Civil Engineering Reference
In-Depth Information
5.6
Ef ect of
In-Situ
Polymerization on Biodegradation
Behavior of Cellulose Nanocomposites
Biodegradability, the property by virtue of which any material is degraded by biological
organisms in nature, is a desired property of the polymers which enhances the value of
a material's application potential by rendering lesser environmental risks on disposal
like in the case of mulching i lms, food packaging materials, etc. So, usage of biode-
gradable polymers/polymer composites which are capable of ef ectively replacing the
non-degradable polymer products is the need of the hour. Biodegradable polymers are
mostly derived from natural resources but their use in consumer products is not always
economically favorable. Synthetic polymers like polyolei ns, acrylics which are widely
used in consumer products are not degraded by microorganisms in the environment
which contribute to their long life. h erefore, recycling and degradation of these poly-
mers is an important issue for environmental protection. Cellulose nanocomposites
can play a major role in enhancing or imparting biodegradability to partially degrad-
able or non degradable polymers.
Maiti
et al.
[68] studied the biodegradation behavior of PMMA/cellulose nanocom-
posites in an aerobic compost environment. PMMA/cellulose nanocomposites were
prepared both by
in-situ
suspension polymerization technique (IPC) and
ex-situ
solu-
tion dispersion technique (EPC). Biodegradation studies of IPC and EPC i lms were
performed in a simulated aerobic compost environment for 60 days. IPC showed
higher weight loss compared to that of EPC and unreinforced PMMA. h e change in
the molecular weights of PMMA in the biodegraded samples was determined by Gel
Permeation Chromatography (GPC). h e chemical structures of the biodegraded sam-
ples were examined with Nuclear Magnetic Resonance (NMR) study which indicated
a signii cant change in the chemical structure of IPC at er biodegradation. h e sur-
face morphologies of the samples before and at er biodegradation were observed under
Scanning Electron Microscope (SEM) (Figure 5.18). [68].
h e surface of IPC0 (at 0 days biodegradation or before biodegradation) appeared
smooth compared to that of EPC0 due to the improved dispersion and less agglomera-
tion of the nanocellulose. At er exposure of the PMMA i lms in compost, numerous
small holes were seen on the surface indicating that the neat PMMA i lms exhibited
completely dif erent pattern of surface morphology at er degradation. h e surface
roughness of the degraded IPC i lms was more prominent than that of the degraded
EPC i lms. h at can be corroborated with the higher weight loss of the IPC i lms than
that of EPC i lms at er composting. A recent study was reported by Sain
et al.
[69] on the
biodegradation behavior of
in-situ
formed PMMA/cellulose nanocomposites in con-
tinuation of the previous work [68]. h e ef ects of maleic anhydride (MA)- and meth-
ylmethacrylate (MMA)-modii ed cellulose micro- and nanoi bers (MACF and MMCF
respectively) on the biodegradation behavior of PMMA/cellulose were evaluated in
this work. h e biodegradation behavior of the MA- and MMA-modii ed nanocellu-
lose-reinforced PMMA nanocomposite i lms (designated as IM and IMM respectively)
was studied by soil burial method in two types of soils (Soil A and Soil B). h e results
indicated that MA-modii ed
in-situ
composites (IM) showed a higher weight loss and
