Compatibilizing effect of isocyanate functional group on polyethylene terephthalate/low density polyethylene blends

To evaluate the compatibilizing effects of isocyanate (NCO) functional group on the polyethylene terephthalate/low density polyethylene (PET/LDPE) blends, LDPE grafted with 2-hydroxyethyl methacrylate-isophorone diisocyanate (LDPE-g-HI) was prepared and blended with PET. The chemical reaction occurred during the melt blending in the PET/LDPE-g-HI blends was confirmed by the result of IR spectra. In the light of the blend morphology, the dispersions of the PET/LDPE-g-HI blends were very fine over the PET/LDPE blends. DSC thermograms indicated that PET microdispersions produced by the slow cooling of the PET/LDPE-g-HI blends were largely amorphous, with low crystallinity, due to the chemical bonding. The tensile strengths of the PET/LDPE-g-HI blends were higher than those of the PET/LDPE blends having a poor adhesion. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 447–453, 1998     

Influence of the transesterification catalyst structure on the reactive compatibilization and properties of poly(ethylene terephthalate) (PET)/dibutyl succinate functionalized poly(ethylene) blends

The transesterification between poly(ethylene terephthalate) (PET) and dibutyl succinate functionalized polyethylene (POF) was studied by preparing blends in a discontinuous mixer in the presence of different Zn and Ti catalysts. In particular the catalytic activities of Zn(OOCCH₃)₂, Ti(OBu)₄, ZnO and TiO(OCCH₃)₂ were compared. The mechanism of reactions occurring in the melt was studied both by a model compounds approach and by characterizing the macromolecular products of the melt processing by means of selective extractions, infrared analysis and the determinations of the molecular weight of PET. The results are discussed in terms of electrophilicity and nucleophilicity of the different catalysts. The catalysts structure also affected the phase distribution. In fact from a morphologic point of view in PET matrix blends the use of zinc derivatives yielded preferentially dispersed-like phase distribution, while the use of titanium derivatives resulted in partially co-continuous phase morphology. The stability of the attained phase distribution was also monitored during compression moulding and it evolved rapidly in fully dispersed phase morphology. The tensile properties of compression moulded films revealed that the occurred reactions and morphological assessment induced a general decrease of tensile modulus and an increase of elongation at break.     

Formation and morphology of cellulose acetate butyrate (CAB)/polyolefin and CAB/polyester in situ microfibrillar and lamellar hybrid blends

Cellulose acetate butyrate (CAB)/iPP (isotactic polypropylene), CAB/HDPE (high density polyethylene), CAB/PET (poly ethylene terephthalate), CAB/PTT (poly trimethylene terephthalate), CAB/PBT (poly butylenes terephthalate) and CAB/IPET-PEG (poly(ethylene terephthalate-co-isophthalate)-poly(ethylene glycol)) in situ microfibrillar and lamellar hybrid blends at a weight ratio of 80/20 were prepared by melt extrusion. Microfibrillar and lamellar hybrid morphologies of CAB/polyolefin and CAB/polyester blends under different force fields were investigated. The formation process of in situ microfibrillar and lamellar hybrid blends were analyzed and proposed.     

高分子共混物中Friedel-Crafts烷基化反应原位增容与催化降解机理

采用GPC方法对共混组分的分子量、接枝率和降解度等数据进行分析, 发现AlCl₃催化剂对PS/POE共混物的作用表现在原位增容和催化降解两个方面. 结合Friedel-Crafts烷基化反应的特点细化反应过程, 发现PS/POE共混物在AlCl₃作用下发生接枝反应时, 有大量碳正离子出现, 而碳正离子周围的电子重排会导致分子链断裂, 从而引起共混组分出现大幅度降解. PS/POE/AlCl₃共混物中原位接枝与催化降解是一对竞争性反应, 同时存在, 并相互竞争.     

Polymorphism of nylon-6 in nylon-6/nanoclay/functionalized polyolefin blends

The crystallization behavior of Nylon-6 and the interaction in Nylon-6/nanoclay/functionalized polyolefin blends were investigated by X-ray diffraction and Fourier transform infrared spectroscopy. For samples without any thermal history, the interaction between Nylon-6 and nanoclay or the interaction between Nylon-6 and functionalized polyolefin favors the formation of γ form crystal. In contrast, the presence of both nanoclay and functionalized polyolefin together in Nylon-6 was found to have an antagonistic effect on each other's ability to promote the formation of γ form crystal. This was attributed to the complex interactions between the constituents. The crystallization behavior of Nylon-6 in Nylon-6/nanoclay/functionalized polyolefin blends is clearly affected by the cointeraction of these effects. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1494–1502, 2007     

