The compound of cage octa(aminopropylsilsesquioxane) (POSS-NH 2 ) was prepared in higher yield by the hydrolysis and polycondensation of trifunctional monomer H 2 NCH 2 CH 2 CH 2 Si(OC 2 H 5 ) 3 in the mixture of solvents acetonitrile and 1-propanol, with tetraethyl ammonium hydroxide (Et 4 NOH) as the catalyst. The effects of various parameters influencing the reaction, such as monomer concentration, nature of solvents, and the content of catalyst, were investigated. Results showed that the better values of these reactive factors were nH 2 O/nXSiY 3 ¼ 8-9/1 (molar ratio), nEt 4 NOH/nXSiY 3 ¼ 0.0045 (molar ratio), respectively. The use of acetonitrile as a solvent favors the deposition and formation of the product. The existence of the higher boiling pointing 1-propanol favors the higher reaction temperature, which accelerates the formation of octamer, reduces the reaction time and eventually increases the yield.

No abstract

A series of epoxy resin (EP)/octa(aminpropyl)silsesquioxane (POSS-NH 2 ) organic-inorganic hybrid composites (EP/POSS-NH 2 100/0, 95/5, 90/10, and 80/20 wt/wt) were prepared by melt casting and then curing. Viscoelastic and mechanical properties of these composites were studied by dynamic mechanical analysis and mechanical testing, respectively. Scanning electron microscopy was used to study of the micromorphologies of the composites and to elucidate the toughening mechanisms of POSS-NH 2 . POSS units incorporated into the epoxy network showed good compatibility with the resin matrix. Phase separation was not observed even at high POSS content (20 wt%). Incorporation of POSS macromer into the epoxy network after curing increased the glass transition temperature, slightly narrowed the temperature range widths of the glass transition, and lowered the intensities of their loss moduli peaks of the resultant composites. The glass transition temperature of EP/ POSS-NH 2 composites increased significantly with increasing POSS content at lower POSS content (<10 wt%), while increased slightly at higher POSS content. Both impact and flexural strengths of the hybrids reached their optimum values when 10 wt% content of POSS was introduced. POLYM. COMPOS., 28:175-179, 2007.

Meiyu is a unique rainy season over the Yangtze and Huaihe River valleys (YHRV), which persists from mid-June to mid-July and accounts for about 50% of the accumulated June-July-August (summer) rainfall in the region (Ding & Chan, 2005;Tao & Chen, 1987). The 2020 summer was marked by the longest Meiyu season over the past 60 years, which started on June 1 and ended on August 2 with a duration of 62 days, about twice of the climatology (Ding et al., 2021). The record-long Meiyu season caused accumulated rainfall averaged over the YHRV (28°-33°N, 110°-122°E) exceeding +720 mm (Figure S1a), setting the highest record since 1961 (Figure S1b). The associated severe floods affected about 45.5 million people and caused a direct economic loss of more than 100 billion Chinese Yuan (Wei et al., 2020). An accurate prediction of this kind of extreme event is imperative for agriculture, the economy, and human health.

No abstract