Experimental results
Dynamic mechanical test
Figure 2 shows the temperature dependences of the dynamic
storage moduli,E0
, of the neat epoxy resins and the composites
with different EEWRs. The dynamic storage moduli of the
neat epoxy resins and the composites decreased gradually as
the temperature increased in the glassy states and decreased
rapidly in a narrow temperature range near the glass transition
temperatures. After that, the moduli increased gradually in the
rubbery states. The dynamic storage moduli in the glassy and
rubbery states, as well as the glass transition temperature, were
clarified to be strongly dependent on the EEWRs. For both the
neat epoxy resins and the composites with a higher EEWR, the
dynamic storage modulus was larger in the glassy state but
smaller in the rubbery state. A comparison of the moduli of the
composites and the neat epoxy resins with the same EEWR
showed that the composites (Fig. 2b) had a consistently higher
storage moduli than those of the neat epoxy resins (Fig. 2a)
because the composites were reinforced by silica particles that
had a high elastic modulus.
The results of tan d for the neat epoxy resins and composites
are shown in Fig. 3. The tan d of both the composites
and the neat epoxy resins had one sharp peak, similar to
general epoxy resin. The temperatures at the peaks of the
tan d, namely, the glass transition temperatures, were found
to decrease as the ratios of the EEWRs increased.
Bending test
Figure 4 shows the typical load–deflection curves of the threepoint
bending tests for the neat epoxy resins and the composites.
The load–deflection relations for the neat epoxy resins
and the composites were linear and curved near the maximum
load, indicating that they were either brittle or quasi-brittle.
Experimental resultsDynamic mechanical testFigure 2 shows the temperature dependences of the dynamicstorage moduli,E0, of the neat epoxy resins and the compositeswith different EEWRs. The dynamic storage moduli of theneat epoxy resins and the composites decreased gradually asthe temperature increased in the glassy states and decreasedrapidly in a narrow temperature range near the glass transitiontemperatures. After that, the moduli increased gradually in therubbery states. The dynamic storage moduli in the glassy andrubbery states, as well as the glass transition temperature, wereclarified to be strongly dependent on the EEWRs. For both theneat epoxy resins and the composites with a higher EEWR, thedynamic storage modulus was larger in the glassy state butsmaller in the rubbery state. A comparison of the moduli of thecomposites and the neat epoxy resins with the same EEWRshowed that the composites (Fig. 2b) had a consistently higherstorage moduli than those of the neat epoxy resins (Fig. 2a)because the composites were reinforced by silica particles thathad a high elastic modulus.The results of tan d for the neat epoxy resins and compositesare shown in Fig. 3. The tan d of both the compositesand the neat epoxy resins had one sharp peak, similar togeneral epoxy resin. The temperatures at the peaks of thetan d, namely, the glass transition temperatures, were foundto decrease as the ratios of the EEWRs increased.ทดสอบการดัดโค้งรูปที่ 4 แสดงเส้นโค้งปกติโหลด – โก่งของ threepointดัดสำหรับโลหะมีความเรียบร้อยและการคอมโพสิตความสัมพันธ์ที่โหลด – โก่งสำหรับโลหะมีความเรียบร้อยและคอมโพสิตมีเส้นตรง และโค้งใกล้สูงสุดโหลด ระบุได้ว่า พวกเขาเปราะบาง หรือเปราะกึ่ง
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