Preparation and Characterization of Monodispersed Polystyrene Particle/Carbon Nanotube Composites

本研究採乳化聚合方式製備粒徑尺寸均一的單分散聚苯乙烯（Polystyrene, PS）乳液微粒。以苯乙烯為反應單體，利用甲醇（油相）並搭配去離子水作為共溶劑，再以陰離子型界面活性劑十二烷基硫酸鈉(Sodium dodecylsulfate, SDS)作為乳化劑、陰離子型氧化物過硫酸鉀（Potassium presulfate, KPS）作為起始劑，並控制相關條件進行不同尺寸大小、粒徑均一的單分散PS乳液微粒的製備，藉由SEM、TEM的分析結果得知，本研究已可成功製備出粒徑尺寸在100 nm至400 nm 之間的單分散PS乳液微粒。以FTIR、界面電位儀、元素分析儀的結果得知不同尺寸的單分散PS微粒基本化學特性並無特殊的差異。經由DSC與TGA的熱分析鑑定結果，單分散性PS微粒的熱穩定特性及熱裂解活化能值隨著尺寸的上升而稍微下降，推測其原因為不同配方條件導致小尺寸PS微粒的分子量比大尺寸PS微粒還高所導致的些微熱性質差異，但是其熱裂解機制一樣。 本研究另外採用水系及醇系等低環境危害程度的溶劑，進行單分散PS微粒及多壁奈米碳管（Multi-walled carbon nanotubes, MWNT）的摻混處理，利用超音波震盪分散輔助的溶液混合法將PS微粒與MWNT進行混合、再經乾燥、製粉、壓錠成型等程序製備出單分散PS微粒/MWNT導電高分子複合材料。本研究重點在於探討單分散PS微粒與不同MWNT添加量之間的分散情況與導電度變化以及熱穩定性及熱裂解行為等物理性質的表現。從DSC及TGA的實驗結果得知，複材的熱穩定性質隨奈米碳管添加量增加而有上升的趨勢，並且其所需熱裂解活化能亦有些許的提高。複材的導電度亦隨著MWNT添加量的改變而有明顯的提升，從MWNT含量為1.5 wt%的導電度6×10-8 S/cm到添加量為6.5 wt%的4.9×10-4 S/cm。以DMA測量結果發現其動態熱機械性質亦隨著MWNT含量的增加而有明顯的上升，與PS微粒基材相比，6.5 wt%的PS/MWNT導電複材的動態儲存模數提高了114％。另外亦比較100 nm至400 nm等不同尺寸的單分散PS微粒對於MWNT分散在PS微粒基材中的情況與導電度變化，研究中發現大尺寸的單分散PS微粒對於MWNT的分散效果比小尺寸的PS微粒還要好，因此添加等量MWNT所製成PS/MWNT複合材料，大尺寸單分散PS微粒比小尺寸PS微粒有更好的導電特性表現。 由於在研究過程中發現，PS微粒與奈米碳管之間的作用力相對微弱，因此本研究另外探討以單分散PS微粒作為核心模版，在1M的HCl溶液中，由於單分散PS微粒表面帶有負電荷，因此會吸引帶有正電荷的苯胺離子吸附在PS微粒表面，再藉由添加氧化起始劑使苯胺離子聚合成導電高分子聚苯胺（Polyaniline, PANI）薄層。實驗中探討不同苯胺濃度比例所形成的聚苯胺披覆層對核心PS微粒的性質影響，以及該複合微粒的導電特性，期許導電高分子複材能有更好的導電性。由SEM及TEM分析結果得知帶負電位的單分散PS球表面確實披覆上PANI導電層並且形成核殼結構微粒，而且隨著PANI比例的增加，PANI薄層厚度亦隨之增加，並使其膜層產生類似松果般的鋸齒狀形貌。而在導電度的量測上亦發現披覆上PANI薄膜的複合微粒具有很好的導電特性，最佳導電度可以達到3 S/cm左右。另外亦對該複合微粒進行熱性質分析及等溫熱裂解活化能計算，由實驗結果均發現複合微粒的熱性質隨著PANI比例的增加皆產生提升的趨勢，顯示出PANI薄層對於PS核心微粒亦扮演著熱保護層的角色。 由於披覆上PANI導電層的PS複合微粒，如預期般擁有較佳的導電特性，因此再經由溶液混合方式額外添加1～3 wt%的羧酸化改質奈米碳管（c-MWNT）於不同單分散粒徑的PS/PANI複合微粒中，觀察c-MWNT是否能在導電性質上作進一步的提升。從實驗結果中發現額外添加1～3wt%的c-MWNT於大尺寸的PS/PANI複合微粒中，其對導電度的提升已經不明顯，推測是由於導電性PANI薄膜已在複材中形成良好的導電通路。另外在小尺寸的PS/PANI複合微粒中，添加1～3wt%的c-MWNT對導電度的提升則有明顯效果，顯示c-MWNT彌補了在PS微粒表面披覆不完全的導電性PANI薄膜，使其複材具有更好的導電通路而使得導電度明顯的上升。