• Journal of Adhesion and Interface
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• v.16 no.2
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• pp.55-62
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• 2015

It was investigated that the effect of surface modification and concentration of fumed silica on the adhesion properties and thermal stability of 2-EHA/AA pressure sensitive adhesive (PSAs) prepared by UV irradiation. The influence of repeating units of crosslinking agent on PSAs were also studied. From SEM analysis, PSAs synthesized with surface modified silica had finer dispersion of silica particles in polymer matrix due to the interfacial interaction. Results of the study showed that increase in tack and peel strength when under 0.3 wt% of silane treated silica were added in the reaction mixture. The addition of PEGDMA for crosslinking agent offers positive effect on adhesion properties in comparison with PSAs using EGDMA for crosslinker, which may be attributed to high mobility of ethylene oxide repeating units in PEGDMA. From the thermal degradation residue of PSAs, it was revealed that thermal stability was improved with silica addition due to the strong interfacial bonding between silane modified silica and polymer matrix, which may act as a thermal barriers into 2-EHA/AA PSAs.

• Polymer(Korea)
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• v.26 no.5
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• pp.653-660
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• 2002

The volume phase transition of poly(N-isopropylacrylamide) (PNIPAAm) and poly (N-isopropylacrylamide-co-sodium methacrylate) (P (NIPAAm-co-SMA)) hydrogels crosslinked with poly (ethylene glycol) diacrylate (PEGDA) was investigated in consideration of water content and surface area. The volume phase transition temperature of hydrogel was not affected by the concentration of crosslinking agent, which increased over 40$\^{C}$ by incorporating a small amount of SMA. Higher volume phase transition temperature was obtained when PEGAD was used as a crosslinking agent, suggesting that the chain length of crosslinking agent had a significant effect on the volume phase transition temperature. The surface area of PNIPAAm and P (NIPAAm-co-SMA) gels fell off around the volume phase transition temperature, resulting from the fact that the size of pores reduced remarkably in the course of the volume phase transition. Hence, the surface area and the pore size were considered to be important factors indicating the volume phase transition.

• Fibers and Polymers
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• v.5 no.3
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• pp.230-233
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• 2004

The optimum conditions for durable press treatment of cotton fabrics using glyoxal as a nonformaldehyde crosslinking agent were investigated. Crosslinking reaction was conducted in the presence of different catalysts such as aluminum sulfate, magnesium chloride, or magnesium chloride-citric acid mixture at various mole ratios of catalyst to glyoxal. Aluminum sulfate was proven the most effective one among those used. Glycol addition into a glyoxal padding bath increased the wrinkle recovery angle(WRA) and whiteness of treated fabrics. The optimum mole ratio of glycol to glyoxal was 1:1. Diethylene glycol addition produced better overall performance to the glyoxal-crosslinked fabric compared to ethylene glycol addition.

• Elastomers and Composites
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• v.26 no.1
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• pp.15-22
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• 1991

Blends of ethylene-propylene-diene terpolymer(EPDM) and high density polyethylene(HDPE) have been prepared in a roll mill by the process "dynamic curing" where both blending and a crosslinking reaction was carried out simultaneously. As a crosslinking agent, dicumyl peroxide(DCP) was used. Throughout the experimental ranges, the dynamically cured polyblends were shown to be thermoplastic elastomers except highly crosslinked blends of high compositions of EPDM. The increase of melt viscosity was observed as EPDM composition and DCP contents increased. From DSC determinations, the crystallinity decreased with increasing contents of DCP. The tensile strength and elongation at break generally increased with increasing DCP content and increasing HDPE compositions, but highly depended on the combined effects of decreasing crystallinity and increasing crosslinking density.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.639-643
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• 1999

Interpenetrating polymer networks(IPNs) composed of castor oil(CO) polyurethane(PU) and epoxy resin were prepared by the simultaneous polymerization technique. Two types of PU were prepared using 1,4-butanediol(BD) and BD/trimethylolpropane(TMP) as a chain extending agent and crosslinking agent. The PU/epoxy based on BD as a chain extending agent showed more shift in the damping peak than PU/epoxy based on BD/TMP as the PU content was increased. BDPU/epoxy simultaneous interpenetrating polymer networks(SINs) had a better compatibility than BD/TMP-PU/epoxy SINs. For both systems, it was postulated that unique network formation of PU/epoxy SINs as a chain extending agent and crosslinking agent had occurred to a significant extent of phase mixing. The types of chain extender in the PU were found to be an important factor in determining the phase mixing of the IPNs. When the BD/TMP-PU reaction was faster than epoxy network, the extent of phase mixing was retarded by decreasing entanglement of networks. It was found that both PU/epoxy SINs provided enhanced flexural properties and fracture toughness, fracture surfaces of BDPU/epoxy and BD/TMP-PU/epoxy SINs showed the localized shear deformation and generation of stress whitening associated with the cavitation.

