Dr. Paul DesLauriers. Dr. Max P. McDaniel

Transcription

1 The C2P2 is very pleased to welcome 2 outstanding scientists from Chevron Phillips who will be spending 2 weeks with us in Lyon from 24 May to 6 June. They will give a series of seminars on catalysts and processes for polyethylene, as well as on analytical methods, data treatment and physical properties. These seminars are open to all who are interested, and we encourage as many as possible of you to take advantage. The seminars at located at the Ecole Supérieure de Chimie, Physique, Electronique de Lyon ( Dr Paul DesLauriers and Dr Max P. McDaniel will be happy to meet with our colleagues from Lyon, so if you are interested in talking with them, or want to share some of your work, please let either Christophe Boisson (Christophe.boisson@univ-lyon1.fr) or myself (timothy.mckenna@univ-lyon1.fr) know and we will do our best to facilitate that. Dr. Paul DesLauriers Paul J. DesLauriers is a Polymer Science Research Fellow for Chevron Phillips Chemical Company at the Bartlesville Research and Technology Center, Bartlesville, OK. Before joining Phillips/CPChem in 1989, he worked as a senior research chemist for Pennzoil Petroleum Company (the Woodlands, TX). Paul received a Ph.D. degree (1985) from the University of Southern Mississippi in physical organic chemistry where he studied the chromatography and kinetics of the Pictet Spengler reaction where an β-arylethylamine such as tryptamine undergoes ring closure after condensation with an aldehyde or ketone. Dr. DesLauriers has (co)authored over 60 publications/ presentations, and has been awarded 36 US patents in the area of polymer science. His accomplishments include inventing the technology used for the clear mineral gel product line, Versagel TM currently marketed worldwide by Penreco, and developing the SEC-FTIR methodology for measuring short chain branching in polyolefins (now sold by Agilent Technologies). He has also held adjunct professorships at the University of Tulsa, Rogers State University, and Oklahoma Wesleyan University. He is an active member in the in the ACS Polymer Division. His awards include the Outstanding School-to-Work Partner Award, presented by the Oklahoma Vocational Association, and the Chevron Phillips Excellence, Entrepreneurship, and Expansionism Award. Dr. Max P. McDaniel For four decades Dr. Max P. McDaniel has lead a small group of scientists in the study and derivation of polymerization catalysts at the Phillips Research Center in Bartlesville, Oklahoma. He received a Ph.D. in physical chemistry in 1973 from Northwestern University in Evanston Illinois, where he studied the porosity and redox capacity of chromia catalysts under Prof. Robert L. Burwell. In 1974 he spent one year at the Institute of Catalysis in Lyon, France, as a Chercheur Associé, under Prof. S.J. Teichner. McDaniel joined Phillips Petroleum Company in 1975 to work on Cr/silica catalysts under J. Paul Hogan, discoverer in 1951 of the Phillips polymerization catalyst and founder of the high density polyethylene (HDPE) industry. Since 1975 McDaniel held various technical and managerial positions at Phillips, always involved in Phillips' polyethylene catalyst, resin development, and licensing programs. McDaniel has

2 authored approximately 150 scientific publications and lectures and 400 US patents, and his inventions have won many ACS and industry awards.

3 Seminars Talk 1. An Industrial Perspective on Ethylene Polymerization Two sequential talks by Max McDaniel (catalyst) & Paul DesLauriers (polymer) Tuesday, May 24, 14h-16h30, Room C223 (CPE Bât Grignard) Commercial linear polyethylene (PE), the most commonly used type of plastic, was born over half a century ago with the accidental discovery at Phillips Petroleum Company that chromium oxide supported on silica can polymerize α-olefins. That same catalyst system, modified and evolved, is still used today by Chevron- Phillips and many other companies worldwide, along with metallocenes. These catalysts are now more active and have been tailored in numerous ways for many specialized modern applications. In this talk, and subsequent ones, we review some of the main technical issues involved in the manufacture of PE and provide examples of how that complex chemistry is exploited commercially. We often focus on the polymer molecular weight distribution, which we believe is the surest window into the active sites (which are usually a small minority of all sites) and which sometimes provide unexpected insights into the active species involved. In the first talk Max focuses on the catalyst chemistry and manufacturing issues. In the second talk in this series, Paul describes some of the methods and difficulties of characterizing and improving the polymer. Talk 2: Ethylene-α-Olefin Copolymerization Talk by Max McDaniel Wednesday, May 25, 9h-10h-16h30, Room E109 (CPE) Most commercial grades of polyethylene are actually copolymers of ethylene and another olefin, which is introduced to add short-chain branches and thus disrupt polymer crystallinity. This vastly increases the usefulness of the plastic because it adds flexibility and toughness. The addition of α-olefins to the polymerization contributes not only branching to the polymer, but it also influences catalyst activity, polymer molecular weight, macromer incorporation, and reactor fouling. Some catalysts are more capable than others of comonomer incorporation, and within a particular catalyst some sites are more effective that others, which can place branches selectively into certain regions of the MW distribution. In this talk we review, again from an industrial perspective, the chemistry involved in the formation of copolymers and provide some examples of their use. Talk 3: Estimating Slow Crack Growth Performance of Polyethylene Resins from Molecular Weight and Short Chain Branching Talk by Paul DesLauriers Wednesday, May 25, 10h15-11h45, Room E109 (CPE) Primary structures such as molecular weight and short chain branching, as well as their respective distributions, can be used to formulate a single, primary structure parameter (PSP2) capable of rapidly estimating the potential slow crack growth (SCG) resistance of polyethylene resins as determined by short

