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العنوان
Radiation Preparation and characterization of Polymer Nano-composites using Gamma-Irradiation and Their Potential Applications /
المؤلف
Mostafa, Mai Mostafa Mohammed.
هيئة الاعداد
باحث / Mai Mostafa Mohammed Mostafa
مشرف / El-Sayed Ahmed Soliman
مشرف / El-Sayed Ahmed Abd El-Aziz Hegazy
مناقش / Hanaa Kamal Mohamed
تاريخ النشر
2019.
عدد الصفحات
206 P. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
Organic Chemistry
تاريخ الإجازة
1/1/2019
مكان الإجازة
جامعة عين شمس - كلية العلوم - قسم الكيمياء
الفهرس
Only 14 pages are availabe for public view

from 206

from 206

Abstract

This thesis includes the preparation of nanocomposite films based on natural biodegradable polymer which blended with synthetic one and incorporated with nanofiller by solvent casting method using gamma irradiation from 60Co as initiator.
This work is divided into two main parts:
1-Preparation and characterization of Calcium alginate-Polyacrylamide/Titanium dioxide (CA-PAM/TiO2) nanocomposite films to be used in selective adsorption of Fe (III) from aqueous solution
2-Preparation and characterization of CA-PAM/TiO2/graphite nanocomposite films and their electrical conductivity studies.
The main results obtained by this work can be summarized as follow:
1- Calcium alginate (CA) films prepared based on ionic crosslinking of Sodium alginate films prepared using gamma irradiation and effect of irradiation dose and Sodium alginate (SA) concentration on water solubility (%) of CA films showed that CA film prepared at 10 kGy and at SA concentration 4 (wt/v) has lowest solubility%
2-Effect of CaCl2 concentration and time treatment of SA showed that CaCl2 1% and treatment time 2h is the best condition to prepare CA film with lowest water solubility. 3- Effect of N,N’-Methylene-bis-acrylamide (MBAM) concentration on water solubility % (WS) of Polyacrylamide (PAM) films prepared at irradiation dose 10 kGy using different AAM concentration showed that PAM film prepared at monomer concentration 4 (wt/v) and 3wt% MBAM is stable and has lowest solubility % in water and in CaCl2 soltion and it was found that increasing AAM concentration leads to decrease water solubility of PAM and increasing MBAM more than 3% has no significant effect on water solubility. 4- Effect of CA-PAM composition on water solubility and swelling % indicated that CA-PAM film of composition 50/50 wt% exhibited lowest water solubility and highest swelling %.
5- Effect of glycerol concentration on water solubility, swelling and film thickness showed that increasing glycerol concentration up to 30 wt% cause an increase in water solubility % of CA-PAM film but further increase in glycerol favor stability of the film and decrease water solubility %. Increase glycerol concentration resulted in increasing film thickness.
6-It was found that increasing glycerol concentration leads to increase swelling % due to increasing hydrophilicity of the film.
7- Effect of glycerol concentration on moisture content was studied and it was found that moisture content percent decreased with increasing the plasticizer concentration from 0 to 20 (wt%) then it increased by increasing glycerol concentration more than 20 wt% due to increase free volume between polymer chains so water holding capacity increased.
8- Effect of different TiO2 nanoparticles incorporated into CA-PAM 50/50 wt% on water solubility percent revealed that increasing TiO2 resulted in decrease water solubility 9-Effect of TiO2 nanoparticles concentration on swelling % indicated that swelling % increases with increasing TiO2 content up to 0.3wt% then decrease and equilibrium swelling reached at approximately 2h. 10- Effect of TiO2 on moisture content showed that increasing TiO2 concentrations leads to decrease moisture content %.
11-Effect of CA-PAM composition on mechanical properties showed that there is a significant improvement in the mechanical properties of CA films occurred by copolymerization with PAM
12- Effect of glycerol concentration on mechanical properties of CA-PAM films showed that high glycerol concentration leads to increase film tensile strength and as glycerol concentration increases up to 40 wt% elongation % of the film increases
13- Effect of TiO2 concentration on mechanical properties showed that the increment of TiO2 content from 0 to 0.4wt% leads to increase the tensile strength because of increasing rigidity of the film which also result in increased film toughness and it was found that increasing TiO2 content leads to decrease elongation % which attributed to the phenomenon known as anti-plasticization. TiO2 nanoparticles may act as an anti-plasticizer by enhancing interacting with polymer chains reducing the free volume between them so reduce the film flexibility.
14-The presence of the functional groups of CA, PAM, CA-PAM, TiO2, CA-PAM/TiO2 nanocomposite films were confirmed by the use of FTIR spectroscopy.
