유변학적 물성 측정을 통한 폴리에틸렌의 다분산성 예측

박천일; 박오옥

Korean Journal of Rheology, Vol.10, No.3, 137-142, September, 1998

Export Citation

유변학적 물성 측정을 통한 폴리에틸렌의 다분산성 예측

Estimation of Polydispersity of Polyethylenes via Rheological Properties

박천일, 박오옥

초록

유변물성 자료로부터 고분자의 다분산성을 예측하는 방법은 신속한 중합반응 공정제어를 위해서 중요한 연구분야중 하나이다. 본 연구에서는 다양한 분자량과 분자량 분포를 가진 폴리에틸렌에 대해 Shroff와 Mavridis가 제시한 다분산성 매개변수 ER과 ET를 구하고, 겔투과 크로마토그래피(GPC)에서 얻은 M_w/M_n과의 상관관계를 조사하였다. ER은 M_w/M_n과 비례적인 상관관계를 보여주었으나 ET는 상관성이 없는 것으로 나타났다. ER값에는 분자량 분포도 외에 LCB(long chain branch)의 영향도 큰 것으로 나타났다. 또한 분자량 분포중에서 고분자량 부분의 미미한 변화에도 ER이 크게 변해 GPC보다 다분산성의 변화를 더 민감하게 예측할 수 있었다.

Quantification and prediction of polydispersity of polymers from rheological properties is an important research area for the control of polymerization process In this study polydispersity parameters ER and ET proposed by Shroff and Mavridis were obtained from rheological properties for various polyethylenes with different molecular weights and their distribution. These Polydispersity parameters have been tried to correlate with M_w/M_n obtained from GPC (Gel Permeation Chromatography). ER increased with the increase of M_w/M_n, whereas ET did not show any correlation with M_w/M_n. Especially long chain braches of polyethylene affect the ER value significantly. In addition, even small change of high molecular weight portion in their distribution has a dramatic effect on the ER value, which leads to the conclusion that rheological polydispersity parameter, ER can detect the variation of polydispersity more sensitively than GPC data.

Keywords:Molecular Weight Distribution;Polydispersity;Polyethylene;Viscoelasticity;Storage Modulus;Loss Modulus

[References]

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[1] Bird RB, Armstrong RC, Hassager O, "Dynamics of Polymeric Liquids," 2nd ed., John Wiley and Sons (1987)

[2] Tuminello WH, Polym. Eng. Sci., 26, 1339 (1986)

[3] Bersted BH, Slee JD, J. Appl. Polym. Sci., 21, 2631 (1977)

[4] Woodadams PM, Dealy JM, J. Rheol., 40(5), 761 (1996)

[5] Zeichner GR, Patel PD, Second World Congress of Chemical Engineering, Montreal (1981)

[6] Yoo HJ, Adv. Polym. Technol., 13(3), 201 (1994)

[7] Shroff R, Mavridis H, J. Appl. Polym. Sci., 57(13), 1605 (1995)

[8] Ferry JD, "Viscoelastic Properties of Polymers," 3rd Ed., John Wiley and Sons (1980)

[9] Han CD, Lem KW, Polym. Eng. Rev., 2, 135 (1982)

[10] Han CD, Jhon MS, J. Appl. Polym. Sci., 32, 3809 (1986)

[11] Han CD, Kim JK, Macromolecules, 22, 4292 (1989)

[12] Wasserman SH, Graessley WW, Polym. Eng. Sci., 36(6), 852 (1996)

[13] Nunes RW, Martin JR, Johnson JF, Polym. Eng. Sci., 22, 205 (1982)