聚L-乳酸的热性能研究

为了了解聚L-乳酸(PLLA)自身结构特点,更好地控制其成型加工过程,研究了PLLA的非等温结晶行为、熔融行为和热失重过程。结果表明:降温速率对PLLA的非等温结晶过程具有显著影响,在1℃/min的降温速率下,PLLA的结晶起始温度为121℃,结晶焓为3.363 J/g;PLLA的熔融双峰遵循熔融-再结晶的机理;PLLA热分解温度在300℃左右,且随升温速率的增加而增大。     

1-丁烯-丙烯共聚物结构与性能研究

考察了1-丁烯-丙烯共聚物(B-P)的结晶性能、力学性能和流变行为,并与高全同聚1-丁烯(i-PB)进行了结构与性能的对比。结果表明:少量丙烯的引入,破坏了1-丁烯链段的规整排列,造成结晶度降低,力学性能下降。B-P的剪切速率增加到某一临界值时,材料内部结构发生改变,1-丁烯链段和丙烯链段同时开始运动,发生了剪切变稠,共聚物黏度变大,不易成膜。     

PTT/PETG共混物的热性能和结晶行为研究

主要研究了PTT/PETG共混物的热性能和结晶行为。DSC实验表明:PTT/PETG共混物只有一个Tg,说明两者在无定形区相容性好,而且随着PETG组分的增加,Tg增大。PTT/PETG两组分含量接近时,出现2个结晶峰。热失重分析结果表明:两组分相差较大时,随着PETG含量的增加,共混体系的热稳定性提高。通过观察共混物的结晶形态表明:PTT/PETG为80/20时,其球晶尺寸较大。     

M－POE－g－MAH增韧PBT的力学性能和形貌

研究了一种新型增韧剂(M—POE-g-MAH)对PBT树脂的增韧效果。与传统的纯POE-g-MAH增韧剂(POE-g-MAH)进行对比，考察了增韧剂的组成、用量对共混物力学性能的不同影响，并结合共混物的室温缺口冲击断面SEM照片，分析了共混物发生脆韧转变所对应的微观形貌特征。实验结果表明，在M-POE-g-MAH／PBT共混体系中，POE-g-MAH用量占体系10％左右时共混物发生明显的脆韧转变，而在传统的纯POE-g-MAH／PBT共混体系中，POE-g-MAH用量为15％左右才使共混物发生脆韧转变。M-POE-g-MAH增韧PBT在性能和成本上具有较大的优势，所得共混物产品的性价比较高。     

Polyester-Polyether Block Copolymers II. Thermal and Mechanical Properties of Poly(hexamethylene terephthalate)/Poly(oxytetramethylene) Block Copolymers

The melting and crystallisation behaviour of crystalline phases in poly (hexamethylene terephthalate)/poly(oxytetramethylene) block copolymers have been investigated in relation to copolymer composition and polyether block molecular weight (m.w.). In contrast to that in corresponding homopolymer blends, the polyester crystallinity in the block polymers is greatly reduced by incorporation of polyether units, though some persists even at low polyester contents. Concomitant changes in the glass transition temperatures show part of the polyester component to form a homogeneous component of the amorphous phase. The mechanical properties change with composition in parallel with the changes in copolymer crystallinity and T_g. Copolymers with 20-60 w % of poly(oxytetramethylene) units of m.w. 2000 are highly extensible elastomers. Those with higher m. w. polyether blocks have higher modulus and strength but suffer a serious loss of properties at 60d?C. The observations are interpreted in terms of a model in which polyester crystallites (and polyether crystallites also, for the higher m. w. polyether blocks) are supported within an amorphous matrix by tie-molecules whose nature changes with the copolymer compositions. The results are compared with those for analogous polyester-polyethers having different structural components.     

Synthesis and Properties of Poly(l-lactide)-b-poly (l-phenylalanine) Hybrid Copolymers

Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide.     

新型聚芳醚砜共聚物的制备及其性能

以4,4’-二氯二苯砜、4,4’-二羟基二苯砜和2,4-二羟基二苯砜为单体,通过缩聚合成一系列主链含异构体醚键单元的聚芳醚砜共聚物,利用核磁共振碳谱(13C NMR)、差示扫描量热分析(DSC)和高压毛细管流变仪对产物进行了测试和分析。对比不同产物的熔体黏度、玻璃化转变温度和力学性能,发现随着共聚单元含量的增加,聚芳醚砜共聚物的流动性逐渐提高,玻璃化转变温度逐渐降低,并且屈服点伸长率和缺口冲击强度均逐渐提高。这一结果对实际应用中提高聚芳醚砜树脂流动性和韧性、降低热加工温度等具有重要的指导意义。     

Properties and Phase Structure of the Poly(propylene)-Low-Density Poly(ethylene) Blends

Abstract

The phase structures of PP-LDPE blends in isotropic and oriented states were studied by the methods of DSC and polarization IR spectroscopy. The composition intervals were established that correspond to the formation of interpenetrating network structures. The presence of LDPE increases the degree of PP orientation and the mechanical strength of the blends. This indicates that LDPE acts as a structure-modifying agent, while PP plays the role of strengthening (reinforcing) filler. A relationship between the deformation and strength properties of the oriented films of the PP-LDPE blend and the phase structure of the PP component is demonstrated. The stability of the blend to oxidation in the ozone-oxygen medium is determined by the structure of a less stable system component (PP). The oxidation rate reaches maximum in samples with an isotropic PP structure and is minimum in the blends with highly oriented PP component.     

