PET/PLA共混物中小分子扩散行为的分子动力学模拟

采用分子动力学(MD)模拟方法研究了O2、CO2小分子在不同质量比(90/10、70/30、50/50、30/70和10/90)聚对苯二甲酸乙二醇酯(PET)/聚乳酸(PLA)共混物中的扩散行为,基于Einstein关系式计算了小分子在共混物中的扩散系数。讨论了不同探针半径对自由体积分数(FFV)的影响以及自由体积分数与扩散系数的关系。研究结果表明,探针半径越大,自由体积分数越小;扩散分子的动力学半径越小,在同一比例PET/PLA共混物中的扩散系数越大,与自由体积理论取得统一。当PET/PLA共混物质量比为70/30时共混物的阻隔性能最好。     

PLA/PA11共混物的制备与分子动力学模拟

采用熔融共混法制备了不同比例的(0/100,10/90,30/70,50/50,70/30,90/10,100/0)生物基聚乳酸/尼龙11(PLA/PA11)共混物。通过动态力学性能(DMA)测试、XRD分析、扫描电镜(SEM)形貌观察、力学性能测试、红外光谱(IR)分析和分子动力学(MD)模拟研究了PLA/PA11共混物结构与性能的关系。DMA测试和MD模拟均证明任意比例下PLA与PA11为不相容体系,XRD分析表明当PLA/PA11含量为70/30时,PLA会发生一定程度的结晶,SEM结果显示此时两者会出现明显的界面,力学性能最差,MD模拟的结合能和径向分布函数g(r)表明两者会产生一定的氢键相互作用,但氢键作用较小,不足以改善两者的相容性。     

聚乳酸/聚酯共混体系熔体流变性能研究

对聚酯与聚乳酸共混体系的相容性及熔体流变性能进行了研究。首先制备不同比例的PET/PLA共混体系,并利用示差扫描量热仪(DSC)研究共混体系的相容性,发现m(PLA)/m(PET)在20%以内时相容性较好。而后利用毛细管流变仪研究了不同温度、不同剪切速率下共混体系的熔体流变性能,发现随PLA含量的增大,非牛顿指数先增加后减小,且在m(PLA)/m(PET)=10%时出现极大值;黏流活化能则随PLA含量的增大而降低;另外当m(PLA)/m(PET)=10%时的共混体系可纺性较好。     

PET/PEN共混物的结晶与冷结晶性能及其机理

采用双螺杆熔融挤出法制备了聚对苯二甲酸乙二醇酯(PET)/聚2,6-萘二甲酸乙二醇酯(PEN)共混材料,利用差示扫描量热法(DSC)研究了不同质量比的PET/PEN共混物的熔融与结晶性能。研究结果表明,PET/PEN共混物为部分相容的两相结构。在PET和PEN等质量共混时,可能形成部分相容且彼此交叠的两个连续相。冷却过程中两共混组分既各自形成结晶,又存在一定的共结晶。PET和PEN分子及其链段间互相缠绕和相互作用干扰大分子的结晶过程,导致冷却(降温)过程中结晶不完善和结晶度降低。PET/PEN共混物与PET和PEN一样,具有明显的冷结晶倾向。     

聚氨酯-聚乳酸共混物的制备及性能

通过熔融共混挤出法制备不同质量比的热塑性聚氨酯-聚乳酸(TPU-PLA)共混物,采用SEM、DSC、TG、微卡软化点温度测定仪和熔融流动速率仪对共混物的表面形态结构、热学、高温加工等性能进行研究。结果表明:TPU-PLA共混物表面光滑且呈现出脆性断裂形貌特征,共混体系两种高聚物呈"海岛"分布;TPU-PLA共混体系中PLA与单独PLA相比,玻璃化转变温度Tg由69.60℃(Original PLA)变为57.58℃(PLA70)、53.29℃(PLA50)和55.64℃(PLA30),TPU均匀分散于PLA基体中且相界面分明,这都说明TPU-PLA共混体系为部分相容体系;TPU-PLA共混物的热失重起始分解温度范围为180~200℃,最快分解温度范围为310~350℃,热稳定性良好;TPU含量占共混物10%~30%时,共混物高温的临界变形温度相对单一体系有所提高;随TPU含量的继续增加,共混物熔融指数呈现先增大后减小的变化趋势,其中PLA与TPU质量比为4∶6的TPU-PLA共混物熔融指数达到最大,为1 406g·(10min)-1。     