摘要…………………………………………………………………………I 英文摘要……………………………………………………………….....III 總目次…………………………………………………………………….........V表目次………………………………………………………………............. VII圖目次………………………………………………………………....... VIII 第一章 緒論……………………………………………………………………...1 1-1 研究背景…………………………………………………………..… …...1 1-2 研究動機與目的……………………………………………….…………3 1-3 研究方向與方法…………………………………………………………4 第二章 文獻回顧與理論基礎…………………………………………………..5 2-1單分散性膠體粒子的應用……………………………………….…….5 2-2聚苯乙烯乳液的製備………………………………..…………….…...6 2-3奈米碳管之介紹………………………………………………...…...9 2-4本質型導電高分子……………………………………….……...….12 2-5非本質型導電高分子……………………………………….….…...14 2-6披覆導電高分子的PS複合微粒………………………………….18 2-7高分子複合材料之熱性質…………………………………...…....21 第三章 實驗方法及步驟………………………………………………...27 3-1 實驗藥品…………………………………………………………..27 3-2 材料製備. …………………………………………………………28 3-2-1單分散PS乳液微粒之製備………………………………....28 3-2-2單分散PS微粒純化處理………..……………..….……..…28 3-2-3單分散PS微粒/MWNT導電複合材料之製備…………....29 3-2-4單分散PS微粒表面披覆導電高分子聚苯胺……………...30 3-2-5聚苯胺披覆聚苯乙烯微粒摻混奈米碳管導電複材之製備32 3-3 實驗儀器…………………………………………………………..33 3-4 儀器分析…………………………………………………………..34 3-4-1 Zeta potential測定…………………………………………..34 3-4-2 紅外光譜測定………………………………………………..34 3-4-3 元素分析……………………………………………………..35 3-4-4 場發射式掃瞄式電子顯微鏡（FE-SEM）觀察..………...35 3-4-5 穿透式電子顯微鏡（TEM）觀察………………..………..36 3-4-6 導電度測定…………………………………………………..36 3-4-7 熱分析儀 (DSC、TGA) ………………..…………………37 3-4-8 動態機械分析儀 (DMA) …………………….…………….38 第四章 結果與討論…………………………………………………...............39 4-1不同尺寸單分散PS微粒之鑑定與性質分析………..………….…….39 4-2不同尺寸單分散PS微粒之純化處理及性質分析……………....49 4-3單分散PS微粒/MWNT導電複材之製備與物性分析………….60 4-3-1 MWNT之微結構分析…………….…………………..…....62 4- 3 - 2 以乳液技術輔助超音波處理製備單分散PS-MWNT導電高分 子與其物性分析………………………………………..64 4-3-3 單分散PS-MWNT導電複合材料之熱性質分析……....71 4-3-4 單分散PS-MWNT複合材料之熱裂解動力學分析………75 4-3-5 單分散PS微粒及PS-MWNT複材的熱機械性質分析.....89 4-3-6 單分散PS-MWNT複合材料的導電性質分析…….……...91 4-4 單分散PS-PANI複合微粒之物化特性分析………....………….93 4-4-1單分散PS-PANI複合微粒的微結構分析……...….………94 4-4-2單分散PS-PANI複合微粒的熱性質分析.…………...……101 4-4-3單分散PS-PANI複合微粒的熱裂解動力學分析…….….108 4-4-4單分散PS-PANI複合微粒的導電性質分析…………......118 4-5 單分散PS-PANI複合微粒之物化特性分析………….………..120 4-5-1 改質MWNT的微結構分析……...….….……………..….121 4-5-2 PS-PANI/c-MWNT導電複材的製備及結構分析…... .. 125 4-5-3 PS-PANI/c-MWNT導電複材的熱性質分析…………....131 4-5-4 PS-PANI/c-MWNT導電複材的熱裂解動力學分析..