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
Development of Structural Hierarchy in Injection Molded Dynamically Vulcanized PP/EPDM Blends
M. Cakmak, S. Cronin, May 1999
When injection molded, the polymers exhibit complex structural hierarchy from angstrom size levels up to optical. This is particularly true when the polymers have multiple phases such as in the case of polymer blends. It is as a result of a complex thermal -deformation history that this process imparts on the flowing fluid as it subjects it to severe thermal deformation gradients during the course of its formation. This dependence results in a three dimensionally varying structure and corresponding properties1,23. This complexity further increases with a composition as a variable in a multiphase blends systems as in the case of dynamically vulcanized PP/EPDM blends. In order to understand the details of the spatially varying structural hierarchy, one needs to investigate it using a variety of characterization tools that allows the observation of the localized structure at different size levels. For this purpose, we developed a unique microbeam WAXS instrument that allow us to probe the spatial variation crystalline regions for their order and orientation quantitatively. In this research, the effect of blend composition and processing conditions on the development of structural hierarchy in injection molded parts were studied through optical microscopy and matrixing microbeam X-ray diffraction technique and thermal analysis techniques.
Effect of Pulling Speed on the Sizes of the Liquid, Gel and Solid Zone during Thermoset Pultrusion
Abdelatif Atarsia, Rachid Boukhili, May 1999
The temperature and the degree of cure distributions inside a thermoset composite profile during the pultrusion process are calculated numerically using the finite difference method. The degrees of cure at the beginning of the gel and the solid zones i.e ?GL and ?GS are determined using appropriate experimental techniques. These results enabled us to predict the location and the size of the liquid, gel and solid zones inside a pultrusion die. It is found that the pulling speed affects the size and the position of each zone considerably. The relationships between the sizes of these zones and the pull-force is discussed.
Banning Heavy Metal Pigments in Minnesota - The Next Iceberg?
Terry Golding, May 1999
For several years the Minnesota Legislature, guided by the MPCA (Minnesota Pollution Control Agency), has been evolving a law to significantly reduce heavy metal pigment use in the state. The finalized law takes CONEG (Coalition of Northeastern Governor's) guidelines to a higher level. CONEG was intended to reduce the amount of heavy metals in the consumer waste stream by limiting their use in disposable packaging materials. The Minnesota law applies CONEG limits of lead, cadmium, mercury and hexavalent chromium to all pigments, including plastic colorants. This paper will review the evolution of this law. What could this mean to the plastics industry if similar events occur in other states?
Numerical Investigation on Mixing in a Pin Mixing Section for Screw Extruders
W.G. Yao, S. Tanifuji, K. Takahashi, K. Koyama, May 1999
Non-Newtonian, non-isothermal, 3D finite element simulation of mixing performance in a pin mixing section with different axial gap of pins has been carried out according to their realistic configurations. To learn and to compare the local mixing performance in a standard screw and a pin mixing section, the local mixing efficiency distribution proposed by J. M. Ottino was calculated. Also RTDs of these mixers were calculated to try to measure mixing. Then, the integration of above parameters, which was referred as integral mixing efficiency, gave a quantitative judgement of total mixing ability of the mixer. The calculated result showed a non-linear dependence of mixing ability of a pin mixing section on the axial gap of pins. Finally, the calculation result was compared with the experimental one obtained in our previous study.
Chromatography-Infrared Spectroscopy Characterization of Polymers
James L. Dwyer, May 1999
Polymer systems demonstrate simultaneous multivariate distribution of properties (molecular weight, composition, chain configuration). These molecular properties directly effect the physical properties of the polymer system. The polymer engineer typically adjusts these molecular properties in an attempt to optimize the end-use properties of a polymer. The characterization of the distributed molecular properties and their relationship to end-use physical properties is thus a key to the tailoring and optimization of a polymer product. Polymer analysis methods can be divided into three categories: methods that measure fundamental molecular properties, methods that fractionate a polymer, and physical test methods. Table 1. illustrates some of the principal techniques in each category. Molecular composition and configuration frequently varies across the molecular weight distribution of a polymer. As a result, a spectrum of an whole polymer sample provides at best a limited characterization of the polymer. This paper describes a technique whereby infrared spectroscopy is combined with one of the fractionation methods to obtain a more insightful characterization of a complex polymer system.