聚丙烯酰胺/聚乙烯醇共混物相容性及力学性能的微观理论研究

采用分子动力学的理论方法,从微观分子相互作用的层面研究了PAM/PVA共混体系,分别从组分间的相容性、结合能以及对相关函数分析3方面阐述了共混体系间相互作用的机理及本质,通过对组分不同质量配比体系的静态力学分析,研究了组分不同质量配比对体系力学性能的影响。结果表明,PAM与PVA组成的共混物相容性极好,而体系中单组分间的结合能随着PVA含量的增加反而减小,主要原因是质量相同的PAM链所含极性官能团的数目要高于PVA链;此外,对相关函数分析表明,单组分间主要是通过氢键形成相互作用,且共混体系中酰胺基(—NH2)、羰基(—CO)、羟基(—OH)官能团与周围H原子形成氢键的可能性关系为O(-C=O)O(-OH)N(-NH2),这也是酰胺基(—NH2)、羰基(—CO)、羟基(—OH)官能团极性强弱关系的反映;单组分不同质量配比模型的静态力学分析表明,随着共混体系中PVA组分含量的增加,体系弹性系数、各项工程模量、柯西压值均呈上升趋势,即PVA含量的增加可以明显改善PAM的力学性能及其延展性。     

杜仲胶/天然橡胶共混物的分子动力学模拟和耗散粒子动力学模拟

应用分子动力学(MD)和耗散粒子动力学(DPD)模拟方法对杜仲胶(TPI)、天然橡胶(NR)的相容性进行了研究。采用MD模拟方法,在COMPASS力场下,对纯物质在不同聚合度下的溶度参数、一系列共混比的TPI/NR共混物内聚能密度、Flory-Huggins作用参数进行了模拟计算,确定了纯物质单链的聚合度,经判断各比例共混物的相容性均较好;采用DPD模拟方法对TPI/NR共混体系的相结构进行了研究,从等密度图可以进一步判断共混体系的相容性;分析比较两种纯物质的径向分布函数,揭示了其相互作用的本质;经过分析比较静态力学性能,发现共混比为1/3的TPI/NR共混物性能最佳,其结论与实验结果一致。     

聚醚醚酮与酚酞型聚芳醚砜共混物的相容性特征

本文借助示差扫描量热(DSC),扭辩分析(TBA)和傅里叶变换红外光谱(FTIR)等技术研究了聚醚醚酮(PEEK)/酚酞型聚芳醚砜(PES-C)共混物的相容性特征。结果表明共混物是部分相容的,共混物的相容程度与共混物的热历史有关。在共混物相容程度较高时,共混物的两个 T_g 随共混物组分的改变彼此向对方移动;共混使对应于 PES-CT_g 的玻璃化转变变宽。PEEK/PES-C 共混物的部分相容性从两者有一定程度的分子链水平的相互作用得到证实。     

相容剂增容聚对苯二甲酸乙二醇酯/聚乳酸共混物的制备及结晶性能与热性能EI北大核心CSCD

分别通过扫描电镜(SEM)、差式扫描量热分析(DSC)、X射线衍射(XRD)、热重分析(TG)、核磁共振及红外光谱等研究相容剂种类、含量及聚对苯二甲酸乙二醇酯(PET)/聚乳酸(PLA)配比对PET/PLA共混物的断面形貌、结晶形态及热性能等的影响。SEM和DSC结果表明,相容剂乳酸/丁二醇共聚物(PLLA-g-BDO)及用量对PET/PLA共混物的界面相容影响较大。与未加相容剂比,相容剂使界面从清晰过渡到模糊,界面处未见明显团聚颗粒;相容剂用量为8%时,DSC曲线上仅出现1个熔融峰。DSC和XRD表明,相容剂的引入降低了共混物的结晶度,冷结晶和热结晶过程中分别结晶,结晶的温度范围较宽,热结晶的结晶度大于冷结晶。冷结晶时,柔性链的PLA先结晶,PET后结晶;热结晶时,结晶温度较大组分PET先结晶,PLA后结晶。TG分析表明PET/PLA配比是材料热稳定性的必要条件。     