…..135 4-5-5 PS-PANI/c-MWNT導電複材的電性質分析…............144 第五章 結論…………………………………………………………..….145 參考文獻…………………………………………………………………148 著作目錄. ……………………………………………………………..….153 表目次 表4-1不同尺寸單分散PS乳液之粒徑分析、界面電位及多分散指數 表……………………………………….…………………………..40 表4-2 PS及SDS分子鏈段上的1H NMR化學位移量區間表…...….46 表4-3單分散PS微粒的元素分析組成比例表…………………………47 表4-4不同尺寸單分散PS微粒之熱性質分析數據……………….…..49 表4-5不同尺寸單分散PS微粒經純化處理後的平均分子量及密度..50 表4-6不同尺寸PS微粒純化後之熱性質分析數據…….....................53 表4-7不同尺寸單分散PS微粒純化後的等溫熱裂解速率常數及活化 能…………………………………………………………………...54 表4-8單分散PS微粒及不同MWNT含量所製備PS-MWNT奈米複材 的玻璃轉換溫度（Tg）及熱性質指標溫度表……………….…73 表4-9 單分散PS微粒及PS-MWNT導電複合材料之等溫熱裂解速率 常數及熱裂解活化能表…………………………………………..88 表4-10 單分散PS微粒及PS-MWNT複材之DMA 儲存模數數據….90 表4-11 單分散PS微粒及PS-PANI複合微粒的玻璃轉換溫度（Tg） 及熱性質指標溫度表……………...………………..…….….. 106 表4-12單分散PS-PANI複合微粒之等溫熱裂解速率常數及熱裂解 活化能表……………………………………...………….……..118 表4-13 PS-PANI複合微粒添加不同c-MWNT含量製備成導電複材 的Tg及熱性質指標溫度表……………………………….…...132 表4-14 PS-PANI2複合微粒及PS-PANI2/c-MWNT導電複合材料之 等溫熱裂解速率常數及熱裂解活化能表…………………....143 圖目次 圖3-1 均一尺寸及單分散PS乳液製備流程圖………………………...29 圖3-2 以乳液技術製備PS微粒/奈米碳管導電複合材料之示意圖….30 圖3-3 單分散PS微粒披覆導電高分子PANI之流程圖......................32 圖3-4 四點探針-導電度量測示意圖...................................................37 圖4-1 (a) PS100, (b) PS200, (c) PS300, (d) PS400單分散PS乳液之粒徑 分析圖……………………………………………………….….….42 圖4-2 (a) PS100, (b) PS200, (c) PS300, (d) PS400單分散PS微粒的 FESEM圖…………………………………………………….……43 圖4-3 (a) PS100, (b) PS200, (c) PS300, (d) PS400單分散PS微粒的 FTIR光譜圖…………………………………………………….…44 圖4-4以SDS乳化劑聚合PS及無添加乳化劑聚合PS的NMR光譜圖 ……………………………………………………………………....46 圖4-5 (a)PS100, (b)PS200, (c)PS300, (d)PS400單分散PS微粒的DSC 圖……………………………………………………………….…..48 圖4-6 (a) PS100, (b) PS200, (c) PS300, (d) PS400單分散PS微粒的TGA 圖………………………………………………………………..….48 圖4-7不同單分散尺寸PS微粒在(a)純化處理前（b）純化處理後以 及（c）乳化劑SDS的FTIR圖…………………………………51 圖4-8不同尺寸PS微粒在純化處理後的DSC曲線圖……………….52 圖4-9 (a) PS100, (b) PS200, (c) PS300, (d) PS400微粒經純化處理後的 TGA圖……………………………………………………….…….53 圖4-10純化處理後(a) PS100, (b) PS200, (c) PS300, (d) PS400微粒的等 溫熱裂解之重量損失對時間作圖………………….......…….... 57 圖4-11純化處理後的(a) PS100, (b) PS200, (c) PS300, (d) PS400微粒等 溫熱裂解之重量變化以對數轉換與持溫時間作圖..................59 圖4-12純化處理後的PS微粒以Arrhenius方程式所得之熱裂解速率 (ln kd)與1/T之關係圖……………………………….