Thermal Stabilization of Polymers Containing Residual Catalysts
R.E. Zacharia, S.L. Simon, May 1999
Residual polymerization catalysts are known to promote degradation reactions in many polymeric materials. Such reactions were studied in poly(methyl methacrylate) (PMMA) doped with a typical catalyst at temperatures slightly above Tg using thermogravimetric analysis. Several novel approaches to minimizing the adverse effects of residual catalyst on thermal stability were investigated. Extraction of residual catalyst using liquid CO2 and a fluorinated chelating agent was shown to significantly improve the stability of PMMA film. Encapsulation of the residual catalyst using strongly a binding chelating agent, an azo-derivative of a crown ether, is also shown to enhance thermal stability.
Interfacial Tension Measurement of Polymers with the Pendant Drop Method: A Comprehensive Experimental Review
Kevin Alam, M.R. Kamal, May 1999
The pendant drop apparatus is the most reliable and accurate method of measuring the interfacial tension of polymer melts. However, the lack of a defined experimental method is a possible contributor to conflicting data in the literature. This paper reviews all practical aspects of pendant drop experiments with polymers including material preparation, syringe diameter selection, drop stability, necking and capillary effects, equilibration time and interfacial tension measurement error, repeatability and dependence on drop size. Original experimental data with polyethylene and polystyrene resins is discussed and compared to literature results.
Crystallization Behavior and Crystal Morphology of HDPE-Molecular Weight Dependence
Fang-Chyou Chiu, Qiang Fu, May 1999
A series of high density polyethylene (HDPE) fractions with molecular weight ranges from 1,600 to 325,000 g/mol have been investigated. The results of overall crystallization kinetics study by DSC indicate that the crystallization rate and the Avrami exponent (n) vary with molecular weight and undercooling (?T). Basically, the fraction with a lower molecular weight shows a higher crystallization rate. PLM, TEM and x-ray scattering technique were used to study the crystal morphology under different ?T's. Typical spherulites, axialites and asymmetrically shaped single crystals were observed.
Fabrication and Characterization of Electro-Optic Polymeric E-Field Sensors
R. Sivaraman, S.J. Clarson, D. Naghski, K. Burcham, J.T. Boyd, May 1999
The guiding of light beams along dielectric layers, first realized experimentally in the early sixties has stimulated the growth of a new class of passive and active components using light guided by films deposited on wafer-like substrates. These optical components provide the advantage of greater bandwidth and immunity from electromagnetic radiation hence making them become sufficiently effective to herald the beginning of a sophisticated technology called integrated optics. Current integrated optics technology is based upon inorganic crystalline LiNbO3. The concept of integrating an electro-optic polymer into a reverse poled Mach-Zehnder modulator to be used as an electrode-less E-field sensor is discussed here.
Structural Investigation of Plasma-Polymerized Pyrrole Films
Ning Zhang, Wim J. van Ooij, Shijian Luo, May 1999
Fourier-transform infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy (XPS) have been carried out to characterize plasma-polymerized pyrrole (PPy) films deposited under two deposition conditions, viz. high plasma excitation power/low monomer pressure (i.e. HW/LP) and low plasma excitation power/high monomer pressure (i.e. LW/HP) in RF and DC glow discharges. LW/HP PPy films deposited with a pulsed DC discharge were also investigated. Substantial differences were found between the structures of the films deposited under different conditions. The LW/HP films appeared to contain less unsaturation and conjugation than the HW/LP films. A comparison is made of the FT-IR spectrum of pyrrole monomer with those of PPy films and electrochemically polymerized pyrrole, which consists of disubstituted pyrrole rings. Evidence is presented that in low power RF conditions, the pyrrole ring structure can be maintained. The plasma polymerization processes of pyrrole under different deposition conditions are proposed.
