Uaá #>0&#ی2ñÂ#š*GÌ#:‹##Uë‹#`á#/Œ#6¨#

Demo

1. #g«#

†W e JW ‡Ê : n®B  G® ÒÿÞ&rֆ ú Bv ÿÂ, ÃK†– Z‡® ÂÆ "¢ :ç² ÚÒ& Î&  ÿn6 Þ:. ÊB² â‚vê â&r ‚v² Ök¶ n †

¢Ž& KW’²ê v†‚vÒ ⪮ê 뒲 rÆn6 Þ :.^1,2

ê VÚæ® ªnâ²Ö† †’² rÆr †‡û âîÎ

‚v(vapor grown carbon nanofibers, VGCNFs)& V² FÂV ²rÞ

ßgÊ:.^3-5

VGCNFsê ZÊ^㚠_:² 1000»1300 ×® 6~&r úvÊ î ªR o– ª nâ® JÚÊ® Rkš Æ& ‡û®Æ^6-9 ç

– † ¢Ž& ’W ÆçÊ ‹6 ²ÊZ® k² Žçÿ’²

1-3B², Û®V : :ç®B ‚v® , ŽÊV š ²Vªn  ®

’Æ, N šÿÊ 6VÊ:.^10,11 NBî VGCNFs® ÂÆê ‚vÒ ë

’² ®B §FÊ îÊ¢ þ璲 †J² ÂÆÒ l’Æ, ª¯W

’² : žk®B VGCNFsV 6Úæ® kª² ÿv ¢ šk

":& šÊ *G² ‡š V6 Þ:.^12-16 N6 VGCNFsê k ª C¶ ®" §F ‡ÚÊ Þ JZ‡Ê n®Æ †·  þ ÚÒ& §ÿÊ Vû² ‡š lê6 Þ:.^17,18

², &C2 nê Z†W ‡, g{, Îûk, ‡¶, †

ÖÞ, n® _, Z ^F, gr, K¿"® :ú, ª[ Jb2 G® ÿ² : i– êZ& Î& ÿn6 Þ

:.^19,20 NBî &C2 n® ÊB² BB V ûf& Þ®6

– †W ‡, è– J““n e 6V® V¦ ¢Ž& V

&C2 n® b>š rv®† ZÊr &C2 n& kªÒ þ

Uaá #>0&#ی2ñÂ#š*GÌ#:‹##Uë‹#`á#/Œ#6¨#

`?<sup>%</sup>}¿‹`}¿÷È#

œ­^™¬#^™Ìì¬À#

+5338T#9#49¼#Q:/#5338T#<#8¼#T,#

#

D#Vwxg|#rq#Wkhupdo#dqg#Phfkdqlfdo#Surshuwlhv#ri##

Ydsru#Jurzq#Fduerq#Qdqrilehuv0Uhlqirufhg#Hsr{|#Pdwul{#Frpsrvlwhv#

Vrr0Mlq#Sdun^%/#Hxq0Mxqj#Ohh/#dqg#Mhd0Urfn#Ohh#

Advanced Materials Division, Korea Research Institute of Chemical Technology, P. O. Box 107, Yuseong, Daejeon 305-600, Korea

(Received June 16, 2005;accepted September 5, 2005)

5¨Ü N FÂ&rê 2Vû‡ &C2 n& †‡û âî΂v(VGCNFs)Ò 0, 0.1, 0.5, 1.0 N6 2.0 wt% ¾

š² þV®B, rƲ VGCNFs/&C2 K¿"® JW e †W ‡š 6†®6æ ®V:. VGCNFs/&C2 îÎ K¿"® JW ‡– TMA– DMA² ¢š J®’Æ, †W ‡– "û 2.†– ï® ÿÿ 2.† e †Ü

þ 2.†Ò ®B V†®V:. :. R, VGCNFs® ¾Ê óV¶n³ JW e †W ‡Ê û~š «Î¶

n ÞêÆ, Êê Z® K¿" 2ú²& Þr VGCNFs– &C2 Ê® †W î Z® ûš VŽz ê K¿"® V¦ÂÆ® óV ¢ŽÊÒ f>r:.