……….…60 圖4-13 未改質處理MWNT的SEM圖…………………………………63 圖4-14 未改質處理MWNT的Raman圖……………………………….63 圖4-15 未改質處理MWNT的TEM圖………………………………..64 圖4-16 (a)PS200-MWNT1, (b)PS200-MWNT2, (c)PS200-MWNT3, (d) PS200-MWNT4 導電複材之TEM圖………………………..67 圖4-17 (a)PS400-MWNT1, (b)PS400-MWNT2, (c)PS400-MWNT3, (d) PS400-MWNT4 導電複材之TEM圖………………………..68 圖4-18 PS200-MWNT3 導電複材的FESEM 圖，觀察倍率 (a) 10000 倍，(b) 30000倍……………………………………………….69 圖4-19 PS400-MWNT3 導電複材的FESEM 圖，觀察倍率 (a) 10000 倍，(b) 30000倍……………………………………………….70 圖4-20 PS200-MWNT導電高分子複合材料之（a）TGA，（b）DTG 圖………………………………………………………………...74 圖4-21 PS400-MWNT導電高分子複合材料之（a）TGA，（b）DTG 圖………………………………………………………………...75 圖4-22 單分散PS200微粒在340至400℃的等溫熱裂解TGA分析圖 (a)重量損失對持溫時間，(b) ln W對持溫時間………….....78 圖4-23 單分散PS400微粒在340至400℃的等溫熱裂解TGA分析圖 (a)重量損失對持溫時間，(b) ln W對持溫時間……………..79 圖4-24 (a) PS200-MWNT1, (b) PS200-MWNT2, (c) PS200-MWNT 3, (d) PS200-MWNT4複合材料在340℃至400℃裂解溫度下的 重量對時間之變化圖及(e)PS200-MWNT1,(f)PS200-MWNT2, (g) PS200-MWNT 3, (h) PS200-MWNT4複合材料的ln W對 時間之變化圖…………………………………………………..82 圖4-25 (a) PS400-MWNT1, (b) PS400-MWNT2, (c) PS400-MWNT 3, (d) PS400-MWNT4複合材料在340℃至400℃裂解溫度下的 重量對時間之變化圖及(e)PS400-MWNT1,(f)PS400-MWNT2, (g) PS400-MWNT 3, (h) PS400-MWNT4複合材料的ln W對 時間之變化圖…………………………………………………..85 圖4-26 單分散PS200微粒及PS200-MWNT導電複合材料利用 Arrhenius 方程式以ln kd 對1/T作圖………………………86 圖4-27 單分散PS400微粒及PS400-MWNT導電複合材料利用 Arrhenius 方程式以ln kd 對1/T作圖……………………....87 圖4-28 單分散PS微粒及不同MWNT添加量之PS-MWNT導電複合 材料的導電度曲線圖…………………………………………..92 圖4-29 PS200-PANI複合微粒之FESEM圖…………………………....96 圖4-30 PS400-PANI複合微粒之FESEM圖…………………………....97 圖4-31 PS200-PANI複合微粒之TEM圖……………………………….98 圖4-32 PS400-PANI複合微粒之TEM圖…………………………….…99 圖4-33 (a) PS200微粒,與 (b) PS200-PANI1 (c) PS200-PANI2,(d) PS200-PANI3之複合微粒,及(e)HCl-PANI的FTIR吸收光譜.100 圖4-34 (a) PS400微粒,與 (b) PS400-PANI1 (c) PS400-PANI2,(d) PS400-PANI3之複合微粒,及(e)HCl-PANI的FTIR吸收光譜.100 圖4-35 (a) PS200微粒, (b) PS200-PANI1 (c) PS200-PANI2,(d) PS200-PANI3之複合微粒的DSC圖…………………………..101 圖4-36 (a) PS400微粒, (b) PS400-PANI1 (c) PS400-PANI2,(d) PS400-PANI3之複合微粒的DSC圖…………………………102 