• Polymer(Korea)
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• v.28 no.1
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• pp.18-23
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• 2004

Superabsorbent poly(potassium acrylate-co-acrylamide)s were synthesized in particle form using inverse suspension polymerization technique. Mean diameter of the prepared polymer particles decreased from 300 to 50 $\mu\textrm{m}$ with increasing surfactant concentration. The dynamic and equilibrium swelling behaviors during water absorption and drying process were investigated by weight measurement. The swelling ratio of polymer particles in water changed according to not only polymer crosslinking density, but particle size, saline concentration of aqueous medium, and copolymer compositions. Water sorption amount was increased with decreasing particle size, crosslinking agent concentration, and ion concentration in bulk solution. Being different from the water sorption process, the drying process was not significantly affected by particle size, polymer composition, or crosslinking amount.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.1
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• pp.144-153
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• 2001

The effect of crosslinking on hand of the cellulase treated Tencel fabrics was investigated. Tencel fabrics were crosslinked with DMDHEU, mechanically prefibrillated, hydrolyzed by cellulase, and treated with softener. The treated fabrics were characterized by add-on, weight loss, DP rating, WRA, strength, SEM analysis and hand measurement. As DMDHEU concentration increased, weight loss of DMDHEU/cellulase treated fabrics decreased. However, cellulase treatment decreased DP properties and strength retention. Less fibrils were observed in the cellulase treated fabrics after DMDHEU treatment than the cellulase treated ones. It was confirmed that crosslinking with DMDHEU treatment was effective to control fibrillation. At 5% of DMDHEU concentration, DMDHEU/cellulase treated fabrics showed softer, smoother and bulkier hand compared with other treated fabrics. Among mechanical properties, bending and shearing properties were decreased progressively through DMDHEU, cellulase, and softener treatment. DMDHEU treatment contributed to impart resilience, cellulase treatment to bulkiness and softener treatment to smoothness. As the treatment of DMDHEU, cellulase, and softener progressed NUMREI, FUKURAMI, and THV increased with the exception of KOSHI.

• Textile Coloration and Finishing
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• v.18 no.4
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• pp.20-27
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• 2006

Lyocell is a not only environmentally-friendly but also very advantageous fiber. When Lyocell is soaked in water, its wet tenacity does not decrease and elongation and moisture regain of it are better than cotton. However, one drawback of lyocell is its fibrillation. The fibrills of lyocell were generated during wet process such as scouring and dyeing deteriorates the dyeing color depth and the appearance of fabric. The purpose of this study was to decrease the fibrillation tendency of lyocell fabric using crosslinking agent, epichlorohydrine(ECH). The effects of NaOH scouring and ECH crosslinking were observed. The different types of ECH addition methods to lyocell and the various concentrations of ECH in crosslinking reaction onto dyeing characteristic and fibriallation were investigated. Weight loss and whiteness index of crosslinked lyocell by ECH were examined. K/S values of ECH treated lyocell fabrics dyed with reactive dye were measured and SEM images of untreated and treated lyocells were observed extensively to define the fibrillation tendency. The results were as follows ; 1) ECH treatment showed the effect of weight loss and scouring because ECH crosslinking reaction was conducted in alkaline condition. 2) The increase in ECH concentration from 5 to 30% does not affected K/S value changes. 3) ECH crosslinking can effectively prevent the fibrillation tendency of lyocell.

• Polymer(Korea)
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• v.37 no.6
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• pp.730-735
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• 2013

The physical properties of poly(vinyl alcohol) (PVA) with polyamide-epichlorohydrin (PAE) for wet strength additives in paper industry were investigated. Upon introducing PAE to PVA, not only melting and crystallization enthalpy in DSC but also the area of diffraction peaks in XRD decreased, which represented the fact that PAE acted as a crosslinking agent for PVA. However, this crosslinking seemed to be physical crosslinking having relatively less bonding energy compared to chemical crosslinking since the crystallization in PVA was able to take place by thermal annealing. This physical crosslinking and crystallization by thermal annealing enhanced the thermal stability and mechanical strength in PVA and consequently, these improvements are desired in the paper manufacturing process to increase the dry and wet strength in the paper.

• Membrane Journal
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• v.23 no.6
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• pp.450-459
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• 2013

2,3,5,6-Tetramethyl-1,4-phenylenediamine (TMPD) based polyimide (PI) were crosslinked with 1,2-Diaminoethane (DAE) and 1,6-Diaminohexane (DAH) to enhance gas transport properties. Fourier transform infrared (FT-IR) studies show that imide groups were converted into amide groups during crosslinking process. Thermogravimetric analysis (TGA) results indicate that the degradation temperature of crosslinked PI membranes decreased after crosslinking. This is due to degradation of alkyl group in crosslinking agent. The d-space of crosslinked PI membranes decreased with increasing crosslinking time. The ideal permeability for $CH_4$, $N_2$, $O_2$, and $CO_2$ decreased after crosslinking and the ideal permeability of crosslinked PI membranes induced by DAH is larger than that by DAE. In contrast, the permselectivity of $CO_2/CH_4$, $CO_2/N_2$ and $O_2/N_2$ increased during crosslinking. For the gas pair of $CO_2/CH_4$, the maximum increment is about 39.5% after 6 minutes of DAE crosslinking. Also, that of $O_2/N_2$ gas pair is about 20.5% after 6 minutes of DAE crosslinking. According to these result, DAE is more suitable for enhanced permselectivity than DAH. On the contrary, DAE is not useful for $CO_2/N_2$ separation due to reduction in $CO_2/N_2$ permselectivity after 3 minutes DAE crosslinking.