• Polymer(Korea)
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• v.28 no.2
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• pp.162-169
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• 2004

Poly[styrene-b-(ethylene-1-butene)-b-styrene] triblock copolymer (SEBS) was functionalized with 0 to 3.0 phr maleic anhydride and the amount of dicumyl peroxide used as an initiator was varied from 0 to 0.3phr. The gel content of the modified SEBS was determined by xylene extraction and poly(oxymethylene) was blended with the modified SEBS. The impact, tensile, flexural strength and morphologies of the blends were investigated. The Izod impact strength of poly(oxymethylene) was improved through its blending with modified SEBS. However, the Izod impact strength of poly(oxymethylene)/modified SEBS blend decreased above 5% modified SEBS content. Regarding the effect of dicumyl peroxide content on the Izod impact strength, the blend had a maximum Izod impact strength when poly(oxymethylene) was blended with modified SEBS prepared with 0.1 phr dicumyl peroxide. It was also confirmed by SEM micrographs that the average particle size of modified SEBS in poly(oxymethylene)/modified SEBS blends was smaller than that of SEBS in poly(oxymethylene)/SEBS blends.

• Macromolecular Research
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• v.10 no.4
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• pp.230-235
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• 2002

Alternating polyols of oxymethylene and oxyalkylene were synthesized and used as precursors for thermoplastic poly(ether-ester) elastomers (TPEs). The polyols were synthesized by reacting diols having different methylene units with dichloromethane in the presence of a phase transfer catalyst. The number of methylene units in the alkylene oxides was varied from 3 to 6. TPEs were prepared using the polyols as soft segments and poly(butylene terephthalate) units as hard segments. The polyols and TPEs synthesized were characterized using FTIR, NMR, GPC, DSC, and polarized optical microscopy. The polyols showed a profound odd-even effect on the melting (T$_{m}$) and glass transition temperatures (T$_{g}$). Polyols with odd numbers of methylene groups in the alkylene units have higher transition temperatures than polyols with odd number of methylene groups. The tendency is still kept in TPEs, even though the T$_{g}$ of soft segment in TPEs are slightly higher than those of corresponding neat polyols. The T$_{m}$ and T$_{g}$ of soft segments are almost constant in the range of 20 to 60 wt % contents of soft segments. On the other hand, the normalized heat of fusion of hard segment decreased with increasing the content of loft segment.ent.t.ent.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.708-712
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• 1993

The Polymerization of p-chlorophenyl propargyl ether (CPE) was carried out using various transition metal catalysts. The catalytic activity of $MoCl_{5}$-based catalysts was greater than that of $WCl_6$-based catalysts. $MoCl_5$ alone and $MoCl_{5}$-cocatalyst systems polymerized CPE very effectively to give a high yield of poly(CPE). In most cases, the polymer yield was quantitative and the average molecular weight $({\bar{M}}n)$ was in the range of 9,000 and 17,000. The NMR, IR, UV-visible spectra indicated that the present poly(CPE) has a linear conjugated polyene structure having p-chlorophenyl oxymethylene substituent. The poly(CPE) was mostly dark-brown colored powder and was completely soluble in various organic solvents such as chloroform, methylene chloride, THF, chlorobenzene, etc. The X-ray diffraction analysis indicated that the present poly(CPE) is amorphous.

• Polymer(Korea)
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• v.29 no.1
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• pp.19-24
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• 2005

Polymer blends containing polypropylene (PP) with compatibilizers were prepared using twin screw extruder. Physical properties were investigated using universal test machine (UTM) and Izod impact tester. In the PP/acrylonitrilebutadiene-styrene (ABS) blends, mechanical strength was increased with the addition of PP-g-styrene acryloritrile (PP-g-SAN) compatibilizer, and the ductility was increased with the addition of ethylene-ethyl acrylate-maleic anhydride (E-EAMAH-g-SAN) compatibilizer. For the PP/ABS/ polycarbonate (PC)/Nylon-6,6 blends, impact strength was increased with the addition of ethylene glycidylmethacrylate (E-GMA compatibilizer) up to 0.5 phr. In the case of the PP/ABS/PC/Nylon-6,6/poly(methyl methacrylate) (PMMA)/poly(oxymethylene) (POM)/poly(vinyl acetate) (PVC)/poly(butylene terephthalate) (PBT) blends, mechanical properties were increased by the complex compatibilizing effects of PP-g-SAN, E-EA-MAH-g-SAN and E-GMA, respectively.

• Macromolecular Research
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• v.12 no.1
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• pp.1-10
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• 2004

The structural changes occurring in the isothermal crystallization processes of polyethylene (PE), poly-oxymethylene (POM), and vinylidene fluoridetrifluoroethylene (VDFTrFE) copolymer have been reviewed on the basis of our recent experimental data collected by the time-resolved measurements of synchrotron-sourced wide-angle (WAXS) and small-angle X-ray scatterings (SAXS) and infrared spectra. The temperature jump from the melt to a crystallization temperature could be measured at a cooling rate of 600-1,000 $^{\circ}C$/min, during which we collected the WAXS, SAXS, and infrared spectral data successfully at time intervals of ca. 10 sec. In the case of PE, the infrared spectral data clarified the generation of chain segments of partially disordered trans conformations immediately after the jump. These segments then became transformed into more-regular all-trans-zigzag forms, followed by the formation of an orthorhombic crystal lattice. At this stage, the generation of a stacked lamella structure having an 800-${\AA}$-long period was detected in the SAXS data. This structure was found to transfer successively to a more densely packed lamella structure having a 400-${\AA}$-long period as a result of the secondary crystallization of the amorphous region in-between the original lamellae. As for POM, the formation process of a stacked lamella structure was essentially the same as that mentioned above for PE, as evidenced from the analysis of SAXS and WAXS data. The observation of morphology-sensitive infrared bands revealed the evolution of fully extended helical chains after the generation of lamella having folded chain structures. We speculate that these extended chains exist as taut tie chains passing continuously through the neighboring lamellae. In the isothermal crystallization of VDFTrFE copolymer from the melt, a paraelectric high-temperature phase was detected at first and then it transferred into the ferroelectric low-temperature phase at a later stage. By analyzing the reflection profile of the WAXS data, the structural ordering in the high-temperature phase and the ferroelectric phase transition to the low-temperature phase of the multi-domain structure were traced successfully.