• 펄프종이기술
• /
• 제43권5호
• /
• pp.17-26
• /
• 2011

Drying behavior and physical properties of HwBKP, SwBKP, and OCC handsheets depending on kneading, refining and wet pressing were analyzed. The maximum drying shrinkage velocity was newly adopted to verify the effect of mechanical treatment of pulps by evaluating drying behavior according to varying the kneading, refining and wet pressing treatments. Those various treatments were changed to evaluate the relationship between the maximum drying shrinkage velocity and handsheets properties. When the drying shrinkage and the maximum drying velocity increased by refining and wet-pressing, handsheets strength was increased. The maximum drying shrinkage velocity showed higher correlation with physical properties of paper than WRV at different refining loads at SwBKP and mixed pulp. At high wet-web dryness, drying shrinkage, the maximum drying shrinkage velocity and strength properties of handsheet were increased. It meant that drying shrinkage behavior was highly affected by not only fibers' shrinkage but also fiber bonding. Kneading pre-treatment for KOCC and SwBKP effectively modified fiber properties and increasing paper strength and drying shrinkage. The effect of kneading pre-treatment was also confirmed by the maximum drying shrinkage velocity. Strength properties of mixed pulp handsheets were not increased by the kneading pre-treatment, although the maximum drying shrinkage velocity and WRV was increased. It meant that fibers network bonding of HwBKP was limited because of ves sels and ray cells' interference for bonding. Therefore in order to improve paper strengths containing HwBKP by mechanical treatments, interference of vessels and ray cells for fiber bondings should be carefully controlled.

• 한국의류산업학회지
• /
• 제6권4호
• /
• pp.492-496
• /
• 2004

Shrinkage properties of drawn textured Poly(trimethylene terephthalate, PTT) yarn, which has been developed recently, were investigated to provide fundamental information for the textile industry. Shrinkage ratio characteristics on PTT yarn with six different count were investigated with tension, dry and wet thermal temperature. In non-tension, the shrinkage ratio were increased to increasing temperature at dry and wet thermal treatment, and in tension, the shrinkage ratio were increased to increasing tension at dry and wet thermal treatment.

• 한국의상디자인학회지
• /
• 제24권2호
• /
• pp.1-10
• /
• 2022

The purpose of this study is to analyze the structural properties of 100% wool fabrics knitted with various stitch types and to evaluate dimensional stability from shrinkage in wet cleaning and drying. Materials were weft-knitted from twenty-four different stitches with 7 gauge using a computerized flatbed knitting machine. Weight, thickness, density, and length were measured. A domestic washing machine and a tumble dryer were used for the shrinkage test. The results are as follows: Knitted fabrics were divided into 3 groups based on weight per unit area. Porous knits show light weight whilst milano, pintuck, rib stitches belong to the heaviest group. A positive correlation between weight and thickness was found and the same result was obtained for wale density and weight. Dimensional shrinkage of knitted fabrics was increased during repetitive wet cleaning and drying regardless of knit stitches. Especially, fabrics knitted with float, tuck, cable, and links & links stitches samples were contracted more than 15% in the first treatment whereas 2x1 rib stitch showed 1% shrinkage rate. Fisherman and milano stitches contracted in both course and wale direction with similar shrinkage rates. However, porous knits with float and tuck stitches shrank in course direction by 20% as well as cable samples contracted from 5% to 20% after repeated washing and drying. On the other hand, 30% and 15% contraction of wale direction occurred in orderly float and links & links stitches, respectively. Machine dried knits have a higher shrinkage rate than air-dried knits, but the drying method did not affect to the direction of contraction. In conclusion, variations of knit, tuck, and float stitches affect knit construction and dimensional stability from shrinkage in wet cleaning and drying of wool knitted fabrics.

