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Effect of polymer composition on performance properties of maleate-vinyl ether donor-acceptor UV-curable systems.

The effect of unsaturated unsaturated /un·sat·u·rat·ed/ (un-sach´ur-at?ed)
1. not holding all of a solute which can be held in solution by the solvent.

2. denoting compounds in which two or more atoms are united by double or triple bonds.
 polyester backbone composition on the properties of donor-acceptor UV-cured coatings was explored. The polyesters were designed with similar molecular weights and levels of unsaturation, but with otherwise widely varying backbone compositions. UV-curable coatings were formulated with stoichiometric stoi·chi·om·e·try  
1. Calculation of the quantities of reactants and products in a chemical reaction.

2. The quantitative relationship between reactants and products in a chemical reaction.
 levels of triethylenglycol divinyl ether di·vi·nyl ether
A rapidly acting inhalation anesthetic. Also called vinyl ether.
 and a photoinitiator. The resulting coatings had a broad range of properties, which were found to correlate with the properties and compositions of the polyester backbone polymers. A relatively flexible backbone resulted in lower glass transition temperatures The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state).  ([T.sub.g]). The polymer [T.sub.g] was found to influence the conversion of double bonds achieved during UV curing. Reaction kinetics were evaluated for the coating systems and the results confirmed that the [T.sub.g] of the systems influenced the double bond conversion. Thermal stability and Konig pendulum hardness were also found to vary with the backbone composition of the constituent polyester.

Keywords: Crosslinking, cure, polyesters, UV, EB, radiation cure, mechanical properties, physical properties, esters esters (esˑ·terz), organic compounds synthesized from acids and alcohols, typically possessing fruity aromas.
, reaction kinetics


UV-curable polymers continue to find new applications as environmental regulations continue to propel coatings research into finding zero or low VOC (Vertical Online Community) See vertical portal.  alternatives. Nonacrylate UV-curable coating technology is an area of research interest, especially in view of the health concerns associated with acrylate Noun 1. acrylate - a salt or ester of propenoic acid

salt - a compound formed by replacing hydrogen in an acid by a metal (or a radical that acts like a metal)
 systems. The major categories in nonacrylate technology include cationic cationic

having qualities dependent on having free cations available.

cationic detergents
are wetting agents that disrupt or damage cell membranes, denature proteins and inactivate enzymes.
 polymerization polymerization

Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same.
, thiol-ene systems, and free-radical induced alternating copolymerization copolymerization (kōpäl´imrizā´sh . Some of the benefits to be derived from alternate technologies are those of comparable cure times as acrylates, low toxicity, and, more importantly, that of design flexibility.

Free-radical induced alternating photocopolymerization takes place when an electron-rich vinyl group is mixed with an electron deficient vinyl group. (1-4) It has been found that polymerization kinetics is affected by factors such as photoinitiator concentration, presence of oxygen, light intensity, and composition of the monomer monomer (mŏn`əmər): see polymer.

Molecule of any of a class of mostly organic compounds that can react with other molecules of the same or other compounds to form very large molecules (polymers).
 mixture. (5,6) Studies on systems containing a stoichiometric balance of maleate maleate /mal·e·ate/ (mal´e-at) any salt or ester of maleic acid.

1. A salt of maleic acid.

2. An ester of maleic acid.
 and vinyl ether vinyl ether
See divinyl ether.
 functional groups have been previously reported. (7-9) Lapin et al. studied the properties of oligomers with different backbones and reactive diluents with different functionalities. (8) The oligomers were then combined with the reactive diluents, UV-cured, and their film properties were evaluated. In another study, Noren evaluated the properties of coatings based on a maleate-vinyl ether system wherein the molecular weight and equivalent weight of the unsaturated polyester were varied. (7) There are reports in literature on the mechanistic and stereochemical aspects of donor-acceptor chemistry. (10-16) Gaylord et al. have generated a substantial body of work in the area of donor-acceptor complexes and a few are cited herein. (17-20) Several patents have also been issued in this area. (21-25) There are no accounts of detailed structure-property relationships in donor-acceptor systems wherein the unsaturated polyester backbone is varied by using different monomer combinations.

