Kinetic Investigation of Styrene Free Radical Polymerization by Using Binary Mixtures of Monofunctional Initiators

Polymerization of styrene in presence of two monofunctional initiators is studied kinetically in an ampoule scale. Polymerizations were ceased at different conversions for each ampoule while the temperature was increased almost linearly during the reaction. Three different initiator mixtures were used. The first mixtures were composed of benzoil peroxide (BPO) and t-butyl perbenzoate (TBPB) with various molar ratios and temperature programs. The second and third series were performed on mixtures of BPO and α,α'-azobisisobutyronitrile (AIBN) and AIBN with TBPB, respectively. The experimental results for these series revealed thatincreasing the percentage of TBPB in the initiator mixtures at the same reaction temperature intervals enhanced polymerization rate and molecular weight of the resulting polymers. On the other hand the results from the second series indicated that reducing AIBN in the mixture would have reduction effect on the reaction temperatureintervals while both conversion and the polymer molecular weight are increase

Identification of Mucorales isolates from soil using morphological and molecular methods

Background and Purpose: Soil is the main habitat of saprophytic and pathogenic fungi. Mucormycetes are one of the most parts of soil fungi and certain members are among opportunistic fungi and can cause systemic fungal infections in immunocompromised patients. The majority of human and animal infections are caused by members of the genera Rhizopus, Mucor, Rhizomucor, Lichtheimia (Absidia), Cunninghamella and Mortierella. The objective of this research was to isolate and identify the main genera of Zygomycetes, using molecular assay and morphological features. Materials and Methods: A total of 340 soil samples were collected from different sites of seven public parks and 14 municipality districts in Isfahan. All samples were cultured on appropriate media and incubated at 27° C for 2 to 4 days, and then examined daily for visible fungal growth. PCR-RFLP method and macroscopic, microscopic and physiological characteristics were applied to identify fungal colonies. Results: Four hundred pure colonies belonging to six genera of Zygomycetes including Lichtheimia, Rhizopus, Rhizomucor, Mucor, Cunninghamella and Mortierella were identified. The genus Rhizopus (35.5%) was the most frequent isolate, followed by Mucor (32.25%) and Rhizomucor (27.5%). Conclusion: These finding may help us to understand about the importance of opportunistic fungi in public areas and the risk of exposure with immunocompromised persons