How ARCO Chemical Beat the Weather
1
HowARCO Chemical Beat the Weather (anofeCoipetition) —X—C—0 —CH 2 —C—R *• —X—C—Ο—Η A Better Polyester-But Would It Last? ARCO Chemical developed a new series of polyesters for coatings, and tested their performance under a variety of traditional accelerated weathering tests. A compound based on ARCO Chemical's MPDiol® Glycol (2-methyl-l-3-propandiol) showed unexpected positive results. The well- accepted Norrish Type II degradation mechanism implied that diols with β hydrogens degrade rapidly under the ultraviolet exposure typical of outdoor applications. The test results contradicted this theory, raising questions about the accepted degradation mechanisms. Moreover, some coatings manufacturers, whose formulations did not include β hydrogens, claimed superior weatherability based on the Norrish Type II theory. Photoinduced Norrish degradation mechanisms CH3 I HO-CH2-CH-CH2-OH Was the Theory Wrong? Had the accelerated testing overlooked some factor? Or was there something about this new polyester that caused it to resist degradation? ARCO Chemical needed to know the answer, and so did their customers. The Truth is at the Frontiers A detailed analysis of the degradation mechanism showed that the UV absorption of the polyester was not high enough to support the Norrish Type II mechanism as the major degradation pathway. Instead, oxidation by free radical chain propagation generated by photolysis was much more likely to dominate. Using CAChe's Frontier Molecular Orbital calculations and visualization, ARCO Chemical scientists demonstrated that the β hydrogen of diols and diol esters are less susceptible to radical oxidation than the α hydrogen. The presence or absence of the β hydrogens has little impact on weatherability. The result: the new ARCO Chemical intermediate was successfully commer- cialized as MPDiol Glycol, and is now used in paints, powder coatings, baking enamels, gel coats and other coatings. iPU . Frontier Density contour map of MPDiol® Glycol, showing higher activity at α than β hydrogen site. Sullivan and Cooper, Polyester Weatherability: Coupling Frontier Molecular Orbital Calculations of Oxidative Stability with Accelerated Testing. J. Coatings Technology, 67:847. pp 53-62. August 1995. CAChe* Powerful Desktop Chemistry Tool From Oxford Molecular. CAChe is designed to help experi- mental chemists predict chemical properties, explain reaction mechan- isms, and visualize molecular properties for small molecules containing any element up to 103. • Runs on Macintosh, Windows 95, and Windows NT systems • Unique property driven interface that allows chemists to focus their attention on getting results instead of on the details of the models used to produce them • Includes an economical personal edition, a fuNeatured research version, and client-server versions • Automated property calculation over a series of molecules • Computes UV and visible spectra • Performs conformational searching CAChe is also widely used in educational programs, which Oxford Molecular supports through special academic licensing and its Higher Education Grant Program. t Get a FREE CD with more examples of chemical problem solving with CAChe. Call us at one of the numbers below and ask for our informative pack on CAChe in Research or CAChe in Education. kii We Had a Solution For ARCO Chemical. We Have a Solution for You. m Desktop Chemistry · Molecular Modelinq · Bioinformatics · Databases · Enterprise Systems · Collaborations f Oxford Molecular „_ Solutions for Discovery Research USA tel: 800-876-9994 fax:408-879-6302 Europe/UK tel: +441865 784600 fax: +441865 784601 Worldwide http://www.oxmol.com/ 1-408-879-6300 CAChe is a registered trademark of Oxford Molecular Group PLC or its subsidiaries. Macintosh is a registered trademark of Apple Computer. Windows is a registered trademark of Microsoft Corporation. MPDiol Glycol is a registered trademark of ARCO Chemical Company. CIRCLE 2 5 ON READER SERVICE CARD New Lower Pricing! Γ.,ΊΙΙ fnr Retails MPDiol® Glycol
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Transcript of How ARCO Chemical Beat the Weather
HowARCO Chemical Beat the Weather (anofeCoipetition)
— X — C — 0 — C H 2 — C — R *•
— X — C — Ο — Η
A Better Polyester-But Would It Last? ARCO Chemical developed a new series of polyesters for coatings, and tested their performance under a variety of traditional accelerated weathering tests. A compound based on ARCO Chemical's MPDiol® Glycol (2-methyl-l-3-propandiol) showed unexpected positive results. The well-accepted Norrish Type II degradation mechanism implied that diols with β hydrogens degrade rapidly under the ultraviolet exposure typical of outdoor applications. The test results contradicted this theory, raising questions about
the accepted degradation mechanisms. Moreover, some coatings manufacturers, whose formulations did not include β hydrogens, claimed superior weatherability based on the Norrish Type II theory.
Photoinduced Norrish degradation mechanisms
CH3 I
HO-CH2-CH-CH2-OH
Was the Theory Wrong? Had the accelerated testing overlooked some factor? Or was there something about this new polyester that caused it to resist degradation? ARCO Chemical needed to know the answer, and so did their customers.
The Truth is at the Frontiers A detailed analysis of the degradation mechanism showed that the UV absorption of the polyester was not high enough to support the Norrish Type II mechanism as the major degradation pathway. Instead, oxidation by free radical chain propagation generated by photolysis was much more likely to dominate.
Using CAChe's Frontier Molecular Orbital calculations and visualization, ARCO Chemical scientists demonstrated that the β hydrogen of diols and diol esters
are less susceptible to radical oxidation than the α hydrogen. The presence or absence of the β hydrogens has little impact on weatherability.
The result: the new ARCO Chemical intermediate was successfully commercialized as MPDiol Glycol, and is now used in paints, powder coatings, baking enamels, gel coats and other coatings.
iPU
. Frontier Density contour map of MPDiol® Glycol, showing higher activity
at α than β hydrogen site.
Sullivan and Cooper, Polyester Weatherability: Coupling Frontier Molecular Orbital Calculations of Oxidative Stability with Accelerated Testing. J. Coatings Technology, 67:847. pp 53-62. August 1995.
CAChe* Powerful Desktop Chemistry Tool From Oxford Molecular. CAChe is designed to help experimental chemists predict chemical properties, explain reaction mechanisms, and visualize molecular properties for small molecules containing any element up to 103.
• Runs on Macintosh, Windows 95, and Windows NT systems
• Unique property driven interface that allows chemists to focus their attention on getting results instead of on the details of the models used to produce them
• Includes an economical personal edition, a fuNeatured research version, and client-server versions
• Automated property calculation over a series of molecules
• Computes UV and visible spectra • Performs conformational
searching
CAChe is also widely used in educational programs, which Oxford Molecular supports through special academic licensing and its Higher Education Grant Program. t
Get a FREE CD with more examples of chemical problem solving with CAChe. Call us at one of the numbers below and ask for our informative pack on CAChe in Research or CAChe in Education.
k i i
W e Had a Solution For ARCO Chemical. We Have a Solution for You. m
Desktop Chemistry · Molecular Modelinq · Bioinformatics · Databases · Enterprise Systems · Collaborations
f Oxford Molecular „ _ Solutions for Discovery Research
USA tel: 800-876-9994 fax:408-879-6302
Europe/UK tel: +441865 784600 fax: +441865 784601
Worldwide http://www.oxmol.com/ 1-408-879-6300
CAChe is a registered trademark of Oxford Molecular Group PLC or its subsidiaries. Macintosh is a registered trademark of Apple Computer. Windows is a registered trademark of Microsoft Corporation. MPDiol Glycol is a registered trademark of ARCO Chemical Company.
CIRCLE 2 5 ON READER SERVICE CARD
New Lower Pricing! Γ.,ΊΙΙ fnr Retails
MPDiol® Glycol
