Mezzasalma SA
Materials Science and Engineering Institute, University of Genoa, C.so Perrone 24A, Genoa, 16161, Italy
J Colloid Interface Sci. 1997 Nov 1;195(1):51-8. doi: 10.1006/jcis.1997.5094.
A percolation-based thermodynamical model was able to predict the break-down of bimodal PMMA + I solid particle packings (P-MMA, polymethylmethacrylate; I, solid phase inert to MMA polymerization) due to the polymerization process of the MMA monomers. By slip casting of biphasic PMMA + I aqueous suspensions, homogeneous samples of polymethylmethacrylate and various inert solid aggregates (I = Ca3(PO4)2, ZrO2, Si3N4, and Al2O3) were prepared and embedded in liquid methylmethacrylate to start the kinetics of the network formation. For any I component, breakdown of samples did not occur in well defined PMMA mass concentration ranges, which were strongly related to the signs of PMMA and I surface charges (i.e., isoelectric points) of the aqueous solid monodispersed systems. As application of percolation theory in composite materials suggest, when the samples resisted the polymerization kinetics the occurrence of a percolative behavior was expected. Accordingly, the model was performed by dealing thermodynamically with the physicochemical features of the starting aqueous suspensions (e.g., adsorption from solution at the solid/liquid interface and solid agglomeration) at the percolation threshold in bicontinuous PMMA + I systems during the progress in the polymerization reaction. Thresholds have been regarded as percolation of cubic units and related to the sign of the solid PMMA and I surface charge in aqueous monodispersed systems, namely, to the attractive, neutral, repulsive character of the electrostatic interparticle forces. Once site percolation thresholds were correctly estimated it was shown that the assumption of percolation is compatible with the theoretical model when the solid PMMA mass concentration values are ranging just in the critical ranges experimentally obtained. Copyright 1997 Academic Press. Copyright 1997Academic Press
基于渗流的热力学模型能够预测由于甲基丙烯酸甲酯（MMA）单体的聚合过程导致的双峰聚甲基丙烯酸甲酯（PMMA）+I固体颗粒填料（P-MMA，聚甲基丙烯酸甲酯；I，对MMA聚合呈惰性的固相）的分解。通过对双相PMMA+I水悬浮液进行注浆成型，制备了聚甲基丙烯酸甲酯和各种惰性固体聚集体（I =磷酸钙、氧化锆、氮化硅和氧化铝）的均匀样品，并将其嵌入液态甲基丙烯酸甲酯中以启动网络形成动力学。对于任何I组分，在明确的PMMA质量浓度范围内样品不会发生分解，该范围与水性固体单分散体系中PMMA和I表面电荷的符号（即等电点）密切相关。正如渗流理论在复合材料中的应用所表明的，当样品抵抗聚合动力学时，预计会出现渗流行为。因此，该模型通过在聚合反应进行过程中，在双连续PMMA+I体系的渗流阈值下，对起始水悬浮液的物理化学特征（例如，在固/液界面处从溶液中的吸附和固体团聚）进行热力学处理来执行。阈值被视为立方单元的渗流，并与水性单分散体系中固体PMMA和I表面电荷的符号相关，即与颗粒间静电力的吸引、中性、排斥特性相关。一旦正确估计了位点渗流阈值，结果表明，当固体PMMA质量浓度值仅在实验获得的临界范围内时，渗流假设与理论模型是兼容的。版权所有1997年学术出版社。版权所有1997年学术出版社
