| Polylactic acid is a non-petroleum based polymer, widely source of raw materials, and has good mechanical properties and physical properties, suitable for blow molding, hot forming and other processing methods. With the degree of polymerization (weight) of the PLA is different, it's application range is very wide. It is expected to replace polyvinyl chloride (PVC), polyethylene Propylene (PP), polystyrene, polyester and other polymer materials that are petroleum based and non-biodegradable,and used to produce plastics, film, fiber, medical suture Products. The application is very promising. In recent years, with the expansion of the scope of its application, fire hazards are increasing. Carries on the flame retardant modification and fire hazard research is becoming more and more important.First, this paper prepars flame retardant polylactic acid composites adopting PLA and halogen-free flame retardants (phosphate, ammonium polyphosphate, expandable graphite) for solution mixing and by the way of changing the ratio between flame retardants and the PLA. Through the oxygen index test, the vertical burning test, Smoke density test, we studied flame retardant properties and fire risk,of polylactic acid. Also we Analys flame retardant mechanism by observing the charcoal layer after combustion using Scanning electron microscope. The results show that expandable graphite fire retardant on the polylactide effect is not good, because that the PLA between the expanded graphite swelling up already melting when the expanded graphite after the expansion, so it can not cover up the surface of poly lactic acid, which fail to flame retardant effect. The two kinds of phosphorus flame retardant on the PLA has good flame-retardant effect, while adding more than 8%, V-0 can burn through the vertical level, in particular, When the TPP content is 15%, its oxygen index is as high as 38.6. However, with the flame-retardant effect of the increase in smoke density also increased, when the content is 15% of TPP, MSD (maximum smoke density) is reached 64.33.Second, as polylactic acid into carbon is poor, the author examines adding a kind of Substance that not only to increase its mechanical properties, but also as a charring agent polymer material-polycarbonate (PC). In order to determine whether the PC can play the role as carbon and increase the efficiency of flame retardant, PC and resistance measured by different flame retardants (phosphate, ammonium polyphosphate) in different proportions on the combustion properties of polylactic acid. The results show that the addding PC-retardant polylactic acid, can not achieve the vertical combustion V-0 level due to the combustion of materials with the fire after the drip and igniting absorbent cotton. But the total time from the vertical burning and oxygen index can be seen, PC's to join in the APP-PC-PLA system, played a polymer charring agent. That in PC/APP= 2:8,PC's into a carbon of the best and the oxygen index more than 10% of APP dosage of oxygen index. And the PC's accession to the APP-PC-PLA system is not a smoke effect, but will increase the TPP-PC-PLA system's smoke, therefore if we can resolve to change the combustion of polylactic acid series dripping with the fire problem can find the smallest risk of fire retardant polylactic acid.
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