圖4-37 PS200及PS200-PANI複合微粒之（a）TGA，（b）DTG圖.104 圖4-38 PS400及PS400-PANI複合微粒之（a）TGA，（b）DTG圖.105 圖4-39 (a) PS200-PANI1, (b) PS200-PANI2,(c) PS200-PANI3複合微粒 經由TGA 600℃熱分析後之HRTEM圖……………………..107 圖4-40 (a) PS400-PANI1, (b) PS400-PANI2,(c) PS400-PANI3複合微粒 經由TGA 600℃熱分析後之HRTEM圖……………………..108 圖4-41 PS200-PANI複合微粒於340℃至400℃的等溫熱裂解TGA分 析圖。(a) PS200-PANI1, (b) PS200-PANI2, (c) PS200-PANI3複 合微粒之重量損失對持溫時間作圖；(d) PS200-PANI1, (e) PS200-PANI2, (f) PS200-PANI3複合微粒以ln W對持溫時間作 圖……………………………………………………………......113 圖4-42 PS400-PANI複合微粒於340℃至400℃的等溫熱裂解TGA分 析圖。(a) PS400-PANI1, (b) PS400-PANI2, (c) PS400-PANI3複 合微粒之重量損失對持溫時間作圖；(d) PS400–PANI1, (e) PS400-PANI2, (f) PS400-PANI3複合微粒以ln W對持溫時間作 圖………………………………………………………………...116 圖4-43（a）PS200-PANI,（b）PS400-PANI之複合微粒利用Arrhenius 方程式以ln（kd）對1/T作圖………………………………...117 圖4-44 PS200-PANI及PS400-PANI複合微粒導電度曲線圖……….120 圖4-45 硝酸改質c-MWNT 之FESEM圖……………………………122 圖4-46 硝酸改質c-MWNT 之TEM圖……………………………....123 圖4-47 MWNT及硝酸改質c-MWNT 之FTIR圖………………….. 124 圖4-48 MWNT及硝酸改質c-MWNT 之RAMAN圖…………….…124 圖4-49 MWNT及硝酸改質c-MWNT 之TGA圖…………………….125 圖4-50 c-MWNT含量為(a) 1 wt%, (b) 2wt%, (c) 3wt%之PS200-PANI2/ c-MWNT導電複合材料之TEM圖…………………………...127 圖4-51 c-MWNT含量為(a) 1 wt%, (b) 2wt%, (c) 3wt%之PS400-PANI2/ c-MWNT 導電複合材料之TEM圖……………………….....128 圖4-52 PS200-PANI2/c-MWNT3 導電複合材料之SEM圖(a)10000倍, (b)30000倍……………………………………………………...129 圖4-53 PS400-PANI2/c-MWNT3 導電複合材料之SEM圖(a)10000倍, (b)30000倍……………………………………………………...130 圖4-54 PS200及PS200-PANI與添加0wt%~3wt% c-MWNT之複材的 熱性質分析（a）TGA圖,（b）DTG圖……………………….133 圖4-55 PS400及PS400-PANI與添加0wt%~3wt% c-MWNT之複材的 熱性質分析（a）TGA圖,（b）DTG圖…………………….…134 圖4-56 PS200-PANI2添加(a) 1 wt%, (b) 2 wt%,(c) 3 wt% c-MWNT之複 材的等溫熱裂解重量損失對持溫時間作圖；(d) 1 wt%, (e) 2 wt % ,(f) 3 wt% c-MWNT之複材取自然對數ln W對持溫時間作圖 …………………………………………………………………….139 圖4-57 PS400-PANI2添加(a) 1 wt%, (b) 2 wt%,(c) 3 wt% c-MWNT之複 材的等溫熱裂解重量損失對持溫時間作圖；(d) 1 wt%, (e) 2 wt %,(f) 3 wt% c-MWNT之複材以自然對數ln W對持溫時間作圖 …………………………………………………………………….141 圖4-58 (a) PS200-PANI2/c-MWNT, (b)PS400-PANI2/c-MWNT導電複 合材料利用Arrhenius方程式以ln（kd）對1/T作圖……….142 圖4-59 c-MWNT含量對導電複材的導電度變化趨勢圖…………….14