• 한국의류산업학회지
• /
• 제7권2호
• /
• pp.247-251
• /
• 2005

In this the study, the effects of the manufacturing process conditions on the properties Thick and Thin Diameter yarns(TTD yarns) prepared with hot plate device in the draw winder were determined. Physical properties including wet shrinkage, tenacity and elongation of the samples were measured and thick and thin effect was analysed with the evenness tester. The results were as the follows: There was little change the wet shrinkage of the TTD yarns in the range of $70^{\circ}C{\sim}80^{\circ}C$ of $R_1$ temperature(lower hot cylinder) with the same Hot Plate(H/P) temperature, but the wet shrinkage of the TTD yarns decreased 5-10% when $R_1$ temperature was $90^{\circ}C$. The wet shrinkage of the TTD yarns decreased with the H/P temperature at the same temperature of $R_1$. There was little effect of $R_1$ and H/P temperature on the tenacity of TTD yarns. The elongation of TTD yarns increased with $R_1$ temperature at the same H/P temperature. The elongation of TTD yarns increased little bit for the first time and then decreased above that temperature with increasing H/P temperature at the same $R_1$ temperature. The thick and thin effect on the TTD yarns was obvious in $110^{\circ}C$ of H/P temperature regardless of $R_1$ temperature, while there was no thick and thin effect on the TTD yarns in $140^{\circ}C$ of H/P temperature.

• 한국염색가공학회지
• /
• 제9권4호
• /
• pp.7-19
• /
• 1997

The purpose of the study was to investigate the shrinkage and creep behavior of PET filaments which were prepared at various spinning speeds(3,300, 4,000, 5,000, 6,000, and 7,000m/min) and anneal($120^{\circ}$, 30min & $150^{\circ}$, 40min). In order to determine the shrinkage and creep behavior with the crystallinity change, PET filaments were treated with low(12$0^{\circ}C$, 30min) and high($150^{\circ}$, 40min) temperature conditions with hot air dryer under the constant tension. The results of the study were as follows: as the spinning speed increased, the degree of shrinkage and elongation of the sample treated by wet condition decreased. The sample with 0.01g/d of load under various spinning speeds showed shrinkage behavior and highest shrinkage ratio at $76^{\circ}$ which was Tg of PET. The degree of shrinkage and elongation of the treated sample was less than those of the untreated sample by wet treatment. Especially, there was less degree of shrinkage and elongation of the sample treated by higher temperature condition. In 3,300m/min of spinning speed the draw ratio of undrawn yarn of a mixture of a-axis orientation and c-axis orientation was 2.0, which is similar to the value of the traditional drawn yarn. Finally, there was a big range of shrinkage and elongation by wet treatment in 3,300 m/min of spinning speed.

• 펄프종이기술
• /
• 제43권4호
• /
• pp.49-58
• /
• 2011

The maximum drying shrinkage velocity was proposed to verify bulk and stiffness improvement mechanism during drying according to papermaking parameters. It was based on the wet-web shrinkage behavior without the restraint of wet-web during drying, so intact drying impact could be measured. Bulking agent reduced the drying shrinkage and the maximum drying shrinkage velocity, so paper bulk increased and paper strength decreased. When adding cationic starch to stock with the bulking agent for strengthening, the bulk was increased further with additional decreasing of the drying shrinkage and the maximum drying shrinkage velocity. Paper strength also increased except tensile stiffness index with decreasing the drying shrinkage and the maximum drying shrinkage velocity. When using additional strength additives for strengthening of fiber interfaces extended by bulking agent and cationic starch, amphoteric strength additive increased paper stiffness without loss of paper bulk. It was considered that the added amphoteric strength additives were cross-linked to the stretched cationic starch and this cross-linking increased elasticity of fiber-polymer-fiber interfaces without changing the drying behavior. Paper bulk could be increased with decreasing the maximum drying shrinkage velocity. The drying shrinkage of paper also could be controlled by fiber-to-fiber bonding interfaces by the bulking agent. In this case, paper strength including stiffness was decreased by reducing fiber-to-fiber bonding but it could be improved by strengthening fiber-to-fiber interfaces with polymer complex without loss of bulk.

• 콘크리트학회논문집
• /
• 제23권6호
• /
• pp.741-747
• /
• 2011

이 연구에서는 강도수준 및 강도발현 속도에 따른 콘크리트의 자기수축과 예측모델의 적용성을 비교하였고, 다양한 양생조건을 적용시켜 자기수축을 검토하였다. 연구 결과에 따르면 콘크리트가 강도가 증가할수록 자기수축이 증가하는 것으로 나타났다. 그러나 동일한 콘크리트 강도의 경우라도 강도발현 속도가 빠른 OPC의 경우 초기 자기수축은 크지만 최종 자기수축은 BFS의 경우가 더 큰 것으로 나타났다. 초기 습윤양생은 자기수축 저감에 영향을 미치며 특히 24시간 이상 습윤양생을 실시하면 최종 자기수축은 크게 감소하는 것으로 나타났다. 기존의 EC2모델은 콘크리트 특성을 적절히 반영하지 못하는 것으로 나타났으며 자기수축을 보다 효과적으로 예측할 수 있는 수정 모델식을 제안하였다.