We are particularly interested in using UV-curable polymer systems as laminating layers for use in multilayered mul·ti·lay·ered  
Consisting of or involving several individual layers or levels.
 flexible electronic devices. The performance requirements for this application are complex and challenging. Following curing, the process comprises steps like metallization Met`al`li`za´tion

n. 1. The act or process of metallizing.
, chemical etching, laser ablation Laser ablation is the process of removing material from a solid (or occasionally liquid) surface by irradiating it with a laser beam. At low laser flux, the material is heated by the absorbed laser energy and evaporates or sublimes. , and so on. This translates into a demand for a polymer with a complex mix of properties such as films that cure fast, are hard, flexible, transparent, thermally stable, exhibit good solvent and acid etch resistance, and are dimensionally stable. The objective of this study is to evaluate donor-acceptor technology for this application. A series of polymers were synthesized using a wide range of compositions to potentially yield a range of polymer film properties. This data was then used to assess the technology for flexible electronic device manufacture.



All monomers used for polyester synthesis, except 1,4 CHDA (1,4-cyclohexanedicarboxylic acid) and 2-ethyl hexanol, were purchased from Sigma Aldrich. Diethyl maleate and diethyl fumarate fumarate /fu·ma·rate/ (fu´mah-rat) a salt of fumaric acid.


a salt of fumaric acid.
 used for the model compound study were also purchased from Sigma Aldrich. The 2-ethyl hexanol was purchased from Alfa Aesar and 1,4 CHDA was obtained from Eastman Chemical Company Eastman Chemical Company is a United States based chemical company, engaged in the manufacture and sale of chemicals, plastics and fibers. Eastman has 16 manufacturing sites in 10 countries, supplying its products throughout the world. . Triethyleneglycol divinyl ether (TEGDVE TEGDVE Triethyleneglycol-Divinylether ) and diethyleneglycol monovinyl ether (DEGMVE) were provided by BASF BASF Bar Association of San Francisco (since 1872; San Francisco, California)
BASF Badische Anilin und Soda Fabrik (German chemical products company)
BASF Builders Association of South Florida
. Photoinitiator, 2-hydroxy-2-methyl-l-phenyl-1-propanone (Darocur 1173), was supplied by Ciba. All chemicals were used as received without further purification.

Polyester Design

The unsaturated polyesters were formulated to be hydroxyl hydroxyl /hy·drox·yl/ (hi-drok´sil) the univalent radical OH.

The univalent radical or group OH, a characteristic component of bases, certain acids, phenols, alcohols, carboxylic
 functional with a molecular weight of approximately 800. Compositions were designed so that the average number of double bonds per polymer chain was greater than 2.5 and the desired acid value was less than 30 mg of KOH KOH
The chemical formula for potassium hydroxide, which is used to perform the KOH test. The tests is also called a potassium hydroxide preparation.

Mentioned in: KOH Test


potassium hydroxide.
 per gram of sample. Maleic anhydride Maleic anhydride (cis-butenedioic anhydride, toxilic anhydride, dihydro-2,5-dioxofuran) is an organic compound with the formula C4H2O3 (C=OCH=CHC=O2). In its pure state it is a colourless or white solid with an acrid odour.  was the source of unsaturation in all formulations and the monomers used were varied in order to obtain polyesters with a wide range of backbone structures. Chemical composition of the various polyesters and the symbols used to represent them are noted in Table 1. The amounts of monomer used in each formulation and the theoretical molecular weight of the polymers are listed in Table 2.

Polyester Synthesis

The unsaturated polyesters were prepared using standard melt polyesterification techniques. Monomers were weighed into a 250-ml, three-necked flask, equipped with a mechanical stirrer, temperature controller, condenser condenser

Device for reducing a gas or vapour to a liquid. Condensers are used in power plants to condense exhaust steam from turbines and in refrigeration plants to condense refrigerant vapours, such as ammonia and Freons.
, and a nitrogen inlet. A nitrogen blanket was maintained in the reaction flask during the course of the reaction in order to preclude side reactions, such as oxidation of double bonds. The reaction mixture was heated in a ramped manner and temperatures were set at 60[degrees]C, 120[degrees]C, and 180[degrees]C. Reaction was continued until the desired acid value was reached. Acid value was determined by titration titration (tītrā`shən), gradual addition of an acidic solution to a basic solution or vice versa (see acids and bases); titrations are used to determine the concentration of acids or bases in solution.  with alcoholic KOH.

Polyester Characterization

Polyester resins were characterized for viscosity, molecular weight, and glass transition temperature. Viscosity measurements were made at 100[degrees]C using an ICI (language) ICI - An extensible, interpretated language by Tim Long with syntax similar to C. ICI adds high-level garbage-collected associative data structures, exception handling, sets, regular expressions, and dynamic arrays.  cone and plate viscometer viscometer

Instrument for measuring the viscosity (resistance to internal flow) of a fluid. In one type, the time taken for a given volume of fluid to flow through an opening is recorded.
. Molecular weight was determined using a Waters 2410 gel permeation chromatograph chromatograph /chro·mato·graph/ (kro-mat´o-graf)
1. the apparatus used in chromatography.