Study of the Curing of Polymerizable Reaction Mixtures, PMR-15
K. Jordan, X. Li, O. Iroh, May 1999
The curing of PMR-15 was investigated using Fourier transform infrared spectroscopy (FT-IR) as a function of time (3 ? t ? 150 mins) and temperature (65 ? T ? 300°C). Imidization was measured by the changes in the imide carbonyl absorption at 1778 cm-1. The imide carbonyl absorption increased with temperature and time. Very little Imidization, <5%, occurred at 65°C irrespective of time. However, between 95 and 300°C, the extent of imidization was completed in 2.5 h at 300°C. FTIR also showed that thermal imidization and anhydride formation occurred simultaneously at high curing temperatures and longer curing times. Anhydride formation peaked at 0.5 h of curing at 135°C. Kinetic analysis for imidization was performed at low conversions. An Avrami-type kinetic analysis for imidization was also performed.
Determination of the Mechanism of Formation of Polypyrrole on Reactive Metals by Infrared Spectroscopy
R. Rajagopalan, W. Su, Jude O. Iroh, May 1999
The formation of polypyrrole coatings on steel was performed by an electrochemical process in aqueous oxalate solutions. The pH of the reaction medium and applied current density were varied from 1.2 to 8.4 and 0.56 to 5.63 mA/cm2, respectively. The mechanism of formation of polypyrrole coatings on steel, in acdic medium (pH < 6) was found to differ from that in basic medium (pH = 8.4). In acidic reaction medium, formation of polypyrrole on steel occurred in three stages: (i) dissolution of steel, (ii) passivation of steel and (iii) formation of polypyrrole. No passivation period was observed in the basic medium. The mechanism of passivation of steel and the composition of the coatings was investigated by reflection-absorption infrared spectroscopy. Our results show that increasing the current density decreased the passivation period. In acidic medium (pH =_6.0), minimal passivation time was observed to occur at a pH 2.4. IR analysis shows that passivation of steel was due to the formation and precipitation of FeC2O4.2H2O passive films on steel .
Fatigue Stress-Life Characterization Approach for Continuous Glass Fiber/Thermoplastic Composites
M.N. Bureau, J. Denault, May 1999
The long-term mechanical behavior of continuous glass fiber/thermoplastic composites has been addressed in terms of flexural fatigue stress - life curves. Contrary to other engineering materials submitted to cyclic loading, generally showing a significant stiffness reduction near the end of their fatigue life, the fatigue response of continuous glass fiber/polypropylene (PP) composites shows a progressive damage accumulation that must be considered when fatigue stress - life curves are reported. A fatigue life characterization methodology is proposed.
Influence of Adhesion Promoters on Properties Short Glass Fiber/Polypropylene Composites
Claudine Roux, Johanne Denault, Michel F. Champagne, May 1999
Acrylic acid grafted polypropylene (PP-g-AA) and two maleic anhydride grafted PP (PP-g-MA) of different viscosities and grafting levels are used, together with pyrolyzed fibers and ?-aminopropyl-triethoxysilane sized fibers. Mechanical characterization on injection-molded parts and fragmentation test on single fiber composite (SFC) are performed in order to correlate adhesion and performances. A higher level of grafting appears to be an important factor for best adhesion enhancement. The crystalline morphology was characterized in previous work and was found to play a key role on the resulting properties, in spite of good interfacial interactions. Highly grafted PP-g-MA is the best adhesion promoter characterized in this work.
Effects of Molecular Structure on Macroscopic Mechanical Properties of an Advanced Polymer (LARC™-SI)
Lee M. Nicholson, Jeffrey A. Hinkley, Karen S. Whitley, Thomas S. Gates, May 1999
Mechanical testing of an advanced polymer resin with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The elastic properties, inelastic elongation behavior, and notched tensile strength all as a function of molecular weight and test temperature were determined. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature.
