Nondestructive testing of defects in adhesive joints

Graft-copolymerization of cellulose-based filter paper and its
development as antibacterial food-packaging material
Rasika Tankhiwale* # and S. K. Bajpai
Polymer Research Laboratory, Dept. of Chemistry, Govt. Model Science College (Auto),
Abstract
Jabalpur (M.P.)-482001, India
Email: rasika_81@rediffmail.com
This work describes preparation of nano silver- loaded grafted filter paper. First, the filter
paper was grafted with acrylamide by ceric ammonium nitrate induced free radical
polymerization and then silver nanoparticles were loaded into grafted filter paper by
equilibration in silver nitrate solution followed by citrate reduction. The formation of silver
nanoparticles has been confirmed by TEM and SAED analysis. The particle size of
nanoparticles has been determined by TEM analysis. The novel nano silver-loaded filter paper
has been investigated for its antimicrobial properties against E.coli. This newly developed
material shows strong antibacterial property and thus offers its candidature for possible use as
antibacterial food- packaging material.
Keywords: grafting, hydrogel, silver nanoparticles, E.coli, TEM.
1. Introduction
With the growing public health awareness of disease transmissions and cross-infection
caused by microorganisms, use of antimicrobial materials has increased in many application areas
like protective clothing for medical and chemical works, other health related products [1-2],
antibacterial packaging material that can improve product quality and keep it free from microbial
adhesion [3], etc. Such antimicrobial packaging materials may be produced by introducing silver,
gold or copper nanoparticles into polymer film. In particular, silver has been recognized for its
broad –spectrum antimicrobial activities [4].Silver inactivates bacteria by interacting with the
thiol groups of bacterial proteins and enzymes [5]. It is proposed that silver ions (Ag + ), released
from silver nanoparticles (Ag o ), interact with phosphorous moieties in DNA, resulting in
inactivation of DNA replication. In fact, silver nanoparticles are highly germicidal, quite harmless
to humans and absolutely non-toxic. It has been reported that even the highest concentration of
nano silver causes no side effects [6]. In a recent work by Wen et al [7], human fibroplasts were
grown on various concentrations of silver nanoparticles during the period observation. The results
of their study elucidated the non-toxicity of the interaction of nanometer- scale silver particles
and the membrane surface.
Although synthetic polymeric films are frequently used as packaging material but their nondegradability
has been a matter of great concern for environmentalists, and therefore attempts
have been made to develop such materials which can undergo degradation and are ecofriendly. In
our recent work [8], we have reported a unique approach for in situ formation of ZnO
nanoparticles onto cotton fibers grafted with a copolymer. Now, utilizing this approach, we
hereby report grafting of acrylamide onto filter paper, followed by incorporation of silver
nanoparticles to yield antibacterial antibacterial filter paper. To the best of our belief, no such
work has been reported earlier.
2. Experimental
2.1.Materials
The monomer acrylamide (AAm), crosslinker N,N’-methylene bisacrylamide (MB), and
initiator ceric ammonium nitrate (CAN), nutrient broth and Nutrient m-Endo agars were obtained
1