SUPER POLYOLEFIN BLENDS ACHIEVED VIA DYNAMIC PACKING INJECTION MOLDING:MORPHOLOGY AND PROPERTIES

As a long-term project aimed at developing super polyolefin blends, in this paper we summarize our work on themechanical reinforcement and phase morphology of polyolefin blends achieved by dynamic packing injection molding(DPIM). The main feature of this technology is that the specimen is forced to move repeatedly in the model by two pistonsthat move reversibly with the same frequency during cooling, which results in preferential orientation of the dispersed phaseas well as the matrix. The typical morphology of samples obtained via DPIM is a shear-induced morphology with a core inthe center, an oriented zone surrounding the core and a skin layer in the cross-section areas. Shear-induced phase dissolutionat a higher shear rate but phase separation at low shear rates is evident from AFM examination of LLDPE/PP (50/50) blends.The super polyolefin blends having high modulus (1.9-2.2 GPa), high tensile strength (100-120 MPa) and high impactstrength (6 times as that of pure HDPE) have been prepared by controlling the phase separation, molecular orientation andcrystal morphology.     

Miscibility and crystallization kinetics in blends of poly(ethylene terephtalate) and thermotropic liquid crystal polyesters

Binary blends of poly(ethylene terephtalate) (PET) and thermotropic liquid crystal polyester (TLCP) have been prepared by both solution and melt blending methods. The TLCPs utilized were Vectra (Hoechst Celanese), TR-4, a TLCP synthesized in our laboratory, and a block copolymer consisting of three TR-4 units followed by three PET units. The phase behavior of the blends was studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and optical microscopy. The results show that none of the blends is miscible, but significant interactions exist between the PET phase and the TLCP phase in the case of TR-4 and TR-4 block copolymer blends. These interactions lead to a different nucleation mechanism in these blends compared to that in PET/Vectra.     

Structure and properties of compatibilized recycled poly(ethylene terephthalate)/linear low density polyethylene blends

Blends of recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) were compatibilized with poly(styrene-ethylene/butyldiene-styrene) (SEBS) and maleic anhydride-grafted poly(styrene-ethylene/butyldiene-styrene) (SEBS-g-MA). Effects of compatilizer were evaluated systematically by study of mechanical, thermal and morphology properties together with crystallization behavior of PET. Tensile properties of the blends were improved effectively by the addition of 10 wt% SEBS-g-MA, elongation at break and charpy impact strength were increased with the increasing content of compatilizer. SEBS-g-MA is more effectual on mechanical properties of R-PET/LLDPE blends than SEBS. DSC analysis illustrates crystallinities of PET and LLDPE were increased by compatilizer at annealing condition. WAXD and FT-IR spectra show that annealing influences crystallization behavior of PET. Different compatilizer content results in different morphology structure, in particular, higher SEBS-g-MA content can induce the formation of a salami microstructure.     

Relationships between the molecular architecture,crystallization capacity,and miscibility in poly(butylene terephthalate)/polycarbonate blends: A comparison with poly(ethylene terephthalate)/polycarbonate blends

Poly(butylene terephthalate) (PBT)/polycarbonate (PC) samples, prepared via reactive blending in the presence of Ti‐ and Sm‐based catalysts, resulted in block copolymers whose block length decreased as the mixing time increased. A single homogeneous amorphous phase occurred when the blocks had monomeric sequences shorter than 10 units. Otherwise, a crystalline phase of PBT developed. Also, in poly(ethylene terephthalate) (PET)/PC blends previously studied, the miscibility was strictly correlated with the crystallizability of the system. Therefore, the miscibility of the PBT/PC and PET/PC blends was compared with respect to the tendency of the PBT and PET blocks to crystallize under isothermal conditions. The crystallization rate of the PBT/PC copolymers was faster than that of the PET/PC copolymers with similar block lengths. Accordingly, the minimum crystallizable sequence length of the PBT blocks was shorter than that of the PET blocks (18 vs 31 monomeric unit sequences). This behavior was interpreted as an effect of the more flexible PBT units, which had a greater tendency to fold and crystallize than the PET units. Therefore, PBT, the blocks of which tended to crystallize even if they were very short and phase‐separated, was characterized by a poorer compatibility with PC than that of PET. As a result, the block size had a fundamental role in determining the crystallizability and, therefore, phase behavior of the semicrystalline block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2821–2832, 2004     

具有负泊松比效应的聚烯烃共混物

实验证实用共混法制备的特殊聚烯烃共混物是一种拉伸膨胀材料 (Auxetic) ,测试发现共混物具有明显的负泊松比效应 ,所获得的最稳定体系可以获得 -1 4的泊松比值 ,比目前文献报道的数据减小了 2 0 0 %.采用SEM观察了共混体物拉伸前后的微观结构 ,推断负泊松比效应的产生是由于材料内部发生了空化作用的结果 ,与提出的理论模型基本一致     

Preparation and characterization of heat-resistant PET/bio-based polyester blends for hot-filled bottles