Orientation Effects on the Weldability of Polypropylene Strapping Tape
M.J. Oliveira, D.A. Hemsley, May 1999
Polypropylene strapping tape is commonly sealed by welding using high temperature tools. Despite the widespread use of the technique no work has been done to study the influence of the welding process parameters on the properties of the joint. In this work polypropylene strapping tape, produced with different draw ratios and types of surface embossing, was welded with a standard semi-automatic strapping machine. The effect of the process parameters (temperature, sealing pressure and surface profile of the sealing tool) and the tape properties (draw ratio and embossing pattern) on the microstructure and the joint strength was studied. An optimal temperature range could be identified. The draw ratio of the tape influences the weld efficiency.
Characterization of PP/PPgAA Blends by Contact Angle
S. Flores-Gallardo, S. Sánchez-Valdes, L.F. Ramos de Valle, May 1999
Polypropylene (PP) was functionalized with Acrylic Acid (AA) by means of a radical-initiated melt grafting reaction. The content of AA grafted onto PP was determined by using acid-basic titration. Blends of PP with 0 to 100% wt of Polypropylene grafted with Acrylic Acid (PP-gAA) were prepared by melt mixing. The effect of the modified polymer content on the surface of cast films was characterized through contact angle and ink adhesion measurements as well as attenuated total reflection infrared spectroscopy (FTIR-ATR). The contact angles of water on cast film surfaces of PP/PPgAA blends decreases with increasing modified polymer content. A notorious improvement on ink adhesion on the surface was observed when increasing the content of modified polymer. From FTIR-ATR spectra of the blends, the carbonyl index on the films surface was calculated. It was found that the higher the carbonyl index, the lower the contact angle value for the polypropylene blends.
A Process Comparison of Orbital and Linear Vibration Welding of Thermoplastics
David A. Grewell, Avraham Benatar, May 1999
This paper reviews a study comparing the physical differences between orbital and linear vibration welding of thermoplastics. For the same welding conditions, it was found that orbital welding dissipated 56% more power than linear vibration welding in Phase I (solid-to-solid friction) of the process. Similarly, in phase III (steady state) orbital welding dissipated 100% more power than linear vibration welding. The duration of phase I and phase III was 36% and 50% shorter for orbital welding than for linear vibration welding. A theoretical comparison for phases I and III were consistent with the experimental results. Comparison of micrographs of welded sections shows that orbital welding produces thinner weld lines than linear vibration welding.
Development of Underfilling Encapsulant Based on Ternary Systems of Benzoxazine, Epoxy, and Phenolic Resins
Sarawut Rimdusit, Hatsuo Ishida, May 1999
We have developed a new polymeric system based on the ternary mixture of benzoxazine resin, epoxy resin, and phenolic resin. Low melt viscosity resin renders void free specimens with minimal processing steps. The material properties show a wide range of desirable reliability and processability which are highly dependent on the composition of the monomers in the mixture. A glass transition temperature as high as 170°C and considerable thermal stability up to 370°C can be obtained from these systems. The materials exhibit promising characteristics suitable for application as underfilling encapsulation and other highly fiilled systems. the curing aid of polybenzoxazine. The mixture of these three resins to form the ternary systems is believed to provide a great variety of resin properties suitable for wide applications, particularly in the microelectronic application and the highly filled systems.
Application of Composite Technology to Firearms: A Rifle Barrel
Marlin R. Jiranek II, May 1999
A composite rifle barrel was developed. Initial prototypes were developed to aid in understanding the complex interaction of a steel / graphite fiber-epoxy composite when subjected to the short duration dynamic loading environments caused by firing the rifle. Design improvements include creating residual stresses in the composite and the steel materials, creating crack stops to stop crack propagation through the composite material, and steel / composite interactions during cyclic loading. Ultimately, the composite material was used in conjunction with a steel skeleton to produce a lighter, cooler, longer lasting, and more accurate rifle barrel which is currently in production.
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