最新增塑聚乳酸的热-机械性能表征幻灯片.ppt

p Introductionp Materials and methodsp Results and discussionp Conclusion 1.3 Plasticizing of PLA - common plasticizers food contact agreed plasticizers or polymers:npoly(hydroxybutyrate) -聚羟基丁酸酯npoly(vinylacetate) -聚醋酸乙烯npoly(ethylene oxide) -聚环氧乙烷 npolysaccharides -多糖npoly(ethyleneglycol) -聚乙二醇ncitrate -柠檬酸1.4 New research about plasticizers of PLAnYounes and Cohn: microphase separation occurs at a given composition depending on the molecular weight of PEG (1500 and 35,000 g/mol).nHu et al.: the glass transition temperature of PLAPEG (8000 g/mol) followed the empirical Fox equation but the blends were not stable in time and phase separation was observed. nNijenhuis et al.: the poor long-term stability of blends between PLA and PEG was due to slow crystallization of PEG.nOthers: fatty acid ester is a good plasticizer with a strong hindrance of the crystalline phase development. 2. Materials and methods2.1 MaterialsnPLA 4042D:nPBOH:nDBS:nPEGs:nAGM:2.2 Blending conditionsnMachine: An opened mixer (Brabender, 50 EHT) controlled by a lab-Station driven by the BRABENDER Software Winmix.nConditions: Blending temperature was 180 and blending time 15 min and blade rotation speed was 30 rpm.nSample: 20*20*0.8 cm32.3. Differential scanning calorimeternMachine: PerkinElmer Pyris DSC; Pyris V 3.0 software under Windows NT 4.0 for data collection.nCalibration: Indium and Tin; temperature range +15 to +350.nPretreatment: Heated to 200 for 5 min.nPrecision: 0.5.2.4. Mechanical measurementsnMachine: MTS Synergie RT1000nLoading speed: 1 mm/min for pure PLA and 10 mm/min for plasticized PLA.3. Results and discussion马悦欣马悦欣08S007033 3.1 Solubility parameter calculation 溶度参数的计算溶度参数的计算 3.2 Thermal analysis of miscibility 热分析热分析 3.3 Mechanical properties 机械性能机械性能3.1 Solubility parameter calculation溶解度参数的计算溶解度参数的计算 为了估计两种分子的兼容性，有几种方法可以用于计为了估计两种分子的兼容性，有几种方法可以用于计算溶度参数，本文采用算溶度参数，本文采用Hoy法法计算参数计算参数。溶度参数的确定。溶度参数的确定基于平均分子量。基于平均分子量。 Interaction parameter (相互作用参数相互作用参数) 由等式（由等式（1）计算得到：计算得到：BRTV2211)(1)B是一个是一个0.30.4的常数，符合的常数，符合entropic component ，通常非极性体系采用，通常非极性体系采用0.34熵熵 ？Table 2 Solubility parameter and interaction parameter between PLA and plasticizers（增塑剂）（增塑剂） In Table 2, was calculated for PLA and plasticizers. Interaction parameter was obtained using Eq. (1), without entropic component because of the large polarity(极性极性) of the component used.0.5Miscible;No phase separation Miscibility is generally stated when only one glass transition temperature is recorded on the DSC traces of polymer blends. However, phase separation yielding very little domains of less than 20 nm will not be detected by this technique. Miscibility also yields some changes in crystallization and melting temperatures with the decreasing of the integrated enthalpies ( 总焓变？总焓变？).3.2. Thermal analysis of miscibility 热分析热分析Fig. 1. Thermograms of PLA/plasticizers 90/10 (w/w) heated at 20 min-1 after cooling at 20 min-1 Table 3 Glass transition temperature of pure components and of blends between PLA and plasticizersFox equation：22111gggTwTwTTg 混合体系玻璃化转变温度混合体系玻璃化转变温度Tg1，Tg2 组组分的玻璃化转变温度分的玻璃化转变温度w1，w2 组分的质量分数组分的质量分数(2)Fig. 2. Glass transition temperature of PLA/plasticizers. The dash line represents the Fox equation. (a) PEG 200/PLA; (b) PEG 400/PLA; (c) PEG 1000/PLA(d) AGM/PLA; (e) DBS/PLA; (f) PBOH/PLA The other plasticizers deviate more severely from the Fox relation and yield higher interaction parameters as well. However, even though these blends do not lead to total molecular scale miscibility between PLA and plasticizers, they can offer satisfying compatibility as will be assessed by tensile tests.Table 4 Melting temperature and enthalpies of pure components and melting temperature and enthalpies for PLA in PLA / plasticizers blendsFloryHuggins relation：21121211VHRVTTmomm(3) Tm and T0m are the equilibrium melting points of PLA in blends and neat crystallizing polymer. The subscript 1 indicates the non-crystallizing component (plasticizer) and 2 the crystallizing PLA. V1 and V2 are the molar volume of the repeat units. Hm is the heat of fusion of PLA and 1 is the volume fraction of plasticizerTable 5 Crystallization temperatures of pure components and of PLA/plasticizer blends during heating at a rate of 20 min-13.3. Mechanical propertiesTable 6 Tensile modulus (MPa) of pure PLA and plasticized PLATable 7 Strain at break (%) of pure PLA and plasticized PLATable 8Stress at break (MPa) of pure PLA and plasticized PLAFig. 3. Tensile modulus vs glass transition temperature of plasticizers/PLA blends.4. ConclusionnPlasticizers blended with PLA lowered the glass transition temperature and modified the melting and crystallization characteristics.nIn this composition range, the glass transition temperature is in good agreement with the calculated interaction parametersnMechanical characteristics of these materials showed a decrease in modulus and stress at break.Thank you !