热塑性弹性体在聚丙烯改性中的研究进展

简述了热塑性弹性体(TPE)的分类及其增韧改性聚丙烯(PP)的机理,针对近年来热塑性聚氨酯弹性体(TPU)、热塑性苯乙烯弹性体(TPS)、热塑性聚烯烃弹性体(TPO)等热塑性弹性体改性聚丙烯,以及与增强材料协同改性聚丙烯的研究成果进行了综述,并展望热塑性弹性体改性聚丙烯的研究前景。     

Thermal and mechanical properties of poly(ether ester)-based thermoplastic elastomer composites filled with TiO<Subscript>2</Subscript> nanoparticles

Poly(butylene terephthalate)-block-poly(tetramethylene glycol) (PBT-PTMG)-based thermoplastic elastomer (TPE) was filled with nano TiO₂ particles by direct melt blending. The particle content in matrix was varied from 1.3 to 4.9 vol.%. The samples were characterized using SEM, μCT, DSC, TGA, DMTA and tensile test. SEM examination shows strong interfacial interactions between TPE matrix and TiO₂ particles due to formation of chemical bonds. The incorporation of TiO₂ particles increases overall the thermal properties of soft and hard segments such as the glass transition temperature, the melting temperature, and the thermal stability of material. The tensile properties of TPE are also significantly improved indicated by increased tensile strength and modulus. Increasing particle content leads to increased mechanical properties and thermal stability of composites.     

Effect of morphology on the behaviour of ternary composites of polypropylene with inorganic fillers and elastomer inclusions

The effects of phase morphology, interfacial adhesion, rigid filler particle shape and elastomer volume fraction on the tensile yield strength of polypropylene (PP) filled with inorganic filler (CaCO₃ or Mg(OH)₂) and ethylene-propylene elastomer (EPR) were investigated. Separation of the filler and elastomer particles was achieved using maleic-anhydride-grafted PP (MPP) to enhance the filler-matrix adhesion. Encapsulation of the rigid filler by the elastomer was achieved using maleic-anhydride-grafted EPR (MEPR) to increase the filler-elastomer adhesion. The two limiting morphologies differ significantly in mechanical properties under tensile loading at the same material composition. Elastomer particles separately dispersed in the matrix enhance the shear banding in the bulk matrix which prevents the crazes growing from the filler surface from becoming unstable and, thus, increases the ductility of the material. Encapsulation by an elastomer layer on the filler surface relieves triaxial stresses at the filler surface, changing the major local failure mechanism from crazing to shear yielding and, hence, increasing the ductility of the material. Increase of the elastomer volume fraction also causes, in both cases, an increase in matrix ductility. Composite models are used to predict upper and lower limits of yield strength (_y) for the two limiting morphologies over an interval of elastomer volume fractions (V _e) from 0 to 0.2 at a constant filler loading of 30 vol.% and over a filler volume fraction from 0 to 0.4 at a constant EPR content in the matrix. Satisfactory agreement was found between the experimental data and theoretical predictions.     

Morphology, mechanical and thermal behavior of acrylate rubber/fluorocarbon elastomer/polyacrylate blends

Novel thermoplastic elastomers derived from binary and ternary blends of polyfunctional acrylates, acrylic rubber (ACM) and fluorocarbon rubber (FKM) were analyzed by using Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) and mechanical tests. TEM revealed the presence of a single-phase structure for both acrylate rubber/fluorocarbon elastomer (ACM/FKM) and ACM/polyacrylate binary blends. Increase of FKM concentration in the ACM/FKM/polyacrylate ternary blend resulted in phase separation of FKM from the ternary blend. The FKM formed a dispersed phase with polynodal particle distribution and irregular shape ranging from ellipsoidal to highly elongated form with inclusion of ACM. The FKM/polyacrylate binary blend showed complete phase separation. Ageing of the blend increased the domain size of the dispersed phase. Differential scanning calorimetric (DSC) and DMTA studies showed no major changes in the T _gs of individual polymers in the blend, although the peak tan values were affected on changing the composition of the blends. Vulcanization of the thermoplastic elastomer (TPE) changed the phase morphology with increase in particle size. There is a distinct difference in morphology of statically and dynamically vulcanized blends.     

