Thermal Stability of Poly （acrylonitrile-methyl acrylate） Copolymers

Poly （ acrylonitrile-methyl acrylate） copolymer was synthesized by water depositing polymerization and has a typical feed ratio of 85/15. And then 1 - 3 wt% lauryl alcohol maleic anhydride （LAM） was adopted as stabilizer to mix with the acrylonitrile based copolymer. The mixtures were characterized by using Fourier Transform Infrared Spectroscopy （FTIR）, Nuclear Magnetic Resonance （1 H NMR ）, Gel Permeation Chromatography （ GPC ）, Differential Scanning Calorimetry （DSC）, optic microscope and Ubbelohde viscosimetryr etc. The melting point （Tm） and glass transition temperature （Tg） of the 85/15 AN/MA copolymer mixed with LAM all decrease with the increase of stabilizer content. The lowest Tg and Tm were 116.1℃ and 209. 1℃ respectively at the heating rate of 100℃/min when the content of LAM is 2 wt%. The 85/15 AN/MA copolymer mixed with 1 - 3 w t% LAM possess good thermal stability up to 30 min at 220 ℃.     

Fabrication and Properties of Microencapsulated n-octadecane and Paraffin

Microencapsulated n-alkanes as energy- storage materials have promising application prospects. The ndcrocapsules containing 100 - 50 wt% of n - octadecane, 0 -20 wt% of paraffin and 0 - 30 wt% of cyclohexane were synthesized by in-situ polymerization using melamine- formaldehyde polymer as shell. Cyclohexane was removed after heat-treated the microcapsules at 100℃. The morphologies, cell parameters, phase change properties, thermal stable temperatures of these microcapsules were examined. The diameters of these microcapsules are lower than 5 μm. The effect of paraffin in the microcapsules on the cell parameters of n-octadecane is negligible. The paraff＇m is effectively used as a nucleating agent to decrease the degree of supercooling. The melting enthalpy is decreased from 132 J/g to 111 J/g due to the increase of the cyclohexane contents. The thermal stable temperature is enhanced 6 - 16℃ after heat-treated the microcapsules at 160℃ for 30 min.