热塑性聚氨酯弹性体合金研究进展

热塑性聚氯酯是一类具有良好耐低温、高弹性和耐磨性能的新型弹性体。笔者综述了热塑性聚氯酯弹性体合金的研究进展，分析了国内热塑弹性体生产现状及未来的发展趋势。     

Influence of a nucleating agent on the crystallization behaviour of isotactic polypropylene and elastomer blends

The influence of a nucleating agent on the crystallization behaviour of isotactic polypropylene (iPP), in their blends with poly(styrene-b-ethylene butylene-b-styrene) (SEBS), and a metallocenic ethylene-octene copolymer (EO) was investigated by DSC, optical microscopy and real-time small and wide angle X-ray scattering (SAXS and WAXS) experiments using synchrotron radiation. In non-nucleated iPP/SEBS blends, the crystallization of the iPP matrix occurred in the presence of the styrenic domains which induced a nucleating effect on the process, as observed in the synchrotron experiments. The metallocenic elastomer did not affect the crystallization behaviour of iPP in the iPP/EO blends in non-isothermal experiments, however, the development of crystallinity in the elastomer was restricted. In the nucleated isotactic polypropylene/elastomer blends a significant increase in the crystallinity and the crystallization rate of the iPP matrix was observed due to the presence of the nucleating agent. However, the nucleating efficiency of the additive was strongly affected by the nature and content of the elastomeric component. The nucleating agent efficiency was higher in the presence of the ethylene-octene component than the styrenic elastomer.     

Mechanical and thermal properties of polyolefin thermoplastic elastomer blends

ABSTRACT

Polyolefin thermoplastic elastomers (POEs) are a class of thermoplastic elastomer (TPE) that can be easily processed. POEs have broad applications from automobiles to footwear and it is desirable to be able to alter the microstructure and properties. In this work, a systematic study of how blending and thermal processing of POEs affects mechanical and thermal properties is undertaken. Ethylene-octene copolymer POEs with different degrees of crystallinity are blended, compounded, and moulded and then slow cooled, quenched, or annealed. Differential scanning calorimetry (DSC) results show that the blends are immiscible and that quenching suppresses crystallinity while annealing thickens crystals. More crystals of the same thickness or thicker crystals of the same amount in the blends result in a higher modulus, lower elastic recovery, and more residual strain or permanent deformation after tensile testing. Microstructural control will allow for the optimal design of elastomeric materials with anticipated properties.     

纳米SiO2对动态硫化EPDM／PP热塑性弹性体性能的影响

在开炼机上采用动态硫化的方法制备纳米SiO2改性三元乙丙橡胶（EPDM）／聚丙烯（PP）共混型热塑性弹性体（TPV）,研究了纳米SiO2的加料顺序和用量对热塑性弹性体的力学性能、维卡软化温度的影响．并对改性后的TPV进行返炼．研究其热塑性能。结果表明：将纳米SiO2先与EPDM混炼均匀．然后加入其它助剂．制得EPDM母炼胶,再与PP共混制备得到的TPV力学性能较好,且纳米SiO2用量为4份时TPV的综合性能最佳;随着纳米SiO2用量的增加,TPV的维卡软化温度升高;返炼后的改性TPV力学性能稍有下降,但具有良好的热塑性。     

Adhesion between individual components and mechanical properties of natural rubber-polypropylene thermoplastic elastomeric blends

Adhesion between individual components and the mechanical properties of natural rubber (NR)-polypropylene (PP) thermoplastic elastomeric blends with reference to adhesion have been studied. The adhesion strength between the component phases was varied by incorporating a third component, namely ethylene propylene diene rubber (EPDM) or chlorinated polyethylene (CPE), and their effects on the mechanical properties were also studied. It was observed that the level of adhesion between NR and PP is improved by incorporating 20 parts of EPDM or CPE in NR. The mechanical properties of the blends are also improved for a particular composition. The enhancement in the strength properties and modulus of an NR:X:PP (where X is the third component) (70:10:30 or 70:20:30) blend is apparent when a correction due to the hard-phase contribution of the blend is made by taking the ratio of the strength of the composite to the strength of the hard phase or modulus of the blends. When the three-component blends were compared with a 90:30 blend of NR-PP, the role of adhesion played by EPDM or CPE in improving the strength and modulus could be demonstrated. In fact, there is a direct qualitative relationship between the adhesion and the mechanical properties in such composites. The stronger the adhesion, the greater the tensile strength and modulus. The higher adhesion strength is further reflected from the morphology of various blends. Separation of the phases during swelling and subsequent drying is restricted in the systems exhibiting higher adhesion strength between the components.     

