Chemistry Reference
In-Depth Information
Chapter 4
M. Kanafchian and A.K. Haghi
INTRODUCTION
Clothing is a person's second skin, since it covered great parts of the body and hav-
ing a large surface area in contact with the environment. Therefore, clothing is proper
interface between environment and human body, and could act as an ideal tool to
enhance personal protection. Over the years, growing concern regarding health and
safety of persons in various sectors, such as industries, hospitals, research institutions,
battlefields, and other hazardous conditions has led to intensive research and devel-
opment in field of personal protective clothing. Nowadays, there are different types
of protective clothing. The simplest and most preliminary of this equipment is made
from rubber or plastic that is completely impervious to hazardous substances, air, and
water vapor. Another approach to protective clothing is laminating activated
carbon
into multilayer fabric in order to absorb toxic vapors from environment and prevent
penetration to the skin [1]. The use of activated carbon is considered only a short
term solution because it loses its effectiveness upon exposure to sweat and moisture.
The use of semi-permeable membranes as a constituent of the protective material is
another approach. In this way, reactive chemical decontaminants encapsulates in mi-
croparticles [2] or fills in microporous hollow fibers [3]. The microparticle or fiber
walls are permeable to toxic vapors, but impermeable to decontaminants, so that the
toxic agents diffuse selectively into them and neutralize. All of these equipments could
trap such toxic pollutions but usually are impervious to air and water vapor, and thus
retain body heat. In other words, a negative relationship always exists between ther-
mal comfort and protection performance for currently available protective clothing.
For example, nonwoven fabrics with high air permeability exhibit low barrier perfor-
mance, whereas microporous materials, laminated fabrics, and tightly constructed wo-
vens offer higher level of protection but lower air permeability. Thus, there still exists
a very real demand for improved protective clothing that can offer acceptable levels of
impermeability to highly toxic pollutions of low molecular weight, while minimizing
wearer discomfort and heat stress [4].
Electrospinning provides an ultrathin membrane-like web of extremely fi ne fi bers
with very small pore size and high porosity, which makes them excellent candidates
for use in fi ltration, membrane, and possibly protective clothing applications. Pre-
liminary investigations have indicated that the using of nanofi ber web in protective
clothing structure could present minimal impedance to air permeability and extremely
effi ciency in trapping aerosol toxic pollutions. Potential of electrospun webs for future
protective clothing systems has been investigated [5-7]. Schreuder-Gibson et al. has
shown an enhancement of aerosol protection via a thin layer of electrospun fi bers.
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