8:00 am – 11:30 am:
T7-Plastic Pipe and Fittings: Durability & Design in Plastic Pipe and Fittings
(Moderator: Vivek Rohatgi)-Room S322
8:00 am – 8:30 am:
Examining Design Changes Potentially Influencing the Lifetime of Electrofusion Socket
Jan Poduska, Institute of Physics of Materials, AS CR, Brno
This article deals with lifetime calculations of electrofusion socket joint. Lifetime of electrofusion socket is calculated using a combination of linear elastic fracture mechanics lifetime and finite element modelling. The lifetimes are calculated for a basic situation and then influence of possible design changes on the lifetime is discussed.
8:30 am – 9:00 am:
Application of J-integral Methods to Tough Pipe Materials
Anja Gosch, Montanuniversitaet Leoben
In this work, the fracture resistance of three different and very tough piping materials was characterized for the development of multi-layered pipes based on biomaterials. For these materials both stiff and brittle, and soft and ductile materials are necessary. While the fracture mechanical characterization of the former can be seen as quite straight forward, the later can prove rather difficult. Therefore, two methods from elastic plastic fracture mechanics were examined, applied and discussed in detail for the use with very tough pipe grade materials.
9:00 am – 9:30 am:
Fracture Mechanical Characterization of Non-Virgin Pipe Materials
Andreas Frank, Polymer Competence Center Leoben GmbH
For accelerated characterization of slow crack growth (SCG) properties of modern polyethylene pipe grades the Cyclic Cracked Round Bar Test has been developed. While many investigations on polyethylene are available with this test, only few studies have been published yet with other relevant pipe polymers such as polypropylene or polyvinyl chloride. Moreover, the increased use of non-virgin polymers for structural applications based on reprocessed or recycled resources is becoming a topic of increasing importance. The current paper presents an investigation of the general applicability of the Cyclic Cracked Round Bar Test to the mentioned polymers with a special focus on the sensibility to non-virgin materials. On the one hand the results show that this test can be used for accelerated SCG characterization of all materials. On the other it is demonstrated that the SCG resistance of non-virgin polymers is significantly lower than for virgin pipe grades.
9:30 am – 10:00 am:
Determining Critical Stress for Ductile-Brittle Transition of Polyethylene Pipe Under Creep Loading
Ben Jar, University of Alberta
A new test approach is proposed which uses multi-relaxation stages to determine critical stress for an unusual ductile-brittle (DB) transition of polyethylene (PE) pipe that may occur after subjecting the pipe to constant loading for a long period, often more than 50 years. This paper describes the key concept for the new test approach, and presents results for three PE pipes of which two are 1-inch PE4710 pipes and one 2-inch PE2708 pipe. The results suggest that critical stress for the unusual DB transition should be around 10 MPa for the two PE4710 pipes and 8 MPa for the PE2708 pipe. These values are consistent with their hydrostatic design bases (HDB) that needs more than 1 year to determine using the standard test method. Advantage of this new approach is not just for the short time needed to determine HDB (less than one week), but also for determining the time of occurrence for the unusual DB transition under constant loading. This part of work is on-going, and the results will be presented in the conference.
10:00 am – 10:30 am:
Comparison of Real and Simulated Failure Times Based on the Slow Crack Growth Behavior of Electrofusion Sockets Made of Polyethlene
Isabelle Berger, Polymer Competence Center Leoben
Previous laboratory studies have shown that brittle cracks in Electrofusion sockets (E-sockets) typically initiate in the inner cold zone between the pipe and the socket and lead to brittle failure of the pipe connection. Therefore, a profound understanding of the slow crack growth (SCG) behavior is essential to predict an accurate lifetime for welded joints. Internal pressure tests (IPT) on E-sockets made of different PE grades were conducted to create brittle failure curves in a first test run and to investigate the characteristics of crack initiation and SCG by the use of additional optical analyses in a second test run. Based on these test results and by using a fracture mechanical material law for SCG for one of the investigated PE grades a model for the stress intensity factor KI characteristics in E-sockets at elevated temperature was developed by finite element methods (FEM). The current results demonstrate that a reliable prediction of minimum lifetime of E-sockets with the fracture mechanics approach is possible.