Compatibilisation of various PLA/thermoplastic elastomer blends with diisocyanate coupling agent

Poly(lactic acid) (PLA) is characterised by its inherent brittleness, a detrimental feature for the production of durable bioplastics. PLA has been toughened by a low amount (12?wt-%) of various thermoplastic elastomers (TPE) including poly(ether-b-ester) (PEEs), poly(ether-b-amide) (PEBA) and poly(ether-b-urethane) (PEU). PLA–TPE blends were prepared by using a twin screw extruder. Ductility and impact resistance can be slightly improved with the incorporation of TPEs but but PEBA appears the most efficient. Reactive compatibilisation has been performed with the addition in the melt of a low amount (2?wt-%) of 4,4-methylene diphenyl diisocyanate. All compatibilised blends exhibit high toughness with similar ductility. These blends preserve good stiffness and high tensile strength. Compatibilised PEBA blends can be considered as super tough poly(lactic acid) materials. This work confirms that the flexibility of the elastomer together with the quality of the interfacial adhesion between the rigid (PLA) and the soft (TPE) phases are the primary factors influencing the toughness.     

Effect of nitrocellulose (NC) on morphology,rheological and mechanical properties of glycidyl azide polymer based energetic thermoplastic elastomer/NC blends

As a new kind of propellant binder, energetic thermoplastic elastomer (ETPE ) can improve propellant recyclability and environmentally friendly disposal. The rheological behavior of the ETPE binder can be beneficial to identify suitable and safe conditions for processing ETPE propellants. In this paper, ETPE /nitrocellulose (NC ) blends with different mass ratios of NC to ETPE were prepared by the physical mixing method. The heat of explosion and the morphological, thermal, mechanical and rheological properties of the resulting blends were studied systematically. It was found that the heat of explosion of ETPE /NC blends increased with increasing NC content. SEM images showed that the NC domains in the blends changed from tiny pieces to fibers with increasing NC mass ratio, which indicates phase separation in the blends. The tensile mechanical properties of the blends had a peak value when the NC content was 10 wt%, and then increased with the increasing addition of NC . The thermal behavior made clear that the ETPE and NC were partially miscible. Rheological studies on dynamic strain sweep and frequency sweep demonstrated that the content of NC in the blends had a monotonic effect on their rheological properties at 130 °C. Rheological studies also showed that the rheology of the blends is dependent on temperature. The Cole ? Cole and Han plots confirmed phase separation in the blends. © 2016 Society of Chemical Industry     

Phase behavior, morphology and interfacial structure in thermoset/thermoplastic elastomer blends of poly(propylene glycol)-type epoxy resin and polystyrene–b-polybutadiene

Thermoset/thermoplastic elastomer (TPE) blends of poly(propylene glycol) (PPG)-type epoxy resin (ER) and a diblock copolymer, polystyrene–b-polybutadiene (SB, with 30% styrene content), were prepared using 4,4′-diaminodiphenylmethane (DDM) as curing agent. The miscibility and thermal transition behavior of DDM-cured ER/SB blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The existence of three separate glass transitions, which are independent of the blend composition, indicates that SB is immiscible with DDM-cured ER. Neither the PS block nor the PB block exhibits miscibility with the cured ER. There exist three phases in the blends: a PS microphase, an ER-rich phase and a PB microphase. The phase structure and morphology of the ER/SB blends were studied using both scanning and transmission electron microscopy (SEM and TEM); a variety of morphologies were observed, depending on the blend composition. For the blends with 5 and 10 wt% SB, SB domains with irregular shapes and broadly distributed sizes are dispersed in a continuous cured ER matrix. For the blends with 20–60 wt% SB, interpenetrating bicontinuous phase structures are observed. For the blends with 70 wt% and more SB, a dispersion of cured ER particles in the SB matrix is obtained. The TEM observation showed that the two phases in the blends exhibit a good interfacial adhesion. The interfacial layer between the ER and SB phases varies from 100 to 300 nm for the blend with 20 wt% SB content, SB micelles are formed surrounding the SB domains in the ER matrix. Small-angle X-ray scattering (SAXS) experiments reveal that the SB diblock polymer still exhibits a lamellar microphase structure within the SB phase and the long spacing of lamellae nearly does not change in the blends. The SB diblock copolymer is microphase separated in the macroscopically phase separated ER/SB blends.     