4 term testing methods (1). The calculations of PSP2 principally rely on density estimates on a MW slice by slice basis (2), from which subsequent estimates of melting point and lamella thickness were made in order to obtain the critical chain end-to-end distance required to form a tie chain (i.e., 2l c + l a ) as described by Huang & Brown (3). A single value is obtained by summing these values across the MWD of a resin. PSP2 values capture known structural effects (qualitative and quantitative) on SCG resistance that were previously convoluted. Most notably is the ability of this parameter to successfully predict the effects of SCB placement on SCG properties. We found that PSP2 values corresponded well to SCG resistance in all types of polyethylene resins as reflected by correlations to numerous small scale resins tests. Even when the cited limitations (4) for this method are considered, results demonstrate that PSP2 values can be used to screen resins for potential SCG performance using resin microstructure from either experimental or digitally derived data. Moreover, since this method is based on structural parameters, its use and further development are expected to help better understand the SCG failure mechanisms in PE resins while improving the cost and effectiveness of product design. In this presentation a general review of the PSP2 method will be given, as well as, how various structural changes affect SCG resistance. References [1] P. J. DesLauriers and D. C. Rolhfing, Macromolecular Symposia (2009), [2] P. J. DesLauriers and D. C. Rolhfing, Advances in Polyolefins (2008). [3] Y. L. Huang, N. Brown, Journal of Materials Science (1988), 23, [4] This simplified method uses averages for many values such T m, only partially accounts for chain entanglements and does not consider branch type or orientation Talk 4: Influence of Catalyst Porosity on Its Polymerization Activity Talk 5: Using Catalyst Porosity to Control PE Molding Behavior and Properties Talks by Max McDaniel Thursday, May 26, 9h-10h, 10h15-11h30 Room C223 (CPE Bât Grignard) Unlike refining and other manufacturing, ethylene polymerization is the only industrial process in which the solid catalyst is deliberately designed to fracture and come apart during its lifetime. Thus, the structure and porosity of Cr/silica catalyst has a strong influence on its activity in ethylene polymerization because it determines how much of the surface can participate. In addition, the catalyst porosity also mysteriously determines the character of the polymer it produces. In this talk, silicas of widely varying physical structure were chosen so that the influence of surface area, pore volume, pore diameter, and coalescence could be independently investigated by monitoring the surface activity, and the polymer s molecular weight (MW), MW distribution, melt flow, and its long-chain branch content. The results are discussed with respect to (1) fragmentation of the silica during polymerization, and (2) egress of polymer from pores inside the resulting fragments. The physical principles observed from Cr/silica catalysts were found to be independent from, and additive to, other chemical influences on Cr/silica catalysts. Moreover, they seem to apply to other supports and to metallocene catalysts as well.

