• Title, Summary, Keyword: silicone

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Preparation, Surface Characteristics and Physical Properties of Polyurethane-based Gel-coat Containing Reactive Silicone Oligomers

  • Jang, Su-Hee;Baek, Seung-Suk;Hwang, Seok-Ho
    • Elastomers and Composites
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    • v.51 no.4
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    • pp.269-274
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    • 2016
  • Two different reactive silicone oligomers, hydroxylpropyl terminated PDMS (PDMS-L) and 1-(2,3-dihydroxy-propoxy)propyl terminated PDMS (PDMS-B), were synthesized through hydrosilylation reaction under Karstedt's catalyst. Using the reactive silicone oligomers, two different silicone-modified gel-coat series were prepared to investigate their thermal and mechanical properties as well as surface characteristics according to reactive silicone oligomer contents. In case of thermal stabilities and mechanical properties, the gel-coat series containing PDMS-B showed higher values than that of the gel-coat series containing the PDMS-L. The contact angle for the gel-coat containing both silicone oligomers/was increased with reactive silicone oligomer contents but there was similar surface tension between PDMS-L and PDMS-B.

Treatment and Characterization of Polyethylene Terephthalate Fibers with Silicone Rubber Adhesive for Heat-Resistant Adhesion (실리콘 고무와 내열접착 향상을 위한 Polyethylene Terephthalate 섬유 접착층의 제조 및 특성)

  • Kim, Jihyo;Lee, Sangoh;Lee, Jaewoong
    • Textile Coloration and Finishing
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    • v.31 no.2
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    • pp.107-117
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    • 2019
  • In case of pure rubber materials, the initial quality of the rubber materials would be excellent, however, the durability against external impact might be poor. In order to overcome the relatively low durability, textile cord could be employed with silicone rubber. We have studied the improvement of heat-resistant adhesion properties of silicone adhesives between silicone rubber and PET fibers by applying various conditions including dip solution recipe. The silicone rubber used was a platinum catalyst curing type and platinum catalyst type silicone adhesive was used as an adhesive to obtain an optimum adhesive force. Furthermore, the bonding mechanism between silicone and PET fiber was established.

Effect of Silicone Oil on Properties of Cooking Oils for Pork Cutlet Frying (돼지고기 튀김조리시(調理時) Silicone oil 첨가(添加)가 튀김기름의 성질(性質)에 미치는 영향(影響))

  • Yun, Sook-Ja;Yum, Cho-Ae
    • Korean Journal of Food Science and Technology
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    • v.19 no.6
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    • pp.556-560
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    • 1987
  • In this study, silicone oil was added into soybean oil in order to investigate its effect on acid value (AV), carbonyl value (COV), TBA value, fatty acid composition and color intensity of soybean oil during frying at $170^{\circ}C$. It was found that the AV, COV and TBA value were significantly decreased as the concentration of silicone oil increased from 0 to 5 ppm in soybean oil after frying for 7 hours. The color intensity was also decreased by 26% of color of 7 hours-heated soybean oil without silicone oil addition. Little changes in fatty arid composition was measured between the samples after 7 hours frying. From the overall result of this study, addition of silicone oil by 1 ppm was recommended for effective reduction of rancidity development of soybean oil ing frying.

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Compatibility Study of HNBR/Silicone Rubber Blends (HNBR/Silicone 고무의 상용성에 관한 연구)

  • Oh, Taeg-Su;Ryou, Jin-Ho;Kim, Chang-Hee
    • Elastomers and Composites
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    • v.31 no.2
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    • pp.111-121
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    • 1996
  • The characteristic of silicone rubber can be seen from its resistance to both low and high temperature, whereas HNBR is resistant only in high temperature moderatly although it can be compounded to give good tensile properties, good oil resistance while silicone rubber severely lacks in these qualities. This study was initiated a balance of properties by blending HNBR and silicone rubber which is not considered for commercial blending; blends of HNBR with silicone rubber tend to show immiscible due to dissimilar nature of silicone and HNBR, the possibility of phase separation cannot be ruled out, in unfilled system after vulcanisation leading to premature failure. Attempt has been made to improve compatibility and minimise the layer seperation by the use of compatibilizer. Both filled and unfilled systems, in presence and absence of compatibilizer have been studied. Improvement in tensile properties of the blends or are observed as compared to the non-blended rubber. Different ratios of HNBR and silicone rubber are represented in this study. Blends of HNBR with silicone rubber were immiscible system. The tensile strength increased with filler loading.

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Blends of Silicone Rubber and Liquid Crystalline Polymer

  • Shivakumar E.;Das C. K.;Pandey K. N.;Alam S.;N.Mathur G.
    • Macromolecular Research
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    • v.13 no.2
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    • pp.81-87
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    • 2005
  • Blends of silicone rubber (VMQ) and liquid crystalline polymer (LCP) were prepared by the melt mixing technique. Mechanical, XRD, thermal and dynamic mechanical investigations are reported for the pure silicone rubber and blends. The mechanical properties, viz. the tensile strength, tear strength and elongation at break, of the silicone rubber decreased with the addition of LCP. The SEM study on the tensile fractured surface of the blends revealed that they had a two phase structure, and that the failure was mainly due to fiber pull out, which suggests that the VMQ and LCP are incompatible in all of the proportions examined in this study. However, the FTIR study shows that there was a partial interaction between the VMQ and LCP, but which may not be sufficient to grip the fibrils under the applied load. In the XRD analysis, it was observed that the crystalline structure of the silicone rubber deteriorated in the presence of LCP. The DMA study suggested that the storage modulus of the silicone rubber was improved with the addition of LCP, due to the high modulus of the LCP phase. The thermal stability of the silicone rubber was greatly reduced by the addition of LCP, due to the latter having a thermal stability lower than that of silicone rubber.

