Environmental Engineering Reference
In-Depth Information
(a)
(b)
100
100
80
75
60
50
40
PP
LM-PP/PP
PP
NPs/PP
NPs (LM-PP)/PP
NPs (HM-PP)/PP
25
HM-PP/PP
NPs/PP
NPs (LM-PP)/PP
NPs (HM-PP)/PP
20
0
0
200
300
Temperature (°C)
100
200
300
Temperature (°C)
400
500
600
100
400
500
600
(c)
(d)
100
104.1°C
91.4 J/g
LM-PP
HM-PP
80
60
Cooling
40
LM-PP (air)
LM-PP (nitrogen)
Heating
20
HM-PP (air)
136.8°C
88.9 J/g
HM-PP (nitrogen)
0
100
200
300
Temperature (°C)
400
500
600
40
80 120
Temperature (°C)
160
200
figure 4.4
TGA thermograms of PP, M-PP/PP blends, and PNCs in (a) air and (b) nitrogen, (c) TGA of lM and HM in both air and
nitrogen, and (d) DSC of lM-PP and HM-PP. Adapted with permission from Ref. [20]. © RSC.
MR is a phenomenon where resistance of a material changes when an external magnetic field is applied. Giant magnetore-
sistance (GMR) is the large resistance change that occurs when the relative orientation of the magnetic domains in adjacent
layers is adjusted from antiparallel to parallel under an applied magnetic field. It is defined as the ratio (
R
AP
-
R
P
)/
R
P
, where
R
P
and
R
AP
are the resistances of materials for parallel and antiparallel alignments, respectively. The GMR phenomenon was first
discovered in multilayered structural materials, in which ferromagnetic Fe metal layers were separated by a nonmagnetic Cr
layer in 1988. large GMR values can be obtained typically at very low temperatures, while obtaining large-room-temperature
GMR is still a challenge. In addition, similar GMR was reported in granular-structured materials, in which a granular structure
with ferromagnetic nanograins is dispersed in a nonmagnetic metal. The first reported granular GMR was in Cu/Co composites
where Co granules were embedded in a Cu matrix [26]. Since then, other metal composites have been found to exhibit GMR
with a reported maximum signal of 60% at 4.2 K [27].
Most recently, molecular and composite systems have exhibited interesting MR phenomena in which both positive and neg-
ative resistance changes were observed upon applying an external magnetic field. This is intriguing, in particular, for conduct-
ing polymer-based multifunctional nanocomposites, as the conducting polymer is a conjugated structure with electrons being
exchanged and transported along the backbone in the case of oxidative remediation of heavy metal species. Figure 4.7 shows