• Bulletin of the Korean Chemical Society
• /
• 제31권11호
• /
• pp.3252-3258
• /
• 2010

In this study, the effects of the various parameters of spinning and drawing processes on the properties of polyester full drawn yarn (FDY) prepared by steam processing during high-speed spinning were investigated using several techniques. The wet shrinkage ratio of the FDY was able to be manipulated by controlling the temperature and draw ratio. The FDY made using the steam high speed spinning technique exhibited identical properties (such as tenacity, elongation, and wet shrinkage ratio) to that of regular FDY, made using the spin-draw process. FDY prepared using the steam process during high-speed spinning showed excellent dyeability. The dye pick-up of the polyester yarn spun at high-speed spinning was found to be improved when dyed under an atmospheric pressure of $100^{\circ}C$. This result was the same as regular FDY dyed under a high pressure of $130^{\circ}C$.

• Advances in concrete construction
• /
• 제7권3호
• /
• pp.175-181
• /
• 2019

Low-calcium fly ash (LCFA) were used to prepare cement/LCFA specimens in this study. The basic physical properties including water demand, fluidity, setting time, soundness and drying shrinkage of cement/LCFA paste were investigated. The effects of curing time, immersion time and wet-dry cycles in 3% $Na_2SO_4$ solution on the compressive strength and the microstructures of specimens were also discussed. The results show that LCFA increases the water demand, setting time, soundness of cement paste samples. 50% and 60% LCFA replacement ratio decrease the drying shrinkage of hardened cement paste. The compressive strength of plain cement specimens decreases at the later immersion stage in 3% $Na_2SO_4$ solution. The addition of LCFA can decrease this strength reduction of cement specimens. For all specimens with LCFA, the compressive strength increases with increasing immersion time. During the wet-dry cycles, the compressive strength of plain cement specimens decreases with increasing wet-dry cycles. However, the pores in the specimens with 30% and 40% LCFA at early ages could be large enough for the crystal of sodium sulfate, which leads to the compressive strength increase with the increase of wet-dry cycles in 3% $Na_2SO_4$ solution. The microstructures of cement/LCFA specimens are in good agreement with the compressive strength.

• 한국건축시공학회지
• /
• 제18권1호
• /
• pp.33-40
• /
• 2018

우리나라의 많은 건설 공사에서는 건축물이 고층화 되면서, 공기단축 및 물의 처리 곤란 등의 이유로 고강도 콘크리트일지라도 습윤양생을 실시하지 않고 공사를 진행하는 경우가 존재한다. 이와 같이 건조 상태로 양생하게 되면 압축강도 감소, 건조수축 및 자기수축 등 수축변화가 크게 증가할 것으로 예상된다. 또한 본 연구팀에서는 기존의 연구로서 유지류를 콘크리트에 혼합할 경우 비누화 반응을 이용하여 콘크리트의 자기수축 저감 및 내구성 향상에 대한 연구를 진행한바 있다. 그러므로 본 연구에서는 양생방법을 비양생 건조, 유화처리정제식용유(ERCO) 도포 후 건조, 7일 수중양생 후 건조 및 28일 수중양생 후 건조 등 양생 방법 변화에 따른 혼화재 다량치환 모르타르의 압축강도 특성, 수분증발에 따른 수축변화 특성에 대하여 분석하였다. 실험결과는 양생방법으로 비양생 건조를 실시하게 되면 28일 수중양생을 실시하였을 경우보다 약 50% 전후의 강도저하와 1.9배의 수축 길이변화율 증가로 나타나, 혼화재 다량치환 고강도 모르타르에 있어 습윤양생이 매우 중요하게 영향을 미치는 것을 알 수 있었다. 단, ERCO 도포의 경우는 강도 및 수축변화측면에서 무양생인 건조보다는 우수하지만 7일 수중양생 후 건조보다는 성능이 저하하는 것으로 나타났다.