The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of the b-PP was increased with increasing the initiator content. On the introduction of the a...
The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of the b-PP was increased with increasing the initiator content. On the introduction of the alkylamine as the branching agents the MFI of the b-PP was increased, while that of the b-PP with the pentaerythritol triacrylate (PT) was decreased. It may be caused by the chain scission of the i-PP backbone due to the reduced thermal stability of the i-PP on the melt blending. The MFI of the b-PP without the antioxidant was increased due to the chain scission occurred during the melt processing, while on the introduction of the antioxidant, the MFI of the b-PP was decreased. The crystallization temperature of the b-PP was higher than that of PP, which was attributed to the branched chain structure. It was found that the PT was the most effective functional monomers for enhancing the melt properties of the b-PP.
The branched polypropylene (b-PP) was prepared by melt blending process with initiator, antioxidant, and functional monomers to improve the melt strength through the melt grafting. The melt flow index (MFI) of the b-PP was increased with increasing the initiator content. On the introduction of the alkylamine as the branching agents the MFI of the b-PP was increased, while that of the b-PP with the pentaerythritol triacrylate (PT) was decreased. It may be caused by the chain scission of the i-PP backbone due to the reduced thermal stability of the i-PP on the melt blending. The MFI of the b-PP without the antioxidant was increased due to the chain scission occurred during the melt processing, while on the introduction of the antioxidant, the MFI of the b-PP was decreased. The crystallization temperature of the b-PP was higher than that of PP, which was attributed to the branched chain structure. It was found that the PT was the most effective functional monomers for enhancing the melt properties of the b-PP.
* AI 자동 식별 결과로 적합하지 않은 문장이 있을 수 있으니, 이용에 유의하시기 바랍니다.
가설 설정
The absorption peak (Ig) observed at 840 cm'1 was attributed to the C-CH3 vibration in the z-PP backbone. The ratio of the relative absorbance between the Ipr and L_pp (IpT/0pp) for the b-PP was shown in Figure 6. The PT incorporated by recombination reaction such as branching or crosslinking would influence significantly the relative intensity of that. The ratio of the relative absorbance peaks (WL-pp) was increased with PT content, which suggested that more PT content might enhance the recombination reaction between the z-PP and PT [24].
6. The melting temperature (Tm), crystallization temperature (Tc), and the enthalpy of the crystallization (Hc) for the z-PP were 163 ℃, 108 ℃, and 93 J/g, respectively. The variations of the Tc for the b-PP with the branching agents are shown in Figure 7.
The melting temperature (Tm), crystallization temperature (Tc), and the enthalpy of the crystallization (Hc) for the z-PP were 163 ℃, 108 ℃, and 93 J/g, respectively. The variations of the Tc for the b-PP with the branching agents are shown in Figure 7. The introduction of the alkylamine (DA, OA, and HA) have no significant effect on the thermal properties of the z-PE and the Tc of the Z?-PP was slightly higher that that of the Z-PP on the addition of the branching agents having aliphatic alkyl chains. However, on the introduction of the PT, the Tc was significantly increased up to 122 ℃ with increasing the content.
that the Tc of the b-PP was higher than that of the linear PP at the same TREF elution temperature and the nucleation density of the Z?-PP was much higher than that of the linear precursor [31], and they suggested that the increase in the Tc may result from the increased nucleation density by the branching or crosslinking of the linear PP. The variations of the Tc with the content and the type of the branching agents are shown in Figures 8. The Tc of the b-PP was higher than that of the z-PP and was increased with PT content. It could be seen that the PT having the tertiary structure had significant effect on the Tc of the z-PP compared with the alkylamines (DA, OA, and HA) having the linear structure.
b)The value oftotal torque for 5 min during the melt blending.
제안 방법
The z-PP was melt blended with different I-MB contents to investigate the effect of the chemical reaction by the z-PP and organic peroxide on the apparent and thermal characteristics of the melt blends. As the reaction time was increased from 5 min to 15 min, the amount of bubble was increased, which was caused by the oxidation reaction by organic peroxide.
대상 데이터
, and it has a melt flow index (MFI) of 7 g/10 min. The initiator masterbatch (I-MB) of commercial grade Perkadox 14S which contains 10 wt% of bis(t-butyl-peroxy-i-propylbenzene) was used as the initiator. Dodecylamine (DA), hexadecylamine (HA), octadecylamine (OA), trimethylolpropane triacylate (TT), pentaerythritol triacrylate (PT), and thiourea (TU) used as the branching agents in this research were purchased from Aldrich Co.
이론/모형
The MFI measurement was carried out in a Dynisco melt indexer at 190 ℃ using a load of 2.16 kg according to the ASTM-D1238 standard. The gel content was determined by extracting the soluble portion with p-xylene in a Soxhlet at 140 ℃ for 2 hr in accordance with the ASTM-D2675 standard.
