增韧环氧树脂的微结构和力学性能的正电子湮没

用正电子湮没方法（PALS）和动态力学分析（DMA）方法研究了增韧剂和温度对环氧树脂的自由体积和力学性能的影响．根据正电子素（o-Ps）湮没寿命τ3随温度的变化，玻璃化转变温度Tg和次级转变温度Tβ被确定．实验结果表明，在稀释环氧树脂基体中加入增韧剂会使样品中产生较强界面相互作用，并且明显地改变了材料的结构转变温度Tg和Tβ，使得增韧样品比稀释样品具有更高的玻璃化转变温度Tg．一个很有意义的发现是，低温下力学性能的改变明显地大于室温下力学性能的改变．文中从原子尺度自由体积特性和界面相互作用的角度探讨了温度对样品力学性能影响的机理．     

β成核剂改性聚丙烯的研究

研究了β晶型成核剂对聚丙烯力学性能和热学性能的影响,并对其进行了DSC、正交偏光显微镜和电镜观察.研究表明:添加β成核剂后,聚丙烯晶型由α晶型向β晶型转变,韧性大大增强.β成核剂用量在0.2%时,冲击强度比未加成核剂时提高了3倍左右,其拉伸强度几乎没有变化,其软化点提高了15~20℃.     

钇对陶瓷刀具材料Al2O3/TiCN的强韧化效应

在已 研制的含烯土Ａｌ２Ｏ３／ＴｉＣＮ陶瓷刀具材料的基础上，采用ＳＥＭ，ＴＥＭ和能谱分析等方法探讨了Ｙ的强韧化效应。稀土增强Ａｌ２Ｏ３／ＴｉＣＮ陶瓷刀具材料力学性能改善的原因在于，Ｙ的添加能在一定程度上积聚杂质，Ｗ，Ｆｅ和Ｃｒ等，从而起到清洁界面、提高界面结合强度的作用。     

Simultaneously Boosting Toughness and Tensile Strength for Polyamide 6/montmorillonite Nanocomposite by a Pressure-Induced Flow Field

Nanocomposites of polymers and montmorillonite (MMT) represent a type of important hybrid material. However, unlike in some natural hybrid materials where much improved mechanical properties are achieved by an ordered assembly (layered, sheet-like or fibrous morphology) of complementary hard and soft components on nano- and microscopic scales, the exfoliated MMT nano-sheets are generally randomly dispersed in bulk polymeric matrices. In this paper we utilized a pressure-induced flow (PIF) field to orient MMT nano-sheets and generate stratified morphologies in polyamide 6 (PA6)/MMT nanocomposite bulk material. The toughness and tensile strength can be simultaneously increased. In particular, the impact strength increased up to 10 fold higher than the same material obtained by conventional processing methods. The mechanism for enhancement could be the confinement of crack propagations and the tortuous energy dissipating paths, which are attributed to the oriented MMT and the anisotropic hierarchical morphologies formed during PIF-processing.     

Toughening of Poly (Butylene Terephthalate) with Epoxy-Filled Poly (Ethylene–Octene) Copolymer

Toughened poly (butylene terephthalate) (PBT) with triglycidyl isocyanurate (TGIC)-filled poly (ethylene–octene) (POE) was prepared by melt reaction extrusion. For retarding the reaction extent between PBT and the epoxy component, the TGIC was first blended with POE to enwrap its reactive epoxy groups. Then, the TGIC-filled POE was used to melt blend with PBT. The Fourier transform infrared (FTIR) spectra showed that no other peaks appeared in the POE/TGIC specimens except for those originally existing in pure POE and TGIC. The rheological results further confirmed that no reaction occurred between the epoxy and the POE matrix. When the POE/TGIC was blended with PBT, a distinct increase of the viscosity suggested that the migration of the TGIC from POE to PBT during the melt processing induced chain extension reactions of PBT. The results obtained from DSC and DMA revealed that the chain extension of PBT induced by the reaction with TGIC restricted the mobility of PBT chains leading to a limitation of the recrystallization-remelting process and an increase of the glass transition temperature of PBT. The mechanical tests showed that the presence of TGIC in the POE phase distinctly improved the toughness of PBT. Compared to the case of a PBT/POE (80/20, wt%/wt%) blend, the elongation at break and impact strength of the system filled with 5 phr TGIC were increased more than three and six times, respectively.     