5 Talk 6: Some Issues Involved in the Commercial Use of Metallocene Catalysts for Ethylene Polymerization Talk by Max McDaniel Thursday, May 26, 14h-15h30 Room C223 (CPE Bât Grignard) During the past decade metallocene catalysts, and their resultant polymer characteristics, have become widely accepted in the commercial world of polyethylene. The steric and electronic environment around the active metal (Zr, Hf, or Ti) plays a dominant role in determining the activity of the catalyst, the polymer molecular weight produced, the MW breadth, and how effectively short-chain and long-chain branching is incorporated within the MW distribution. In this talk we discuss, again from an industrial perspective, some of the responses and difficulties in the manufacture of PE using metallocene catalysts. This includes the activation (ionization) of such compounds, some aspects of their behavior during polymerization in a large reactor, and the combination of multiple metallocenes to achieve specialty polymer grades. Talks 7 & 8: An Industrial View of Long-Chain Branch Formation in PE Two sequential talks by Max McDaniel (catalyst) & Paul DesLauriers (polymer) Monday, May 30, 9h-10h30 and 10h45-11h45, Room E109 (CPE) During the polymerization of ethylene, the vinyl end-groups on some PE chains (called macromers ) are further inserted by an active site into another growing chain, thus creating a long-chain branch (LCB) analogous to the incorporation of 1-hexene or other α-olefins to create a short-chain branch (SCB). While LCB occurs very rarely compared to SCB, it nevertheless has high significance in commercial PE manufacture, because it exerts a powerful influence on the molding behavior of the polymer, and even on its physical properties. Thus, control of LCB is a top priority in the design of new catalysts. Actually LCB formation is much more selective than is usually envisioned from the simple, widely-accepted mechanism of random macromer insertion. Several catalyst and reactor variables can swing LCB content over an extremely wide range under otherwise identical catalyst and reaction conditions using Cr/silica or metallocene catalysts. In this talk we review some of the mechanistic modifications that are needed to account for these observations, and that are used commercially to control LCB. The catalyst is the main focus by Max in the first talk. In the second talk in this series Paul describes in greater detail some of ways used to measure LCB and the accompanying pitfalls of each method. Talk 9: Comparison of Organo-Cr Catalysts with Supported Cr Oxide Talk by Max McDaniel Monday, May 30, 14h-15h15, Grand Amphi CPE Although the Phillips Cr oxide catalysts are widely used in PE manufacturing, many organo-chromium compounds display equal or better activity in the polymerization of ethylene when supported on an acidic carrier. Although not as well known, these catalysts often produce similar polymers and offer some

6 operational advantages, such as better hydrogen sensitivity, in-situ generated comonomer, or the ability to continuously make and fine-tune a catalyst at the PE plant site in real time. In this talk we compare the two types of chromium catalyst, using the polymer molecular weight distribution to draw insights into the active species involved. Surprisingly, the character of these active species seems to be dominated mostly by the support and not the organic ligand. N.B. This talk will be part of a workshop on Cr-based catalysts for ethylene polymerisation, run in collaboration with the group of Prof Elena Groppo of the Department of Chemistry of the University of Turin (IT). Dr Groppo will give 2 short presentations at 15h30 (titles to be announced). Talk 10: Chemometric Tools for Designing PE Catalyst and Products Parts I, II, III Talks by Paul DesLauriers Part I Tuesday, 31 March, 14h-15h30 Room F004 (CPE) Part II Wednesday, 1 June, 14h-15h30 Room E109 (CPE) Part III Thursday, 2 June, 14h-15h30 C223 Notable since the 1970 s, chemometrics have been used to find underlying trends in complex data in the fields of economics, psychology, and chemistry. The term chemometrics generally describes methods that typically involve pattern recognition and classification as well as multivariate calibration and other quantitative predictive applications. More basically, Beebe et al (1) define chemometrics as the entire process whereby data (e.g., numbers in a table) are transformed into information used for decision making. These mathematical, statistical, or graphical methods attempt to correlate the observed change in the collective attributes of a sample set to the change in the selected property for those same data. In particular, instrumental data at evenly spaced intervals, such as that obtained from spectrographic, chromatographic or thermal analysis are well suited for chemometric analysis. In this three lecture series, the general use of chemometric techniques in the design of polyethylene catalyst and products will be presented. In the first lecture, Characterization, Modeling and Chemometric Tools for PE, the complexity of polyolefin products, selected characterization methods and an overview of chemometric techniques (particularly patent recognition) will be discussed and examples given. The second lecture, Using Chemometric Methods for Predictive Modeling of PE resins, will address the specific applications of Principle Component Analysis and Partial Least Square (PLS) Regression for various polymer characterization data and its correlation to various physical properties. Lastly, the third lecture Modeling the Model: Virtual Reactors and More, will outline how combinations of chemometric approaches such as PLS and Response Surface Design methods provides a way to map the catalyst, reactor, structure and property space of PE resins. Although these methods are directly applied to polyolefin systems, the general research approach and design philosophy should find use in any application where there is a need to better understand the underlying trends in complex data. REFERENCES 1. K. R. Beebe, R. J. Pell, M. B. Seasholtz (1998) Chemometrics: A Practical Guide, Also see R. G. Brereton (2003) Chemometrics; Data Analysis for the Laboratory and Chemical Plant both from, John Wiley & Sons, New York.

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