Seung Sang Hwang

Influence of the mechanical properties of the dispersed phase upon the behaviour of nylon/rubber blends: crosslinking effect

Abstract Rubber-modified polyamides were obtained directly by blending modified poly(styrene-b-butadiene-styrene) (SBS) triblock copolymer used as the rubbery component and nylon 6. The rubber was modified with various amounts of maleic anhydride (MA) with the aid of dicumyl peroxide. In this study, the influence of MA concentration on the crosslinking level of the rubber and its effect on the blend properties were investigated. Crosslinking level of MA-modified SBS was measured using isooctane, the calculation being done following the Flory-Rehner equation. Impact testing of the blends revealed a maximum peak in impact strength versus rubber crosslinking level. However, the maximum was not so eminent as we expected. Explanations about the impact behaviour of the blends related to toughening mechanisms are presented.

Low Dielectric Materials for Microelectronics

Over the past half century, low dielectric materials have been intensively researched by ceramic and polymer scientists. However, these materials possess a vast myriad of electrical, thermal, chemical, and mechanical properties that are just as crucial as the name that classifies them. Therefore, in many cases, the applications of low dielectric constant materials are dictated by these other properties, and the choice of low dielectric material may have a tremendous effect on a device’s performance and lifetime.

Preparation and characterization of organic-inorganic hybrid materials via sol-gel reaction for interlayer dielectrics

Abstract Polyimides containing hydroxyl group, so-called poly(hydroxy-imide)s, were prepared by the thermal imidization in the presence of m-cresol. The poly(hydroxy-imide)s exhibited high resistance to thermal degradation, with 10% weight loss temperature starting at near 527°C in air. The organic/inorganic hybrid materials were prepared with TEOS by acid-catalyzed sol-gel reaction of sol-gel polyimide precursors obtained from the coupling reaction of the poly(hydroxy-imide) with 3-(triethoxysilyl)propyl isocyanate. All of the cured hybrid films spin-coated on ITO glass are transparent. The initial decomposition temperature was recorded at 356°C. The dielectric constant of a hybrid material film was 3.24 at the frequency of 10kHz. The hybrid materials retained the coefficient of thermal expansion up to 3 ppm/°C below Tg and 30 ppm/°C above Tg.