Abstract:In this work, the thermal and mechanical properties of vapor grown carbon nanofibers (VGCNFs)-reinforced difunctional epoxy (EP) composites were investigated in the presence of the 0, 0.1, 0.5, 1.0, and 2.0 wt% VGCNFs. The thermal properties of the VGCNFs/EP composites were studied by thermo-mechanical analysis (TMA) and dynamic mechanical analysis (DMA). The mechanical properties of the VGCNFs/EP composites were also examined by universal testing machine (UTM), falling impact test, and the friction and wear tests. From experimental results, the thermal and mechanical properties of the VGCNFs/EP composites were improved with increasing the VGCNFs contents. This was due to the increase of crosslinking structure of the composites, resulting in improving the mechanical interlockings between VGCNFs and epoxy resins in the present composite system.

Keywords: vapor grown carbon nanofibers, epoxy resin, thermal and mechanical properties, crosslinking structure, mechanical interlocking.

†To whom correspondence should be addressed. E-mail: psjin@krict.re.kr

V®B k·š û2ú† Z² $– FÂ:Ê ßn6 Þ:.^21,22

†Òr, N FÂ&rê VGCNFs ¾& †Î VGCNFs/&C2 K

¿"® TMA– DMAÒ wk®V6, VGCNFs® ¾& †Î †

W ‡š ¢šJ† ZÊ UTM e †þ ¢úÒ :2®V:.

ÊÒ Ê J““n e †nÒ wk®V’Æ VGCNFs® ¾

 ªV K¿"® JW e †W ‡& N®ê Wû& V®

B 6†®6æ ®V:.

2. /

2.1 ÷#

N FÂ&r kª² ÿ² ‚vê ÒN Showa Denko® vapor grown carbon nanofibers(VGCNFs)ÊÆ, :ú² ÿr &C2 n

ê Z ÿgΠê¯(R)® diglycidylether of bisphenol A(DGEBA)

 YD-128(V:1.17 g· cm^-3, f: 11500»13500 cps, E.E.W185»190 gÜeq^-1)Ò ÿ®V:. ªr²ê †® rÞÎ 4,4-diaminodiphenyl- methane(DDM)š ÿ®V’Æ Table 1& ÿ² VGCNFs® ’‡š, Figure 1&ê ÿ² &C2 n– ªr® ª¯W ÂÆ3š WW î:.

2.2 YJFQIv2&'#(´÷£#g»#

VGCNFs/&C2 K¿"Ò rÆ®6æ, &C2 ¾– 100’² Òk®â ®6 VGCNFs® Zî² 70 × Kzf&r 242Z Ê Æ®B nÚ e ê® ÿ:Ò rƲ  VGCNFs® ¾š 0, 0.1, 0.5, 1.0, 2.0 wt%² ª2úÊr ’¿®V:. ÊÒ 60 ×&r Ó 22 Z /ž î Ún³ ¦n² , DDMš 21 phrš þV®B DDM Ê šZÞ ÿÊr  Kzf&r f«®6 †B Gš †®B, :® 6ŠÒ Zÿ f’² ² vf 2& ’¿² 2"Ò RÛ²

 Kzf&r ~ ãÒ 5 ×/min² ®B 70 ×(30 min), 140 × (2 h) N6 180 ×(1 h)® 3> ª Êʚ Wÿ®B VGCNFs/

&C2 K¿"Ò rÆ®V:.²³ rÆr VGCNFs/&C2 K¿

"ê VGCNFs® ¾ rr& †Ò WW VE-0.0, VE-0.1, VE-0.5, VE-1.0, N6 VE-2.0² ÛÛ®V:.

2.3 ?L#|#

VGCNFs/&C2 K¿"® JW ‡š 6†®† Z®B ~

ª& †Î 1~&W ®n® ªÒ wk®ê û®Î TMA(Q400, TA instrument)Ò ÿ®B T^g Z® J““n(thermal expansion co- efficient)Ò â ÚZ† ®&r ~ ãÒ 10 ×/min’² ®B 30»300 × ~ êZ&r wk®V:. Ê¢, ÿ² 2® †ê 0.5Ý0.5Ý0.5 cm³Ê:.

VGCNFs/&C2 K¿"® Ƈš& †Î /W f‡ ‡š

¢šJ6æ /W†Ús(DMA2980, TA) û®Ò Êÿ®B â ÚZ† ®&r 30»300 × ~ êZ&r ~ ãÒ 5 ×/min²

®B wk®V:. Ê¢, /nê 1 HzÊ6 C– 5 amp² 6k®

V:.

