超臨界二氧化碳制備聚乳酸開孔微孔材料2-3ShiENCN.

1、Microcellular PLA-based foams with open cell structure and tailored cell morphology by batch foaming process with supercritical CO2超臨界二氧化碳制備聚乳酸開孔微孔材料超臨界二氧化碳制備聚乳酸開孔微孔材料及其結(jié)構(gòu)調(diào)控研究及其結(jié)構(gòu)調(diào)控研究2016 Poly-Foam Conference Presenter: Xuetao Shi, Guangcheng Zhang匯報人：史學(xué)濤，張廣成Department of Applied Chemistry, Northwes

2、tern Polytechnical University西北工業(yè)大學(xué)理學(xué)院應(yīng)用化學(xué)系2016年10月Outline 匯報提綱1234Background背景介紹Preparation of PLA blends 聚乳酸多相體系制備Microcellular foaming of PLA blends聚乳酸微孔發(fā)泡 Conclusion 結(jié)論2Background 研究背景Lactic acidLactide分子間氫鍵Life cycleApplication3PLA LandfillIncinerationCompostingBiomassBackground 研究背景PLA for Pac

3、kaging ApplicationPLA in tissue engineering 4PLA as the most widely used biopolymer聚乳酸是目前最常用的生物材料聚乳酸是目前最常用的生物材料 Good transparency 透光性Degradation 降解性Biocompatibility 生物相容性Processability 優(yōu)異加工性NervousCardiovascularCutaneousMusculoskeletalBackground 研究背景5PLA Foaming聚乳酸發(fā)泡研究聚乳酸發(fā)泡研究ChallengeLow melt streng

4、th低的熔體強度Application: Alternative of polystyrene foam as packaging, cushioning, construction, thermal and sound insulation materials.聚乳酸泡沫可作為聚苯乙烯泡沫的替代品廣泛用于包裝、建筑以及保溫隔音材料。 Application: PLA foams in tissue engineering with outstanding biocompatibility and degradability 聚乳酸泡沫因其優(yōu)異的生物相容性和可降解特性可應(yīng)用于組織工程領(lǐng)域。 O

5、pen-cell structure 開孔結(jié)構(gòu)StrategyMolecular weight and structure 聚合物結(jié)構(gòu)和分子量u Chain extenderu Modifying the L/D ratio configurationu Varying the PLAs molecular weightCompounding with additives 和其他聚合物以及填料共混 Objective 研究目標Microcellular PLA-based foams with open cell structure聚乳酸開孔微孔材料聚乳酸開孔微孔材料 Tissue engin

6、eering組織工程6Enable cell adhesion, migration, proliferation滿足細胞黏附，遷移和增殖的要求High porosity 空隙率biocompatible, nontoxic, nonimmunogenic生物相容性，安全無毒，無免疫性Biopolymer 生物材料Batch Foaming by Supercritical CO2超臨界二氧化碳間歇發(fā)泡方法PLALDPEHDPEEVAABSPPPCEVOHTPOPHBPEOPCLPEGPBSPBATPEGPHBVPTATPVOHBiodegradable Polymer Blends生物可降解

7、聚合物共混Preparation of PLA blends 聚乳酸共混體系制備Extrusion pelletization 擠出造粒擠出造粒7Sheet extrusion 片材擠出片材擠出Haake PolylabOS system哈克單螺桿體系哈克單螺桿體系 PLA/PBAT(or PBS) 聚乳酸共混體系PBAT 聚對苯二甲酸丁二醇酯和己二酸丁二醇酯共聚物聚對苯二甲酸丁二醇酯和己二酸丁二醇酯共聚物8PBS 聚丁二酸丁二醇酯聚丁二酸丁二醇酯Fracture surface morphology (a)PLA/10%PBAT(b)PLA/10%PBSPhase morphology of

8、 PLA/PBS blends PLAPLA/10%PBS9PLA/50%PBSPLA/30%PBSPLA/40%PBSViscoelastic properties of the PLA blends 流變性能10Angular frequency dependence of * (left) and G (right) at 180 角頻率對復(fù)合黏度（左圖）和損耗模量（右圖）的影響 Thermal behavior of PLA blends 多相體系熱性能11PLA/PBAT blendsPLA/PBS blends Tm-PBS(C)Tg(C)Tcc(C)Tm-PLA(C)Hc (J/

9、g)Hm (J/g)X (%)PLA-59.3100.7166.231.8240.809.7PLA/10PBS110.357.591.1165.519.0445.9331.9PLA/20PBS111.757.784.6165.419.3243.7432.6PLA/30PBS112.854.995.6165.7-46.21-PLA/40PBS113.155.491.2165.7-43.42-PLA/50PBS113.354.594.5166.0-52.44-Gaseous mass-transfer behavior 氣體傳質(zhì)行為12Solubility of CO2 in PLA and PL

10、A blends at 12 MPa and at 45 C超臨界二氧化碳在 聚乳酸及其共混物的飽和吸收（12MPa, 45）PLA/PBAT blendsPLA/PBS blendsSc-CO2 has a higher solubility in the PLA matrix compared to that of PA66, PP and PC 超臨界二氧化碳在聚乳酸體系中有著較高的飽和吸收度The equilibrium gas concentration decreases with the increasing of the second phase content 二氧化碳飽和吸