Investigation on thermoplastic co‐poly(ether‐ester) elastomer toughened poly(methylmethacrylate) blends

Blends of poly(methyl methacrylate) (PMMA) and copoly(ether‐ester) (COPE) elastomer have been prepared in different compositions namely, 95/5, 90/10, 85/15, and 80/20 wt % (PMMA/COPE), by melt mixing technique using twin screw extruder. The influence of COPE content on the mechanical properties especially impact strength, thermal behavior, and chemical resistance of PMMA have been investigated. The impact strength of the PMMA/COPE blends for all the compositions were found to be improved remarkably as compared to the virgin PMMA without affecting the other mechanical properties significantly. Various composite models, such as series model, parallel model, Halpin‐Tsai equation, and Kerner's model have been used to fit the experimental mechanical properties. The effect of chemical and thermal ageing on the performance of the PMMA/COPE blends was also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

纳米SiO2对天然橡胶/聚丙烯共混型热塑性弹性体的改性

在双辊电热式塑炼机上采用动态硫化法制备了天然橡胶/聚丙烯共混型热塑性弹性体(NR/PP TPV)。考察了纳米S iO2的加入顺序及其用量对NR/PP TPV力学性能的影响,研究了纳米S iO2填充改性TPV的耐溶剂性能和耐热变形性能,并用扫描电镜(SEM)观察了其两相结构和断面形貌。结果表明,纳米S iO2先与NR混炼均匀,再加入小料和硫黄所得的NR母炼胶与PP制备的TPV力学性能较好,且最佳的纳米S iO2加入量为3份;纳米S iO2改性的NR/PP TPV具有良好的耐溶剂性能和耐热变形性能;纳米S iO2提高了NR与PP相间结合强度。     

三元乙丙橡胶/聚丙烯动态硫化热塑性弹性体的相态结构

用扫描电镜研究了三元乙丙橡胶(EPDM)聚/丙烯(PP)动态硫化热塑性弹性体(TPV)相态结构的形成过程,探讨了交联密度、制备工艺、螺杆转速对EPDM/PP TPV相态结构的影响。结果表明,采用以酚醛树脂为硫化剂的动态硫化工艺制备的EPDM/PP TPV,其相态结构实现了由EPDM和PP组成的双连续相到以EPDM为分散相、PP为连续相的转变;当硫化剂用量为7份时,橡胶相硫化速率和交联密度最大;当螺杆转速为180 r/m in时,反应性挤出工艺较之密炼机工艺制备的EPDM/PP TPV的橡胶粒子更细小、分散更均匀。     

共混型聚丙烯/超细粉末丁苯橡胶全硫化热塑性弹性体的制备及其结构与性能

以全硫化超细粉末丁苯橡胶(PSBR)与聚丙烯(PP)为原料,采用双螺杆挤出机共混方法制备PP/PSBR全硫化热塑性弹性体。通过透射电镜观测,发现PP/PSBR全硫化热塑性弹性体具有和动态硫化方法制备的热塑性弹性体相似的微观形态,PSBR粒子作为分散相分散在连续相PP中;所制备的热塑性弹性体的力学性能与PP的相对分子质量、共聚与否、PSBR含量及其交联度有关;通过流变行为研究,发现此类全硫化热塑性弹性体为假塑性流体,且橡胶的含量对热塑性弹性体的黏度影响很小;采用差示扫描量热法对PP/PSBR全硫化热塑性弹性体中连续相PP的结晶行为进行了研究,发现连续相PP的结晶温度提高,表明PSBR对PP有异相成核作用。     

Influence of rubber particle size on mechanical properties of polypropylene–SEBS blends

