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 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, Northwestern Polytechnical Un

2、iversity 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,1,2,3,4,2,Background 研究背景,Lactic acid,Lactide,分子間氫鍵,Life cycle,Application,3,PLA,Bioplastics,Drug delivery,Tissue Engineering,Landfill,Incineration,Composting,Biomass,Background 研究背景,PLA for Packaging Application,PLA in tissue engineering,4,PLA as the mo

3、st widely used biopolymer 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,Nervous,Cardiovascular,Cutaneous,Musculoskeletal,PLA stereocomplex,1,2,PLA fiber,3,PLA foam,Background 研究背景,5,PLA Foaming 聚乳酸發(fā)泡研究,Challenge,Low melt strength 低的熔體強(qiáng)度,Application:

4、 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。,Open-cell structure

5、開孔結(jié)構(gòu),Strategy,Molecular weight and structure 聚合物結(jié)構(gòu)和分子量 Chain extender Modifying the L/D ratio configuration Varying the PLAs molecular weight,Compounding with additives 和其他聚合物以及填料共混,Objective 研究目標(biāo),Microcellular PLA-based foams with open cell structure 聚乳酸開孔微孔材料,Tissue engineering,組織工程,6,Batch Foamin

6、g by Supercritical CO2 超臨界二氧化碳間歇發(fā)泡方法,Preparation of PLA blends 聚乳酸共混體系制備,Extrusion pelletization 擠出造粒,7,Sheet extrusion 片材擠出 Haake PolylabOS system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,8,PBS 聚丁二酸丁二醇酯,Fracture surface morphology,(a)PLA/10%PBAT,(b)PLA/10%PBS,Phase morphology of P

7、LA/PBS blends,PLA,PLA/10%PBS,9,PLA/50%PBS,PLA/30%PBS,PLA/40%PBS,Viscoelastic properties of the PLA blends 流變性能,10,Angular 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,11,Example,Gaseous mass-transfer behavior 氣體傳質(zhì)行為,12,Solubili

8、ty of CO2 in PLA and PLA 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）,Sc-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 二氧化碳飽和吸收度隨

9、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,13,Plots of measured desorption weight fraction (Md) against the square root of desorption time (td),CO2 diffused followed the Fickian diffusion mechanism in a short time, followed by a more slowly decreasing 二氧化碳在聚乳酸體系中的解吸附短時間遵循Fickian擴(kuò)散機(jī)理，

10、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。,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,14,DSC heating curves for PLA samples (a) without CO2, (b) with saturated sc-CO2 and (c) af

11、ter 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,Batch foaming processing 間歇發(fā)泡法,15,Sc-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45,Foaming temperature: 150 , 160 or 170 for time (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 s

12、ample 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,16,150 160 170,PLA,PLA/10PBAT,PLA/10PBS,Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡,17,3s 6s 15s,PLA 160,PLA/10PBAT 160,PLA/10PBS 170,Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡,Cell growth,12 hours 24h

13、ours 36hours,PLA,PLA-PBAT,PLA-CaCO3,PLA-PBAT-CaCO3,18,Average cell size,Cell density,Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡,PLA PLA/PBS,12 h,24 h,36 h,19,Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡,20,Foam morphology of PLA systems 聚乳酸體系微孔發(fā)泡,21,21,Conclusion 結(jié)論,Sc-CO2 has a relative high solubility i

14、n 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 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 mat

15、rix 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.,22,Conclusion 結(jié)論,The low melt strength and the toughness of second phase are the dominated reason for the formation of the open cell structu

16、re. 第二相體系較低的熔體強(qiáng)度和其內(nèi)在韌性開孔結(jié)構(gòu)形成的主要原因。,The microcellular morphology of PLA-based foams can be tailored by controlling the foaming stage. 超臨界間歇發(fā)泡技術(shù)可以通過不同階段的發(fā)泡進(jìn)行泡孔結(jié)構(gòu)的調(diào)控.,As desorption time increases, less CO2 contents in the PLA-based samples leads to bigger cell size with smaller cell density and more uniformity of the final foams. 隨著解吸附時間的增長，聚乳酸體系中較低的二氧化碳含量將利于平均泡孔尺寸的增大泡孔密度的降低，泡孔的均勻性更好。,23,Research group 課題組 High Performance Polymer foams,Professor