11、收度隨著聚乳酸多相體系中第二相含量的增大而降低Gaseous mass-transfer behavior 氣體傳質(zhì)行為13Plots of measured desorption weight fraction (Md) against the square root of desorption time (td)Gas desorption of PLA/PBAT blendsCO2 diffused followed the Fickian diffusion mechanism in a short time, followed by a more slowly decreasing

12、二氧化碳在聚乳酸體系中的解吸附短時間遵循Fickian擴散機理，而后緩慢降低CO2 contents reach a plateau with solubility of around 3g CO2/100g polymer 經(jīng)過長時間解吸附后聚乳酸體系中二氧化碳含量降至3g CO2/100g polymer左右。Samples Dd (m2/s)PLA4.37E-12PBAT6.05E-12PLA/10PBAT2.15E-12PLA/10PBAT/5CaCO36.98E-13101520253035404504812162024t1/2d (sec1/2) Md( g CO2/100g po

13、lymer) Thermal properties of PLA samples with different CO2 content不同二氧化碳含量下的聚乳酸體系熱性能對比14DSC heating curves for PLA samples (a) without CO2, (b) with saturated sc-CO2 and (c) after desorption for 12 hours聚乳酸共混體系不同二氧化碳含量下的DSC曲線及其主要參數(shù)對比SamplesPLAPLA-10%PBATPLA-5%CaCO3PLA-10PBAT-5CaCO3Tga59595858b37404

14、039c40454547Tcca102899999Texa154151154154Tma166165166166b168168170170c169169169169Xc a9.6%20.4%17.4%15.3%b36.7%35.2%37.9%37.1%c33.8%32.6%37.6%35.1%Batch foaming processing 間歇發(fā)泡法15Sc-CO2 saturation pressure was fixed to be 12MPa at 45 固定超臨界飽和條件為：壓力12MPa，溫度45Foaming temperature: 150 , 160 or 170 for t

15、ime (3s, 6s or 15s) 發(fā)泡溫度設(shè)定為150，160或170，發(fā)泡時間為3s，6s 或15s Foaming after CO2 in the PLA sample desorption for different times 二氧化碳飽和吸收的聚乳酸體系在解吸附一定時間后發(fā)泡Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡16Influence of foaming temperature 150160170PLAPLA/10PBATPLA/10PBS50m50m50m50m50m50m50m50m50mFoam morphology of P

16、LA systems 聚乳酸體系微孔發(fā)泡17Influence of foaming time 3s6s15sPLA160PLA/10PBAT160PLA/10PBS17050m50m50m50m50m50m50m50m50mFoam morphology of PLA systems 聚乳酸體系微孔發(fā)泡Cell growth010203040500h12h12h36h24h12h0h36h24h12hPLA-PBAT-CaCO3PLA-CaCO3 PLA-PBAT Average cell size (m)PLA 0h106107108109101010110h12h12h Cell den

17、sity (cell/cm3)PLA-PBAT-CaCO3PLA-CaCO3 PLA-PBAT PLA 36h24h12h0h36h24h12h0h12 hours 24hours 36hours PLA PLA-PBATPLA-CaCO3 PLA-PBAT-CaCO318Average cell sizeCell densityInfluence of CO2 contents (PLA/PBAT ) Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡PLA PLA/PBS 12 h24 h36 h19Influence of CO2 contents (PLA

18、/PBS ) 50m50m50m50m50m50mFoam morphology of PLA systems 聚乳酸體系微孔發(fā)泡20 Influence of CO2 contents 050100150200250300350400450500550024681012141618202224 Gas concentration Md( g CO2/100g polymer)t1/2d (sec1/2) PLA PLA/10PBAT PLA/10PBSabcdefghijklPLAPLA/10PBATPLA/10PBS0h12h24h36h12h24h36h50m50m50m50m50m50

19、m10m10m10m10m10m10mFoam morphology of PLA systems 聚乳酸體系微孔發(fā)泡 21Formation of open cell structure abcdefPLA/PBATPLA/PBS5m10m10m10m10m5m21Conclusion 結(jié)論Sc-CO2 has a relative high solubility in the PLA systems due to the carbonyl groups 超臨界二氧化碳在聚乳酸及其復(fù)合體系中有著較高的溶解度CO2 diffused followed the Fickian diffusion

20、 mechanism in a short time, then the CO2 contents decreased more slowly to a plateau 二氧化碳的解吸附過程在短時間內(nèi)遵循Fickian定律，而后經(jīng)長時間緩慢將至 3 gCO2/100g polymer. The second phase separated in the PLA matrix as domains and the formed interface between PLA and the second phase provides the heterogeneous nucleating sites 聚乳酸中的第二相在基體中以顆粒狀分散，由此形成的界面在發(fā)泡過程起到作為成核點的作用. 22Conclusion 結(jié)論The low melt strength and the toughness of second phase are the dominated reason for the formation of the open cell structure. 第二相體系較