低熔点聚(对苯二甲酸/间苯二甲酸)丙二醇酯-聚乙二醇流变性能的研究

采用Rosand RH7型毛细管流变仪,对聚(对苯二甲酸/间苯二甲酸)丙二醇酯-聚乙二醇共聚物(PTTI-PEG)的流变性能进行了研究,并与常规PTT和PET的流变特性进行了比较。结果显示:共聚酯PTTI-PEG是典型的假塑性流体,随着温度升高,剪切黏度下降,非牛顿指数增大;随着剪切速率增大,黏流活化能降低。从PTTI-PEG、PET和PTT的流变性能比较发现,PTTI-PEG的流变曲线与PET和PTT的流变曲线在一定温度下较为吻合,这为PTTI-PEG与普通PET和PTT进一步复合纺丝提供了参考。     

SEBS-g-MAH增韧聚乳酸的性能研究

采用哈克密炼机制备了聚乳酸(PLA)与马来酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚弹性体(SEBS-g-MAH)的共混物,并对共混物的力学性能、流变性能和微观结构进行了分析。结果表明,共混物的拉伸强度随着SEBS-g-MAH含量的增加而下降,断裂伸长率随着SEBS-g-MAH含量的增加而增大。当SEBS-g-MAH的含量为30 %时,共混物的冲击强度提高了2.5倍,共混物的韧性得到提高。随着SEBS-g-MAH含量的增加,PLA熔体黏度的变化趋势与SEBS-g-MAH越来越相似,即熔体黏度随着频率的增大而下降。扫描电镜分析表明,MAH基团改善了两相间的界面作用,增韧作用明显。     

三水合硝酸钕与18—冠—6配合物在乙腈中相平衡的研究

采用半微量相平衡方法研究了三元体系Ｎｄ（ＮＯ３）３．３Ｈ２Ｏ－１８Ｃ６－ＣＨ３ＣＮ在３０３．１５听溶解度，测定了饱和溶液的折光率。     

Properties of Block Copolymers of Poly(Butylene Terephthalate) and Polyoxytetramethylene Glycol

Synthesis of polyester thermoelastoplasts, block copolymers of polyoxytetramethylene glycol and poly(butylene terephthalate) of the polyblock type, was developed and implemented in pilot industrial conditions. POTM blocks act as flexible molecular decouplings that give the copolymer elasticity, while PBT blocks form physical linkages and are responsible for the mechanical strength and hardness of the material. The composition of the reaction systems, process stage sequence, and synthesis parameters are optimized for block copolymers with a concentration of the flexible POTM block of 65-10 wt. % and a molecular weight of 1000. The structure is investigated, and the physicochemical and mechanical properties of the material obtained are determined. It was found that the concentration of flexible blocks has a determining effect on the physicochemical structure and properties of the block copolymers. For a 40% concentration of the flexible block, the character of the concentration curves of the physicomechanical indexes changes significantly due to phase-structural transformations in the block copolymers.     

Melt Crystallization Behavior and Spherulitic Morphology of Poly(Trimethylene Terephthalate)/Poly(Propylene Glycol) Copolymers with Different Poly(Propylene Glycol) Molecular Weights

Poly(trimethylene terephthalate)/poly(propylene glycol) (PTT/PPG) copolymers with different PPG molecular weights (400–4,000?g?/mol) were successfully synthesized and characterized. Double melting endotherms during isothermal melt crystallization were observed by differential scanning calorimetry. Middle-temperature melting endotherms in all copolymers were stronger than that in PTT homopolymer and became smaller with the increasing PPG molecular weight. Nonisothermal crystallization kinetics of all samples were analyzed by Ozawa and Mo models. Polarized optical microscopy micrographs revealed that ring-banded spherulitic morphology was relatively easier to be observed in copolymers with higher PPG molecular weight at lower crystallization temperature, and PPG molecular weight nearly had no influence on the band spacing.     

