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Professor: Cheng-Ho Chen Graduate: Po-Huei Tseng Date: 101.12.19. Outline. Introduction Experiment Results and Discussion Conclusions References. Introduction(1).
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Professor: Cheng-Ho Chen Graduate: Po-Huei Tseng Date: 101.12.19
Outline • Introduction • Experiment • Results and Discussion • Conclusions • References
Introduction(1) • Ionomers: macromolecules composed of a small but significant proportion of constitutional units (less than 10%) containing an ionic and/or ionizable group. • The ionic groups cause a micro-phase separation of the ionic moieties (ionic aggregation) within the non-ionic matrix and act as physical crosslinks. • Ionomers of low glass-transition non-crystalline polymers can be used as ionic thermoplastic elastomers (TPEs) if the ionic aggregates are sufficiently weakened at the processing temperatures.
Introduction(2) • TPEs: melt-processable polymers composed of a continuous elastomeric phase. • Both the precursor elPP-g-MA and the ionomers were synthesized by melt-processing. • The neutralization reaction was monitored by infrared spectroscopy and a method is proposed to determine the effective neutralization degree (ND). • Various forms of sodium hydroxide and sodium acetate were used to compare their efficiency of elPP-g-MA neutralization.
Outline • Introduction • Experiment • Results and Discussion • Conclusions • References
Characterization • Quantification of the grafted species • Differential scanning calorimetry (DSC) • Size exclusion chromatography(SEC) • Fourier transform infrared (FTIR) spectroscopy • Thermogravimetric analysis (TGA) • Rheological properties
DSC • Crystallinity and Tg of elPP-g-MA and ionomers: evaluated from a second heating ramp from -50 to 220℃ at 10℃/min. • The device was calibrated with indium and zinc.
SEC • The mobile phase: 1,2,4-trichlorobenzene(TCB) • The concentration of the sample: 2 mg/mL in TCB • dissolution: shaking at 160℃ for 1 h • The injection volume: 215 μL • Temperature: held constant at 145℃
FTIR • the peak height of the 973 cm-1 absorption band to an absorbance of 1 • The frequency range of absorption bands area: 1.carbonyl of the anhydride (1750-1830 cm-1) 2.carbonyl of the carboxylic acid (1650-1750 cm-1)
TGA • heating rate: 10℃/min under air atmosphere(100 mL/min) • temperature: 25-600℃
Rheological properties Equipment: Rubber Process Analyser RPA 2000, Alpha Technologies Frequency sweep tests: performed at 120℃ at a strain rate of 10% over an angular frequency ranging from 300 to 1 rad/s
Outline • Introduction • Experiment • Results and Discussion • Conclusions • References
elPP-g-MA Characterization The degradation of the molar mass is caused by a side reaction, β-scission, occurring during the functionalization. The crystallinity of elPP-g-MA is strongly reduced with respect to the starting PP, due to the epimerization reaction occurring in the presence of peroxide and NBS.
Ionomer ND determination(2) 1790 1715 1570 1863
Ionomer ND determination(3) • If the ND were calculated on the basis of the decrease of the anhydride band at 1790 cm-1 from elPP-g-MA (AanhelPP-g-MA) to ionomer (Aanhionomer), it would be overestimated due to the carboxylic acid functions contribution.
Influence of the nature of the base on ND NaOH 2.5 M > NaOH sol. ≒ NaAc*3H2O sol. > NaAc 2.5 M > NaAc. anh. sol.
Ionomer Characterization • DSC • TGA • Rheology
DSC • elPP-g-MA: Tg is around -4.2℃ and a weak broad melting peak. • Ionomers: only Tg • Tg for all the ionomers are similar to the one of elPP-g-MA.
Conclusions • The choice of the base has a strong influence on the neutralization degree. • As the neutralization yield never reaches 100%, the excess of the added sodium hydroxide may lead to corrosion. • Sodium acetate is preferred over sodium hydroxide. • The thermal stability in air atmosphere, shear storage modulus and complex viscosity in the flow region were largely increased as a function of the neutralization degree.
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