动态全硫化热塑性弹性体EPDM／PP拉伸蠕变行为的研究

Santoprene是当前颇具代表性的动态全硫化共混型热塑性弹性体EPDM/PP品种,其EPDM形成分散相,PP形成连续相。本文依据它的这种结构特征,引用高柳素夫模型,计算出模型中各单元的重量比、体积比和拉伸蠕变柔量,由此推论它的蠕变行为。     

共混型热塑性弹性体的形变机理

热塑性弹性体的性能与其相形态密切相关。文中简要综述了与共混型热塑性弹性体相形态相关的几个参数,包括两相相容性、橡胶相的粒径、塑料相的结晶度。重点介绍了共混型热塑性弹性体形变机理的几种模型,包括不均匀变形、有限元模型、微孔模型等。最后对其发展进行了展望。     

Crack toughness behavior of binary poly(styrene-butadiene) block copolymer blends

Fracture behavior of binary blends comprising styrene-butadiene block copolymers having star and triblock architectures was studied by instrumented Charpy impact test. The toughness of the ductile blends was characterized by the dynamic crack resistance concept (R curves). While the lamellar thermoplastic star block copolymer shows elastic behavior (small scale yielding and unstable crack growth), adding 20 wt% of a triblock copolymer (thermoplastic elastomer, TPE) leads to a strong increase in crack toughness. The stable crack propagation behavior of these blends was described by the crack resistance curve (R) concept of elastic-plastic fracture mechanics. This concept allows the determination of fracture mechanics parameters as resistance against stable crack initiation and propagation. Two brittle to tough transitions (BTT) are observed in the binary block copolymer blend: BTT1 at 20% TPE and BTT2 at about 60% TPE. The strong increase of toughness at 60 wt% TPE indicates a tough/high-impact transition as a measure for the protection against stable crack initiation.The kinetics of stable crack propagation is discussed with respect to deformation mechanisms and crack-tip blunting behavior. The analysis of fracture surface by SEM revealed three different types of deformation mechanisms depending on the weight fraction of TPE: coalescence of microvoids (similar to semicrystalline polymers), shear flow (typical of many amorphous polymers like polycarbonate) and tearing (similar to elastomers). Our investigations on nanostructured binary block copolymer blends show new possibilities to tailor the toughness of polymer materials associated with complex morphology-toughness correlations. This may lead to new materials concepts for toughened nanostructured polymers, which still maintain excellent transparency.     

国内开发与应用PP/EPDM-TPE的状况

以PP/EPDM(聚丙烯/三元乙丙橡胶)型TPE(热塑弹性体)为例,介绍了国内进行PP基TPE的研制与生产状况及其在汽车、电器和包装等领域的应用.     

新型树脂根管充填材料的制备与性能

以热塑性聚烯烃弹性体（TPE）和乙烯 醋酸乙烯酯共聚物（EVA）为基体树脂, 硫酸钡（BaSO₄）、气相白炭黑（气相SiO₂）和羟基磷灰石（HA）为无机填料, 制备了新型树脂根管充填材料（NRCFM）, 着重对NRCFM 的组成进行了筛选与优化, 并对NRCFM在pH值为7.0和9.5的人工唾液介质中的稳定性进行了研究。实验结果表明, NRCFM的最佳组成为: TPE 30 g、EVA 5 g、BaSO₄45 g、 气相SiO2 10 g、 HA 10 g, 由此制备的NRCFM具有适宜的力学性能和优异的耐介质稳定性, 其邵氏A硬度88.9、 拉伸强度1.99 MPa、 断裂伸长率457％, 在pH值为7.0和9.5的人工唾液介质中浸泡30天后的质量变化小于0.5％。      