PC／PET共混物相容性和结晶行为的研究

本工作用差动扫描量热计(DSC)、动态粘弹仪(DMA)、密度梯度、激光小角散射仪(SALS)和光学解偏振仪研究了国产聚碳酸酯/聚对苯二甲酸乙二醇酯(PC/PET)共混物的相容性和结晶行为。DSC研究结果表明,共混物中在PET含量为60％以下时,只有一个玻璃化转变温度(T_g),说明共混物是完全相容的;在PET含量大于60％时,共混物呈现出两个玻璃化转变温度,并发生内移,说明共混物是部分相容的。用DMA测试也得到同一结果。共混物中PET的结晶动力学与一般结晶高聚物相似,等温结晶前期符合Avrami方程,等温结晶后期偏离Avrami方程。     

Polymer blends based on PEO and starch: Miscibility and spherulite growth rate evaluated through DSC and optical microscopy

The miscibility and PEO spherulite growth rate in PEO/starch blends (starch from cassava) were evaluated using the depression in the melting point (by DSC) and optical polarized microscope, respectively, and compared to pure PEO. The PEO/starch blend ratio changed from 100/0 to 60/40 (weight/weight). The starch induces changes in PEO crystallization on PEO/starch blends but the crystallization rates do not change linearly to the blend ratio. For 90/10, 80/20, 70/30, 65/35 and 60/40 ratios, lower values for the equilibrium melting temperature were observed as compared to the pure PEO. The obtained interaction parameter value was ? 0.25 by the use of Nishi–Wang equation. The depression in the equilibrium melting temperatures and the negative value for the polymer–polymer interaction parameter suggest that the blends are miscible in the molten state in the range of investigated ratios, except for the 95/05 ratio in which the equilibrium melting temperature increased relative to the pure PEO. The miscibility should be due to the H-bonds among the hydroxyl groups from starch and oxygen atoms of repeat units of PEO.     

Properties of epoxidized palm oil plasticized polytlactic acid

In this study, epoxidized palm oil (EPO) was utilized as a plasticizer for polylactic acid (PLA) using chloroform as a solvent by solution casting process at six weight ratios of PLA/EPO, 95/05, 90/10, 80/20, 70/30, 60/40, and 50/50, respectively. Fourier-transform infrared (FTIR) spectroscopy was used to identify the functional groups of PLA, EPO, and PLA/EPO blends. Thermal stability, mechanical, and morphological properties of the blends were investigated by thermogravimetric analyzer (TGA), tensile properties measurements, and scanning electron microscope (SEM) technique, respectively. The FTIR spectra indicate that there are some molecular interactions by intramolecular hydrogen bond between PLA and EPO. All sets of PLA/EPO blends show high thermal stability and significant improvement of mechanical properties compare to pure PLA. The highest elongation at break (about 210%) was obtained when the ratio of PLA/EPO blend was 80/20. Morphological results of PLA/EPO blends show that ESO was good miscible with PLA.     

梯形聚苯基倍半硅氧烷/聚甲基丙烯酸甲酯溶液浇注共混物的相容性

用溶液浇注法制备了具有不同质量配比的高分子量、低分子量梯形聚苯基倍半硅氧烷（ＰＰＳＱ）与聚甲基丙烯酸甲酯（ＰＭＭＡ）的共混物。用扭辫分析技术研究了不同分子量ＰＰＳＱ与ＰＭＭＡ间的相容性及热历史对其相容性的影响。ＰＰＳＱ、ＰＭＭＡ在其溶液浇注膜中是部分相容的。红外光谱分析表明，低分子量的ＰＰＳＱ（Ｙ）与ＰＭＭＡ间有较强的相互作用，故其与ＰＭＭＡ的相容性比高分子量ＰＰＳＱ的好。热历史对该类溶液浇注共混体系的相容性影响较大，加热使ＰＰＳＱ（Ｙ）／ＰＭＭＡ共混物分相，但加热可增加高分子量ＰＰＳＱ与ＰＭＭＡ间的相容性。     

