EPOXY HOÁ CAO SU THIÊN NHIÊN LỎNG CÓ NHÓM HYĐROXYL CUỐI MẠCH BẰNG AXIT 3-CLO PERBENZOIC

EPOXIDATION OF HYDROXYL-TERMINATED LIQUID NATURAL RUBBER BY 3-CHLOROPERBENZOIC ACID The epoxidation reaction of hydroxyl-terminated liquid natural rubber (~ 4510) by 3-chloroperbenzoic acid in dichloromethane at 250C was studied. The FTIR, 13C- NMR, 1H-NMR and DEPT spectra show that epoxidized liquid natural rubber (~4560¸4880) has been formed.

TỔNG HỢP CAO SU THIÊN NHIÊN LỎNG CÓ NHÓM HYDROXYL CUỐI MẠCH BẰNG PHƯƠNG PHÁP FENTON QUANG HOÁ 1. NGHIÊN CỨU ẢNH HƯỞNG CỦA CÁC ĐIỀU KIỆN PHẢN ỨNG FENTON QUANG HOÁ

SUMMARY Some reaction conditions of the Photo Fenton process to prepare hydroxyl-terminated liquid natural rubber (LNR-OH), such as pH, H2O2/Fe2+ ratio, reaction time, reaction temperature, initial concentration of natural rubber (NR)  have been investigated in detail. It was shown that at pH ~ 3,  H2O2/Fe2+ ratio ~ 1,5, concentration of NR ~ 5%, T ~ 35 oC the Photo Fenton process took place the best resulting in the formation of LNRs-OH, that have Mv ~ 4,500 and 3,800 after  80 h and 100 h, respectively. Keywords. liquid natural rubbers, Fenton reaction, hydroxyl-terminated liquid natural rubber

Những vấn đề lý luận và thực tiễn về sửa đổi, bổ sung hiến pháp năm 1992 : Sách chuyên khảo

363 tr. ; 21 cm

Spectacular infrastructure and its breakdown in socialist Vietnam

No material resource and public good is more critical to sustaining urban life than water. During postwar reconstruction in Vietnam, planners showcased urban infrastructure as a spectacular socialist achievement. Water-related facilities, in particular, held the potential for emancipation and modernity. Despite East German-engineered systems, however, taps remained dry in socialist housing. Lack of water exposed existing hierarchies that undermined the goal of democratic infrastructure yet enabled new forms of solidarity and gendered social practice to take shape in response to the state's failure to meet basic needs. Infrastructural breakdown and neglect thus catalyzed a collective ethos of maintenance and repair as the state shifted responsibility for upkeep to disenchanted tenants. I track these processes in a housing complex in Vinh City, where water signified both the promises of state care and a condition of its systemic neglect. [materiality, infrastructure, socialist modernity, urbanization, decay, maintenance and repair, water, Vietnam] No material resource and public good is more critical to sustaining urban life than water. During postwar reconstruction in Vietnam, planners showcased urban infrastructure as a spectacular socialist achievement. Water-related facilities, in particular, held the potential for emancipation and modernity. Despite East German-engineered systems, however, taps remained dry in socialist housing. Lack of water exposed existing hierarchies that undermined the goal of democratic infrastructure yet enabled new forms of solidarity and gendered social practice to take shape in response to the state's failure to meet basic needs. Infrastructural breakdown and neglect thus catalyzed a collective ethos of maintenance and repair as the state shifted responsibility for upkeep to disenchanted tenants. I track these processes in a housing complex in Vinh City, where water signified both the promises of state care and a condition of its systemic neglect