Isotactic polypropylene blends with 0–20 vol % thermoplastic elastomers were prepared to study the influence of elastomer particle size on mechanical properties. Polystyrene-block-poly(ethene-co-but-1-ene)-block-polystyrene (SEBS) was used as thermoplastic elastomer. SEBS particle size, determined by means of transmission electron and atomic force microscopy, was varied by using polypropylene and SEBS of different molecular weight. With increasing polypropylene molecular weight and, consequently, melt viscosity and decreasing SEBS molecular weight, SEBS particle size decreases. Impact strength of pure polypropylene is almost independent of molecular weight, whereas impact strength of polypropylene blends increases strongly with increasing polypropylene molecular weight. The observed sharp brittle–tough transition is caused by micromechanical processes, mostly shear yielding, especially occurring below a critical interparticle distance. The interparticle distance is decreasing with decreasing SEBS particle size and increasing volume fraction. If the polypropylene matrix ligament between the SEBS particles is thinner than 0.27 μm, the blends become ductile. Stiffness and yield stress of polypropylene and polypropylene blends increase with increasing polypropylene molecular weight in the same extent, and are consequently only dependent on matrix properties and not on SEBS particle size. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1891–1901, 1998     

Rheological,mechanical, thermal,and morphological properties of polypropylene/ethylene‐octene copolymer blends

Rheological and morphological studies were performed on polymer blends of ethylene‐octene copolymer [polyethylene elastomer (PEE)] and polypropylene (PP). The viscosities of PEE, PP, and PEE/PP blends were analyzed using an Instron capillary rheometer and a Rheometrics Dynamic Stress Rheometer, SR 200. A non‐Newtonian flow behavior was observed in all samples in the shear rate range from 27 to 2700 s⁻¹, whereas at shear rates in the range from 0.01 to 0.04 s⁻¹, a Newtonian flow behavior was verified. The scanning electron micrographs showed that dual‐phase continuity may occur between 50 and 60 (wt %) of PEE. This result is consistent with the Sperling's model. The mechanical analysis showed that PEE/PP, with 5 wt % of PEE, presented an increase on the mechanical properties and as the PEE content increased, a negative deviation in relation to an empirical equation was observed. Thermal analysis showed that there were no change in the crystallization behavior of the matrix when different elastomer contents were added. Dynamic mechanical thermal analysis showed that samples with low PEE contents presented only one peak, indicating a certain degree of miscibility between the components of these blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 692–704, 2000     

The study of polystyrene blends: The relationship of phases and structure in blends of polystyrene with ethylene–propylene diene monomer rubber and its grafted copolymer

Pressed films of blends of polystyrene (PS) with ethylene–propylene diene monomer rubber (EPDM) or grafted copolymer of styrene (St) onto EPDM (EPDM-g-St) rubber were examined by small-angle X-ray scattering (SAXS), and scanning electron microscope (SEM). Small-angle X-ray scattering from the relation of phase was analyzed using Porod's Law and led to value of interface layer on blends. The thickness of interface layer (σ_b) had a maximum value at 50/50 (PS–EPDM-g-St) on blends. The radius of gyration of dispersed phase (domain) and correlation distances a_c in blends of PS–EPDM-g-St were calculated using the data of SAXS. The morphology and structure of blends were investigated by SEM. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 805–810, 1998     

Preparation and characterization of blends of high density polyethylene and poly(ethylene‐co‐1‐octene) elastomer

Mechanical, thermal, and morphological properties of blends of high density polyethylene and poly(ethylene‐co‐1‐octene) (PEO) were evaluated. The blends were prepared in a single screw extruder at 230°C and 50 rpm with volume fraction of elastomer varying in the range from 0.05 to 0.8. Factors such as chemical similarity and melt viscosity favor the interdiffusion process of phases, resulting in better interfacial adhesion. A synergistic effect on the strength at break and elongation at break for a particular range of blend composition was observed. Blends with a volume fraction of PEO higher than 5% presented a super tough behavior at room temperature. Thermal analysis showed that there is a certain degree of interaction between high density polyethylene and PEO. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1991–1995, 2001     

Influence of interactions on the mechanical,morphological and thermal properties of in situ ternary composites based on fluorocarbon elastomer,acrylic elastomer and liquid crystalline polymer blends

