Shigeki Hikasa

Influence of Elastomer Modification on Impact Strength of PP/Elastomer/CaCO3 Composite

Polypropylene (PP)/elastomer/fine filler particle ternary composite was prepared using polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) or carboxylated SEBS (C-SEBS) as elastomer and calcium carbonate (CaCO3) having mean size about 160 nm as filler. First, SEBS (or C-SEBS) and CaCO3 particles were mixed to form master batch. Second, the prepared master batch and PP matrix were kneaded. In the PP/SEBS/CaCO3 ternary composite, CaCO3 particles and SEBS particles were dispersed in the PP matrix separately. In the PP/C-SEBS/CaCO3 ternary composite, CaCO3 particles were encapsulated in C-SEBS and formed a core–shell structure at lower CaCO3 concentration; however, some CaCO3 particles were dispersed in PP matrix at higher CaCO3 concentration. In the PP/SEBS/CaCO3 composite, the impact strength increased with the amount of incorporated CaCO3 particles. Whereas, in the PP/C-SEBS/CaCO3 composite, the impact strength increased with the amount of CaCO3 particles dispersed in PP matrix. The master-batch method was found to be useful for improving the dispersibility of CaCO3 particles than the commonly used single-batch method.

Influence of Filler Size on Impact Properties of PP/Elastomer/Filler Ternary Composites

Influence of filler size on impact properties for polypropylene (PP)/elastomer/filler ternary composites was investigated. Calcium carbonate (CaCO3) particles with a diameter in the range from 120 to 1200 nm were used as a filler and polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) was used as an elastomer. In the PP/SEBS/CaCO3 ternary composite, CaCO3 particles and SEBS particles were dispersed in the PP matrix separately. In the case that SEBS elastomer volume fraction was below 0.12, the impact strength improved gradually with a decrease of CaCO3 mean diameter from 1200 to 160 nm. In the case that SEBS volume fraction was above 0.17, the impact strength improved significantly by the incorporation of CaCO3 particles with a mean diameter in the range from 120 to 900 nm. However, the impact strength hardly improved by the incorporation of CaCO3 particles with a mean diameter of 1200 nm.

Glass Transition Behaviour of PMMA/PVA Incompatible Blend

Dynamic viscoelastic properties and morphology of poly(methyl methacrylate) (PMMA)/poly(vinyl alcohol) (PVA) blend prepared by melt kneading was investigated. These solubility parameter values differ greatly. Two kinds of PVA with saponification degrees of 88 and 98 mol.% were used. Micrometre-order domains were observed by scanning electron microscopy for 88 mol.% PVA, whereas no clear domain was observed for 98 mol.%. Both the blends were incompatible systems because two loss modulus peaks based on PMMA and PVA were observed by dynamic mechanical analysis. The loss modulus peak based on the PMMA-rich phase was higher than that of pure PMMA; the increase of the corresponding glass transition temperature (Tg) caused by blending was more remarkable for 98 mol.% PVA than 88 mol.%. It was thought that the intermolecular interaction of OH group in PVA and carbonyl group in PMMA caused the increase in Tg, but no clear evidence of the interaction for the blend was observed by a Fourier transform infrared spectroscopic analysis. The poly(vinyl acetate)/PMMA blend was incompatible. The unsaponificated vinyl acetate unit in PVA decreased the interaction between PMMA and PVA. This is the reason why the effect of Tg rising was lower for 88 mol.% PVA than for 98 mol.%.

Influences of Morphology on Mechanical Properties of Polypropylene/Elastomer/CaCO3 Ternary Composites

Relation between impact and mechanical properties and morphology of polypropylene (PP)/elastomer/filler ternary composite was investigated. Polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) or carboxylated SEBS (C-SEBS) was used as elastomer and calcium carbonate (CaCO3) having mean size about 160 nm was used. In the PP/SEBS/CaCO3 ternary composite, CaCO3 particles and SEBS particles were dispersed in the PP matrix separately. In the PP/C-SEBS/CaCO3 ternary composites, CaCO3particles were embedded in C-SEBS, namely the core–shell particles were formed at lower CaCO3 concentration. However, some CaCO3 particles were dispersed directly in PP matrix at higher CaCO3 concentration. In order to clarify the influence of morphology, the measured modulus and tensile yield stress were compared with the predicted values by some prediction laws. In the PP/SEBS/CaCO3 composite, the impact strength increased with the amount of incorporated CaCO3 particles. Whereas, in the PP/C-SEBS/CaCO3 composite, the impact strength increased dependent on the amount of CaCO3 particles dispersed directly in PP matrix. From the observation of fractured surface, it was found that the impact strength is strongly affected by the morphology and dispersibility of CaCO3 particles.

