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Preparation of Needle-Like Nano-PS by Emulsion Polymerization under Unnatural Conditions

Author: LiuZuoHong
Tutor: MengQingYun
School: Beijing University of Chemical Technology
Course: Chemical Engineering and Technology
Keywords: Emulsion polymerization Unnatural conditions Electric field PS PP Mechanical Properties
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 29
Quote: 1
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Abstract


With the rapid development of nano-technology, nanomaterials has a wide range of applications in microelectronics,chemical,metallurgy, national defense and pharmaceutical industries because of their unique properties. On to summarize the results of previous research and innovation,the needle-like nano-PS was prepared by emulsion polymerization method under unnatural conditions-electric field conditions. Discussed influencing factors to the stability of polymerization reaction,including the amount of initiator, emulsifier and the change of monomer proportion.Through the experiment, we can obtain the best reaction conditions to prepare the copolymer.The monomer conversion is higher when the amount of initiator at 0.4%.With the increasing of initiator, the stability of emulsion polymerization enhanced and the monomer conversion increased when the amount of initiator is constant. The conversion rate achieved 42.87% for the maximum, when the quality of emulsifier accounted for 4% of monomer. With the change of ratio,the molecular weight gradually decreased, but the polymer particle size all less than 100nm.So it has little effect on the particle size. The conversion rate was affected,when the ratio of oil phase changed. The conversion rate reached the maximum,when 20% oil phase existed,and with the ratio of oil further increase,the emulsion was instability. Polymerization temperature was controlled at 70℃-75℃,and the best reaction time is 5h under certain stirring speed.Polypropylene is a general thermoplastic which has excellent overall performance, but its high brittleness and bad toughness limit its scope of application. Self-made needle-like nano-PS was added to PP as a modifier,studying its mechanical properties. The addition of nano-PS powder can improved mechanical properties of PP. The result shows that its tensile strength are up18.69% and gap impact strength are up 77.7% with its bending strength constant.The best amount of the powder was 2%.

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