氏名　Warunee　Klinklai
学位の種類　博士（工学）
学位記番号　博甲第283号
学位授与の日付　平成15年9月30日
学位論文題目　Polymer Electrolyte Prepared from Highly Purified Natural Rubber　（高純度天然ゴムから調製したポリマー電解質）
論文審査委員
　主査　教授　五十野　善信
　副査　教授　西口　郁三
　副査　教授　塩見　友雄
　副査　助教授　竹中　克彦
　副査　助教授　河原　成元

• 論文目次
• 論文要旨

［平成15（2003）年度博士論文題名一覧］ ［博士論文題名一覧］に戻る．

CONTENTS

BIBIOGRAPHY　p.i

ABSTRACT　p.iii

CONTENTS　p.v

Chapter1　INTRODUCTION
1.1 General introduction　p.1
1.2 Purification of natural rubber　p.4
1.3 Epoxidation of natural rubber　p.7
1.4 Ionic conductivity of natural rubber　p.9
1.5 Outline of this thesis　p.11
1.6 Reference　p.13

Chapter2　DEPROTENIZATION OF NATURAL RUBBER WITH UREA
2.1 Introduction　p.18
2.2 Experriment　p.20
　2.2.1 Sample preparation　p.20
　2.2.2 Total nitrogen content measurement　p.22
　2.2.3 FT-IR　measurement　p.22
　2.2.4 Amount of allergenic proteins　p.23
2.3 Results and discussions　p.23
　2.3.1 Deprotenization of natural rubber with urea　p.23
　2.3.2 FT-IR　measurement　p.35
　2.3.3 Amount of allergenic proteins　p.37
2.4 Conclusions　p.38
2.5 Reference　p.39

Chapter3　PREPARATION AND CHARACTERIZATION OF LIQUID DEPROTEINIZED NATURAL RUBBER HAVING EPOXY GROUP
3.1 Introduction　p.41
3.2 Experimental　p.42
　3.2.1 Chemicals　p.42
　3.2.2 Preparation of peracetic acid　p.42
　3.2.3 Deprotenization of natural rubber　p.43
　3.2.4 Epoxidation of natural rubber　p.44
　3.2.5 Depolymerization of epoxidized natural rubber　p.44
　3.2.6 SEC measurement　p.45
　3.2.7 Gel content and total nitrogen natural rubber　p.46
　3.2.8 NMR and DSC measurements　p.46
3.3 Results and discussions　p.47
　3.3.1 Epoxidation of natural rubber and DPNR　p.47
　3.3.2 Epoxidation and depolymerization of natural rubber and DPNR　p.52
3.4 Conclusions　p.57
3.5 Reference　p.57

Chapter4　IONIC CONDUCTIVITY LIQUID NEPROTENIZED NATURAL RUBBERHAVING EPOXY GROUP MIXED WITH ALKALIMETAL SALTS
4.1 Introduction　p.59
4.2 Experimental　p.60
　4.2.1 Preparation of liquid epoxidized DPNR（LEDPNR）　p.60
　4.2.2 Preparation of polymer-salt electrolyte film　p.61
　4.2.3 SEC measurement　p.62
　4.2.4 NMR measurement　p.62
　4.2.5 DSC measurement　p.64
　4.2.6 Impedance analyzer　p.64
4.3 Results and discussions　p.65
　4.3.1 Ionic conductivity of LEDPAR with alkali metal salts　p.65
　4.3.2 NMR measurement　p.68
　4.3.3 Salts concentrations　p.72
4.4 Conclusions　p.78
4.5 Reference　p.78

Chapter5　Summary　p.80
LIST OF TABLES　p.i
LIST OF FIGURES　p.ii
LIST OF PUBLICATIONS AND PRESENTATIONS　p.v
ACKNOWLEDGEMENTS　p.ix

Natural rubber obtained from Hevea brasiliensis may have a potential to be a raw material to prepare functional organic materials. However, the rubber may still be an agricultural product, because non-rubber constituents present in natural rubber have prevented organic reactions of the rubber through side reactions. To solve the problem, in the present study, deproteinization, epoxidation and depolymerization were made for natural rubber. The resulting rubber was proved to be the liquid deproteinized natural rubber having both epoxy groups and well-defined terminal units, being a polymer electrolyte to transport lithium ion without any effect of the proteins.
To remove proteins present in natural rubber, natural rubber latexes, that is, fresh latex and preserved high ammonia latex, were deproteinized with urea in the presence of sodium dodecyl sulfate. Concentration of urea, temperature, pH and time for the incubation were investigated to remove the proteins effectively. Under the best conditions, the total nitrogen content and the amount of allergenic proteins for the deproteinized rubber prepared from fresh natural rubber latex were 0.004 wt% and 1.0　g/ml, respectively, suggesting the rubber was the hyper-deproteinized natural rubber. The hyper-deproteinized natural rubber was also prepared from a commercial high ammonia latex after enzymatic deproteinization followed by urea-treatment.
The highly deproteinized natural rubber was subjected to epoxidation and depolymerization in latex stage in order to prepare the polymer electrolyte having the polar epoxy groups and well-defined terminal units. Glass transition temperature （Tg） and gel content of natural rubber increased after the epoxidation, both of which were dependent upon an amount of peracetic acid. The gel content was significantly reduced by oxidative depolymerization of the rubber with （NH4）2S2O8 in the presence of propanal. The resulting rubber was proved to be the liquid deproteinized natural rubber having the polar epoxy groups, low Tg, low Mn and well-defined terminal units, that is, LEDPNR.
Ionic conductivity of LEDPNR mixed with alkali metal salts was investigated through impedance analysis to clarify an effect of proteins present in the rubber. The LEDPNR, thus used, was prepared from depolymerization of epoxidized natural rubber latex, which was deproteinized by incubation of the latex with proteolytic enzyme
and surfactant. The ionic conductivity of the resulting LEDPNR depended on the alkali metal salts, that is, lithium （trifluoromethanesulfonyl）imide （LiTFSI） and lithium perchlorate （LiClO4）, where the ionic conductivity of LEDPNR/LiTFSI was higher than that of LEDPNR/LiClO4. The difference in the ionic conductivity was attributed
to the solubility of the salts through both high-resolution solid-state 13C-NMR spectroscopy and measurements of spin-lattice relaxation time. The ionic conductivity of LEDPNR/LiTFSI was also dependent upon concentration of LiTFSI and the conductivity reached the highest value at 20 wt%, which was different from the monotonic increase in the ionic conductivity of liquid epoxidized natural rubber prepared from untreated natural rubber latex.