A new class of blend system comprising weather resistant acrylonitrile/styrene/acrylate (ASA) terpolymer and Zn-ionomer was developed. Based on Zn-ionomer content, the blend system either forms ‘mushroom’ or ‘brush’ type conformation which affected dynamic rheology, DSC, DMA and creep properties differently. Formation of ionic crosslinkings by Zn-ionomer in ‘brush regime’ as well as limited ionic crosslinkings in ‘mushroom regime’ resulted in different nature molecular chain relaxation response. The DSC endotherm peak and glass transition temperature were also influenced by the type of conformation and ion-dipole interaction between the blend components. The tan δ from DMA study also reflected the similar trend. The creep deformation behavior of the blend was found to be dependent on highly deformable Zn-ionomer content and with temperature. The Findley model analysis suggests the ionic crosslinkings may be the possible reason for controlled creep deformation of the blend. 相似文献
The deformation and fracture behavior of sulphonated polystyrene ionomers, and of blends of these with polystyrene have been investigated. The microstructure of the ionomer, which varies with ion content, appears to have a significant effect on mechanical properties. Both tensile strength and toughness increase appreciably at ion contents near 5 mol%, where clusters become dominant over ion pairs and multiplets. In blends of the ionomers and polystyrene, phase separation occurs and the ionomer component appears in the form of fine particles dispersed in the polystyrene matrix. These particles possess a greater effective entanglement density than the matrix, as a result of ionic crosslinking, and they provide reinforcement against early craze breakdown and fracture. Tensile strength and fracture energy increase rapidly as the ionomer concentration in the blend is increased and they become essentially independent of blend ratio above about 10 wt% of the ionomer. Tests carried out on thin film specimens of the blends show that the dispersed ionomer particles adhere well to the matrix and contribute to the fracture energy both by inducing matrix crazing and by internal fibrillation within the particles.Dedicated to Professor Hans-Henning Kausch on the occasion of his 60th birthday. 相似文献
Two samples have been prepared to study the effect of interchain crosslinking on the heat shrinkability of the blends. In the first sample low‐density poly(ethylene) is blended with ethylene acrylic rubber while in the second one glycidyl acrylate‐grafted low‐density poly(ethylene) is blended with ethylene acrylic rubber. It is revealed that interchain crosslinking in the glycidyl acrylate grafted low‐density poly(ethylene) and ethylene acrylic rubber improves the heat shrinkability in the second sample. 相似文献
A high molecular weight styrene ionomer containing 5 mol% sodium methacrylate was blended with a styrene oligomer (MW 800) and investigated by dynamic mechanical techniques. The focus of the study is on the dynamic melt rheology of these materials, whose ratios by weight of ionomer to oligomer are 60/40, 40/60, and 25/75. The glass-transition temperature and ionic transition are first characterized by torsion pendulum measurements as a function of temperature. It appears that a maximum level of plasticization is achieved for the ionic regions, the extent depending on sample history. Time–temperature superposition is obeyed by the blend of 60 wt% ionomer, but not by the other two blends. Relaxations due to the ionic regions are clearly evident in the relaxation spectra of all three blends. Above a particular temperature, the 25 wt% blend indicates an Arrhenius type of dependence. 相似文献
A family of conformational rheological models for multi‐component miscible polymer blends is developed using a modified form of the Poisson bracket formulation. Two conformation tensors called c 1 and c 2 are introduced to show the orientation of the first and the second components of a blend, respectively. The mobility tensor and the energy function for each blend component are expressed in terms of these conformation tensors. The interaction effects are also included by energy expressions. The predictions of this family of “volume‐preserving” models are illustrated for a Hookean‐type energy function and several expressions of the modified mobility tensors. The results are illustrated for material functions in transient (start‐up and relaxation) and steady shear flows. The predictions are compared with experimental data taken from the literature for a miscible polymer blend. Study of the model sensitivity to its parameter shows that model predictions can cover a wide range of rheological behavior generally observed for multi‐component miscible polymer blends in steady and transient shear flows.
Experimental data and model predictions for steady shear viscosity for HDPE/LDPE blends. 相似文献
The post‐functionalization of poly(3‐hexylthiophene) (P3HT) via various synthetic routes is reported. Well‐defined and monofunctionalized ω‐thiol‐terminated P3HT, ω‐carboxylic acid‐terminated P3HT, ω‐acrylate‐terminated P3HT, and ω‐methacrylate‐terminated P3HT are obtained in high yields through a straightforward procedure. From those, different novel P3HT‐based graft copolymers are synthesized following two routes: “grafting onto” and “grafting through” (macromonomer polymerization) methods. The synthesis of three types of graft copolymers is described. Each one has “rod” P3HT‐grafted side chains on a “coil” main chain, which can be polyisoprene, poly(vinyl alcohol), or poly(butyl acrylate). Each copolymer is characterized by size‐exclusion chromatography and NMR. 相似文献
The thermal behaviour of natural rubber/acrylonitrile butadiene rubber (NR/NBR) was studied using thermogravimetry (TG) and differential scanning calorimetry (DSC) in terms of blend ratio, crosslinking systems, fillers and compatibilizer (neoprene) were analyzed. The presence of NBR markedly increases the thermal stability of their blends and it lies in between NR and NBR. DSC studies revealed the thermodynamic immiscibility of the NR/NBR blends by the presence of two distinct glass transition temperatures and the immiscibility was prominent even in the presence of a compatibilizer. 相似文献
The plasticization by 4-decylaniline (4DA) of a microphase-separated poly(ethyl acrylate) ionomer containing sodium carboxylate groups is examined. Dynamic mechanical thermal analysis, supplemented by differential scanning calorimetry, shows that the matrix and cluster glass transitions (Tg's) in the ionomer are both depressed by ca. 1°C/wt % 4DA; this, in turn, is similar to the Tg depression in the blend of the parent poly(ethyl acrylate) (PEA) with 4DA. There is no evidence of 4DA crystallinity in the blend. Small-angle x-ray scattering (SAXS) measurements show that the ionomer peak increases in intensity and decreases in scattering angle with increasing concentration of 4DA in the blend; the corresponding Bragg spacing, initially at 2.3 nm, increases by ca. 0.04 nm/wt % 4DA. These results, supported by preliminary spectroscopic measurements, are attributed to hydrogen bonding interactions between the amine groups of 4DA and the ester groups in PEA and the ionomer, rendering the blend miscible. It is argued that the uniform distribution of 4DA throughout the material plasticizes both phases of the ionomer by adding free volume; this also accounts for the increase in the characteristic spacing detected by SAXS. 相似文献