The Future of Plasticizers: Biobased and Oligomeric

The deficiencies of popular phthalate plasticizers(ready migration from a polymer matrix into which they have been incorporated,flammability,environmental pollution,human health risks)have stimulated efforts to develop new effective,nonmigrating,low-cost,nontoxic replacements.In the main,these have been based on readilyavailable,nontoxic biobased precursors.Some,including those prepared from plant oils,have been generated from biomaterials themselves.However,the more numerous and generally more effective have been generated from discrete compounds produced from various biomaterials.Several structural features of effective plasticizers have been recognized.Polar functionality is required to assure compatibility with a wide range of polymeric materials,including poly(vinyl chloride)(PVC),the most heavily plasticized polymer.A branched structure greatly enhances the effectiveness of compounds used as plasticizers.An oligomeric structure may strongly limit or prevent migration from a polymer matrix.Hyperbranched oligomers of defined structure derived from the readilyavailable,inexpensive,nontoxic biomonomers,glycerol and adipic acid contain all these features and are excellent plasticizers.They contain ester functionality,are highly branched,and display a large number of end groups,all of which contribute to their effectiveness as plasticizers.

Combustion of nitrate ester plasticized polyether propellants

Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism different from both double-base propellants and composite propellants.In order to study the combustion mechanism of NEPE propellants,we improved the free radical cracking model of previous research to make it capable of predicting the burning rate of NEPE propellants.To study the combustion characteristics and provide data support for the model,an experimental system was built and four kinds of NEPE propellants with different compositions and grain size distributions were tested.The results show that our modified model can reflect the combustion characteristics of NEPE propellants with an acceptable accuracy.The difference between the model and the experimental data is mainly caused by uncertain environmental factors and the ignorance of interactions between components.Both the experimental data and the results predicted by the model show that increasing the backpressure helps to increase the burning rate of NEPE propellants.Furthermore,the grain size of the oxidizer inside the NEPE propellant has a more severe impact on the burning rate but a lighter impact on the burning rate pressure exponent in comparison with the grain size of aluminum.For aluminum-free NEPE propellants,the reaction in the gas phase is dominant in the combustion process while adding aluminum into the propellant makes the solid phase dominant in the final stage.The combustion of fine aluminum particles near the burning surface generates heat feedback to the burning surface which evidently influences the surface temperature.However,the agglomeration of coarse aluminum particles has little effect on the burning surface temperature.

Analysis of the influencing factors of PAEs volatilization from typical plastic products

The primary emphasis of this research was to investigate the foundations of phthalate（PAEs） pollutant source researches and then firstly confirmed the concept of the coefficient of volatile strength, namely phthalate total content in per unit mass and unit surface area of pollutant sources. Through surveying and evaluating the coefficient of volatile strength of PAEs from typical plastic products, this research carried out reasonable classification of PAEs pollutant sources into three categories and then investigated the relationship amongst the coefficient of volatile strength as well as other environmental factors and the concentration level of total PAEs in indoor air measured in environment chambers.Research obtained phthalate concentration results under different temperature, humidity,the coefficient of volatile strength and the closed time through the chamber experiment. In addition, this study further explored the correlation and ratio of influencing factors that affect the concentration level of total PAEs in environment chambers, including environmental factors, the coefficient of volatile strengths of PAEs and contents of total PAEs in plastic products. The research created an improved database system of phthalate the coefficient of volatile strengths of each type of plastic goods, and tentatively revealed that the volatile patterns of PAEs from different typical plastic goods, finally confirmed that the coefficient of volatile strengths of PAEs is a major factor that affects the indoor air total PAEs concentration, which laid a solid foundation for further establishing the volatile equation of PAEs from plastic products.