• Textile Coloration and Finishing
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• v.16 no.1
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• pp.53-58
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• 2004

The preparation of responsive fibers from acrylic fibers is studied. Various responsive fibers, such as fibers which change their color on exposure to light or with change in temperature, have been developed and are used commercially However, the responsive material in these fibers are not the fiber itself but chemicals in microcapsules attached to the fibers by finishing, and few fibers exhibit responsive properties by itself. The partial hydrolysis of polyacrylonitrile fibers to obtain pH responsive fibers is presented in this paper. Partial hydrolysis was effected by control of the concentration of the sodium hydroxide used in the hydrolysis, hydrolysis temperature and time. The degree of hydrolysis was evaluated by nitrogen content of the hydrolyzed fibers and their response, change in length, to aqueous solutions of varying pH was studied by continually changing the pH. Significant changes in lengths with pH were observed and the gel transition behavior varied with the conditions of hydrolysis. The hysteresis of the length change was also studied to evaluate the possibilities of using hydrolyzed acrylic fibers as pH sensors.

• Resources Recycling
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• v.10 no.2
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• pp.13-19
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• 2001

Several hydrolyzed extruded PAN's were prepared through reaction of extruded PAN (7.5% methyl acrylate) with NaOH in methanol at various temperatures and times. These were amidoximated with hydroxylamine in MeOH and/or $H_2$O to introduce an excellent adsorption capacity of heavy metal ions. Amidoximated hydrolyzed extruded fAN showed superior swellability to non-hydrolyzed extruded PAM. The amidoximated extruded PAN hydrolyzed for 6h at $60^{\circ}C$ showed the best dimensional stability. Amidoximated hydrolyzed extruded PAN has more adsorption capacity of $Cu^{2+}$ than that of $Ni^{ 2+}$ These PAN derivates also showed an excellent selectivity for adsorption of metal ions.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.347-347
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• 2003

폴리아크릴로니트릴을 NaOH로 가수분해시키면 carboxylate anion과 carboxanlide기가 생성되며, 물을 흡수할 경우 sodium carboxylate기의 해리로 팽윤이 크게 일어나므로 고흡수성을 지니게 된다. 일찍이 flory[1]는 가교된 고분자 전해질이 고흡수성을 나타내는 겔을 형성할 것으로 예측한 바 있다. 이 가교 결합이 아크릴 섬유의 부분 가수분해에 대한 자료는 새로운 기능을 부여하면서 섬유의 물성을 어느 정도 유지하는데 요구되는 조건을 제시하게되므로 향후 아크릴 섬유의 개질에 활용될 수 있다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.345-346
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• 2003

폴리아크릴로니트릴을 NaOH로 가수분해시키면 carboxylate anion과 carboxamide기가 생성되며, 물을 흡수할 경우 sodium carboxylate기의 해리로 팽윤이 크게 일어나므로 고흡수성을 지니게 된다[l]. 일반적으로 섬유가 팽윤을 하면 수축하며, 가수분해된 폴리아크릴로니트릴 섬유는 흡수되는 물 속의 염의 농도 또는 pH에 따라 팽윤도가 다르기 때문에 가수분해된 시간과 pH조건 변화에 따라서 수축하는 정도가 다르다. 과거의 연구결과에 의하면 아크릴 섬유는 2M HCI에서 최소의 길이로 수축하며, 2M NaOH에서 최대의 길이가 나타난다고 하였다[2]. (중략)

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3163-3172
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• 2010

In this work, a novel method to synthesis of an acrylic superabsorbent hydrogel was reported. In the two stage hydrogel synthesis, first copolymerization reaction of acrylonitrile (AN) and acrylamide (AM) monomers using ammonium persulfate (APS) as a free radical initiator was performed. In the second stage, the resulted copolymer was hydrolyzed to produce carboxamide and carboxylate groups followed by in situ crosslinking of the polyacrylonitrile chains. The results from FTIR spectroscopy and the dark red-yellow color change show that the copolymerization, alkaline hydrolysis and crosslinking reactions have been do take place. Scanning electron microscopy (SEM) verifies that the synthesized hydrogels have a porous structure. The results of Brunauer-Emmett-Teller (BET) analysis showed that the average pore diameter of the synthesized hydrogel was 13.9 nm. The synthetic parameters affecting on swelling capacity of the hydrogel, such as AM/AN weight ratio and hydrolysis time and temperature, were systematically optimized to achieve maximum swelling capacity (330 g/g). The swollen gel strength of the synthesized hydrogels was evaluated via viscoelastic measurements. The results indicated that superabsorbent polymers with high water absorbency were accompanied by low gel strength. The swelling of superabsorbent hydrogels was also measured in various solutions with pH values ranging from 1 to 13. Also, the pH reversibility and on-off switching behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents. Finally, the swelling of synthesized hydrogels with various particle sizes obey second order kinetics.