2. to analyze by chromatography.


1. to analyze by chromatography.

 equipped with a refractive index A property of a material that changes the speed of light, computed as the ratio of the speed of light in a vacuum to the speed of light through the material. When light travels at an angle between two different materials, their refractive indices determine the angle of transmission  detector. A 1% sample solution in tetrahydrofuran tetrahydrofuran: see furfural.  using a flow rate of 1 ml/min was used. Calibration was performed using polystyrene standards. Differential scanning calorimetry Differential scanning calorimetry or DSC is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as a function of temperature.  (DSC (1) (Digital Signal Controller) A microcontroller and DSP combined on the same chip. It adds the interrupt-driven capabilities normally associated with a microcontroller to a DSP, which typically functions as a continuous process. See microcontroller and DSP. ) measurements were conducted using a TA Instruments Q1000 series DSC. The testing method used was a heat-cool-heat cycle. The samples were first equilibrated at -70[degrees]C and then subjected to a heat cycle at the rate of 5[degrees]C/min to 200[degrees]C, followed by cooling to -70[degrees]C at a rate of 10[degrees]C/min and a final heating cycle at a rate of 5[degrees]C/min to 200[degrees]C. The ratio of maleate to fumarate isomers isomers (ī´sōmurz), 1. organic compounds having the same empirical formula–i.e.
 was determined by [.sup.1.H] NMR NMR: see magnetic resonance.  on a Varian Unity/Inova-400NB (400 MHz (MegaHertZ) One million cycles per second. It is used to measure the transmission speed of electronic devices, including channels, buses and the computer's internal clock. A one-megahertz clock (1 MHz) means some number of bits (16, 32, 64, etc. ).



Coating formulations were prepared by combining the unsaturated polyester and triethyleneglycol divinyl ether in a ratio of 1:1 of the reactive functional groups, viz. maleate to vinyl ether functionality. The mixture was homogenized ho·mog·e·nize  
v. ho·mog·e·nized, ho·mog·e·niz·ing, ho·mog·e·niz·es
1. To make homogeneous.

a. To reduce to particles and disperse throughout a fluid.

 using heat. Four percent photoinitiator, based on the combined weight of resin and reactive diluent diluent /dil·u·ent/ (dil´oo-int)
1. causing dilution.

2. an agent that dilutes or renders less potent or irritant.

Serving to dilute.

, was added to the formulation followed by mixing to obtain a homogeneous mixture. The coatings prepared from polyesters 1 to 10 were designated as A to J, respectively (see Table 1). For example, coating A was prepared by combining 5.63 g of the unsaturated polyester, 2.12 g of triethyleneglycol divinyl ether, and 0.464 g of the photoinitiator.

Model formulations were prepared by combining the model ester compound with DEGMVE in a ratio of 1:1 of the reactive functional groups, namely ester to vinyl ether functionality. The mixture was homogenized and 4% of the photoinitiator, based on the combined weight of model ester and reactive diluent, was added to the formulation followed by mixing to obtain a uniform mixture.

Coating Characterization

Coatings were deposited onto a substrate using a drawdown Drawdown

The peak to trough decline during a specific record period of an investment or fund. It is usually quoted as the percentage between the peak to the trough.

 bar with a 4 mil clearance. Substrates used were aluminum for hardness measurement and glass to obtain free films for DMTA DMTA Dynamic Mechanical Thermal Analysis
DMTA Davis Music Teachers' Association
DMTA Demented Minds Think Alike
DMTA Digital Media Teaching Aids
DMTA Diversity-Multiplexing Tradeoff Analysis
 and other tests. Application was followed by curing of samples under ultraviolet (UV) light until films that were nontacky to touch were obtained. A Dymax 200 EC silver lamp (UV-A UV-A or UVA

ultraviolet radiation with a range of 320-380 nanometres
, 365 nm) with an intensity of 35 mW/[cm.sup.2], measured with an International Light digital radiometer radiometer (rā'dēŏm`ətər), instrument for detection or measurement of electromagnetic radiation; the term is applied in particular to devices used to measure infrared radiation.  (Model IL1400A), was used as the source for UV radiation. Testing of film samples was performed after allowing the samples to equilibrate e·quil·i·brate  
v. e·quil·i·brat·ed, e·quil·i·brat·ing, e·quil·i·brates

To be in or bring about equilibrium.
To maintain in or bring into equilibrium.
 at room temperature for at least 24 hr.

