Crystallization behavior of PLA in PLA/NR compared with dynamic vulcanized PLA/NR

Authors

  • Chanchai Thongpin Faculty of Engineering and Industrial Technology, Silpakorn University
  • Sitthikorn Klatsuwan Faculty of Engineering and Industrial Technology, Silpakorn University
  • Pongkuan Borkchaiyapoom Faculty of Engineering and Industrial Technology, Silpakorn University
  • Saraya Thongkamwong Faculty of Engineering and Industrial Technology, Silpakorn University

Abstract

PLA has been an interesting biopolymer widely used in various applications. It has been widely known that crystallization of PLA is rather slow. After melt processing, crystallinity of PLA could be lost. The study of PLA added with fibers, particles or even nano-particles has been studied extensively. Nonetheless, the suffering in some mechanical characteristic such as toughness has been encountered. Our research was aimed to enhance toughness of PLA by melt blending NR, and dynamic vulcanized NR into PLA using an internal mixer. PLA:NR and PLA:NR vulcanizate with the ratio of 90:10, 80:20, 70:30, 60:40 and 50:50 were studied. Crystallization behavior and thermal stability of the blend were investigated using DSC and TGA respectively. It was found that, for the former systems, at low content of NR, i.e. 10-30 %, rubber particles were found to be presented as spherical disperse phase in PLA. Meanwhile at higher content, such as 40-50 % NR, polymers were found as co-continuous. Having NR in PLA did not affect Tg of the plastic but could induced cold crystallization and subsequently the crystallinity of the plastic. This resulted in the change of melting temperatures of PLA. Surprisingly, at the temperature higher than Tm of PLA, exothermic behavior upon heating was found, at the content at 10-30 % of NR. This is the cross polymerization between NR and PLA molecule and cause the rapidest degradation temperature of polymer blend to be increased. In the case of PLA:NR vulcanizate, dispersed NR particles were also present in PLA continuous phase. But the particles were found larger at the higher content of NR. The effect of NR particle onto the crystallization of PLA was found to be similar to the previous case. However, the cross polymerization between two polymers was not found in DSC thermograms. This also resulted in the two distinct degradation steps in the blends and less stability of PLA upon TGA than the previous system.

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References

Madhavan Nampoothiri, K., Nimisha Rajendran, Nair., Rojan Pappy, John. (2010). An overview of the recent developments in polylactide (PLA) research. Bioresour. Technol. 101(22) : 8493-8501.

Conn, R. E., Kolstad, J. J., Borzelleca, J. F., Dixler, D. S., Filer Jr, L. J., LaDu, Jr., B. N. and Pariza, M. W. (1995). Safety Assessment of Polylactide (PLA) for Use as a Food-contact Polymer. Food Chem. Toxicol. 33(4) : 273-283.

Hassan,Azman.,Wahit, Mat Uzir.,Balakrishnan, Harintharavimal.,Yussufa, A. A., Abdul Razak and Shamsul Bahri.(2010). Novel toughened polylactic acid nanocomposite : Mechanical, thermal and morphological properties. Mater. Design. 31(7) : 3289-3298.

Tetsuo, Takayama and Mitsugu, Todo. (2006). Improvement of impact fracture properties of PLA/PCL polymer blend due to LTI addition. J Mater Sci. 41(15) : 4989-4992.

Myung Chan Kim, T.M. (2009). Degradation properties of PLA and PHBV films treated with CO2-plasma. React. Funct. Polym. 69 : 287-292.

Yu, L., Dean, K. and Li, L. (2006). Polymer blends and composites from renewable resources. Prog. Polym. Sci. 31(6) : 576-602.

Kajornchaiyakul, V. (2006). Natural rubber : Prodution and Applications. Bangkok: The Thailand Research Fund (TRF).

Kajornchaiyakul, V. and Na-Ranong, N. (2002). Rubber Technology Handbook. Bangkok : Rubber Research Institute Of Thailand.

Bitinis, N., Verdejo, R., Cassagnau, P., and Lopez-Manchado, M. A. (2011). Structure and properties of polylactide/natural rubber blends. Mater. Chem. Phys. 129(3) : 823-831.

Holden, G. (2000). Understanding Thermoplastics Elastomers. Munich : Hanser Gardner Publications.

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Published

2013-06-30

How to Cite

[1]
C. Thongpin, S. Klatsuwan, P. Borkchaiyapoom, and S. Thongkamwong, “Crystallization behavior of PLA in PLA/NR compared with dynamic vulcanized PLA/NR”, J Met Mater Miner, vol. 23, no. 1, Jun. 2013.

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Original Research Articles