10:30 am – 11:00 am:
Proposed Allowable Scratch Depth for High-Density Polyethylene (HDPE) Pipes in Safety-Related Nuclear Applications
Prabhat Krishnaswamy, Emc2
Proposed Allowable Scratch Depth for High-Density Polyethylene (HDPE) Pipes in Safety-Related Nuclear Applications Author(s): P. Krishnaswamy1, S. Kalyanam1, Y. Hioe1, S. Pothana1, P. Raynaud2 Affiliation: 1Engineering Mechanics Corporation of Columbus 3518 Riverside Drive, Suite 202, Columbus, OH 43221 firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com 2United States Nuclear Regulatory Commission Rockville, Maryland Patrick.firstname.lastname@example.org The topic of flaw acceptance for HDPE pipes installed in safety-related applications of a nuclear power plant has been of interest over the last decade. From initial analysis and tests on slow crack growth (SCG) in coupon specimens to hydrostatic Notched Pipe Tests (NPT), verification studies have been conducted by several researchers. Recently, the Electric Power Research Institute (EPRI) proposed a flaw acceptance criterion for HDPE pipe based on observations from several rounds of tests on various HDPE resins. The present study proposes acceptable flaw sizes for a range of pipe diameters and thicknesses. The flaw acceptance analyses use the renowned Brown model to transfer PENT values to service life/failure time estimations, evaluate the stress-intensity factors (SIF or KI) for infinitely long axial outer diameter (OD) surface cracks (most conservative approach for flaw acceptance determination), and analyze EPRI NPT data. It is also noted that the Brown PENT model does not accurately incorporate pipe or component geometry effects, and hence needs to be modified to predict the service life of pipes. However, this model can easily be used to determine maximum allowable SIF (KI) for pipes with the same geometry but different PENT values at the same service temperature, using NPT data. The allowable flaw size (scratch depth) analysis method is presented, and the flaw acceptance criteria for various postulated pipe geometries are discussed. In addition, the allowable flaw size method is demonstrated with the example of the largest pipe diameter with the thickest wall installed to-date. In summary, a rigorous conservative approach has been developed using existing data (from EPRI), the Brown PENT model, and a fracture mechanics approach for KI, to determine the maximum allowable axial external scratch depths (flaw sizes) in HDPE parent pipe for all diameters, all wall thicknesses, and PENT ratings from 2,000 to 10,000 hours.
11:00 am – 11:30 am:
Best Paper Award Presentation
Don Duvall, ESi
8:00 am – 11:30 am:
T8-Polymer Analysis: Thermal and Aging Analysis
(Moderator: Ida Chen)-Room S320D
8:00 am – 8:30 am:
KEYNOTE: Effect of Water Vapor on Thermal and Mechanical Properties of an Amphiphilic Block Copolymer Membrane
Daniel Hallinan, Assistant Professor, Florida A & M University and Florida State University College of Engineering
Applications such as CO2 capture and flue gas dehydration require membranes that are mechanically robust at elevated temperatures and that have high selectivity for CO2 and/or water over other gases. Polystyrene-b-poly(ethylene oxide) is an amphiphilic block copolymer that satisfies these requirements. This is due to the mechanical strength of glassy polystyrene (PS) and the hydrophilicity of poly(ethylene oxide) (PEO). The authors have previously shown that PEO indeed is selective for CO2 over other gases1 as well as quantifying the transport of water through PS-b-PEO block copolymers2-3. An important consideration that has not been investigated is the impact of water presence on the properties of PS-b-PEO membranes. We report our findings on the effect of water vapor on the melting temperature of PEO, the glass transition temperature of PS, and the resulting impact on the mechanical properties of the block copolymer. Humidity-controlled differential scanning calorimetry and dynamic mechanical analysis were used to determine these properties. Effective medium and thermodynamic theories are used in an attempt to more fundamentally understand these results.
8:30 am – 9:00 am:
Thermal Investigation Between Pressure Conditioning and Thermal Annealing in Aging Studies of Glassy Thermosets
Brendan Ondra, University of Massachusetts Amherst
This communication presents comparative results between two separate techniques to accelerate physical aging in polymeric glasses: pressure conditioning and thermal annealing. Four different epoxy-based glassy thermosets were synthesized with specific molecular and network structures for further comparison and discussion. The epoxy compositions were synthesized to form glasses with comparable glass transitions but with different crosslink density and backbone stiffness. To analyze the glasses and the extent of aging, Differential Scanning Calorimetry was employed. Additionally, in order to perform the pressure conditioning, a pressurizable dilatometer was designed and built. The results show fundamentally different responses between thermal annealing and pressure conditioning. These differences are detailed and discussed.
Jose Luis Colon Quintana, UW-Madison
Extrusion and injection molding of filled polymers are widely used in industry due to their high strength-to-weight ratios and for their ability to manufacture a variety of geometries while improving the overall mechanical properties. However, filler migration during processing is not fully understood. To gain an improved understanding of this phenomena, samples of polypropylene with different concentrations of glass beads were manufactured using the extrusion process, injection molding process and a screw-less extruder that was built in house. Computed Tomography scanning was performed on the samples to observe particle position and distribution after solidification.