Real time FTIR FTIR Fourier Transform Infrared (spectroscopy)
FTIR Frustrated Total Internal Reflection
FTIR Fourier Transfer Ir
 measurements were made using a Nicolet Magna FTIR spectrometer. A LESCO LESCO Lahore Electric Supply Company (Pakistan)
LESCO Logistics & Environmental Support Services Corporation (Huntsville, Alabama) 
 Super Spot MK II UV curing lamp equipped with a fiber optic light guide was the source for UV irradiation of samples. The uncured sample was spin-coated at an rpm of 3000 onto a KBr disk and was simultaneously exposed to IR and UV irradiation. The sample was placed at a distance of 20 mm from the end of the fiber optic cable Noun 1. fiber optic cable - a cable made of optical fibers that can transmit large amounts of information at the speed of light
fibre optic cable

transmission line, cable, line - a conductor for transmitting electrical or optical signals or electric power
. Light intensity at the sample was 10 mW/[cm.sup.2]. In all cases, IR data collection was continued after UV irradiation was stopped.

Photo-DSC measurements were obtained using the TA Instruments Q1000 DSC outfitted with a photocalorimetric accessory (PCA (tool, programming) PCA - A dynamic analyser from DEC giving information on run-time performance and code use. ). The samples were subjected to UV irradiation for 150 and 300 sec at an intensity of 40 mW/[cm.sup.2] using fiber optic light guides.


Dynamic mechanical properties of cured films were evaluated using a dynamic mechanical thermal analyzer (DMTA 3E, Rheometric Scientific). Free films 3 mm long, 5 mm wide, and 0.05-0.08 mm thick were characterized using settings at a frequency of 10 rad/sec and heating rate of 5[degrees]C/min over a temperature range of -50[degrees]C to 250[degrees]C. The geometry employed was that of rectangular tension/compression. Thermogravimetric analysis Thermogravimetric Analysis or TGA is a type of testing that is performed on samples to determine changes in weight in relation to change in temperature. Such analysis relies on a high degree of precision in three measurements: weight, temperature, and temperature change.  was run using a Perkin Elmer thermogravimetric analyzer and samples were heated from 25[degrees]C to 650[degrees]C, at a rate of 10[degrees]C/min. Film hardness was measured using a BYK-Gardner pendulum hardness tester on aluminum panels and Konig hardness value was reported in seconds.


Polyester Synthesis

The unsaturated polyester resins described in Table 2 were synthesized and characterized. The results are outlined in Table 3. The number average and weight average molecular weights The weight average molecular weight is a way of describing the molecular weight of a polymer. Polymer molecules, even if of the same type, come in different sizes (chain lengths, for linear polymers), so we have to take an average of some kind.  obtained using GPC (1) A PC that uses the Linux-based gOS operating system. See gOS.

(2) (GPC Group) Originally the Graphics Performance Characterization committee of the NCGA, the GPC Group is now part of Standard Performance Evaluation Corporation (SPEC) and oversees the following
 are in reasonable agreement with design values. Polydispersity (PD) of the synthesized polyesters was found to range between 1.40 and 2.15, typical of polymers synthesized by step growth polymerization.

Analysis of glass transition temperatures shows that compositions containing HD yield comparatively lower glass transition temperatures than compositions without it. It is further seen that HD in combination with TEG teg also tegg  
A sheep in its second year or before its first shearing.

[Origin unknown.]

Noun 1. teg - two-year-old sheep
lamb - young sheep
 further lowers the glass transition temperature. Compositions consisting of only flexible monomers HD/DEG/CHDA have the lowest glass transition temperatures.

The viscosity of the polyester resins varies as a function of composition. With a few exceptions, the viscosity trend is similar to the glass transition trend. Compositions that contain HD generally show lower viscosity as compared to those without it. The HD/TEG combinations lowers the viscosity further. The HD/TEG/CHDA combination yields the lowest viscosity. As expected, a combination of HD/CHDM/EH also yields a very low viscosity. The composition TMP/HD/CHDA/MA has a higher viscosity that may be attributed to the fact that this is a branched polymer due to the presence of the trifunctional monomer, TMP TMP (thymidine monophosphate): see thymine. . It is also observed that polyesters that contain IPA IPA - International Phonetic Alphabet  yield higher viscosity and glass transition temperatures than those containing 1,4-CHDA.


