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Manuscript Title: Simulation of ultrasonic degradation of macromolecules in solution.
Authors: A. Linkens, J. Niezette, J. Vanderschueren
Program title: USSI
Catalogue identifier: ACYN_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 15(1978)375
Programming language: Fortran.
Computer: IBM 370/158.
Operating system: MAX II RELEASE ULG 0.4.1, VS2-R01.6.
RAM: 96K words
Word size: 8
Keywords: Ultrasonation, Macromolecular solution, Degradation rate, Molecular weight Distribution, Simulation, Solid state physics, Other.
Classification: 7.7.

Nature of problem:
Two main aspects are to be considered in ultrasonic degradation of polymers in solution - what is the rate of chain breakage and where are the points of breakage located along the polymer chain. The study of the degradation process is based on the determination of the molecular weight distribution (polydispersity PDIS) and of the average molecular weights (number AMWN or weight AMWW) in function of the irradiation time. We have compared these experimental data with simulated values obtained by computer, for testing different hypothesis concerning the rate expression and the breakage model. Some simulation programs were already announced but, so far as we know, have never been published. Our program is designed to be very general and the four breakage models programmed should cover most of the possible cases.

Solution method:
The method used to simulate ultrasonic action on polymers is quiet simple: we start from the initial molecular weight distribution and we follow during the time, how the number of molecules of each length is modified by breakage and redistribution of broken segments.
The program USSI is convenient for testing a large number of rate expression and breakage models.

Unusual features:
ENTRY statements are used to optimise computation; however we have enclosed comments ("C****** instruction") to help users to suppress the ENTRY statements if necessary.
As output of USSI is often rather important, we have designed the program to occupy complete pages whatever type of line printer is used (72, 80, 135,... character width printers; printer width is introduced via COMMON/PAGE/). This however implies the use of 2 and 4 byte INTEGER variables and variable formats which may reduce the portability of the program.

Running time:
58 s.