Lamellae Evolution of Stereocomplex-Type Poly(Lactic Acid)/Organically-Modified Layered Zinc Phenylphosphonate Nanocomposites Induced by Isothermal Crystallization

Stereocomplex-type poly(lactic acid) (SC-PLA)/oleylamine-modified layered zinc phenylphosphonate (SC-PLA/m-PPZn) nanocomposites are successfully fabricated using a solution mixing process. Wide-angle X-ray diffraction (WAXD) analysis reveals that the structural arrangement of the oleylamine-modified PPZn exhibits a large interlayer spacing of 30.3 Å. In addition, we investigate the temperature effect on the real-time structural arrangement of PPZn and m-PPZn. The results indicated that the lattice expansion of m-PPZn with increasing temperature leads to an increase in the interlayer spacing from 30.3 to 37.1 Å as the temperature increases from 30 to 150 °C. The interlayer spacing decreases slightly as the temperature further increases to 210 °C. This behavior might be attributed to interlayer oleylamine elimination, which results in hydrogen bonding destruction between the hydroxide sheets and water molecules. As the temperature reaches 240 °C, the in situ WAXD patterns show the coexistence of m-PPZn and PPZn. However, the layered structures of m-PPZn at 300 °C are almost the same as those of PPZn, after the complete degradation temperature of oleylamine. The morphology of the SC-PLA/m-PPZn nanocomposites characterized using WAXD and transmission electron microscopy (TEM) demonstrates that most partial delamination layered materials are randomly dispersed in the SC-PLA matrix. Small-angle X-ray scattering reveals that higher crystal layer thickness and lower surface free energy is achieved in 0.25 wt% SC-PLA/m-PPZn nanocomposites. These results indicate that the introduction of 0.25 wt% m-PPZn into SC-PLA reduces the surface free energy, thereby increasing the polymer chain mobility

Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites

This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVDF/magnetite nanocomposites are increased as the loading of magnetite nanoparticles increases. The piezoelectric responses of PVDF/magnetite films are extensively increased about five times in magnitude with applied strength of electrical field at 35 MV/m. The magnetic properties of PVDF/magnetite nanocomposites exhibit supermagnetism with saturation magnetization in the range of 1.6 × 10−3–3.1 × 10−3 emu/g, which increases as the amount of magnetite nanoparticles increases. The incorporation of 2 wt % magnetite nanoparticles into the PVDF matrix improves the thermal stability about 25 °C as compared to that of PVDF. The effect of magnetite particles on the isothermal degradation behavior of PVDF is also investigated

Crystallization and Enzymatic Degradation of Maleic Acid-Grafted Poly(butylene adipate-co-terephthalate)/Organically Modified Layered Zinc Phenylphosphonate Nanocomposites

Biodegradable nanocomposites were successfully synthesized using the maleic acid-grafted poly(butylene adipate-co-terephthalate) (g-PBAT) and organically modified layered zinc phenylphosphonate (m-PPZn), containing covalent linkages between g-PBAT and m-PPZn. Differential scanning calorimetry, wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM) were used to determine the crystallization behavior and morphology of g-PBAT/m-PPZn nanocomposites. The isothermal crystallization kinetics of g-PBAT/m-PPZn nanocomposites was determined using the Avrami equation. It was found that the half-time for the crystallization of the neat g-PBAT matrix is larger than that of g-PBAT/m-PPZn nanocomposites. This result suggests that the incorporation of m-PPZn can improve the crystallization rate of nanocomposites. The WAXD and TEM data illustrate that most of the m-PPZn layered materials are partially intercalated or exfoliated in the g-PBAT matrix. As the enzyme, lipase from Pseudomonas sp. was used for the enzymatic degradation tests. The degradation rates of the neatly fabricated g-PBAT copolymers using the heat pressing technique increase in the order of g-PBAT-80 > g-PBAT-50 > g-PBAT-20. The growing degradation rate of g-PBAT-80 is due to the growing amount of the adipate acid group and the increasing chain flexibility of the polymer backbone. Moreover, the increasing loading of m-PPZn enhances the weight loss of nanocomposites, suggesting that the existence of m-PPZn enhances the degradation of g-PBAT copolymers. The degradation rate of the freeze-drying samples containing a highly porous structure is greater than those prepared using the heat pressing technique

Correction: Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites. Materials 2015, 8, 4553–4564

In the published manuscript, “Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites. Materials 2015, 8(7), 4553–4564” [1], we detected that in three places the explanations were slightly incorrect. We apologize for any inconvenience this may have caused. [...

Synthesis, Physical Properties and Enzymatic Degradation of Biodegradable Nanocomposites Fabricated Using Poly(Butylene Carbonate-Co-Terephthalate) and Organically Modified Layered Zinc Phenylphosphonate

A new biodegradable aliphatic-aromatic poly (butylene carbonate-co-terephthalate) (PBCT-85) with the molar ratio [BC]/[BT] = 85/15, successfully synthesized through transesterification and polycondensation processes, was identified using 1H-NMR spectra. Various weight ratios of PBCT/organically modified layered zinc phenylphosphonate (m-PPZn) nanocomposites were manufactured using the solution mixing process. Wide-angle X-ray diffraction and transmission electron microscopy were used to examine the morphology of PBCT-85/m-PPZn nanocomposites. Both results exhibited that the stacking layers of m-PPZn were intercalated into the PBCT-85 polymer matrix. The additional m-PPZn into PBCT-85 copolymer matrix significantly enhanced the storage modulus at −70 °C, as compared to that of neat PBCT-85. The lipase from Pseudomonas sp. was used to investigate the enzymatic degradation of PBCT-85/m-PPZn nanocomposites. The weight loss decreased as the loading of m-PPZn increased, indicating that the existence of m-PPZn inhibits the degradation of the PBCT-85 copolymers. This result might be attributed to the higher degree of contact angle for PBCT-85/m-PPZn nanocomposites. The PBCT-85/m-PPZn composites approved by MTT assay are appropriate for cell growth and might have potential in the application of biomedical materials

FPGA Design of Enhanced Scale-Invariant Feature Transform with Finite-Area Parallel Feature Matching for Stereo Vision

In this paper, we propose an FPGA-based enhanced-SIFT with feature matching for stereo vision. Gaussian blur and difference of Gaussian pyramids are realized in parallel to accelerate the processing time required for multiple convolutions. As for the feature descriptor, a simple triangular identification approach with a look-up table is proposed to efficiently determine the direction and gradient of the feature points. Thus, the dimension of the feature descriptor in this paper is reduced by half compared to conventional approaches. As far as feature detection is concerned, the condition for high-contrast detection is simplified by moderately changing a threshold value, which also benefits the reduction of the resulting hardware in realization. The proposed enhanced-SIFT not only accelerates the operational speed but also reduces the hardware cost. The experiment results show that the proposed enhanced-SIFT reaches a frame rate of 205 fps for 640 × 480 images. Integrated with two enhanced-SIFT, a finite-area parallel checking is also proposed without the aid of external memory to improve the efficiency of feature matching. The resulting frame rate by the proposed stereo vision matching can be as high as 181 fps with good matching accuracy as demonstrated in the experimental results