Presence of PAM within CA confirmed by new peaks appeared in CA-PAM at 3183 cm−1, corresponding to of N ̶ H stretching vibration of secondary amide. The peak observed at 1658 cm−1 was due to the carbonyl (C=O) stretching of secondary amide. Broad peak around 3361 cm−1 in the spectrum of calcium alginate due to the stretching vibration of O-H groups shifted to 3349 cm−1 with increase in intensity due to overlapping of O-H stretching of alginate and N-H stretching of amide groups. For TiO2 nanoparticles, a clear band emerges in 498 and 794 cm-1 which corresponding to the vibration of Ti ̶ O ̶ Ti. The spectrum of the nanocomposite films showed that the absorption band of−OH group at 3349 cm−1 shifted to lower wave number at 3338 cm−1 which attributed to increase the number of hydrogen bonds or electrostatic interaction between TiO2 and functional groups in CA-PAM. The spectrum of the nanocomposite films showed an appearance of band at 484 and 794 cm−1 which corresponding to Ti _O_ Ti vibration indicating TiO2 reacting with polymer
15-SEM of the prepared films showed that a certain morphological changes occur by adding PAM to CA and CA-PAM film showed more roughness than CA film and incorporation of TiO2 leads to a porous structure and it was shown that TiO2 nanoparticles were approximately well dispersed in the film matrix except some aggregation can be observed with the nanocomposite containing the highest concentration of TiO2 (0.5 wt%)
16- X-Ray diffraction of CA showed that a strong and sharp diffraction peak appeared at 2θ 31.77O indicates crystalline structure of CA which shifted to lower values of 2θ and decreased its intensity due to copolymerization with PAM. The XRD pattern of CA-PAM/TiO2 showed that; most peaks of TiO2 are disappeared indicating that TiO2 nanoparticles were dispersed inside the film matrix. The broad peak at 2θ 29◦ in XRD of TiO2 appeared in nanocomposites but shifted to higher value indicating the interaction occurred between TiO2 and CA-PAM. The mean crystal sizes of TiO2 in the CA-PAM films contain 0.1, 0.3 and 0.5 wt% of TiO2 were 93.8 and 27.7, 74.9 nm, respectively which confirm preparation of nanocomposite structure.
17- The melting behavior of CA, CA-PAM, PAM films and were investigated using Differential scanning calorimetry (DSC). The little increase in Tm of CA film from 241 to 243 OC due to blend formed with Polyacrylamide and change in size of crystallites of CA due to presence of polyacrylamide and a new peak at 376 OC which related to PAM observed in CA-PAM blend film which proves the formation of copolymer. DSC curve of CA-PAM/TiO2 nanocomposites showed that increasing TiO2 content from 0.1 to 0.3 wt% leads to shift Tm from 243 to 262OC but presence of high content of TiO2 (0.5wt%) caused a noticeable decrease of Tm.
18-Thermal stability of the prepared films studied using Thermal gravimetric analysis (TGA) which indicated that CA-PAM has more thermal stability than CA and adding TiO2 at concentration 0.3 wt% increases its thermal stability and residual weight remaining at maximum temperature 600 OC was in the following order CA-PAM/TiO2˃CA-PAM˃CA.
Application of the Prepared Nanocomposites in Waste Water Treatment
Adsorption studies of Fe (III)
19- Effect of different TiO2 content on removal percent Fe (III) from aqueous solution was studied to find that incorporation of TiO2 nanoparticles at 0.3 wt% resulted in improvement removal % from 63 to 91.2% but high concentration of TiO2 nanoparticles greater than 0.3 wt% resulted in increasing the crosslinking density of the nanocomposite. Therefore, more compact network structure formed thus the spaces left for metal ion adsorption decreased and removal % decreased.
20-Effect of pH on Fe (III) adsorption revealed that the maximum adsorption was attained at pH 3.
21-Effect of initial Fe (III) concentration on adsorption showed that the adsorption capacity of Fe (III) at equilibrium (qe) increases with increasing initial concentration. CA-PAM/TiO2 nanocomposites exhibited higher equilibrium adsorption capacities than CA-PAM.
22-Time profile of adsorption indicated that the state of equilibrium adsorption reached at about 120 min
23- Effect of temperature on adsorption process indicated that increasing temperature from 30 to 45 OC leads to increase removal % of Fe (III) due to enhance the mobility of metal ions with increasing temperature as well as greater activity of binding sites as temperature increases but further increase in temperature to 55OC decreases the removal %
24- Thermodynamic study showed that enthalpy change of adsorption (ΔH) for CA-PAM and CA-PAM/TiO2 nanocomposite film was 204 and 299 KJ/mol, respectively indicated that the adsorption is chemisorption. The positive values of ΔH suggesting that the adsorption is endothermic in nature and it is also obvious that the adsorption enthalpy change for CA-PAM/TiO2 is larger than that of CA-PAM. It means that the interaction between Fe (III) and nanocomposite film is stronger and then leads to an enhanced adsorption.
