Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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  • Article
    Citation - Scopus: 2
    Film-Formation Property of Vinylidene Chloride-Methyl Methacrylate Copolymer Latex. Ii. Effect of Latex Storage Temperature
    (2002) Cai,W.D.; Ramesh,N.; Tihminlioglu,F.; Danner,R.P.; Duda,J.L.; Dhaan,A.
    Changes in the minimum film-formation temperature (MFFT) of 91:9 wt% vinylidene chloride (VDC)-methyl methacrylate (MMA) latex prepared by the seeded batch process during storage at 5, 20, and 40°C were investigated. MFFT of the latex rose the fastest at 20°C. Infrared absorption of fresh and stored latexes and wide-angle X-ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes indicated a much greater increase in polymer crystallinity during latex storage at 20°C than at 5 and 40°C. Observed increases in MFFT during latex storage correlated with increases in polymer crystallinity. Infrared absorption of polymer stored at 5-60°C in the dry state, such as lyophilized polymer and coating film, indicated that a polymer crystallinity increase was greater during storage at higher temperatures. These results showed that crystallization behavior of 91:9 wt% VDC-MMA copolymer latex differed from that of VDC-MMA copolymer in the dry state.
  • Article
    Citation - WoS: 17
    Citation - Scopus: 18
    Crystallization of Poly(vinyl Alcohol) During Solvent Removal: Infrared Characterization and Mathematical Modeling
    (John Wiley and Sons Inc., 2007) Wong, Sim-Siong; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.
    Crystallization of semicrystalline polymer films during drying has a significant effect on the rate of solvent removal. Understanding and controlling the crystallization kinetics is important in controlling residual solvent levels and drying kinetics. The degree of crystallinity of the poly(vinyl alcohol) films during multicomponent drying was investigated using Fourier transform infrared spectroscopy (FTIR). The 1141 cm-1 band is sensitive to the degree of crystallinity of the polymer and the growth of intensity of this band was monitored as drying progressed. The results from the FTIR studies were comparable to the results obtained from differential scanning calorimetry. Studies were conducted to test the effect of initial solvent composition (water-methanol mixture), drying temperature, and polymer molecular weight on the rate of crystallization and the final crystallinity of the films. An increase in initial methanol composition increased the crystallization rate but did not affect the final degree of crystallinity. An increase in drying temperature and decrease in polymer molecular weight increased the rate of crystallization as well as the final degree of crystallinity. Based on the experimental data, rate constants for crystallization kinetics were extracted from our previously developed model based on free volume theory. The experimental data and the simulation results showed good agreement. The ability of the free volume theory to illustrate the crystallization behavior validated the model and improved its capability.