Coating formulations were prepared with the unsaturated polyesters and stoichiometric amounts of triethyleneglycol divinyl ether plus a photoinitiator. The coating formulations were evaluated for cure characteristics, and then the mechanical and thermal properties of the cured films were studied.

REAL TIME INFRARED SPECTROSCOPY: Real-time IR was used to study the disappearance of the vinyl ether peak at 1639 [cm.sup.-1] as well as to monitor the extent of reaction. Since the donor-acceptor polymerizations are stoichiometric, the conversion of vinyl ether groups also indicated the conversion of maleate/fumarate groups. In order to study the effect of composition on the extent of cure, samples were subjected to a 150-sec UV light exposure and typical results obtained are shown in Figure 1. The degree of conversion was calculated using equation (1):

% conversion = ((([A.sub.1639])[.sub.0]-([A.sub.1639])[.sub.t])/([A.sub.1639])[.sub.0])x100 (1)

where ([A.sub.1639])[.sub.0] is the absorbance absorbance /ab·sor·bance/ (-sor´bans)
1. in analytical chemistry, a measure of the light that a solution does not transmit compared to a pure solution. Symbol .

 at time=0 and ([A.sub.1639])[.sub.t] is the absorbance at time t.

It was also observed that the conversions were a function of both the polymer composition and the exposure time. The change in vinyl ether conversion as a function of different UV exposure times is illustrated in Figure 2. In light of this, RTIR RTIR Round the Island Race (UK)  experiments were conducted for all samples at several exposure times. Percent conversions were calculated at 30 and 150 sec and compiled in Table 4.


The data shows that complete conversion was not obtained. This may be attributed to an increase in viscosity as cure proceeds and the subsequent inability of the reacting moieties to find each other due to sluggish segmental segmental /seg·men·tal/ (seg-men´t'l)
1. pertaining to or forming a segment or a product of division, especially into serially arranged or nearly equal parts.

2. undergoing segmentation.
 mobility. A general trend was observed: when the constituent polyester had a higher [T.sub.g], lower conversions were observed, and vice versa VICE VERSA. On the contrary; on opposite sides. . Another factor that influenced conversion was the viscosity of the coating. Coating H, despite having a low [T.sub.g], showed very low conversion that may have been due to high viscosity of the constituent polyester, which in turn could be attributable to the presence of a tri-functional monomer. Thus, the initial viscosity of the polyester has an impact on the ultimate conversion achieved.

PDSC Parti Democrate Social Chretien (Democratic Social Christian Party, Congo)
PDSC Panasonic Disc Services Corporation (Torrance, California) 
): Heat flow for cure reaction was determined for coatings, including the model compound formulations, using a PDSC. Two different UV exposure times were used: 300 sec and 150 sec. The purpose of the longer exposure was to force complete conversion of double bonds. The shorter exposure was used to obtain conversion data comparable to RTIR. Model compounds were prepared by combining diethyl maleate and diethyl fumarate separately with DEGMVE. The [T.sub.g]s of diethyl maleate and diethyl fumarate cured with DEGMVE were determined using a DSC and were found to be -10.88[degrees]C and -14.8[degrees]C, respectively. Since the [T.sub.g]s of model polymers were below the temperature used for the PDSC experiments (30[degrees]C), we assumed that no vitrification vit·ri·fi·ca·tion
The process of using heat and fusion to convert dental porcelain to a glassy substance.

 had occurred, thus the heat evolved in the curing of the model compounds represented the maximum achievable.



The PDSC results are compiled in Tables 5 and 6 for different UV exposure times. Heat of reaction data was further converted into double bond conversion, using inputs from NMR and PDSC. The calculations that were used to convert data are described as follows.

The heat of reaction (J/g) was calculated by integrating the area under the curve from 0 to 2.5 min (UV exposure=150 sec) from the PDSC and converted to kJ/C=C (total unsaturation). NMR was used to determine % maleate and % fumarate in the constituent polyester samples. Theoretical heat of reaction was calculated using equation (2):

[H.sub.max(theo)] = (M*[H.sub.M]) + (F*[H.sub.F]) (2)


[H.sub.max(theo)] = Maximum theoretical heat of reaction

M = fraction maleate determined by NMR

F = fraction fumarate determined by NMR

[H.sub.M] = Heat of reaction for diethyl maleate/vinyl ether

[H.sub.F] = Heat of reaction for diethyl fumarate/vinyl ether

Percentage of double bond conversion was obtained as per equation (3):

% double bond conversion = [Heat of reaction/[H.sub.max(theo)]] x 100 (3)

Kinetic studies confirmed that as UV exposure time increased, the double bond conversion increased. It was seen that the polyester [T.sub.g] significantly influenced the double bond conversion. A general trend observed was that as the [T.sub.g] increased, the conversion decreased (depicted in Figures 3 and 4).