热塑性弹性体的研究与产业化进展

化学合成型和共混型热塑性弹性体类型、市场概况、产业化进展及最新研究发展方向进行了论述。介绍了几种具有市场应用前景的新型热塑性弹性体品种,如聚酰胺类TPE、热可逆共价交联类TPE、茂金属催化聚烯烃类TPE、甲壳型液晶类TPE、生物基TPE、新型热塑性硫化橡胶等,对它们的制备方法、性能特点及市场发展概况进行了详细论述,并对它们的应用领域和产业化方向进行了评述和展望。     

Partially crystallized elastomer as a nanocomposite model

Data on the influence of crystallization on the mechanical properties of elastomers — the elastic modulus, the relaxation properties, in particular, restorability in compression, and the tensile strength — have been generalized. These data have been compared to those on the influence of active fillers and a much higher crystallization efficiency has been shown. The size of single crystals has been evaluated for most crystallizable rubbers. It has been inferred that the nanosize of single crystals of elastomers and their direct bond with the elastomer matrix influence the mechanical properties of elastomer materials. In considering a partially crystallized elastomer as a nanocomposite model, one can formulate requirements imposed on efficient nanofillers for elastomer materials. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 19–23, September–October, 2005.     

采用β成核动态硫化PP/EPDM共混物增韧聚丙烯

采用β成核的动态硫化iPP/EPDM共混物即热塑性硫化胶(TPV)改性聚丙烯,并与通用增韧剂聚烯烃弹性体(POE)、三元乙丙橡胶(EPDM)增韧聚丙烯进行比较,考察了增韧体系的力学性能、热性能和相形态.结果表明,随增韧剂含量的增加,增韧体系的拉伸屈服强度和弯曲模量均有所下降,而冲击强度提高.TPV改性体系的强度、模量和...     

Furan-Based Bionanocomposites Reinforced with a Hybrid System of Carbon Nanofillers

Bionanocomposites based on poly(trimethylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PTF-b-F-PTMO) with various contents of carbon nanofibers, graphene nanoplatelets and a hybrid system of these nanoparticles are synthesized via in situ polymerization. The dispersion of nanoparticles in the nanocomposites is determined using a scanning electron microscope and optical microscopy images. The thermal properties are studied employing differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The melt viscosity of the synthesized materials is determined using rheological measurements. Mechanical properties, along with the thermal and electrical conductivity, are also analyzed. The synthesized polymer nanocomposites are processed using injection molding and they display mechanical properties of elastomers during mechanical testing, which indicates that the obtained materials are, in fact, thermoplastic elastomers (TPE). Compared to a neat matrix (PTF-b-F-PTMO 50/50), the incorporation of nanoparticles causes an increase in the value of the degree of crystallinity and the value of the tensile modulus values (E) of the nanocomposites. Such reinforced bionanocomposites are especially interesting from an applicative point of view. They can be used as components of fuel systems, bumpers, or cupholders.     

Abrasive wear in filled elastomers

The abrasive wear of rubbers is strongly affected by the filler particles dispersed in the elastomer matrix. The fillers are incorporated usually for the purposes of mechanical reinforcement and improving the conductivity of the neat resins. It is found that the wear rates of the filled silicone rubbers increase slowly with filler concentration until a critical volume fraction,v _c, is reached, at which point they increase very rapidly with increasing filler concentration. This behaviour appeared to be universal in all the filled silicones we studied, regardless of the type of filler and silicone rubber used. However the magnitude of the critical filler fraction,v _c, can be changed significantly with the filler shape, resin cross-linking density and filler surface treatments. No reasonable relationship could be found between this wear behaviour and the mechanical properties measured in a macroscopic manner. Experimental evidence suggests that the incipient cracks that lead to wear losses may start within the thin layers of highly stressed material, the damage zones, surrounding the rigid particles. A simple model taking into account the stress concentration induced by the rigid fillers shows excellent correlation between the wear rate and the damage zones volume. With this new model, the observed wear behaviours can be explained satisfactorily.     

