<p> The polymerization of styrene initiated with gamma radiation as well as thermal initiation was studied at temperatures, 150, 155, 160, 165, 180 and 200C and dose rates of 0.072-0.1836 M Rads/hour. In all cases the reactions were studied up to 100% conversion and the following results were obtained. (1) Rate of polymerization was independent of dose rate. (2) 165C was considered to be the temperature at which the radiation polymerization system in the case of styrene reaches a limiting rate of initiation caused by high temperature and dose rate. (3) Self-production of ethynylbenzene in the system at 200C probably caused retardation of the initial rate of polymerization. (4) No significant gel effect was observed in the investigated temperature range. (5) Polystyrene produced by radiation at high temperatures has a very low average molecular weight. (6) A general mechanism was proposed based on the characteristics of the reactions. (7) A temperature range was proposed as an optimal reaction temperature for radiation polymerization of styrene. </p> / Thesis / Master of Engineering (MEngr)

The cause of unintentional initiations of energetic materials is an important area of study due to the risks that comes with storing energetic materials such as high explosives. The current models used to simulate the process of heating energetic materials by a hot metal fragment do not give reliable predictions. The objective of this thesis is to study the current models in order to get a better understanding of how to improve the accuracy of the simulations. The heat transfer in the fragment and energetic material is modeled using the heat equation and the reaction rates in the chemical decomposition of the energetic material are modeled using Arrhenius equations. This study shows the importance of accurately implementing the contact area and heat transfer coefficient between the fragment and the energetic material. The thermal conductivity has a significantly smaller affect on the initiation time compared to the heat transfer coefficient. Furthermore, the dimensions of the fragment affect the resulting simulations greatly, while the dimensions of the energetic material only does so for sufficiently small dimensions. / Orsaken till oavsiktliga initieringar av energetiska material är ett viktigt studieområde på grund av riskerna som följer med att lagra energiskt material, så som sprängämnen. De nuvarande modellerna som används för att simulera uppvärmningsprocessen av energetiska material med ett hett metallfragment ger inte tillförlitliga förutsägelser. Syftet med denna uppsats är att studera de nuvarande modellerna för att få en bättre förståelse för hur man kan förbättra noggrannheten i simuleringarna. Värmeöverföringen i fragmentet och det energetiska materialet modelleras med hjälp av värmeledningsekvationen och reaktionshastigheterna i den kemiska nedbrytningen av det energetiska materialet modelleras med hjälp av Arrhenius-ekvationer. Denna studie visar vikten av att korrekt implementera kontaktytan och värmeöverföringskoefficient mellan fragmentet och det energetiska materialet. Den termiska konduktiviteten har en betydligt mindre effekt på initieringstiden jämfört med värmeöverförings- koefficienten. Vidare så påverkar fragmentets dimensioner de resulterande simuleringarna i hög grad, medan dimensionerna av det energetiska materialet gör så endast för tillräckligt små dimensioner.