Study on the Miscibility and Phase Behavior of Polyoxymethylene with Novolak

1. IntroductionPolyoxymethylene (POM) is an engineering plasticwith good processibility, low water and oil absorbabilities, and excellent electric and thermal properties, which has found application in the fields of vehicles, electronic appliances and sophisticated machinery. However, its low notched impact strength constitutes its main weakness[lro3). Various elastomers wereemployed for blending with POM, such as the thermoplastic polyurethane, ethylene-propylene copolymer,styrene-butadiene…     

PBT／PET共混体系的晶区的相容性及形态结构

用广角Ｘ射线衍射法（ＷＡＸＤ）、差示扫描量热法（ＤＳＣ）以及红外光谱法（ＩＲ）等方法证明了在聚对苯二甲酸丁二酯（ＰＢＴ）／聚对苯二甲酸乙二酯（ＰＥＴ）共混体系中两组分是晶相分离的，而不生成混晶。动态力学分析结果表明，ＰＢＴ、ＰＥＴ两组分晶区之间的无定型部分仍具有相容性，共混体系的形态结构因组分比不同而变化。长周期Ｌ、无定形区厚度Ａ以及晶区厚度Ｃ均随ＰＢＴ含量的增加而减小。结晶温度升高，有利于晶区厚     

淀粉接枝共聚物在淀粉/聚乳酸共混体系中的作用

研究了淀粉／聚乳酸共混体系的相容性，考察了淀粉－聚醋酸乙烯酯和淀粉－聚乳酸接枝共聚物对淀粉／聚乳酸共混体系相容性的影响。发现上述两种接枝共聚物均可有效地增加淀粉与聚乳酸的相容性，从而提高共混体系的耐水性的力学性能。     

Effect of starch type on miscibility in poly(ethylene oxide) (PEO)/starch blends and cytotoxicity assays

This study reports results on the miscibility of polymer blends based on PEO and different starches (unmodified, cationic, and hydrophobic) and their respective cytotoxicity. Films of PEO/starch blends at different weight ratios (95/05, 90/10, 80/20, 70/30, 65/35, and 60/40), as well as films of pure PEO as control, were prepared by casting methodology. Several techniques, such as SEM, WAXS, FTIR, and FT-Raman spectroscopy were used in this study for evaluating blend miscibility. The results revealed that the miscibility of such blends is dependent on the type of starch used. Regarding the PEO/unmodified starch blends, it was concluded that the system is miscible in the ratio range from 90/10 to 65/35. Although the PEO/hydrophobic starch blends are miscible in all the studied range, blends of PEO and cationic starch are immiscible, regardless the blend ratio. The different samples presented distinct cytotoxic behaviors. PEO and hydrophobic starch presented no relevant toxicity (CC_50/72 > 2.5 mg/mL). Otherwise, the cationic starch was the most harmful for the cells. The blends presented cytotoxicity values between those of PEO and cationic starch.     

聚甲醛/聚醚型聚氨酯共混体系的溶混性及微晶结构

用ＤＳＣ法研究了聚甲醛和聚醚型聚氨酯共混体系的溶混性,ＷＡＣＤ分析表明,ＰＥＵ未能进入ＰＯＭ的晶胞及晶粒中,两者仅在ＰＯＭ的无定形区域形成可溶混结构,且ＰＯＭ的（１１０）晶面法向微晶尺寸Ｌ１０是随机分的增加面在的。     

生物降解聚甲基乙撑碳酸酯/聚乳酸共混复合材料的制备与性能

利用熔融共混制备了可以完全生物降解的聚甲基乙撑碳酸酯/聚乳酸共混复合材料(PPC/PLA),通过万能试验机、差示扫描量热分析仪(DSC)、热重分析仪(TG)以及扫描电子显微镜(SEM)分别研究了复合材料的力学性能、相容性、结晶性、热稳定性及微观形态。结果表明,PLA的引入提高了复合材料的拉伸强度和热稳定性,复合材料是相容性较好的两相体系,二组分的比例对复合材料的熔点和结晶度有一定的影响。