 2000

Rheological data are used in the plastics industry for polymer characterization, quality control, process control, and process modeling. In each of these fields, there remain significant barriers to progress. The challenges in polymer characterization are to develop experimental techniques for the rapid and precise measurement of linear viscoelastic properties and for evaluating the response of a melt to extensional deformations. A powerful aid in keeping a manufacturing process under statistical control is the use of an on-line rheometer as a process sensor for automatic control. A remaining challenge is the development of an in-line melt rheometer that would eliminate the need for gear pumps and reduce the time delay resulting from the transit of melt from the sampling point to the rheometer. While computational fluid dynamics has been applied with success to the simulation of several melt forming processes, major problems remain when melt elasticity plays an important role. In addition, present simulation techniques do not incorporate models for gross melt fracture, sharkskin and wall slip.

Influence of the Percentage of Gel Content on Impact Strength of Cross-Linked Rotationally Moulded Parts

Raquel Soares, J.F. Orr, May 2000

Crosslinking of polyethylene changes the chemical structure of the original thermoplastic polymer. The initial thermoplastic material consists of linear polymer chains and this is transformed into a polymer network with rubber elastic properties. Radical activity during peroxide or radiation crosslinking leads to polymer chain scission, formation of short chain fragments and crosslinking. The resulting polymer network can, therefore, be described as a fairly homogeneous randomised statistical alkyl-chain network. Average molecular weights between crosslinks, gel content ( crosslink density ) and the solvent swelling factor are the main parameters for characterising the structure [1]. A three-dimensional network is thus formed which improves many properties such as heat deformation, abrasion resistance, viscous deformation, chemical resistance, and stress cracking resistance. Impact and tensile strength are also increased, shrinkage is decreased and low temperature properties are improved [2].

The Effect of Monomer Structure on the Adhesive Properties of Thermally Reversible Isocyanate Polymers

D.M. Bigg, R.G. Barry, R.A. Markle, May 2000

The benefits of thermally reversible polymers derives from their structure; they dissociate into much lower molecular weight components when heated above a critical temperature and reform into a polymer when cooled below that temperature. This allows them to flow at a modestly elevated temperature, while exhibiting good strength, adhesion, solvent resistance at lower temperatures. Such polymers can be used as hot melt adhesives that combine the best features of both thermoplastics and thermosets. They can be reheated repeatedly, while producing a crosslinked network at ambient conditions. The properties of reversible isocyanate polymers depend on the structure of the monomers incorporated into the polymer backbone. This paper summarizes the influence of several polyester based monomers on the adhesive characteristics of the resulting polymer.

Influence of Chemical Composition on the Rheological Behaviour of Condensation Reaction Resins

Marc Doyle, Jan-Anders E. Månson, May 2000

A study of Melamine Formaldehyde (MF) resins of different molar ratios was undertaken to asses their chemorheological and thermorheological properties. MF resins polymerise via a polycondensation reaction involving condesation of up to 10 wt. % of water on cure. This results in rapid and extensive foaming of the resin when cured under atmospheric pressure. To accomplish the study, both foaming dynamics and bulk properties of MF were analysed; the former yielded results on the influence of initial moisture content on reaction rate and on curing kinetics including gel and vitrification times, while the latter yielded true G' and G' values and consistent glass transition temperature readings. The different molar ratios were found to affect curing kinetics in terms of large differences in gelation and vitrification times, and to yield high glass transition temperatures.

Through-Transmission Infrared Welding (TTIR) of Teflon TFE (PTFE)

Robert A. Grimm, May 2000

Through-transmission infrared (TTIR) welding of Teflon®TFE using a Teflon®PFA interlayer was demonstrated to be a well-controlled process that resulted in strong joints. The interlayer was formulated with low levels of carbon black to increase its absorption of the infrared radiation. Designed experiments were used to provide some understanding of important factors.

Methods for Making Nearly Invisible Welded Joints in Clear Polymers

R.A. Grimm, B. Christel, J. Robinson, May 2000

Several ways are described to produce very nearly invisible joints in two transparent polymers. Particles of optically opaque materials can be embedded or deposited on the surfaces of clear acrylic or other polymers through grit blasting, printing processes, use of very lightly colored inter-layers, or spraying/ink deposition. High weld energies such as are found in YAG lasers or xenon heating systems are very capable of producing nearly invisible joints. Light colors other than clear can be welded in this manner as well.

Influence of Mica and Talc Fillers on the Properties of Rotationally Moulded LLDPE

A. Robert, J.F. Orr, R.J. Crawford, May 2000

This paper describes the results from an investigation of the effects of talc and mica on the properties of rotationally moulded Linear Low Density Polyethylene (LLDPE). This work concentrates on the effects of the particle sizes and the types of coupling agent. Results show that introducing finer grades of talc and mica improves the impact strength. It has also been found that a maleic anhydride modified polyethylene can achieve better overall properties than a titanate-coupling agent.