The mechanical, morphological and thermal properties of the binary and ternary blends of a fluorocarbon elastomer (FKM), an acrylic elastomer (ACM) and a liquid crystalline polymer (LCP) were investigated. The ternary blends were prepared by varying the amount of the LCP but fixing the ratio of the FKM and ACM. Addition of a third component, a polyacrylic rubber which interacted with the LCP, facilitated the structural development of the LCP phase by acting at the interface. The mechanical properties of the ternary blends were substantially improved because of both the fibril generation and adhesion of rubber particles on the LCP fibrils, which were attributed to the ACM interaction. Morphological investigations suggest that the fine fibrillation of the LCP domains is more apparent in the ternary blends than in the binary blends of FKM and LCP prepared under the same processing conditions. Thermogravimetric analysis (TGA) revealed an improved thermal stability of the FKM in the presence of the LCP for the binary blends, but a lower thermal stability for the ternary blends. Copyright © 2005 Society of Chemical Industry     

Design and properties of a series of high‐temperature thermoplastic elastomeric blends from polyamides and functionalized rubbers

A series of high‐temperature thermoplastic elastomers (TPEs) and thermoplastic vulcanisates (TPVs) were successfully developed based on two different types of heat resistant polyamide (PA) (25 parts by weight)—PA‐12 and PA‐6, in combination with three different functionalized rubbers (75 parts by weight) of varying polarity, e.g., maleic anhydride grafted ethylene propylene diene terpolymer (MA‐g‐EPDM), sulphonated ethylene propylene diene terpolymer, and carboxylated acrylonitrile butadiene rubber, by melt mixing method. These rubbers have low level of unsaturation in its backbone, and the plastics showed high melting range. Thus, the developed TPEs and TPVs were expected to be high temperature resistant. Resol type resin was used for dynamic vulcanization to further increase the high temperature properties of these blends. Interestingly, initial degradation temperature of the prepared blends was much higher (421 °C for MA‐g‐EPDM/PA‐12) than the other reported conventional TPEs and TPVs. Fourier transform infrared analysis described the interactive nature of the TPEs and TPVs, which is responsible for their superior properties. The maximum tensile strength with lowest tension set was observed for the carboxylated acrylonitrile butadiene rubber/PA‐12 TPV. Mild increase in mechanical properties without any degradation was observed after recycling. Dynamic mechanical analysis results showed two distinct glass transition temperatures and indicated the biphasic morphology of the blends, as evident from the scanning electron microscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45353.     

Comparison of structure and properties of conventional and “high‐crystallinity” isotactic polypropylenes and their blends with metallocene‐catalyzed linear low‐density polyethylene. I. Relationships between rheological behavior and thermal and physical properties

The present study was conducted to compare the structure and properties of conventional and so‐called “high‐crystallinity” (hcr) polypropylene (PP) and to establish characteristic features of the latter that are responsible for its superior thermal and mechanical performance. Moreover, structure–properties relationships of hcr PP blends with metallocene‐catalyzed, linear low‐density polyethylene (mLLDPE) were compared with those of conventional PP/mLLDPE blends. In Part 1, relationships between rheological behavior (viscosity and melt density) and thermal (transition temperatures and level of crystallinity) and mechanical properties (impact strength and Young's modulus) were analyzed with reference to composition. The rheological and MDSC tests showed that both types of the blends were miscible at the processing temperatures, whereas immiscible in the solid state and in vicinity of the PP melting point. It was found that the improved mechanical properties and the extraordinary high crystallization temperature of hcr PP (and, correspondingly, hcr PP/mLLDPE blends) are not due to the assumed high level of crystallinity but due to alteration of internal structure of this polypropylene. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1591–1599, 2000     

Structural characterization of semicrystalline polymer blends by small-angle neutron scattering

A series of phase-separated polyethylene-polypropylene blends, which have undergone different thermal treatments, have been analysed by small-angle neutron scattering (SANS). The coherent scattering from normal hydrogenated blends is virtually zero, but strong contrast may be induced by partial or complete deuteration (labelling) of either phase. Here, the scattering from blends with complete labelling of the polyethylene phase was analysed to provide the domain dimensions by means of a theory due to Debye using an exponential correlation function. By this means the mean chord intercept lengths of both phases were shown to be in the range 1000–10000Å. The scattering from blends with partial labelling of the polyethylene was analysed to give the radius of gyration of the molecules in the polyethylene domains, which was found to be close to that measured in the homopolymer. For melt-quenched blends the deuterated polyethylene was shown to be statistically distributed in the polyethylene phase, whereas for slow-cooled blends, partial segregation of the labelled molecules occurred.