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|標題:||Preparation and Thermal Stability of Phosphorus / Nitrogen Containing Polymers
|關鍵字:||聚丙烯;polypropylene;靜電分散;相變化;含磷環氧樹脂;難燃特性;極限氧指數;electrostatic dissipating properties;phase behaviors;phosphorus-containing epoxy resins;flame retardant properties;LOI||出版社:||化學工程學系||摘要:||
第一部份為聚醚胺與聚丙烯接枝馬來酐共聚合物，是由聚丙烯接枝馬來酐與各種胺類反應而來。反應形成類似梳子狀的支鏈型共聚合物，其具有親油聚丙烯主鏈段、親水聚醚胺側鏈段與醯胺(imide)鍵結等特性；將對其靜電分散(electrostatic dissipating properties)的性質、相變化(phase behaviors)及熱烈解行為進行探討。
(2) 經由DSC的觀察可以了解聚丙烯主鏈段與親水聚醚胺側鏈段的分子間作用力與相變化。其聚丙烯主鏈段的熔點與熔解熱(melting enthalpy)由於聚醚胺側鏈段的作用力而改變；側鏈段的POE結晶度則變小甚而消失。而側鏈段的聚醚胺長度與結晶度，以及側鏈段的可反應末端基之交聯密度等影響其相變化的結果。當加入金屬離子時，側鏈段的POE與其作用力會使POE有自我聚集(aggregation)的現象發生而容易導致結晶。
(3) 經由TGA的觀察可了解此雙性(amphiphilic)高分子共聚合物之熱烈解與熱氧化現象。其相對之熱穩定性與其結構中的POE、POP鏈段組成及末端基之不同有關，比較起始的各種胺類原料，氮氣中其分子量大小與分子結構組成為其主要的影響因子；而在空氣的熱氧化作用下，末端基為主要的影響因子。聚醚胺與聚丙烯接枝馬來酐之共聚合物可形成三級胺、amido acid salt與金屬鈉鹽錯合物等，可使聚丙烯主結構熱穩定性提高，尤其是在空氣熱氧化下，其相對穩定性趨勢如下：PP-g-MA/EDA > PP-g-MA/DAP >> PP-g-MA/ED2001 >> PP-g-MA/M2070 = PP-g-MA/D2000 > ED2001 > D2000 = PEG2000 > PPG2000；PP-g-MA/Na+ > PP-g-MA。而在550℃的氦氣下，將PP-g-MA/ED2001共聚物高溫裂解，使其裂解片段透過GC/Mass分析，可發現聚丙烯裂解為olefins/dienes，而聚醚胺則為vinyl ethers；聚丙烯主鏈與聚醚胺側鏈段的裂解乃是獨立的，整體熱安定性與熱裂解行為受到側鏈段分子結構、側鏈段分子量、側鏈段末端基與金屬鹽類等因素的影響。
(A). Thermal properties of poly(oxyalkylene)imide grafted polypropylene
In part one, a series of poly(oxyalkylene)imide grafted polypropylenes were prepared from the reaction of maleated polypropylenes (PP-g-MA) and various amines. The reactions afforded analogous comb-like copolymers consisting of a lipophilic polypropylene backbone, hydrophilic poly(oxyalkylene) pendants and imide linkages. Their electrostatic dissipating properties, phase behaviors and thermal degradations were studied.
(1) Their electrostatic dissipating properties were correlated with the chemical functionalities. Increasing weight amount or decreasing crystallinity of the poly(oxyethylene) pendants lowered the polymer surface resistivity significantly from 10>12 to 106.9ohm/sq. Factors including hydrophilicity, the presence of amine functionality or sodium ion in the structures also affected the copolymer electrostatic dissipating ability. A mechanism involving hydrogen bonding with moisture was proposed.
(2) The phase behaviors were measured by using a differential scanning calorimeter (DSC) to understand the interacted phase behaviors between the PP backbone and the pendant poly(oxyethylene) segments. In the constructed copolymers, the melting points and melting enthalpy of the PP backbone from the parent PP-g-MA shifted slightly while the grafted POE segmental crystallinity shifted more dramatically or even disappeared. The changes in phase behavior were influenced by the length of the crystalline pendants and the amounts of crosslinked structures. When incorporating sodium ion, the ionic interactions between the ether oxygen of POE segments and sodium ion could enhance the POE segmental aggregation together and hence crystallized easily.
(3) Thermal and thermooxidative degradation of a family of amphiphilic copolymers consisting of a PP backbone and several POE/POP pendants were investigated by using a thermal gravimetric analysis (TGA). Their relative stability was correlated to the chemical structures with respect to the POE versus POP in pendants and the terminal functionalities. In comparing the starting amines, molecular weight and the types of polymer backbone were the main controlling factors for thermal stability in nitrogen, while the terminal amine contributed most to the thermooxidative stability in air. In the amine-grafted PP copolymers, the functional groups including the tertiary amine, amido acid salt and sodium salt complexes significantly stabilized the PP copolymers, particularly in oxidative condition. The following trends of relative stability in air were observed: PP-g-MA/EDA > PP-g-MA/DAP >> PP-g-MA/ED2001 > > PP-g-MA/M2070 = PP-g-MA/D2000 > ED2001 > D2000 = PEG2000 > PPG2000; PP-g-MA/Na+ > PP-g-MA. Under the condition of helium gas and at 550℃, the representative PP-g-MA/ED2001 copolymer was pyrolyzed into fragments of olefins/dienes from PP backbone as well as vinyl ethers from POE pendants, as observed by GC/Mass spectroscopy. Reaction pathways for degradation and the controlling factors for the thermal and thermooxidative stability of these functionalized PP copolymers are discussed.
(B). Preparation and flame retardant properties of phosphorus-containing epoxy resins
In part two, a phosphorus-containing epoxy resin, bis(3-t-butyl-4-glycidyloxyphenyl-2,4-di-t-butylphenyl)resorcinol diphosphate (GDP), was synthesized and subsequently cured with non-phosphorus containing amines, and/or novel phosphorus-containing aromatic or polyoxyalkylene amines. Chemical structures were characterized with FTIR, NMR, elemental analysis, GPC and amine titration, etc. The introduction of soft -P-O- linkage, polyoxyalkyene, or hard aromatic group into the backbones of the synthesized phosphorus-containing amines provides epoxy polymers with high phosphorus contents and tailored flexibility. The reactivity of curing reactions was affected by phosphorus-functionalities. Thermal analysis of DSC and TGA reveals moderate Tgs and thermal stability. Furthermore, high char yields of 30% in TGA analysis and high LOI values of 30-32 indicate that these phosphorus-containing epoxy polymers possess excellent flame retardant properties.
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