• International Journal of Precision Engineering and Manufacturing-Green Technology
• /
• v.5 no.5
• /
• pp.651-658
• /
• 2018

We comprehensively investigated the wrinkles of a stiff layer covering a spherical void embedded in a rubber matrix after the void experienced inflation or contraction. We developed an easy experimental way to realize the inflation and contraction of the voids. The inflation took place in a void right beneath the surface of the matrix and the contraction happened in a void at the bottom of the rubber matrix. In the inflation, the wrinkle at the center of the deformation was random, and the pattern propagated into rabyrinthine, herringbone, and then oriented parallel lines as the position was away from the center of the inflation to the edge. The cracks were concentric, which were perpendicular to the parallel wrinkled pattern. In the contraction, the wrinkle was simply concentric around the surface of the void without any crack. The cracks were found only near the center of the deformation. The strain distribution in the stiff layer after the inflation and contraction was theoretically analyzed with simulations that were in excellent agreement with the experimental results.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.335-335
• /
• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.

• Journal of the Korean Home Economics Association
• /
• v.43 no.1 s.203
• /
• pp.167-176
• /
• 2005

This study was intended to investigate the wearing conditions of shirts, and examine the preferred subjective sensation for shirt fabrics. A questionnaire survey was conducted on 469 university students (male students $45.3\%$, female students $54.7\%$) in the Cheongju area, Korea. Frequency, descriptive analysis, $\x^2$ and t-tests were used for data analysis. The results were as follows: Regardless of gender, most owned 4 shirts in the autumn, which were each worn once or twice week. Generally, patterned shirts were less favored than those with solid colors, regardless of gender, but the color of the shirts differed slightly according to gender. Most students gathered items from those displayed in the store as their source of information on shirts, and tended to purchase items worth $30,000\~50,000$ won at franchised stores with friends of the same gender. They almost always looked carefully at the size and brand, but the care label and fiber content were rather neglected during the purchase. While purchasing their shirts, the following elements were considered, in this order of importance: size; color; fitness; comfort; price; tactile sensation. Light, dense, soft, warm, wrinkle-free, dry and strong sensation of the shirt fabrics were the strongest preferences for a purchase. There were partially significant gender differences in the subjective sensation of shirt fabrics.