DYNAMIC MECHANICAL THERMAL ANALYSIS Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature. Techniques include:
  • Differential scanning calorimetry
  • Dynamic mechanical analysis
  • Thermomechanical analysis
 (DMTA): DMTA was used to determine the glass transition temperature and crosslink density of the coatings. The values obtained are shown in Table 7. As expected, the crosslink densities and glass transition temperatures were found to vary as a function of composition.

Backbone structure influences the [T.sub.g] of coatings. The presence of aromatic and/or cyclic monomers resulted in coatings with high [T.sub.g] values. It was seen that coatings that comprised flexible monomers like HD or EH showed relatively low [T.sub.g].

The crosslink density fell into a rather narrow range, with the exception of samples F and J. Since we attempted to maintain the same vinyl (maleic) functionality for all of the polyesters and also since the crosslinking reaction was stoichiometric, this was not unexpected. Samples F and J, which had much lower crosslink density, were made from polyesters 6 and 10. These polydesters had the highest acid values, which suggests that the degree of polymerization The degree of polymerization, or DP, is the number of repeat units in an average polymer chain at time t in a polymerization reaction [1]. The length is in monomer units. The degree of polymerization is a measure of molecular weight.  was not as high for these two polymers as the others. Thus, lower crosslink density was a result of the lower vinyl functionality.

Thermogravimetric Analysis

Thermal stability of the cured coatings was compared for weight loss at a temperature of 150[degrees]C and the values were found to be less than 4%, which may be attributed to moisture loss or a volatilization volatilization /vol·a·til·iza·tion/ (vol?ah-til-i-za´shun) conversion into vapor or gas without chemical change.

See evaporation.
 of low molecular weight, unreacted components in the crosslinked film. A temperature of 150[degrees]C was chosen based on the temperature that the coating would be subjected to during the subsequent manufacturing process. The thermal stability curves are shown in Figure 5.

Coatings with an aromatic backbone showed better thermal stability at a temperature of 600[degrees]C. It was also seen that coatings containing CHDA showed lower thermal stability at a temperature of approximately 200[degrees]C, as in the case of E, and at 600[degrees], in the case of coatings H and F.


Pendulum Hardness

Koing pendulum hardness was determined for the coatings and, as expected, it was found to change with the composition. Figure 6 illustrates the trend observed for hardness values. A general trend observed was that formulations with aromatic backbones like A, B, C, D, E, and I showed generally higher hardness values. The hardness values also appeared to be related to the degree of crosslinking. Coatings F and J had a low crosslink density, resulting in a low pendulum hardness value.


Donor-acceptor radiation-curable coatings can be designed in order to meet specific application requirements. This is achieved by varying the composition of the unsaturated polyester backbone. Polyester properties such as viscosity and glass transition temperatures were found to change as the proportion of flexible monomers used were changed. Further trends in property changes were observed when the coatings prepared from these polyesters were tested. Cure times and conversions were found to vary as a function of both composition and UV exposure times. Kinetic studies using PDSC confirmed the observation from RTIR that [T.sub.g] influenced the double bond conversion. It was seen that lower polyester [T.sub.g] resulted in higher conversion, and vice versa. The study also confirmed the RTIR observation that higher conversion is obtained when the UV exposure time is increased. The glass transition temperature and crosslink densities were found to be different when the composition changed. The coatings prepared exhibited good hardness values and higher hardness values were observed in compositions containing aromatic or aromatic-like monomers. All coatings exhibited good thermal stability.


We would like to thank the Defense Microelectronics Activity (contract #DMEA DMEA Delta-Montrose Electric Association (Colorado)
DMEA dimethylethylamine
DMEA Defense Minerals Exploration Administration
DMEA Department of Mineral and Energy Affairs (South Africa) 
90-02-C-0224) for funding this project.


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Neena Ravindran, Ankit Vora, and Dean C. Webster ([dagger])--North Dakota State University It is accredited by the North Central Association of Colleges and Schools and in 2004 was designated by the National Security Agency as a National Center of Academic Excellence in Information Assurance Education.

DSU is home to the Smith-Zimmermann Heritage Museum and the Karl E.

Presented at the e|5 2004, sponsored by RadTech International North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. , May 2-5, 2004, in Charlotte, NC.