2.4 {L#|#

VGCNFs/&C2 K¿"® †W ‡– ASTM 399& V®B

"û2.†(#1125, Lloyd LR 5k, UTM)Ò Êÿ² single edge notch(SEN)- three point bending 뒲 ‹Z bŠÎ‡(critical stress intensity factor, KIC) hš ®B ¢šJ®:.²⁴Ê¢, 2® ή  Êê ¦.® 1/2

² 6k®6 span-to-depth ratioê 4:1² cross-head speedê 1 mm/min

’² Æ^®B wk®V:.

K¿"® ÿÿkê ï® ÿÿ 2.†(DTI-605, Daekyung Tech) Ò ÿ®B wk®V’Æ, Ê¢ ²6 ®k èÊê 1 m, ®g– 2 kg

’² 6k®V:.

2.5 {· ó#|

rÆr VGCNFs/&C2 K¿"® Ƈš& †Î † e þ

‡– V†2 ®&r ball-on-disk k2Ò Vê NšR g_ k 2® 2.†(PD-102, R&B)Ò Êÿ®B wk®V:. 2– ÚÊ 30 mm ¦.V 10 mmÎ &fk’² rÆ®V’Æ, ~, Šz² 2

&r † âZf® ãê 500 rpm’² ®B Òk Šâ, ß 3 kg®

6k3 ®gš ballR disk g_Ê& V²  wk®V:.

3. ûG Z ë«

3.1 ?L#|

J““nê ~ª& †Î ®nª(dimensional change)Ò î

 NîZ® †† h’²Ö† ¶ n ޒÆ, J““n h

†– kΪ Ê® g{š V®2úê ْ² ¢zŽ Þ:.

ÒnW’² J““nê :¢ 3 (1)& ®Ê ¶ n Þ:.

T L

k L

∆

×

×

=∆ ^sp

α (1)

B†r, αê J““n, L– ~&r 2 ŽÊ, ∆Lspê ²V«

{&r 2 ŽÊ® ª, kê Jkn, ∆^Tê ~ ~Ò î

:.

VGCNFs® ¾& †Î VGCNFs/&C2 K¿"® JW 

‡– TMAÒ Êÿ®B J““nÒ T^gZ² wk®B ¢šJ®

:. ~ª& †Î 1~&W ®n® ªÒ Figure 2&, ¾& † Î K¿"® J““nÒ Figure 3& WW î:. R² r, VGCNFs® ¾Ê óV¶n³ ~ª& †Î ®n ª

Figure 1. Chemical structures of the DGEBA and DDM used.

H2C H C O

H2

C O C

CH3

CH3 O

H2 C C

H H2 C O OH

C CH3

CH3

CH2 H C O H2 C O n

DGEBA

H2N H2

C NH2

DDM Table 1. Characteristics of the VGCNFs Used

Characteristics Values Young’s modulus(GPa)

Maximum tensile strength(GPa) Diameter(nm) Specific surface area(m²ág^-1)

Length(µm)

150»200 1»3 100»200

37 10»20

– fâ®ê ٚ V†¶ n ÞêÆ, Êê VGCNFs® ¾Ê ó V®Ê 6Úæ :ú–® Žçÿš Ê 6Úæ ® J

& V² kš V®2r JW ‡Ê ûn† ¢Ž’² f>r :. B² VGCNFs® ¾Ê óV¶n³ J““nV 皢êÆ Êê kª² ÿr VGCNFsV J& V² ‡Ê n®B &

C2 n& Ú~& †Ò &C2 ÖÂÆ& vÛr Jš ·n¾

’²¾ K¿"® Ö§{R Âï r3¶š fâ2r RW’² J““nÒ fâ2úê ْ² V†r:.

Figures 4– 5ê ~ ª& †Î K¿"® Vû ‡¶R tan δ Ò WW î ÙÊ:. Figure 4&r Jê j– oÊ, vZÊ WC R 6Š WC þ¦ VGCNFs® þV² ÎÊ Vû ‡¶Ê ó V®ê ٚ ¢ n Þ:. Êê š²ÊWÊ Æ VGCNFsV 6Úæ

ښ Ê®ê K¿"® kª C¶š ®² ‡¶Ê ó V®ê ْ² f>r:. B², tan δ® ’Â&r tan δ® ²VfÊ î

îê ~ê T^gÒ ®N®Æ rn &C2 n& šÊ VGCNFs®

¾Ê óV¶n³ T^gV çâ óV®:V VE-2.0&rê 154.01 ײ

š¦W Ââ óV² ٚ «Î¶ n Þ:. Êê TMA® R&r

¢ n ÞEÊ VGCNFsV &C2 n–® Žçÿš Ê 6Úæ

® v/‡š V®2ú² ’ÂV zÎ ’² Ê/² ْ² f>r:.