9:30 am – 10:00 am:
Role of Functionalization of Nanoclay Particles on Diffusion Properties of Commercial Gasoline Through Polymere Membranes
James Sloan, US Army Research Laboratory
In this work, we consider the effect of the addition of functionalized clay particles to a polyether based polyurethane that is a candidate to be used as for flexible storage containment for a variety military fuels. We have synthesized urethanes and fully incorporated functionalized layered silicate inorganic nanoclay with concentrations varying from 0% to 20% by weight. The clays were functionalized with polar hydroxyl groups (-OH) and nonpolar long alkyl chains (-CH3-(CH2)14-CH3) and we evaluated the transport properties of military grade fuels. We found the addition of the nonpolar alkyl functionalized nanoparticles, actually increased both the transport rate and the fuel solubility of the resultant composite.
10:00 am – 10:30 am:
Analytical Characterization of Commercial Products: Cool Comfort Technologies for Bedding Products
Praveenkumar Boopalachandran, Associate Research Scientist, Dow Chemical
Dow polyurethane (PU) business is investigating into cool comfort technologies for bedding products (pillows, mattresses), as it is a major driver in the market. Recently, there have been many enquiries around the commercial benchmark products (‘commercial product A’ and ‘commercial product B’) that sparked the interest for the Dow PU marketing team. There is an overwhelming interest to understand these materials and its composition. Analytical techniques utilized in this study for the deformulation of the two commercial products identified the presence of styrenic block copolymer (SEBS) as the major polymeric species. In addition, long chain aliphatics identified as mineral oil was observed in both products. Furthermore, a filler identified as talc was present in ‘commercial product B’.
10:30 am – 11:00 am:
TGA-FTIR Unleashed At Last – Introducing a Fully-Integrated, Transfer Line-Free Coupling for Evolved Gas Analysis of Polymers
Bob Fidler, NETZSCH Instruments N.A. LLC
Evolved gas analysis improves the value of TGA data by allowing the identification of the chemical species evolved during decomposition. FTIR is particularly advantageous when organic molecules and IR active gases are being analyzed from the TGA sample. This lecture will introduce an innovatively designed TGA-FTIR and STA-FTIR (STA = Simultaneous DSC-TGA) for evolved gas analysis. The unique coupling system has the FTIR now mounted directly above the sample cell, eliminating the need for a long transfer line. The system allows immediate response from the FTIR when the sample loses mass. The lack of the transfer line allows for analysis of gas species that would ordinarily condense in a standard heated transfer line in addition to dramatically reducing bench space normally required for TGA-FTIR.
11:00 am – 11:30 am:
Polyetheretherketone (PEEK) Exposure to ZnBr2 Completion Fluids at High Temperatures and Pressures: Identification and Quantification of Small Molecular Decomposition Products
Joseph Baker, Texas A&M University
Polyetheretherketone (PEEK) polymers are utilized in applications of extreme service environments in the oil and gas industry. However, their outstanding physical properties diminish after long-term exposure to highly concentrated ZnBr2 completion fluids under the extreme downhole conditions. PEEK is an insoluble polymer at room temperature and sparingly soluble at elevated temperatures in only a few special solvent mixtures. The research presented in this contribution is focused on detailed analytical studies to elucidate the molecular mechanisms that lead to the decomposition pathways during the degradation processes. This investigation includes determining the factors that hasten the polymer decomposition. Completion fluids composed of high concentrations of ZnBr2 and/or CaBr2 were applied to the long-term studies of the polymer at the continuous use temperature of 260 °C at a high pressure of 20 bar. The chemical changes of PEEK under the drilling conditions are visually obvious only when ZnBr2 completion fluids are applied. Since the PEEK polymer cannot be solubilized (which is needed for many analytical high resolution measurements) we chose to study the small molecules released during the PEEK treatment. Identification and quantification of the small molecules released into the completion fluid during the PEEK degradation could be achieved with solution NMR and the use of a calibrated standard. The identification was confirmed with other analytical techniques like mass spectrometry. Mechanistic studies based on the identification of the small molecules reveal the simultaneous occurrence of several decomposition pathways. For example, bromination by the ZnBr2 in the completion fluids, radical based decompositions, and hydrolysis under acidic conditions. The dominant reaction taking place in the PEEK polymer is C-C bond cleavage at the ketone group. The smaller molecules produced from this initial cleavage at the ketone are then degraded in a secondary process, for example, by hydrolysis. Finally, the degradation mechanisms found for PEEK were also established for another polymer with similar composition. Studying the chemically related polyetherketoneketone (PEKK) polymers in the described standardized manner, after exposure to identical conditions, led to the same decomposition pathways. Therefore, it is expected that future investigations of other polyaryletherketone (PAEK) polymers will reveal the same general degradation mechanisms as described for PEEK and PEKK in this contribution.