Surface treatment of CaCO3 with a mixture of amino- and mercapto-functional silane coupling agents and tensile properties of the rubber composites

Abstract In order to reinforce the composite consisting of isoprene rubber (IR) and calcium carbonate (CaCO3) particles, the surface treatment of CaCO3 particles with a mixture of amino- and mercapto-functional silane coupling agents was investigated. The quantity of chemisorbed silanes in treated CaCO3 measured using thermogravimetry was greater for amino- than for mercapto-silane and for the tri- than for the dialkoxy structure. Second, the molecular mobility of polycondensate of the mixtures with the trialkoxy structure measured using 1H pulse nuclear magnetic resonance had the least molecular mobility, i.e., formed the highest density network. The greater values of stress at 500% strain, fracture stress, and elongation at break were determined for the treatment with amino- and mercapto-functional silanes having a trialkoxy structure from the stress-strain curves of composite. The mixture treatment with dialkoxy structure and with amino- or mercapto-functional silane only did not improve the mechanical properties sufficiently. Interactions between the amino group and the CaCO3 surface, covalent bonding between the mercapto group and the IR, and high density network formation of trialkoxy silane were important for improving the mechanical properties of the composite.

Effect of the degree of crosslinking on the interfacial layer structure of poly(vinyl chloride) dispersed with crosslinked poly(n-butyl methacrylate) particles

Abstract The interfacial layer structure of a model incompatible polymer blend system was analyzed using 1H pulse nuclear magnetic resonance (pulse NMR) spectroscopy. Non-crosslinked and crosslinked poly(n-butyl methacrylate) particles with a mean size of ca. 0.9 μm were prepared by seeded emulsion polymerization, and the degree of crosslinking was varied. The particles were powdered using a freeze-dry method and dispersed in poly(vinyl chloride) by melt blending. Dynamic mechanical analysis indicated that the non-crosslinked particles were completely compatible. In contrast, mutual diffusion of the polymer chains in the crosslinked particles was restricted within the particle/matrix interfacial layer. As a result, an incompatible phase structure in which the crosslinked particles were dispersed in the continuous phase was formed. Pulse NMR analysis indicated that the interfacial layer thickness was in the range of 17–98 nm. The thickness decreased with an increase in the degree of crosslinking in the particles. The interfacial layer thickness in the particles was approximately 10 times larger than that for the incompatible polymer pair. Tensile test results indicated that the elongation at break was dependent on the thickness of the interfacial layer. The yield stress was developed for the particles with high hardness that was independent of the interfacial thickness.

Influence of Morphology on Mechanical Properties under the Combined Use of SEBS and EOr as Elastomer in PP/Elastomer/Filler Ternary Composites

The influences of combined elastomers on impact properties and morphology of polypropylene (PP)/elastomer/CaCO3 ternary composites were investigated. In the case that polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) and poly(ethylene-co-octene) (EOR) were used as elastomers, a sea-island structure consisting of EOR dispersed phase and SEBS continuous phase was formed. The elastomer and the CaCO3 particles were separately dispersed in PP matrix. In the case that carboxylated SEBS (C-SEBS) and EOR were used, the C-SEBS particles were dispersed in the EOR particles. Almost all of the CaCO3 particles were dispersed in the PP matrix, although some of the CaCO3 particles were dispersed in the C-SEBS/EOR combined particles. Impact strength improved with an increase of incorporated CaCO3 particles. The effect of elastomer on the impact strength was SEBS ≥ SEBS/EOR > EOR = C-SEBS/EOR > C-SEBS. The morphology formed by elastomer and CaCO3 particles strongly affected the impact properties of the ternary composites.