聚甲基乙烯基硅氧烷增韧聚苯硫醚的力学性能研究

通过熔融共混制备了聚苯硫醚/无苯基聚甲基乙烯基硅氧烷(PPS/NPMVS)共混物及聚苯硫醚/单苯基聚甲基乙烯基硅氧烷(PPS/SPMVS)共混物,并对该共混物体系的微观形貌及力学性能进行了分析表征。结果表明,弹性体在共混物中均匀分散,弹性体的加入对PPS基体起到明显的增韧效果;当弹性体的含量为3 %（质量分数,下同）时,2种共混材料的增韧性能最佳,PPS/NPMVS共混材料的断裂伸长率相对于PPS基体提高了3.9倍,PPS/SPMVS共混材料的断裂伸长率相对于PPS基体提高了2.4倍;当NPMVS含量为10 %时,PPS/NPMVS共混材料的冲击强度相对于PPS基体提高了1.8倍,当SPMVS含量为3 %时,PPS/SPMVS共混材料的冲击强度相对于PPS基体提高了1.4倍。     

凹凸棒石/聚乳酸纳米复合材料的力学性能和流变性能

采用熔融共混法制备凹凸棒石(ATT)质量分数分别为1%、3%和5%的ATT/聚乳酸(PLA)纳米复合材料,研究了ATT/PLA纳米复合材料的力学性能和流变性能。红外光谱分析结果表明:ATT与PLA基体之间存在较强的相互作用,使得二者之间具有较好的相容性。当ATT含量低于5%时,其可均匀分散在PLA基体中,而达到5%时,则会发生部分团聚。添加ATT后,PLA基体从脆性材料变为韧性材料,ATT起到增韧作用,并显著提高了复合材料的力学性能。当ATT含量为3%时,断裂伸长率达到26.36%,比纯PLA增加了297.6%,并且复合材料的冲击强度也比纯PLA增加了19.7%。ATT/PLA纳米复合材料的复数黏度、储能模量和损耗模量随ATT含量的增加呈先增大后减小趋势。由于ATT与PLA之间有良好的结合力,ATT的加入增大了复合材料的弹性和黏性,且低频区的变化明显高于高频区的变化。     

氯化聚丙烯相关物性参数的测定

用反向色谱、激光浊度等方法测定了氯化聚丙类的相变温度、溶度参数、氢键力以及在不同溶剂中的溶解情况。结果表明：氯化聚丙烯是一种非晶态的弱极性物质，软化点在60－90℃附近；溶度参数约为16.72-21.15(J/cm^3)^1/2；在溶度参数接近时，一般弱极性溶剂为氯化聚丙烯的良溶剂，中等极性溶剂为其微溶溶剂。     

尼龙6/锌中和乙烯-丙烯酸共混物的性能研究

用熔融共混法将锌中和乙烯-丙烯酸(Zn-EAA)接枝尼龙6(PA6),从而制得改性尼龙6,采用示差扫描量热法(DSC),X-射线衍射(XRD)和红外光谱分析(FTIR)等手段系统研究了不同含量的锌中和乙烯-丙烯酸对此体系中尼龙6晶体结构的影响.结果表明通过熔融共混,Zn-EAA很好的接枝到尼龙6分子上,改变了PA6的晶体结构,并且使PA6的结晶度降低.当Zn-EAA质量含量为3%时,阻隔性能最好,相对于纯尼龙6,提高了40%.     

聚乳酸/醋酸淀粉/有机蒙脱土纳米复合材料性能的研究

采用熔融插层法制备了聚乳酸/醋酸淀粉/有机蒙脱土（PLA/AS/OMMT）纳米复合材料,利用差示扫描量热仪、动态流变仪和扫描电子显微镜分析了OMMT对纳米复合材料热性能、流变行为和相形态的影响。结果表明,OMMT的加入降低了纳米复合材料的玻璃化转变温度和结晶温度;位于相界面的OMMT增强了PLA和AS两相间的相互作用并降低界面张力,使分散相AS颗粒的尺寸减小、尺寸分布变窄,有效抑制了AS的聚集。     

聚偏氟乙烯熔体的流变特性

综述了聚偏氟乙烯树脂的性能、其熔体的流变特性及在熔融加工领域的广泛应用,详细介绍了剪切变稀的非牛顿流体流变行为及其影响因素。通过分子链支化、共混和共聚可改善PVDF熔体的流变性能,以满足不同性能制品的需求以及进一步拓宽熔融加工成型方法。     

Enhanced temperature-stability in tunable dielectric properties of (1-x) (K0.49Na0.49Li0.02)(Nb0.8Ta0.2)O3-xCaZrO3 ceramics

(1-x)(K_0.49Na_0.49Li_0.02)(Nb_0.8Ta_0.2)O₃-xCaZrO₃ (x=0, 0.025, 0.05 and 0.075, abbreviated as KNLNT-1000xCZ) ceramics were prepared by a solid state method. The correlations between phase constitution, domain configuration and tunable dielectric properties are investigated. Due to the combined effects of multi-phase coexisting and nanoscaled domain, KNLNT-50CZ has a high dielectric tunability (60.0%) at the room temperature and 1?kHz under the electric field of 30?kV/cm. More importantly, the high tunability can be maintained stable in the temperature range of 25–150?°C with a smaller variation of ±?10%, which is superior to most of other tunable dielectric materials. The excellent temperature stability in tunable dielectric properties is ascribed to the diffused phase transition and coexistence of multi-phases in this temperature range. Therefore, our work has provided a new promising candidate for temperature-independent tunable dielectric materials.