* Dept. of Coatings and Polymeric Materials, 1735 NDSU NDSU North Dakota State University  Research Park Dr., P.O. Box 5376, Fargo, ND 58105.

([dagger]) Author to whom correspondence should be addressed. Email:
Table 1 -- Polyester Compositions

Polyester  Monomer Composition (a)  Coating

 1         NPG/IPA/DEG/MA           A
 2         CHDM/DEG/AA/IPA/MA       B
 3         DEG/PG/IPA/MA            C
 4         HD/TEG/IPA/MA            D
 5         HD/NPG/TEG/IPA/MA        E
 6         HD/NPG/TEG/CHDA/MA       F
 7         DEG/HD/CHDA/MA           G
 8         TMP/HD/CHDA/MA           H
 9         DEG/NPG/IPA/MA           I
10         HD/EH/CHDA/MA            J

(a) NPG: neopentyl glycol, IPA: isophthalic acid, DEG: diethylene
glycol, MA: maleic anhydride, CHDM: 1,4-cyclohexane dimethanol, AA:
adipic acid, PG: propylene glycol, HD: 1,6-hexane diol, TEG: triethylene
glycol, CHDA: 1,4-cyclohexane dicarboxylic acid, TMP: trimethylol
propane, EH: 2-ethyl hexanol.

Table 2 -- Formulations and Theoretical Molecular Weight of Polyester

Polyester  NPG    DEG    TEG    CHDM   1,6 HD  TMP    IPA    AA

 1         0.878  0.627                               0.206
 2                0.953         0.713                 0.198  0.146
 3                1.421                               0.160
 4                       0.491         1.015          0.218
 5         0.512         0.236         0.767          0.210
 6         0.512         0.236         0.768
 7                0.824                0.625
 8                                     1.161   0.387
 9         0.950  0.570                               0.166
10                       1.334

                                  Mol. Wt.
Polyester  1,4 CHDA  EH     MA    (Theo.)

 1                          1.00   672
 2                          1.00   780
 3                          1.00   776
 4                          1.00   953
 5                          1.00   776
 6         0.235            1.00   679
 7         0.172            1.00   772
 8         0.333            1.00  1034
 9                          1.00   727
10         0.200     0.111  1.00   776

Table 3 -- Properties of the Unsaturated Polyesters

                       Viscosity (Poise)
Polyester  Acid Value  at 100[degrees]C   [bar.M.sub.n]

 1         21          5.4                1352
 2         17          7.1                1157
 3         15          4.2                1193
 4          6          4.6                1803
 5         13          5.0                2341
 6         29          2.2                1337
 7         14          3.4                1492
 8         16          9.5                1829
 9          2          5.8                1256
10         30          2.4                1394

Polyester  [bar.M.sub.w]  PD    [T.sub.g][degrees]C

 1         1888           1.40  -12.47
 2         1927           1.67  -15.50
 3         2112           1.77  -18.73
 4         3254           1.80  -35.61
 5         3193           1.36  -28.04
 6         1965           1.47  -31.97
 7         2489           1.67  -41.07
 8         3933           2.15  -36.62
 9         2323           1.85   -9.57
10         2263           1.62  -39.36

Table 4 -- Conversion of Vinyl Ether Groups at 1639 [cm.sup.-1] After UV
Exposure Times of 30 and 60 sec

Coating                           A       B      C       D       E

% Conversion after 30 sec          39      55     59      65      61
% Conversion after 150 sec         61      69     73      77      75
Polyester [T.sub.g] ([degrees]C)  -12.47  -15.5  -18.73  -35.61  -28.04

Coating                           F       G       H       I      J

% Conversion after 30 sec          60      50      53     45      63
% Conversion after 150 sec         84      63      57     62      84
Polyester [T.sub.g] ([degrees]C)  -31.97  -41.07  -36.62  -9.57  -39.36

Table 5 -- Heat of Reaction Using PDSC and Double Bond Conversion After
UV Exposure=150 sec

                        No. of                          Heat of
                        Maleic                          Reaction
                        Units/   % Maleate  % Fumarate  (J/g): UV
                        Polymer  from       from        Irradiation
Composition   Notation  Chain    NMR        NMR         = 150 sec