25-Reusability studies indicated that nanocomposite film is more stable under experimental condition and has good reusability which is economic important point and maintains about 90 % of its original efficiency after final cycle and CA-PAM film maintains only 50%
26-Selective removal of Fe (III) over other interfering metal ions Cu (II) and Co (II) carried out and it was found that both CA-PAM and CA-PAM/TiO2 nanocomposite films exhibit very low removal percent of Cu (II) and Co (II) with high removal % of Fe and selective studies clarified that CA-PAM/TiO2 nanocomposite films have adsorption capacity, distribution ratio and selectivity coefficient greater than that related to the CA-PAM. So CA-PAM/TiO2 nanocomposite film is more efficient in selective adsorption of Fe (III) due to improved surface area and functional groups in the nanocomposite.
Preparation of CA-PAM/TiO2/graphite nanocomposite films
27-Graphite incorporated in CA-PAM/TiO2 nanocomposite films contain 0.3 wt% of TiO2 nanoparticles and its effect on water solubility, swelling % indicated that increasing graphite resulted in decreasing water solubility and swelling % of the CA-PAM/TiO2 nanocomposite films due to formation of compact polymer network structure by increasing graphite content which act as a barrier against water absorption.
28-Effect of graphite content on size change of the nanocomposite films during swelling showed that at graphite concentration 1.5wt% little change in size occurred during swelling process as increasing graphite content decreases the gap size between filler and polymer
29- It was found that moisture content % decreases with increasing graphite concentration in nanocomposite films
30- Effect of different graphite content on mechanical properties was studied and it was found that increasing graphite concentration resulted in more flexible nanocomposite film with improved tensile strength.
31- FTIR studies showed a slight shift of the O–H band at 3338 cm-1 in spectrum of CA-PAM/TiO2 nanocomposite film to lower value with a reduction in the intensity and appeared at 3269 cm−1 by incorporation of graphite due to hydrogen bonding interaction between graphite and CA-PAM/TiO2 nanocomposite film
32- SEM studies of the surface morphology of the CA-PAM/TiO2/graphite nanocomposite films clearly revealed the adhesion of graphite to the film matrix and pores formed by adding graphite which consequently become smaller with increase graphite concentration
33- The XRD analysis for pure graphite and CA-PAM/TiO2 nanocomposite film containing two different graphite concentrations 0.5, 1.5 wt% were studied and the results confirmed that graphite is dispersed inside the polymer matrix the mean crystal sizes of graphite< 100 nm to confirm nanocomposite structure
34- TGA analysis indicated that the addition of 0.5 wt% of graphite make decrease in thermal stability of CA-PAM/TiO2 nanocomposite films then increased by increasing graphite content to 1.5 wt% due to enhancement in network structure.
Conductivity studies
35-Effect of CA-PAM composition on electrical conductivity indicated that CA-PAM films of composition 50/50 and 30/70 wt% exhibit high electrical conductivity values 2.8×10-7 and 1.7×10-7 Ω-1cm-1, respectively.
PAM exhibited conductivity 6.2×10-11 Ω-1.cm-1 which increased to 2.8×10-7 by copolymerization with CA due to increased amount of mobile ions
36- Effect of TiO2 nanoparticle concentration on electrical conductivity indicated that increasing TiO2 up to 0.3wt% causes increasing in electrical conductivity to become 6.1×10-6 Ω-1cm-1 due to presence of more mobile ions by incorporation of TiO2. Then further increase in TiO2 decreases conductivity due to the formation of more crosslinked network structure which restricts movement of mobile ions.
37- Graphite added at different concentration to CA-PAM/TiO2 nanocomposite films contain 0.3 wt% TiO2 and it was found that adding graphite resulted in increasing electrical conductivity and it was found that the conductivity increases as graphite content increases to reach 1.8×10-2 Ω-1cm-1 at graphite content 1.5 wt%. As high graphite content resulted in formation of network of graphite so conductivity is increased due to formation of electrically conducting pathway inside the CA-PAM/TiO2 nanocomposites and presence of TiO2 facilitate electron transfer through these conducting pathways.
CA-PAM/TiO2/graphite nanocomposite films are mechanically stronger, more flexible and exhibited higher electrical conductivity than CA-PAM/TiO2 nanocomposites films without graphite and can be used in some electronic applications such as rechargeable batteries, electrode coating, …etc.