3.2 {L#|#

bŠÎ‡(fracture toughness)– K¿"® :r Wÿ& Þ gê

®â 6zÊÒ ¶ ÃÊÆ, :ú&r kª‚v² ÂïÊ Zbv

¢ VÃ®ê ‡ÊÒ ¶ n Þ:.²⁵

Figure 6– VGCNFs/&C2 K¿" bŠÎ‡(K^IC) hš î

ْ²r, VE-2.0&r Ó 4.236 MPa· m^1/2² Vû Æ hš V&š ¢ n Þ:. Êê Figure 7® SEM R&r ¢ n ÞEÊ VGCNFsV

&C2 :ú& î Ún 6Ò² VGCNFs/&C2 ’¿’š

k‡®6 n² n§ š²ÊWš lâ nÆ VGCNFs æV V

6 Þê k·R ’W ‡ G’² ήB Îֲֆ® ÿÿš

šª2r R† ¢Ž& VGCFs® ¾Ê óV¶n³ n² bŠÎ

‡š lê ْ² f>r:.

Figure 2. Thermal expansion curves of VGCNFs/EP composites.

.0 .1 .2 .3

VE-0.0 VE-0.1 VE-0.5 VE-1.0 VE-2.0 316#

315#

314#

313#

#

Dimentional change(mm)

# 3# 433# 533# 633#

Temperature(×)

Figure 3. Coefficients of thermal expansion(CTE) of VGCNFs/EP com- osites as a function of VGCNFs content.

:813#

:518#

:313#

9:18#

# CTE(µm/m×)

# 313# 318# 413# 418# 513#

VGCNFs content(wt%)

0.0 0.5 1.0 1.5 2.0

5 0 5

0 below T_g

above T_g

53;#

537#

533#

4<9#

4<5#

4;;#

Figure 4. Storage modulus(E’) vs. temperature plots of VGCNFs/EP composites as a function of VGCNFs content.

613 518 513

418

Log storage modulus(E′, MPa)

3# :3# 473# 543# 5;3#

Temperature(×)

5 0 5

0 VE-0.0

VE-0.1 VE-0.5 VE-1.0 VE-2.0

Figure 5. Loss tan δ vs. temperature plots of VGCNFs/EP composites as a function of VGCNFs content.

415#

31;#

317#

313#

Tan δ

83# 433# 483# 533# 583#

Temperature(×)

0 4 8

2 VE-0.0

VE-0.1 VE-0.5 VE-1.0 VE-2.0

Figure 6. KIC values of VGCNFs/EP composites as a function of VGCNFs content.

8

7

6

5 KIC(MPa.m1/2 )

313# 318# 413# 418# 513#

Contents of VGCNFs(wt%)

2 3 4 5

ÿÿkê K¿"® †W ‡š îê gê² Ãÿ’² 2Ê ÿÿš q®š ¢ "V bŠnê îš &²:.²⁶ Figure 8–

rÆr VGCNFs/&C2 K¿"® ÿÿkÒ î ْ²r, VGCNFs® ¾Ê óV¶n³ K¿"® ÿÿkV :ê  ûš «Î¶ n ÞêÆ, Êê ´® ʇ R– Ò®®ê ْ

² VGCNFsV ÿÿ& ®Ê r3r Âï ‡ûš Ê®B ZW’

² K¿"® ÿÿ‡Ê ûn† ¢Ž’² f>r:.

3.3 {· ó#|#

†– g_®ê ¦ ’V Î{š qê 2&r ² Ê :Î ² & VW’² ÊÆî Êz ¶ ¢& g_ Ê® gv

û’² r3®ê VÃ{ÊÆ ÊÒ 3’² îÊ :¢R o:.²⁷ FµL (2) B†r, Fê †{, L– n ®g, µê †nÒ î:.

