Inorganic filler (silica and alumina, etc.) is widely used in polymer composites to improve various physical properties of the materials, such as mechanical strength and modulus, rigidity and heat-resistance. At the same time, the cost of the ...
Inorganic filler (silica and alumina, etc.) is widely used in polymer composites to improve various physical properties of the materials, such as mechanical strength and modulus, rigidity and heat-resistance. At the same time, the cost of the polymer composites can be greatly decreased by replacing the volume of expensive resin with cheap fillers. It is often necessary to treat filler with surface-modifying agents such as silane and titanate coupling agents in order to obtain improved dispersibility, mechanical and electrical properties, water resistance and reinforcement in plastics systems. In this study, we chose silane coupling agents as surface-modifying agents for the inorganic fillers such as crystalline silica, fused silica and alumina. And the inorganic fillers were subjected to surface treatment with the following four types silane coupling agent: MTMS (γ-methacryloxy propyl trimethoxy silane), GMS (γ-glycidoxy propyl trimethoxy silane), MCMS (γ-mercapto propyl trimethoxy silane), AES (γ-amino propyl triethoxy silane). The mechanical performance of a composite material strongly depends on the properties of the filler-matrix interface and, in particular, on the level of adhesion between the matrix and the reinforcing filler. The level of adhesion is determined by the surface energies of both adherents. The surface free energy, which describes the interactionpotential of a given surface, has two components: the dispersive component originating from dispersive or London interaction, and the specific component due to all other types of interactions. Inverse gas chromatography (IGC) at infinite dilution conditions may be successfully applied to the determination of the surface properties of various solids. IGC allows the detection of the solid surface properties, using molecules of known properties, or probes, which are injected into a chromatographic column filled with the solid of interest. In this study, we chose IGC for the detection of the possible differences in the dispersive component of the surface free energy, γ^(D)_(S) values of untreated crystalline silica, fused silica and alumina and the silicas and aluminas surface-treated with silane coupling agents. Furthermore, we calculate the values of various parameters -the specific component of the free energy of adsorption,△G^(SP)_(A) , the enthalpy of specific adsorption,△H^(SP)_(A) , the acidic constant of a solid, K_(A), the basic constant of a solid, K_(D), and S_(C)(K_(D)/K_(A))- in order to examine the possible differences in the acid-base properties of untreated and surface-treated fused silicas and aluminas. The carbon contents of the silane coupling agents adsorbed on the surface of the silicas and aluminas were determined by means of a carbon determinator. If the assumption is made that each silane coupling agent molecule occupies an area of 50~100Ų, the adsorption amounts show that multilayers are generally adsorbed onto their surfaces. The values of γ^(D)_(S) decreased with increasing IGC measuring temperature in all cases. Silica and alumina are an oxide with a relatively low surface energy. The γ^(D)_(S) values of the crystalline silica were lower than those of the fused silica at the same measuring temperature. The γ^(D)_(S) values of the crystalline silica, fused silica and alumina surface-treated with MTMS were higher than those of the others, while the γ^(D)_(S) values of the crystalline silica, fused silica and alumina surface-treated with AES were the lowest at the same measuring temperature. This result indicated that while the AES-treated silica and alumina are suitable for polymers with relatively low γ^(D)_(S) value such as epoxy resin, the MTMS-treated silica and alumina are suitable for polymers with high γ^(D)_(S) value such as polyester. The crystalline silica, fused silica and alumina surface-treated with GMS and MCMS are suitable for most polymers, because their γ^(D)_(S) values are close to those of almost all resins. By using n-alkanes and polar solutes as probes, the -△G^(SP)_(A) values were determined from the plots of [RTlnV_(N)] vs. ◁수식 삽입▷(원문을 참조하세요) of the solutes. The values of -△H^(SP)_(A) were determined from the temperature dependence of -△G^(SP)_(A). These values were found to correlate with Gutmann's electron donor numbers, DN, and the new electron acceptor numbers, AN*, introduced by Riddle-Fowkes in units of kcal·mol^(-1), i.e., in the same units as the donor numbers. The acid-base properties of the untreated crystalline silica, fused silica and alumina and the surface-treated fused silica and alumina were characterized by means of two parameters describing their acidity (K_(A)) and basicity (K_(D)) in consistent units. The results suggested that the acid-base properties of the untreated crystalline and fused silica are acidic, and acid-base property of the untreated alumina is amphoteric. The acid-base properties of the fused silicas and aluminas surface-treated with GMS and AES are considered to be slight basic, while those of the fused silicas and aluminas surface-treated with MTMS and MCMS are considered to be amphoteric. The fused silicas and aluminas surface-treated with GMS and AES are suitable for basic polymers, and the fused silicas and aluminas surface-treated with MTMS and MCMS are suitable for both acidic and basic polymers.
