Polylactic Acid (PLA), the fully biodegradable bio-based polymer, is regarded as the shining candidate to replace many kinds of the petroleum-based plastics. However, the poor heat-resistance and brittleness of PLA turn out to be challengeable for both academic and industrial fields.

Since 2009, Prof. Jin Zhu’s group of the Ningbo Institute of Materials Technology and Engineering (NIMTE), has been focusing on the PLA material innovation. After successfully developing the heat-resistance transparent PLA materials which is the first and only transparent heat-resistance PLA plastic in the world (Heat Resistant Polylactic acid with Good Clarity，2011 ANTEC 2011，Boston.), they switched their interest to how to efficiently and cheaply plasticize the PLA material while keeping the PLA composite fully degradable. Recently, the group has made some attractive progress toward this aim by using the modified starch and plant oil together. The experimental result shows that the toughness and the impact strength of PLA/starch composite have been effectively improved.

The researchers used Hexamethylenediisocyanate (HDI) and Maleic Anhydride (MA) to chemically modify the starch granules respectively, and chose plant oils, like epoxidized soybean oil , castor oil and tung oil anhydride (Fig.1), as soft interfacial layer individually between PLA and starch.

The PLA/starch/Plant oil tri-component composite is then mixed and extruded by the lab-scale extruder. It is very important to keep proper plant oil content. The mechanical property could not be improved that much if the plant oil concentration is either lower or higher than the optimal value, at which the elastic and smooth oil layer is formed between PLA and starch granules.

Three papers about the progresses have been published in Carbohydrate Polymers (2013, 92: 810– 816; 2013, 94: 235– 243; 2013, 95: 77-84)

Professor Jin Zhu jzhu@nimte.ac.cn

Research Gruop Url : http://english.nimte.cas.cn/rh/rd/bp

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