B², †Ê: Ê® †nê ²Ê "†:(asperities)® k,

þ Ûæ:R ² ²Ê "†:® †(ploughing), ² Ê:  Ê® §(adhesion) G® :ç² K¿W Wû:& †Î®Æ, ÊÒ 3

’² îÊ :¢R o:.²⁸

µµdµaµp (3) B†r, µ^dê ²Ê "† k(asperity deformation) †‡Ú, µ^aê

§ †‡Ú, µ^pê † †‡Úš î:. Ê ‡Ú:® V W †Bê †® Ê{, , ²Ê® k, N6 ®® Wûš

qê †Ê® 2& ®Ê²:.²⁹

², þ® vk– ²Ê ’²– k& ®² þ, Fþ,

§þ, ª¯W †R þ® †NWÎ z V² zÛn6 ޒ

Æ, :r® þZ&ê ", ç/ÆÊ, ® G® ¿& †Ò Ê:® †B&ê ~ÊV Þ" K¿W’² îò:.²⁹

VGCNFs® ¾& †Î K¿"® /†& ®² †{ e 

Figure 7. SEM image of VGCNFs/EP composites; (a) VE-0.1, (b) VE-0.5, (c) VE-1.0, and (d) VE-2.0.

+d,# +e,#

+f,# +g,#

Figure 8. Impact strength of VGCNFs/EP composites as a function of VGCNFs content.

453 433

;3 93 73 Impact strength(kgf)

# 313# 318# 413# 418# 513#

Contents of VGCNFs(wt%)

0 0 0 0 0

Figure 9. Friction force and coefficient of VGCNFs/EP composites as a function of VGCNFs content.

415 413 31;

319 317

Friction force(N)

3# 314# 318# 413# 513#

Contents of VGCNFs(wt%)

.4 .6 .8 .0

.2 Friction force

Coefficients of friction 3158#

3153#

3148#

3143#

#

Coefficients of friction(µ)

†nÒ wk®V’Æ, N RÒ Figure 9& î:. R&r

¢ n ÞEÊ VGCNFs® ¾Ê Wšn³ K¿"® †{R

†nV :Æ VGCNFs® ¾Ê óV¶n³ †{R †

nV fâ®ê ٚ ¢ n Þ:. Êê kªÎ VGCNFsÒ þV¾& †Ò ’ ÊÊ V †Ê& þRW’² k‡n

† ¢ŽÊ:.

Figure 10– VGCNFs® ¾& †Î þæ:š î ْ²r, rn &C2& šÊ VGCNFsÒ þV² K¿"®  ç– þ æ:š îêÆ, Êê VGCNFsV V †Ê& ’ Êš

®B †R þÒ fâ2ú† ¢ŽÊÒ f>r:.²⁹

4. û«

N FÂ&rê VGCNFs ¾& †Î VGCNFs/&C2 K¿"Ò rƲ , VGCNFs® ¾ªV JW e †W ‡& N®ê W ûš ¢šJ®:.

:. R, VGCNFs® ¾Ê óV¶n³ K¿"® JW ‡

Ê nÊê ٚ «Î¶ n ÞêÆ, VGCNFs ¾Ê óV¶n

³ J““nV fâ®ê ٚ V†nê ْ² Jš kªÎ VGCNFsÒ &C2 n& þV¾& †Ò &C2® V¦ª& Wû

š R VGNFs/&C2 K¿"® JW ‡Ê ûr ْ² f

>r:. B² VGCNFs® ¾Ê óV¶n³ bŠÎ‡ êâÎ K^IC hR ‹ÿkV :ê ٚ V†¶ n ÞêÆ &C2 n&

ÎÖ ®gÊ VÊÊ VGCNFsV ÎÖ ÿÿ& V² barrier C¶š

®B ZW’² K¿"® §{ šª Zš VŽ: R† ¢ŽÊ Ò f>r:. N6 VGCNFs® ¾Ê óV¶n³ †{Ê óV

®6 †nê fâ®VêÆ, Êê kªÎ VGCNFs& ®² ’

 ÊÊ V †Ê& þRW’² k‡n:ê ٚ JBR ê ÙÊÆ, ÊB² ’ Ê® k‡’² þæ:Ê fâ®V:

6 f>r:.

ƒ+S

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Figure 10. Wear loss of VGCNFs/EP composites as a function of VGCNFs content.

315:

3157 3154 314;

3148 3145

Wear loss(mm)

# 313# 318# 413# 418# 513#

Contents of VGCNFs(wt%)

2 5 8 1 4 7