Inorganic filler (silica and alumina, etc.) is widely used in polymer composites to improve various physical properties of the materials, such as mechanical strength and modulus, rigidity and heat-resistance. At the same time, the cost of the polymer composites can be greatly decreased by replacing the volume of expensive resin with cheap fillers. It is often necessary to treat filler with surface-modifying agents such as silane and titanate coupling agents in order to obtain improved dispersibility, mechanical and electrical properties, water resistance and reinforcement in plastics systems. In this study, we chose silane coupling agents as surface-modifying agents for the inorganic fillers such as crystalline silica, fused silica and alumina. And the inorganic fillers were subjected to surface treatment with the following four types silane coupling agent: MTMS (γ-methacryloxy propyl trimethoxy silane), GMS (γ-glycidoxy propyl trimethoxy silane), MCMS (γ-mercapto propyl trimethoxy silane), AES (γ-amino propyl triethoxy silane). The mechanical performance of a composite material strongly depends on the properties of the filler-matrix interface and, in particular, on the level of adhesion between the matrix and the reinforcing filler. The level of adhesion is determined by the surface energies of both adherents. The surface free energy, which describes the interaction potential of a given surface, has two components: the dispersive component originating from dispersive or London interaction, and the specific component due to all other types of interactions. Inverse gas chromatography (IGC) at infinite dilution conditions may be successfully applied to the determination of the surface properties of various solids. IGC allows the detection of the solid surface properties, using molecules of known properties, or probes, which are injected into a chromatographic column filled with the solid of interest. In this study, we chose IGC for the detection of the possible differences in the dispersive component of the surface free energy, γ^(D)_(S) values of untreated crystalline silica, fused silica and alumina and the silicas and aluminas surface-treated with silane coupling agents. Furthermore, we calculate the values of various parameters -the specific component of the free energy of adsorption,△G^(SP)_(A) , the enthalpy of specific adsorption,△H^(SP)_(A) , the acidic constant of a solid, K_(A), the basic constant of a solid, K_(D), and S_(C)(K_(D)/K_(A))- in order to examine the possible differences in the acid-base properties of untreated and surface-treated fused silicas and aluminas. The carbon contents of the silane coupling agents adsorbed on the surface of the silicas and aluminas were determined by means of a carbon determinator. If the assumption is made that each silane coupling agent molecule occupies an area of 50~100Ų, the adsorption amounts show that multilayers are generally adsorbed onto their surfaces. The values of γ^(D)_(S) decreased with increasing IGC measuring temperature in all cases. Silica and alumina are an oxide with a relatively low surface energy. The γ^(D)_(S) values of the crystalline silica were lower than those of the fused silica at the same measuring temperature. The γ^(D)_(S) values of the crystalline silica, fused silica and alumina surface-treated with MTMS were higher than those of the others, while the γ^(D)_(S) values of the crystalline silica, fused silica and alumina surface-treated with AES were the lowest at the same measuring temperature. This result indicated that while the AES-treated silica and alumina are suitable for polymers with relatively low γ^(D)_(S) value such as epoxy resin, the MTMS-treated silica and alumina are suitable for polymers with high γ^(D)_(S) value such as polyester. The crystalline silica, fused silica and alumina surface-treated with GMS and MCMS are suitable for most polymers, because their γ^(D)_(S) values are close to those of almost all resins. By using n-alkanes and polar solutes as probes, the -△G^(SP)_(A) values were determined from the plots of [RTlnV_(N)] vs. ◁수식 삽입▷(원문을 참조하세요) of the solutes. The values of -△H^(SP)_(A) were determined from the temperature dependence of -△G^(SP)_(A). These values were found to correlate with Gutmann's electron donor numbers, DN, and the new electron acceptor numbers, AN*, introduced by Riddle-Fowkes in units of kcal·mol^(-1), i.e., in the same units as the donor numbers. The acid-base properties of the untreated crystalline silica, fused silica and alumina and the surface-treated fused silica and alumina were characterized by means of two parameters describing their acidity (K_(A)) and basicity (K_(D)) in consistent units. The results suggested that the acid-base properties of the untreated crystalline and fused silica are acidic, and acid-base property of the untreated alumina is amphoteric. The acid-base properties of the fused silicas and aluminas surface-treated with GMS and AES are considered to be slight basic, while those of the fused silicas and aluminas surface-treated with MTMS and MCMS are considered to be amphoteric. The fused silicas and aluminas surface-treated with GMS and AES are suitable for basic polymers, and the fused silicas and aluminas surface-treated with MTMS and MCMS are suitable for both acidic and basic polymers.
주제어
#Silica, Alumina Inverse gas chromatography (IGC) Dispersive component of the surface free energy Specific component of the free energy of adsorption Enthalpy of specific adsorption Acid-base properties Silane coupling agents
학위논문 정보
저자
양영철
학위수여기관
전북대학교 대학원
학위구분
국내박사
학과
자원.에너지공학과
발행연도
2007
총페이지
xvii, 126p
키워드
Silica, Alumina Inverse gas chromatography (IGC) Dispersive component of the surface free energy Specific component of the free energy of adsorption Enthalpy of specific adsorption Acid-base properties Silane coupling agents
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