Effects of modified hyperbranched polyester as a curing agent on the morphology and properties of dynamically cured polypropylene/polyurethane blends

The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, has been applied to prepare polypropylene (PP)/polyurethane (PU) blends. Boltorn^TM H20 (H20) hyperbranched polyester containing 16 hydroxyl end gropus and pentaerythritol are used as curing agents, respectively, for curing PU oligomer during blending with molten PP. To improve the compatibility of cured PU particles with PP matrix, H20 is partly functionalized with stearic acid. The morphology, mechanical properties, thermal properties and melt flow index (MFI) of the PP/PU blends with different curing agent are investigated. Compared with pentaerythritol, SEM photographs show that H20 partly functionalized with stearic acid effectively reduces the size and size distribution of cured PU particles in PP/PU blends which also is proved by MFI measurement. Consequently, the dynamically cured PP/PU blends with modified H20 have better mechanical properties than those cured with pentaerythritol. The shifts of crystallization peaks to higher temperatures for all PP/PU blends indicate that PU particles in the blends can act as effective nucleating agents. Moreover, due to the smaller size of PU particles PP/PU blends cured with modified H20 have higher crystallization temperatures than those blends cured with pentaerythritol at the same PU content.     

Mechanical and interfacial properties of wood and bio-based thermoplastic composite

The aim of this investigation was to study a new family of wood polymer composites with thermoplastic elastomer matrix (pebax® copolymers) instead of commonly used WPC matrices. These copolymers are polyether-b-amide thermoplastic elastomers which present an important elongation at break and a melting point below 200 °C to prevent wood fibers degradation during processing. Moreover these polymers are synthesized from renewable resources and they present a hydrophilic character which allow them to interact with wood fibers. We have used two pebax® grade with different hardness and three types of wood fibers, so the influence of the matrix and wood fibers characteristics were evaluated. Composites were produced using a laboratory-size twin screw extruder to obtain composite pellets prior to injection moulding into tensile test samples. We have evaluated fibers/matrix interaction by differential scanning calorimetry (DSC), infrared spectroscopy (IRTF) and scanning electron microscopy (SEM). Then, the mechanical properties, through tensile test, were assessed. We also observed fibers dispersion into the matrix by tomography X. DSC, IRTF and SEM measurements confirmed the presence of strong interface interactions between polymer and wood. These interactions lead to good mechanical properties of the composites with a reinforcement effect of wood fibers due also to a good dispersion of fibers into the matrix without agglomerate.     

动态光交联法制备PP/EPDM热塑性弹性体的力学及热性能

采用动态光交联法制备了PP/EPDM热塑性弹性体。动态力学热分析(DM TA)和扫描电子显微镜(SEM)及力学性能测试表明:动态光交联能明显提高PP与EPDM间的相容性,从而显著提高PP/EPDM热塑性弹性体的拉伸性能和缺口冲击强度。并结合DM TA、差热扫描量热仪(DSC)等手段,证实了动态光交联过程中产生了少量的接枝共聚物PP-g-EPDM。     

Optimization Techniques for Improving the Performance of Silicone‐Based Dielectric Elastomers

Dielectric elastomers are possible candidates for realizing products that are in high demand by society, such as soft robotics and prosthetics, tactile displays, and smart wearables. Diverse and advanced products based on dielectric elastomers are available; however, no elastomer has proven ideal for all types of products. Silicone elastomers, though, are the most promising type of elastomer when viewed from a reliability perspective, since in normal conditions they do not undergo any chemical degradation or mechanical ageing/relaxation. Within this review, different pathways for improving the electro‐mechanical performance of dielectric elastomers are highlighted. Various optimization methods for improved energy transduction are investigated and discussed, with special emphasis placed on the promise each method holds. The compositing and blending of elastomers are shown to be simple, versatile methods that can solve a number of optimization issues. More complicated methods, involving chemical modification of the silicone backbone as well as controlling the network structure for improved mechanical properties, are shown to solve yet more issues. From the analysis, it is obvious that there is not a single optimization technique that will lead to the universal optimization of dielectric elastomer films, though each method may lead to elastomers with certain features, and thus certain potentials.