Three-dimensional Fluorescence Quantification Of Inorganic Particle Dispersity For Property Evaluation In Polymer Composites

Polymer composites have been widely used in aerospace,biomedical,electrode and packaging materials,due to their excellent mechanical,electrical and optical properties.Inorganic additives have been used as anti-aging agents and flame retardants to construct functional polymer composites.Inorganic particles are usually present in the polymer matrix as aggregates in different forms.Their dispersion degree will affect the interfacial interaction between the two particles,determining the macroscopic properties of the composites.Quantifying the dispersion of inorganic particles is important for studying the microstructure of composites and optimizing the properties of composites.However,most of the current inorganic particle dispersion evaluation methods are based on two-dimensional images at the nanometer scale,which is difficult to evaluate the overall distribution of inorganic particles.On the other hand,these methods focus on the aggregation state of inorganic particles,while the uniformity of inorganic particle distribution is usually ignored.In order to achieve a three-dimensional quantitative analysis of the inorganic particle dispersion,this paper established a quantitative evaluation method for the three-dimensional dispersion of the inorganic particle in composites through fluorescence localization and three-dimensional imaging.Both the dispersion uniformity and aggregation of the inorganic particles of the inorganic particle were considered in the proposed strategy,and the relationship between the inorganic particle dispersion and the properties of polymer composites was established.The proposed method can be used for the three-dimensional quantitative evaluation of the dispersion of inorganic particle in polymer composites with different film-making processes and different compositions,which provides a basis for exploring the relationship between dispersion and composite properties and optimizing the properties of composites.The details of the study are as follows:1.Fluorescence quantification of inorganic particle dispersity for anti-aging evaluation of polymer composites.In this work,we have established a fluorescent imaging and quantification strategy to evaluate the dispersity of inorganic particles in the polymers,taking layered double hydroxide/low-density polyethylene（LDHs/LDPE）composite as a model system.The dispersity of LDHs particles was regulated by the treatment in acetone.Confocal laser scanning microscopy（CLSM）was employed to provide a three-dimensional visualization of LDH particles,and the volume distributions of LDHs were utilized for the quantification.A comprehensive methodology was performed,taking the standard deviations of the average volume for the uniformity evaluation and aggregation index（A）to assess the secondary sizes of the aggregates.More importantly,a positive correlation has been established between the dispersity of LDH particles and the anti-aging behaviors（manifested as carbonyl index,C.I.）of the composites:C.I.=0.0219+0.0391A.Such a quantitative relationship is beneficial for the process optimization and performance promotion for the polymeric composites.It is believed that this strategy will be further extended for other composites.2.Generalization of the three-dimensional fluorescence quantification method for inorganic particle dispersion in different polymeric composites.In this work,we have applied the proposed strategy in PP-based composites prepared by different approaches,and the effects of preparation process,particle size and particle morphology on the dispersion were studied.The results showed that（1）the inorganic particle of the composites prepared by the micro-nano layer-stacking method showed the best dispersion state,better than solvent reflux and open milling;（2）the LDHs with smaller particle size were more easily aggregated,due to the larger specific surface area and inter-particle force;（3）the spherical Si O₂possessed better dispersion,which can be attributed to the smaller contact area between the spherical inorganic particle particles and smaller interparticle interactions.This method provided new ideas and methods for the evaluation of inorganic particle dispersion in polymer composites of different systems.It is anticipated that this strategy could provide theoretical guidance and technical support for the design and construction of advanced polymer materials.