성능/효과
It was expected that the value of the MFI for the b-PP was lower than that of the z-PP because of the high viscosity in the molten state and the network structure formed on the introduction of the branching or crosslinking in the main chain. The changes of the MFI of the b-PP with various branching agents are shown in Fig나re 1, and the compositions with the content and type of the branching agent are presented in Table 2. It was reported that the value of the MFI was increased irrespective of the content of the branching agent when the I-MB content was over 0.2 wt%, while at lower content of the I-MB the MFI was decreased with increasing the content of the branching agent [24]. Thus, the I-MB content of 0.
Usually, as the branching or crosslinking was occurred in the z-PP backbone, it was expected that the value of the MFI was lower than that of the MFI of the z-PP due to the higher melt viscosity and network structure. However, the value of the MFI of the b-PP with the branching agents such as DA, HA, and OA was increased significantly as shown in Figure 2. The MFI of the b-PP with PT was decreased down to 10.8 g/10 min with increasing PT content and was higher than that of the z-PP (7.9 g/10 min), which was attributed to the chain scission by the oxidation of the i-PP backbone. Therefore, the TP and TM as the antioxidant in this research were added to the b-PP for preventing the chain scission by the oxidation reaction of the z-PP main chain, and their chemical structures were shown in Figure 3.
in Table 3. It could be seen that there was no evidence of any gel formation on the introduction of the DA, OA, and HA regardless of the content of the branching agent, which indicated that on the introduction of the branching agents having the aliphatic alkyl chains the gel was not formed irrespective of the chain length. For the Z?-PP with PT, no formation of the gel was occurred below the content of 0.
Also, the 1 wt% TP and 1 wt% TM were simultaneously added to the b-PP because the introduction of both the phenol-based TM and phosphorous-based TP could improve the thermal stability [25]. The variations of the MFI of the b-PP with PT content are 아】own in Figure 4. For the b-PP with DA, HA, and OA, the introduction of the antioxidant has no significant effect on the value of the MFI. However, on the addition of the antioxidant, the MFI of the b-PP with PT was decreased, and that of the MFI for the b-PP with PT, TT, and antioxidant was significantly decreased down to 5.
However, the melt blends with both the initiator and branching agent exhibited the increase in the viscosity and the decrease in the MFI, and those values were higher than those of the i-PP. From the above results, it may be concluded that the amount of organic peroxide and the type of the branching agent can significantly influence the branching of the i-PP, and that the excessive addition of the I-MB may cause the chain scission of the z-PP backbone, resulting in both the decrement of the molecular weight and the increment of the amount of bubble. It was expected that the value of the MFI for the b-PP was lower than that of the z-PP because of the high viscosity in the molten state and the network structure formed on the introduction of the branching or crosslinking in the main chain.
The Tc of the b-PP was higher than that of the z-PP and was increased with PT content. It could be seen that the PT having the tertiary structure had significant effect on the Tc of the z-PP compared with the alkylamines (DA, OA, and HA) having the linear structure. This result was attributed to the nucleating effect of the PT incorporated in the b-PP, resulting in the increment of the Tc.
참고문헌 (36)
B. K. Kim and C. H. Choi, J. Appl. Polym. Sci., 60, 2199-2206(1996)
J. L. Throne in 'Thermoforming', Hanser Publishers, Munich, Vienna, New York, 1987
D. V. Rosato in 'Blow Molding Handbook', Hanser Pub-lishers, Munich, Vienna, New York, 1987
J. N. McDonald in 'Encyclopedia of Polymer Science and Engineering', 2nd ed. (H. F. Mark, N. M. Bikales, C. G. Overberger, and G, Menges Eds.), Vol. 16, p.807, John Wiley & Sons Inc., New York, 1989
E. Kokko, A. Malmberg, and J. V. Seppala, J. Polym. Sci., Part A, Polym. Chem., 38, 676 (2000)
T. Noma, T. Murata, Y. Masubuchi, J. Takimoto, and K. Koyama, Polym. Prep. Jpn., 46, 3829 (1997)
S. Lieber and H. H. Brintzinger, Macromolecules, 33, 9192？9199 (2000)
A. J. DeNicola, A. F. Galambos, and M. D. Wolkowicz in 'Polymeric Materials Science and Engineering', ACS Fall Meeting, Vol. 67, p.106, Washington DC, USA, 1992
F. Rybnikar, L. Pospisil, and J. Jankar, J. Mater. Sci. Lett., 9,499 (1990)
A. R. Oromehie, S. A. Hashemi, I. G. Meldrum, and D. N. Waters, Polym. Int., 42, 117 (1997)
※ AI-Helper는 부적절한 답변을 할 수 있습니다.