Reactive rubbers as toughening agents for thermoset polyester resins. Molecular analysis by FTIR and fracture behavior of the resulting blends

A reactive rubber obtained by isocyanation of hydroxyl-terminated polybutadiene was used as toughening agent for an unsaturated polyester resin. Both the isocyanation and the successive reaction between the modified rubber and the polyester were investigated by Fourier-transform infrared spectroscopy (FTIR). Fracture measurements at high and low strain rate were carried out on the cured materials to test their toughness. The failure mechanisms were established by morphological analysis of fractured surfaces, performed by scanning electron microscopy. © 1993 John Wiley & Sons, Inc.     

碳酸钙粒子增韧高密度聚乙烯的脆韧转变-Wu氏增韧理论聚合物共混物脆韧转变判据的适用条件

采用不同尺寸的碳酸钙粒子增韧高密度聚乙烯,研究了不同温度下共混体系的临界粒子间距与碳酸钙粒子尺寸和含量之间的关系,确定了温度是Wu氏增韧理论临界粒子间判据适用性的重要影响因素。 结果表明,在17 ℃下,临界粒子间距与碳酸钙粒子的尺寸和含量无关,该条件下Wu氏增韧理论临界粒子间距判据是适用的;而随着温度的升高,发现临界粒子间距依赖于碳酸钙粒子的尺寸,表明高温条件下,Wu氏增韧理论临界粒子间距判据不再适用。     

聚酯热熔胶增韧环氧树脂

利用扫描电子显微镜研究了聚酯热熔胶PE30增韧环氧树脂的微观相结构;利用DSC、DMA和TGA研究了聚酯热熔胶PE30对环氧树脂耐热性能的影响;测试了环氧树脂的冲击强度、弯曲强度和断裂韧性,考察了聚酯热熔胶PE30对环氧树脂力学性能的影响。结果表明,聚酯热熔胶PE30的最佳质量分数为15%,在固化过程中环氧体系发生诱导相分离,相结构由单相到连续相再到反转相;断裂韧性和冲击强度分别提高了127%和250%;弯曲强度和弯曲模量分别降低27%和44%;而体系玻璃化转变温度与起始热失重温度下降约1.5%,损耗峰温度下降约2.5%,说明聚酯热熔胶PE30可以在很大程度上提高环氧树脂的韧性,同时保持其耐热性能基本不变。     

聚乳酸/聚氨酯/聚乙烯吡咯烷酮降解材料的制备与性能

采用熔融共混法制备了聚乳酸(PLA)/聚氨酯(PU)/聚乙烯吡咯烷酮(PVP)复合材料,利用红外光谱(FTIR)、扫描电镜(SEM)、偏光显微镜和降解性能测试对其结构和性质进行了表征分析.结果表明:PU和PVP在基体PLA中可均匀分散且有效结合,该复合材料的拉伸强度可达69.18 MPa,断裂伸长率可提高1倍.降解实验表明,复合材料在不同介质中均呈现出随降解时间的延长,质量不断降低的趋势.     

Preparation and Properties of Polylactide/Poly(ethylene-co-octene)/nano-SiO2 Ternary Composites

Polylactide (PLA)/poly(ethylene-co-octene)(POE) blends with various contents of nano-SiO₂ were prepared via melt mixing. The structure and properties of the PLA/POE/nano-SiO₂ ternary composites were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheometry, and tensile testing. The particle size of the dispersed POE phase first decreased with increasing nano-SiO₂ content and then remained constant. Nano-SiO₂ played an important role in the heterogeneous nucleation of PLA, which resulted in an increase of the crystallinity of PLA. The synergistic effect of both POE and nano-SiO₂ can significantly improve the toughness, strength, and modulus of PLA. When the ratio of PLA/POE/nano-SiO₂ was 90/10/0.5, PLA/POE/nano-SiO₂ composite had the best comprehensive properties.