• Carbon letters
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• v.10 no.3
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• pp.217-220
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• 2009

In this study, porous electrospun carbon fibers were prepared by electrospinning with PAN and $MgCl_2$, as a MgO precursor. MgO was selected as a substrate because of its chemical and thermal stability, no reaction with carbon, and ease of removal after carbonization by dissolving out in acidic solutions. $MgCl_2$ was mixed with polyacrylonitrile (PAN) solution as a precursor of MgO with various weight ratios of $MgCl_2$/PAN. The average diameter of porous electrospun carbon fibers increased from 1.3 to 3 ${\mu}m$, as the $MgCl_2$ to PAN weight ratio increased. During the stabilization step, $MgCl_2$ was hydrolyzed to MgOHCl by heat treatment. At elevated temperature of 823 K for carbonization step, MgOHCl was decomposed to MgO. Specific surface area and pore structure of prepared electrospun carbon fibers were decided by weight ratio of $MgCl_2$/PAN. The amount of hydrogen storage increased with increase of specific surface area and micropore volume of prepared electrospun carbon fibers.

• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.8-8
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• 1990

A new method for the graft polymerization of acrylonitrile onto starch is presented. Graft polymerization of acrylonitrile onto starch and the subsequent hydrolysis in sodium hydroxide solution to prepare absorbents is well known. This process has been utilized to produce the commercial product, Super Slurper. In a typical batch process, ~5% starch in water mixture is gelatinized at $95^{\circ}C$ under stirring for 1 hour then cooled to room temperature. The graft polymerization itself is carried out for approximately 2 hours at $25~30^{\circ}C$ on the gelatinized starch by eerie ion initiation. In this study, graft polymerization of acrylonitrile onto starch via a reactive extrusion process which is a continuous, efficient process is described. Initial concentration of starch in water is 35% and the reaction temperatures are between $50~80^{\circ}C$. However, the most significant difference in the reactive extrusion process is the short time in which the graft polymerization takes place. Preliminary results on the properties of graft polymerization products obtained from the reactive extrusion process are compared to those obtained from the batch process as well as the absorbency of the hydrolyzed samples. Absorbent material has also been prepared by sequential grafting and saponification in the extruder followed by a 2 hour heat treatment of the extrudate in an air circulated oven at $100^{\circ}C$.

• Membrane Journal
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• v.23 no.4
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• pp.283-289
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• 2013

Poly(vinyl alcohol) (PVA) coating solution containing glutaraldehyde (GA) and maleic anhydride (MA) as crosslinking agents was coated onto hydrolyzed poly acrylonitrile (PAN) hollow fiber membranes. The permselectivities of the resulting composite membranes prepared varying the reaction temperature and the concentration of the crosslinking agents were tested for 90 wt% ethanol aqueous mixtures by the pervaporation technique at $60^{\circ}C$. In general, the flux decreased while the selectivity increased for the increases of the reaction temperature and the crosslinking concentration. In case of GA as a crosslinking, the flux $165g/m^2hr$ and the separation factor 81 were obtained at GA 11 wt% and the reaction temperature $120^{\circ}C$. And for the case of MA, the flux $174g/m^2hr$ and the separation factor 73 were obtained at MA 11 wt% and the reaction temperature $120^{\circ}C$.

• Membrane Journal
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• v.28 no.4
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• pp.279-285
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• 2018

The pervaporation separation of isopropanol/water mixture was carried out on a series of chemically cross-linked poly(vinyl alcohol)(PVA) composite membranes. The membranes were prepared by casting three kinds of PVA solutions with varying concentrations of PVA and GA onto polyacrylonitrile (PAN) support followed by thermal cross linking. As the PVA concentration increased, the flux decreased but separation factor was increased. It was confirmed that the composite membrane coated with PVA-3 (98~99% hydrolyzed) at a concentration of 7 wt% PVA and 20 wt% glutaraldehyde (GA) exhibited a flux of $209g/m^2h$ and a separation factor of more than 100. The submerged module test was carried out with controlled feed tank temperature and IPA concentration of the feed solution. The continuous concentration of IPA solution was increased from 90% to 99% after 60 h.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.309-315
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• 1976

An efficient separation method and the utilization of sericin are searched. Sericin was extracted with hot water from cocoons under atmospheric pressure. The separated sericin was gel-filtrated with Sephadex G-75 and G-150 at room temperature and at $70^{\circ}C$. The results indicated that sericin is consisted of only one fraction in elution diagram. In the graft copolymerization of acrylonitrile to sericin ceric ammonium nitrate was chosen as an initiatior. A maximum yield was obtained at certain concentration of the initiator confirming our previous experiments. Viscosity measurement of alkali-hydrolyzed graft copolymers indicated that the polyacrylonitrile graft had the molecular weight in the range of 7,000.