Effects of Inorganic Fillers on Mechanical Properties of Silicone Rubber

  • Kim, Gyu Tae;Lee, Young Seok;Ha, KiRyong
    • Elastomers and Composites
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    • v.54 no.2
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    • pp.142-148
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    • 2019
  • In this study, the effects of filler particle size and shape on the physical properties of silicone rubber composites were investigated using inorganic fillers (Minusil 5, Celite 219, and Nyad 400) except silica, which was already present as a reinforcing filler of silicone rubber. Fillers with small particle sizes are known to facilitate the formation of the bound rubber by increasing the contact area with the polymer. However, in this experiment, the bound rubber content of Celite 219-added silicone composite was higher than that of Minusil 5-added silicone composite. This was attributed to the porous structure of Celite 219, which led to an increase in the internal surface area of the filler. When the inorganic fillers were added, both thermal decomposition temperature and thermal stability were improved. The bound rubber formed between the silicone rubber and inorganic filler affected the degree of crosslinking of the silicone composite. It is well-known that as the size of the reinforcing filler decreases, the reinforcing effect increases. However, in this experiment, the hardness of the composite material filled with Celite 219 was the highest compared to the other three composites. Furthermore, the highest value of 2.19 MPa was observed for 100% modulus, and the fracture elongation was the lowest at 469%. This was a result of excellent interaction between Celite 219 filler and silicone rubber.

Effects of Silicone Surfactant on the Cell Size and Thermal Conductivity of Rigid Polyurethane Foams by Environmentally Friendly Blowing Agents

  • Han, Mi-Sun;Choi, Seok-Jin;Kim, Ji-Mun;Kim, Youn-Hee;Kim, Woo-Nyon;Lee, Heon-Sang;Sung, Joon-Yong
    • Macromolecular Research
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    • v.17 no.1
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    • pp.44-50
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    • 2009
  • Rigid polyurethane foams (PUF)s were synthesized with environmentally friendly blowing agents such as a cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only for four different silicone surfactants having different silicone/polyether ratios. An attempt was made to reduce the thermal conductivities of the PUF samples by varying the concentration and the silicone/polyether ratio of the various silicone surfactants. The scanning electron microscopy (SEM) results indicated an optimum concentration of the silicone surfactant of about 1.5 to 2.5 phpp for various surfactants to reduce the cell size and lower the thermal conductivity. The silicone surfactant having a higher silicone/polymer ratio showed a smaller cell size and, therefore, demonstrated the lower thermal conductivity of the PUF samples. From the relation between the thermal conductivity and the cell size of the PUF samples, the smaller cell size improved the thermal insulation property of the rigid PUF for both the PUF samples blown by the cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only. If the blowing agent is fixed, then the cell size is an important factor to decrease the thermal conductivity of the PUF samples. These results indicated that rigid PUF samples having lower thermal conductivity can be obtained by choosing a silicone surfactant containing a higher silicone/polyether ratio, as well as an optimum content of the surfactant.

Combination Surgery of Silicone Tube Intubation and Conjunctival Resection in Patients with Epiphora

  • Kim, Seon Tae;Jin, Long Yu;Ahn, Hee Bae
    • Korean Journal of Ophthalmology
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    • v.32 no.6
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    • pp.438-444
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    • 2018
  • Purpose: To compare the success rates of performing only silicone tube intubation versus carrying out both conjunctival resection and silicone tube intubation. Methods: The subjects of this study involved 62 patients (96 eyes) between October 2015 and May 2017 who were diagnosed as having punctal stricture or nasolacrimal duct stenosis. Out of 96 eyes, 47 underwent only silicone tube intubation, and 49 underwent both silicone tube intubation and conjunctival resection. Three parameters were measured at 1, 3, and 6 months after the surgery: the area of the tear meniscus using RTVue-100 anterior segment optical coherence tomography, the height of the tear meniscus using a slit lamp microscope, and the subjective satisfaction of patients as a result of improved sympotms like epiphora. The surgery was considered successful when the patients' experienced the resolution of symptoms and reduction of the area and height of the tear meniscus. Results: The area of the tear meniscus, height of the tear meniscus, and subjective satisfaction of patients was superior in the group that underwent both silicone tube intubation and conjunctival resection compared silicone tube intubation only. Based on these results, the success rate of the surgery was 68.9% in the group that underwent only silicone tube intubation and 78.7% in the group that underwent both silicone tube intubation and conjunctival resection. Conclusions: The resection of relaxed plica semilunares seems to increase the success rate of silicone tube intubation through the reduction of the area and height of the tear meniscus. Therefore, after determining the degree of conjunctivochalasis, if it was found to be severe, a combination with conjunctival resection was expected to increase the success rate of the surgery.