To improve the glass transition temperature (T_g) and heat resistance of polyethylene terephthalate (PET) bottle, poly (ethylene glycol 1,4-cyclohexane dimethylene isosorbide terephthalate) (PEICT) with a unique cyclic structure was introduced into PET. The miscibility of the PET/PEICT blends and their feasibility as a heat resistant bottle were investigated. The introduction of PEICT into PET increases the T_g and the PET/PEICT blends exhibit a single T_g, indicating good miscibility between PEICT and PET. Furthermore, the T_g and crystallinity of the PET/PEICT blends can be adjusted by controlling the amount of PEICT added. The PET/PEICT blends were transparent in the visible light range (no significant change in transparency) because the blends were truly miscible as confirmed by Fox equation. As expected, the introduction of PEICT into PET bottle allows for improved heat resistance and shape stability due to the rigid molecular structure and chirality of the two tetrahydrofuran rings in the isosorbide group of PEICT. Based on our results, the as-prepared PET/PEICT blends with controllable high heat resistance can be used as a cost-effective alternative material for various hot-filling conditions in the beverage industry by adjusting the optimal ratio of PEICT to PET for each product (e.g. fruit juice, tea).     

磷酸三苯酯对PBT／PET共混体系结晶行为的影响

用广角Ｘ－角线衍射法和差法扫描量热法研究了磷酸三苯酯对ＰＢＴ／ＰＥＴ共混体系结晶行为影响，结果表明：ＴＰＰＷ作为该共混体系的稳定剂，只能延长在熔融状态下酯交换反应发生的时间，ＴＰＰ含量一定时，熔融时间增加，ＰＢＴ，ＰＥＴ之间的酯交换反应同样会发生，不同熔融时间，就要求ＴＰＰ的用量也不相同。ＴＰＰ在ＰＢＴ／ＰＥＴ共混体系中没有结晶成核剂的作用，它也不改变ＰＢＴ，ＰＥＴ的结晶结构。     

Melt-crystallization behavior and isothermal crystallization kinetics of crystalline/crystalline blends of poly(ethylene terephthalate)/poly(trimethylene terephthalate)

The melt-crystallization and isothermal melt-crystallization kinetics of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends (PET/PTT) were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy. Although PET and PTT in the binary blends are miscible at amorphous state, they will crystallize individually when cooled from the melt. In the DSC measurements, PET component with higher supercooling degree will crystallize first, and then the crystallite of PET will be the nucleating agent for PTT, which induce the crystallization of PTT at higher temperature. On the other hand, in both blends of PET80/PTT20 and PET60/PTT40, the PET component will crystallize at higher temperature with faster crystallization rate due to the dilute effect of PTT. So the commingled minor addition of one component to another helps to improve the crystallization of the blends. For blends of PET20/PTT80 and PET40/PTT60, isothermal crystallization kinetics evaluated in terms of the Avrami equation suggest different crystallization mechanisms occurred. The more PET content in blends, the fast crystallization rate is. The Avrami exponent, n = 3, suggests a three-dimensional growth of the crystals in both blends, which is further demonstrated by the spherulites formed in all blends. The crystalline blends show multiple-melting peaks during heating process.     

烯烃聚合催化剂的研究进展

获得高性能聚烯烃材料是化学家们不断的追求。烯烃聚合催化剂的结构对其催化性能有重要影响,而聚烯烃的改性则能够改善聚合物实际应用中表面形貌、本体性能中存在的缺陷,如通过改性可增加聚合物韧性、降低聚合物表面的摩擦系数或提升表面能等。 本文系统总结了金属烯烃聚合催化剂研究进展,包括Ziegler-Natta催化剂、茂金属催化剂、非茂金属催化剂的结构及调控策略,探讨了位阻效应、双金属协同效应以及其他效应对催化效果的影响。     

PET/LCP反应性共混物的非等温结晶动力学

采用DSC方法研究了聚对苯二甲酸乙二酯 (PET)和热致性液晶共聚酯 6 0PHB PET (LCP)体系在少量扩链剂双 (2 唑啉 ) (BOZ)存在下形成的反应性共混物的非等温结晶动力学 .结果表明反应性共混物的Avrami指数均在 3 0～ 4 5之间 ,BOZ的加入使反应共混物中PET组分的结晶速率降低 ;表明BOZ对酯交换的促进作用 ,使所生成的共聚酯中PET嵌段的数均序列长度变短 ,而使结晶在某种程度上较为困难 ,但对体系的成核和结晶生长机理无明显影响 .结果还表明 ,随冷却速率的增大结晶峰向低温方向移动     

Effect of dispersed phase composition on morphological and mechanical properties of PET/EVA/PP ternary blends

