الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 240 |  |  |
| | | from | 240 | | |
Abstract
The leather manufacture is one of the oldest industries in Egypt. It includes both public and
private plants. The natural leather products are characterized by relatively good mechanical
properties
e.g. good tensile strenght, suitable elongation and high degree of water absorption. However,
and in some cases there is a need to
·enhance some properties as tensile strenght specially in buffallo
leather.
So, a considerable attention has been paid to the grafting of acrylate monomers (methyl acrylate-
ethyl acrylate- butyl acrylate) onto leather. The application of acrylates is motivated by their
easy polymerizability, commercail availability and relative low price. Grafting is initiated
mainly by Ce(IV) or by bisulfite/persulfate and its adducts as a redox system.
Some kinds of leather need a modification through introducing some functionalized group in very
little amounts which improve their physical and mechanical properties through emulsion
polymerization as a more safe medium which satisfy enrviromental requirements.
We through light on the histology of fresh animal skin, because it is important to the tanner and
leather chemist to know the changes which the structure undergoes when it is converted from skin
into leather.
We also through light on chemical structure of skin proteins to know its reaction with monomers and
the chemical bonds between them. Finally leather production processing is mentioned in short
account.
This study deals with the emulsion polymerization of acrylate monomers onto leather by different
redox initiation systems using sodium dodocyl sulphate as an emulsifier, the present study can be
classified into three parts:-
1-First part:-
Chemical modification of leather by grafting emulsion polymerization of methyl acrylate, ethyl
acrylate and butyl acrylate monomers and emulsion copolymerization of methyl acrylate with butyl
acrylate and ethyl acrylate with butyl acrylate using different developed redox pair initiation
systems consisting of potassium persulfate as an oxiding agent and ketonic sodium bisulfite adducts
as reducing agents. The effect of different redox pair initiation systems and their concentrations,
emulsifier concentration, monomers concentration on the kinetics of emulsion polymerization were
studied.
1-The effect of time on grafting :
The degree of grafting increases with increase in time up to 140 min, after which the degree of
grafting tends to level off.
2-The effect of temperature:-
The degree of grafting of vinyl monomers onto leather was found to increase with increasing the
reaction temperature up to 60 oc. Further increase in temperature slightly decreases grafting
degree.
3- The effect of different initiators systems:-
The rate of grafting emulsion polymerization of ethyl acrylate monomer was found to be dependent on
the developed redox pair initations systems[KPS/SBS, KPS/ASBS, KPS/MEKSBS, KPS/MBKSBS]
concentrations.lt increases by increasing initiators concentrations. These values are 0.26, 1.76,
·1.60 and 0.37 respectively. It is dear that the calculated power for redox pair initiation
systems with respect to rate of grafting are higher than the obtained for the classical one.
4- The effect of monomer concentration using different initiators systems:-
The rate of grafting is proportional to the power of monomer
concentration for developed redox systems KPS/SBS, KPS/ASBS, KPS/MEKSBS, KPS/MBKSBS, being
0.51, 1.70, 1.00 and 0.83
respectively. These can be attributed to the activity of the developed
redox system to promote initiation and propagation for emulsion more than the classical
one.
5-The effect of emulsifier concentrations using different initiators systems:-
The rate of grafting emulsion polymerization is proptorional to emulsifier concentration.The
emulsifier power was found to be 0.44,
0.33 and 0.60 for redox systems KPS/ASBS, KPS/MEKSBS and
KPSI MBKSBS . which are slight greater than the classici system KPS I SBS (0.27)
6-The effect of initiator concentration with different monomers:-
Grafting yield increased with increasing of KPS I ASBS initiator
concentration in case of methyl acrylate and butyl acrylate.The power of initiator with respect to
rate of grafting for the examined monomers are 2.33 and 0.47 for methyl and butyl acrylate
respectively.
This indicates that methyl acrylate is characterized by higher reactivity than the other two
monomers.
7-The effect of emulsifier concentration using different monomers:-
The order of reaction with respect to emulsifier concentration are
0.45 and 0.28 for methyl and butyl acrylates, respectively using KPSIASBS as redox system.
8-The effect of different monomers concentrations:-
lt is concluded that an increase in monomer concentration, increases grafting yield, the power of
monomers were found to be
1.75 and 0.66 for methyl and butyl acrylates respectively.
9-Grafting copolymerization:-
Composition of binary mixture as ethyl.acrylate with butyl acrylate and methyl acrylate with butyl
acrylate upon grafting onto leather in the presence of KPS I ASBS as developed redox system and SDS
as an emulsifier was studied.