来源网址：http://www.rsoau.com 2019-02-19 14:21:36
Carbon dioxide emission reduction and plastic biodegradation are two environmental hot spots that people pay attention to. If there is a skill to achieve these two goals together, how happy!
In fact, converting carbon dioxide into biodegradable plastics is no longer desirable.
Structurally, carbon dioxide can be regarded as carbonic anhydride with unsaturated bonds. Therefore, it is possible for carbon dioxide to form polymer data with other monomers in suitable catalysts.
However, although carbon dioxide can react with dozens of compounds to synthesize copolymers, most of the polymers remain at the level of laboratory curiosity because of the low activity and selectivity of catalysts, as well as the difficulty in comparing the thermostability and mechanical properties of the obtained polymers with the existing industrial products.
So far, as long as the copolymers of carbon dioxide and epoxides, especially carbon dioxide and propylene oxide copolymers (PPC), have good biodegradability, relatively low cost, and many use carbon dioxide, the carbon dioxide content in the polymer exceeds 40%, so it has been highly valued.
The advantages of PPC are that it can be composted and degraded completely within 6 months, while traditional plastics usually do not have biodegradable function. At room temperature, the oxygen resistance of PPC plastic film is better than that of nylon and PET (polyethylene terephthalate).
Since the copolymerization of carbon dioxide and epoxides was completed in 1969 by Japanese scientist Akihiro Inoue, many catalytic systems have been developed to form PPC.
Thermodynamic function gap is the biggest development resistance
But now, the industrialization of PPC is still in its infancy. What prevents its industrialization?
For industrial products, the cost and production cycle of polymers are very important. The industrial production of carbon dioxide copolymers has been constrained by the high cost of catalysts, long polymerization cycle and low physical properties of polymers.
However, careful analysis, cost is not the main problem of carbon dioxide-based plastics now facing. In terms of the rare earth ternary catalyst technology developed by Changchun Yinghua Institute of Chinese Academy of Sciences, the cost of catalyst per ton of carbon dioxide plastics is less than 1500 yuan, the cost of synthesis is only 20% to 30% higher than that of polyethylene, and the investment planning is much smaller than that of polyolefin.
Compared with other biodegradable plastics, PPC contains more than 40% carbon dioxide, which is the lowest cost of biodegradable materials. It helps to deal with the cost bottleneck that restricts the development of biodegradable plastics for a long time. Because the existing PPC production equipment planning is small, there is no planned benefit, resulting in its price is still at a higher level compared with general plastics.
With the improvement of process packages and the large-scale planning and application of new efficient and highly selective catalysts, the planned benefits of large-scale production equipment will contribute to the further reduction of cost. It is reasonable to believe that PPC will be competitive in terms of cost performance even when compared with other materials such as polyolefins.
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