Immiscible ternary blends of PET/EVA/PP (PET as the matrix and (PP/EVA) composition ratio = 1/1) were prepared by melt mixing. Scanning electron microscope results showed core‐shell type morphology for this ternary blend. Binary blends of PET/PP and PET/EVA were also prepared as control samples. Two grades of EVA with various viscosities, one higher and the other one lower than that of PP, were used to investigate the effect of components' viscosity on the droplet size of disperse phase. The effect of interfacial tension, elasticity, and viscosity on the disperse phase size of both binary and ternary blends was investigated. Variation of tensile modulus of both binary and ternary blends with dispersed phase content was also studied. Experimental results obtained for modulus of PET/EVA binary blends, showed no significant deviations from Takayanagi model, where considerable deviations were observed for PET/PP binary blends. Here, this model that has been originally proposed for binary blends was improved to become applicable for the prediction of the tensile modulus of ternary blends. The new modified model showed good agreement with the experimental data obtained in this study. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 251–259, 2010     

PET／PA66／液晶共聚酯酰胺共混体系的流变性能

采用ＳＥＭ１、热偏光显微研究了聚对苯二甲乙二酯（ＰＥＴ）／聚酰胺６６（ＰＡ６６）／热致液晶共聚酯酰胺（ＬＣ３０）三元共混物的形态结构;利用Ｉｎｓｔｒｏｎ３２１１型毛细管流变仪研究了共混物的流变性能,结果表明：ＰＥＴ／ＰＡ６６／ＬＣ３０共混物为一热力学不相容的多相聚合物体系,ＬＣ３０的加入提高了ＰＥＴ／ＰＡ６６的相容性,有效地改善了ＰＥＴ／ＰＡ６６共混物的流变性能,ＰＥＴ／ＰＡ６６／ＬＣ３０三元共混     

In-situ Enhanced Toughening of Poly(ethylene terephthalate)/elastomer Blends via Gamma-Ray Radiation at Presence of Trimethylolpropane Triacrylate

Gamma-ray radiation has always been a convenient and effective way to modify the interfacial properties in polymer blends. In this work, a small amount of trimethylolpropane triacrylate (TMPTA) was incorporated into poly(ethylene terephthalate) (PET)/random terpolymer elastomer (ST2000) blends by melt-blending. The existence of TMPTA would induce the crosslinking of PET and ST2000 molecular chains at high temperatures of blending, resulting in the improvement in the impact strength but the loss in the tensile strength. When the PET/ST2000 blends were irradiated by gamma-ray radiation, the integrated mechanical properties could be enhanced significantly at a high absorbed dose. The irradiated sample at a dose of 100 kGy even couldn't be broken under the impact test load, and at the same time, has nearly no loss of tensile strength. Based on the analysis of the impactfractured surface morphologies of the blends, it can be concluded that gamma-ray radiation at high absorbed dose can further in situ enhance the interfacial adhesion by promoting the crosslinking reactions of TMPTA and polymer chains. As a result, the toughness and strength of PET/ST2000 blend could be dramatically improved. This work provides a facial and practical way to the fabrication of polymer blends with high toughness and strength.     

氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物及其马来酸酐接枝共聚物增韧聚对苯二甲酸乙醇酯共混材料的辐射效应

采用双螺杆熔融共混的方法制备了含三羟甲基丙烷三丙烯酸酯(TMPTA)的聚对苯二甲酸乙二酯/氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物（PET/SEBS）和聚对苯二甲酸乙二酯/马来酸酐接枝氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物（PET/SEBS-g-MAH）共混材料,并在Co-60源中对其进行辐照。 通过对共混材料的力学性能、相态结构测和凝胶含量分析,对比研究了辐射对以上2种共混材料结构及性能的影响。 扫描电子显镜观察和凝胶含量分析结果表明,在适量TMPTA存在时,辐射有效地改善了PET/SEBS体系的相容性。 冲击强度的变化证实了这种增容效应,当SEBS的质量分数为20%、TMPTA质量分数为1%,经50 kGy辐照后,冲击强度达到17.3 kJ/m2。 当在SEBS分子链上引入马来酸酐官能团,辐照后,体系的相态结构变化并不明显,冲击强度最大值仅为11.5 kJ/m2,明显低于不含马来酸酐官能团的体系。     

F-C烷基化反应原位增容PS/POE共混物中降解的抑制和增容效果的优化

在聚苯乙烯(PS)/聚烯烃弹性体(POE)/AlCl3共混物中引入苯乙烯(St)单体,增加了共混体系中的不饱和结构,AlCl3催化剂与St反应生成大量的初始碳正离子,这些初始碳正离子进攻POE链生成更多的大碳正离子,进而形成更多的PS-graft-POE共聚物,提高了接枝效率.进而,采用"两次挤出"技术,即先原位增容制成接枝母料,然后接枝母料再与PS和POE二次挤出,可以在一定程度上缓解组份的降解,使共混物的力学性能得到进一步的改善.