Polyester resin cure

The industrial production of an unsaturated polyester resin is controlled by several factors, whose levels confer on it certain properties that are important to other industries that use the resin as raw material for making finished products. In the curing stage, a catalyst is added to accelerate gel formation by the resin. The time when the gel starts to form, after the catalyst is added, is an important characteristic known as gel time. 

Liba and C.E. Luchini, graduate students in chemical engineering, decided to investigate (as an assignment for a chemometrics course) how 

The normal plot of the effects (Fig. 4A.9) is very easy to interpret, and shows that gel time is totally controlled by three factors (5 = dimethylaniline, 4 = copper octanoate and 1 = hydroquinone, in this order of importance). Factors 4 and 5 contribute to lower the gel time, whereas factor 1 tends to increase it. There is no evidence of significant interactions. This is welcome, because it means the factors can be varied independently of one another, at the customer s convenience. The numerical values on the right side of the plot are the cumulative probabilities corresponding to the z values on the left. 

Another interesting point worth mentioning in this application also serves to remind us of a crucial question in any design. Even though changing the levels of the factors directly affects the intensity of the response, we are not always at liberty to change them as we please. This is particularly true of an experiment performed in industry, where the characteristics of the process usually impose several restrictions. All the levels of the factors in this experiment are concentrations, measured in 

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Figure 25.9. Typical exotherm curves for polyester resin cured with 1% benzoyl peroxide over a range of bath temperatures. (Test tubes of 19 mm dia are filled to height of 8 cm with a mixture of resin plus peroxide. The tubes are immersed in a glycerin bath to the level of the resin surface. Temperature is measured with a thermocouple needle whose point is half-way down the resin...

Dimethylethyl 1-methyl-1-phenylethyl peroxide, tert-Butyl a,a-dimethylbenzyl peroxide EINECS 222-389-8 Luperco 801-XL Peroxide, 1,1-dimethylethyl 1-methyl-1-phenylethyl Trigonox T. Used as an initiator for high-temperature cure of polyester resins, curing elastomers, and polymer modification thermoplastic cross-linking. ElfAtnchem N. Am. 

Chem. Descrip. Phenyl diethanolamine CAS 120-07-0 EINECS/ELINCS 204-368-5 Uses Coupling agent for disperse dyes for syn. fibers intermediate for dyes cure promoter for polyester resins curing agent for urethane elastomers intermediate also in hair dyes, heavy-duty detergents, paint strippers... 

Uses Reducing agent in redox-catalyzed polymerization color stabilizer, modifier, catalyst for polyamides antioxidant intermediate for forming metallic salts used as stabilizers accelerator for org. peroxide catalysts improver of polysiloxane resins free radical promoter in emulsion polymerization promoter in polyester resin curing mfg. of self-extinguishing fibers (reacts with polyester resin and polyolefin) color/odor inhibitor, catalyst for some thermoplastics discoloration inhibitor in PE corrosion inhibitor on thin aluminum surfs. lubricity improver in polyphenyl thioether-based lubricants Manuf./Distrib. Akzo Nobel http //www.akzonobel.com, Ferro http //WWW. ferro. com... 

How are vegetable oil-based polyester resin cured Is there any difference in the curing formulation and mechanisms for drying and non-drying oil-based polyesters ... 

Vilas JL, Laza JM, Garay MT, Rodriguez M, Leon LM. Unsaturated polyester resins cure Kinetic, rheologic, and mechanical-dynamical analysis. I. Cure kinetics by DSC and TSR. Journal of Applied Polymer Science, 2001 79(3) 447 57. DOI http //dx.doi.org/10.1002/1097-4628(20010118)79 3<447 AID-APP70>3.0.CO 2-M. 

Unsaturated polyesters are fast-curing, two-part systems that harden by the addition of catalysts, usually peroxides. Styrene monomer is generally used as a reactive diluent for polyester resins. Cure can occur at room or elevated temperature depending on the type of catalyst Accelerators such as cobalt naphthalene are sometimes incorporated into the resin to speed cure. Unsaturated polyester adhesives exhibit greater shrinkage during cure and poorer chemical resistance than epoxy adhesives. Certain types of polyesters are inhibited from curing by the presence of air, but they cure fully when enclosed between two... 

Witzeman (37) studied the effect of resin and crosshnker types on the cure behavior of polyester resins cured with blocked isocyanates. It was found that cure temperatures as low as 129°C to 140°C could be achieved with blocked isocyanates based on the oximes of dusobutyl ketone and diisopropyl ketone. The polyester resin utilized contained stericaUy unencumbered hydroxyl groups to allow unique flow properties at the low curing temperatures. 

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