Model 1       DM                 100                    529.40
Model 2       DF                            100         483.70
NPG/IPA/DEG/  A         2.51      59.18      40.82      275.85
CHDM/DEG/AA/  B         2.38      70.67      29.33      273.70
DEG/PG/IPA/   C         3.06      61.69      38.31      320.97
HD/TEG/IPA/   D         2.15      69.60      30.40      311.20
HD/NPG/TEG/   E         2.69      70.59      29.41      302.47
HD/NPG/TEG/   F         2.30      70.15      29.85      280.57
DEG/HD/CHDA/  G         2.72      81.34      18.66      336.87
TMP/HD/CHDA/  H         3.28      53.05      46.95      291.53
DEG/NPG/IPA/  I         2.77      67.95      32.05      288.27
HD/CHDM/EH/   J         2.39      65.64      34.36      269.50

                                  Heat                         % Double
                        Moles of  Reaction  [H.sub.max(theo)]  Bonds
Composition   Notation  C=C       (kJ/C=C)  (kJ/C=C)           Converted

Model 1       DM        0.0302    175
Model 2       DF        0.0300    161
NPG/IPA/DEG/  A         0.0294     94       170                55
CHDM/DEG/AA/  B         0.0256    107       171                62
DEG/PG/IPA/   C         0.0291    110       170                65
HD/TEG/IPA/   D         0.0288    108       171                63
HD/NPG/TEG/   E         0.0281    108       171                63
HD/NPG/TEG/   F         0.0287     98       171                57
DEG/HD/CHDA/  G         0.0273    123       173                71
TMP/HD/CHDA/  H         0.0234    125       169                74
DEG/NPG/IPA/  I         0.0306     94       171                55
HD/CHDM/EH/   J         0.0249    108       171                63

Table 6 -- Heat of Reaction Using PDSC and Double Bond Conversion After
UV Exposure=300 sec

                        No. of                          Heat of
                        Maleic                          Reaction
                        Units/   % Maleate  % Fumarate  (J/g): UV
                        Polymer  from       from        Irradiation
Composition   Notation  Chain    NMR        NMR         = 300 sec

Model 1       DM                 100                    553.20
Model 2       DF                            100         444.60
NPG/IPA/DEG/  A         2.51      59.18      40.82      289.70
CHDM/DEG/AA/  B         2.38      70.67      29.33      270.33
DEG/PG/IPA/   C         3.06      61.69      38.31      357.63
HD/TEG/IPA/   D         2.15      69.60      30.40      414.50
HD/NPG/TEG/   E         2.69      70.59      29.41      317.30
HD/NPG/TEG/   F         2.30      70.15      29.85      314.00
DEG/HD/CHDA/  G         2.72      81.34      18.66      347.53
TMP/HD/CHDA/  H         3.28      53.05      46.95      287.70
DEG/NPG/IPA/  I         2.77      67.95      32.05      320.47
HD/CHDM/EH/   J         2.39      65.64      34.36      335.03

                                  Heat                         % Double
                        Moles of  Reaction  [H.sub.max(theo)]  Bonds
Composition   Notation  C=C       (kJ/C=C)  (kJ/C=C)           Converted

Model 1       DM        0.0302    183
Model 2       DF        0.0300    148
NPG/IPA/DEG/  A         0.0294     99       169                58
CHDM/DEG/AA/  B         0.0256    106       173                61
DEG/PG/IPA/   C         0.0291    123       170                72
HD/TEG/IPA/   D         0.0288    144       173                83
HD/NPG/TEG/   E         0.0281    113       173                65
HD/NPG/TEG/   F         0.0287    109       173                63
DEG/HD/CHDA/  G         0.0273    127       177                72
TMP/HD/CHDA/  H         0.0234    123       167                74
DEG/NPG/IPA/  I         0.0306    105       172                61
HD/CHDM/EH/   J         0.0249    135       171                79

Table 7 -- Glass Transition Temperature and Crosslink Density of

Coating  [T.sub.g] ([degrees]C)  Crosslink Density (mol/[cm.sup.3])

A        114.96                  5.27 x [10.sup.-3]
B         94.929                 3.66 x [10.sup.-3]
C        104.93                  7.07 x [10.sup.-3]
D         80.478                 3.65 x [10.sup.-3]
E         90.08                  4.96 x [10.sup.-3]
F         90.417                 0.13 x [10.sup.-3]
G         99.983                 5.44 x [10.sup.-3]
H        105.43                  5.54 x [10.sup.-3]
I        139.78                  2.53 x [10.sup.-3]
J        114.91                  0.14 x [10.sup.-3]
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Title Annotation:glass transition temperatures
Comment:Effect of polymer composition on performance properties of maleate-vinyl ether donor-acceptor UV-curable systems.(glass transition temperatures )
Author:Webster, Dean C.
Publication:JCT Research
Article Type:Case study
Geographic Code:1USA
Date:Jul 1, 2006
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