Standard Gel Properties Testing
Arjay Performance Products can be tested with a variety of sample sizes, temperatures and initiator types depending on customer requirement, however, the most standard is as follows:Test No. ATI-G-001
Revised: 11-01-04
Filled-Promoted Polyester Gel Time and Cure Properties
A. Method
An indication of the working time and curing properties are obtained with this test.
A given mass is initiated with a peroxide by weight and the gel time, interval, and
peak exotherm are measured.
B. Apparatus
1. Controlled temperature environment 74 +/- 2 degrees F
2. Humidity at 50% +/- 10% R.H.
3. Laboratory balance capable of .05 gm sensitivity. (digital or triple beam)
4. Type K Thermocouple
5. 8 oz treated paper cups (Sweetheart flexstyle food cups)
6. Polypropylene stir rod (glass or 304 SS may be used)
7. Stopwatch/timer
8. 1" masking tape
C. Reagents
1. Methyl Ethyl Ketone Peroxide.
Lupersol DDM-9 is standard others may be used if specified
2. Benzoyl Peroxide when used is 50% BPO by wt paste
3. Filled polyester
D. Procedures
1. Adjust sample temperature to 77 deg F +/- 1 deg
2. Tare an empty cup and add 100 gm filled polyester if the density is
less than 7.0 lbs/gal OR add 150 grams if the density is greater than 7.0 lbs/gal.
3. Add 1.5% by weight of the appropriate peroxide initiator. For a 100 gram sample add 1.5 grams
of initiator, for a 150 gram sample add 2.25 grams initiator.
4. Start timer
5. Using poly stir rod mix initiator into sample for a minimum of 2 minutes not exceeding 3 minutes.
6. Place sample on insulated surface and prepare thermocouple by using masking tape to cover 3 inch
length of probe where it will be inserted into sample.
7. Insert probe into sample so it is centered and between 1/8 and 1/2 inch from the bottom of the sample cup.
8. Record gel time as indicated with stopwatch when stir rod can no longer be inserted without force.
OR temperature has increased by more than 3 degrees F.
9. Follow temperature increase to peak temperature registered and record as peak exotherm.
10.Record stopwatch time at peak as total time.
E. Calculations
1. Gel Time - Total Time = Interval Time
F. Report
1. Gel Time
2. Interval Time
3. Peak Exotherm
4. Initiator type
5. Sample Mass
6. Sample initial temperature.
Certificates of Analysis accompany each shipment and can also be obtained from:
[Look for Certificate of Analysis by batch]