Blends and interpenetrating polymer networks of polypropylene and polystyrene-block-poly(ethylene-stat-butylene)-block-polystyrene. 2: Melt flow and injection molding properties

Injection molding and melt flow properties of a set of blends prepared by mixing the triblock thermoplastic elastomer polystyrene-block-poly(ethylene-stat-buty-lene)-block-polystyrene with polypropylene and a processing oil are reported. Despite the high viscosity of the thermoplastic elastomer, the melt viscosity of the blends was similar to or lower than that of the pure polypropylene. The rheological behavior of the molten blends seems to be dominated by a low-viscosity melt phase containing mainly polypropylene and oil. The surface of solidified extrudates from the capillary rheometer was rich in polypropylene and free from large domains of the thermoplastic elastomer. Injection molded plates had a similar surface morphology, although in this case, larger domains of the elastomeric phase were found in narrow, band-shaped surface regions. These local surface heterogeneities were probably caused by flow-induced phase segregation during mold filling. Weld lines in injection molded test pieces prepared from blends within the composition range giving interpenetrating network structures had no noticeable effect on either stress-strain behavior or falling dart impact strength.     

Rheological and thermal properties of blends of modified poly(ethylene terephthalate) with p‐acetoxybenzoic acid and poly(butylene terephthalate)

Blending of thermotropic liquid crystalline polyesters (LCPs) with conventional polymers could result in materials that can be used as an alternative for short fiber‐reinforced thermoplastic composites, because of their low melt viscosity as well as their inherent high stiffness and strength, high use temperature, and excellent chemical resistance and low coefficient of expansion. In most of the blends was used LCP of 40 mol % of poly(ethylene terephthalate) (PET) and 60 mol % of p‐acetoxybenzoic acid (PABA). In this work, blends of several copolyesters having various PABA compositions from 10 to 70 mol % and poly(butylene terephthalate) (PBT) were prepared and their rheological and thermal properties were investigated. For convenience, the copolyesters were designated as PETA‐x, where x is the mol % of PABA. It was found that PET‐60 and PET‐70 copolyesters decreased the melt viscosity of PBT in the blends and those PBT/PETA‐60 and PBT/PETA‐70 blends showed different melt viscosity behaviors with the change in shear rate, while blends of PBT and PET‐x having less than 50 mol % of PABA exhibited totally different rheological behaviors. The blends of PBT with PETA‐50, PETA‐60, and PETA‐70 showed the morphology of multiple layers of fibers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1797–1806, 1999     

PA1010/TPU共混物流变性能的研究

以尼龙1010(PA1010)为基体，以聚酯型热塑性聚氨酯弹性体(TPU)为增韧剂，采用Haake PTW16／25p型双螺杆挤出机制备了PA1010／TPU共混增韧尼龙材料。测试了PA1010／TPU共混物的表观粘度、非牛顿指数等流变参数，并重点讨论了其流变性能。实验结果表明：共混物熔体的表现粘度随剪切速率的增大而降低，非牛顿指数小于1，符合假塑性流体流动规律。此外共混物的表观粘度随着组成和温度的变化呈现了一种极为特殊的变化行为。即在相同温度下，共混物的表观粘度随着TPU含量增加而增加；在相同组成下，共混物的表观粘度随着温度升高而升高。     

Studies on the melt flow behavior of thermoplastic elastomers from polypropylene—Natural rubber blends

The melt flow behavior of thermoplastic polypropylenenatural rubber blends has been evaluated with specific reference to the effects of blend ratio, extent of dynamic crosslinking of the rubber phase and temperature, on viscosity, flow behavior index, and deformation of the extrudate. The proportion of rubber in the blend and the extent of dynamic crosslinking of the rubber phase were found to have profound influence on the viscosity of the blends at lower shear stresses. But at higher shear stresses, the effect of blend ratio on viscosity was comparatively less for the uncrosslinked blends than that for the crosslinked blends. At lower shear stress, the viscosity of the blend increased with increase in degree of crosslinking but at higher shear stress, the effect of crosslinking on viscosity was found to vary depending on the ratio of the plastic and rubber components in the blend. The deformation of the extrudates was also very much dependent on both blend ratio and degree of crosslinking.     

Blends of nylon/acrylonitrile butadiene rubber: Effects of blend ratio,dynamic vulcanization and reactive compatibilization on rheology and extrudate morphology

The melt flow behavior of thermoplastic elastomers from nylon and nitrile rubber (NBR) was studied as a function of blend ratio, dynamic crosslinking, compatibilization and temperature. The morphology of the extrudates, i.e., the size, shape and distribution of the domains, was analyzed. Uncompatibilized and compatibilized blends showed pseudoplastic behavior. The viscosity of the blends showed positive deviation from a linear rule of mixtures. Compatibilization using chlorinated polyethylene (CPE) increased the melt viscosity of the blends. The addition of the compatibilizer decreased the domain size of the dispersed phase, followed by an increase after a critical concentration of the compatibilizer, where the interface was saturated. The influence of dynamic vulcanization on the rheological behavior was also studied. The extrudate morphology depended on blend ratio, compatibilization and shear rate.     

共聚聚丙烯(cPP)/线型低密度聚乙烯(LLDPE) 共混体系的流变与结晶形为

用毛细管流变仪研究了共聚聚丙烯(cPP)与线型低密度聚乙烯(LLDPE)共混物熔体的流变行为.讨论了共混物的组成、切应力和剪切速率对熔体流变行为和熔体粘度的影响.测定了不同配比共混物熔体的非牛顿指数.结果表明共混物熔体属假塑性流体,但共混体系粘度随LLDPE加入量的增加变化不大.DSC结晶曲线及扫描电镜(SEM)照片表明,LDPE的加入使cPP的结晶温度变化不大,但对晶体形态有一定影响.LLDPE对cPP有一定的增韧改性作用,当LLDPE质量分数为15%时,共混物的冲击强度增幅在40%左右,而拉伸强度保持率为80%.     

Melt rheology and morphology of LLDPE/EVA blends: Effect of blend ratio,compatibilization, and dynamic crosslinking

The melt rheological properties of linear low‐density polyethylene (LLDPE)/ethylene vinyl acetate (EVA) blends were investigated with special reference to the effect of blend ratio, temperature, shear rate, compatibilization, and dynamic vulcanization. The melt viscosity of the blends determined with a capillary rheometer is found to decrease with an increase of shear rate, which is an indication of pseudoplastic behavior. The viscosity of the blend was found to be a nonadditive function of the viscosities of the component polymers. A negative deviation was observed because of the interlayer slip between the polar EVA and the nonpolar LLDPE phases. The melt viscosity of these blends decreases with the increased concentration of EVA. The morphology of the extrudate of the blends at different shear rates and blend ratios was studied and the size and distribution of the domains were examined by scanning electron microscopy. The morphology was found to depend on shear rate and blend ratio. Compatibilization of the blends with phenolic‐ and maleic‐modified LLDPE increased the melt viscosity at lower wt % of compatibilizer and then leveled off. Dynamic vulcanization is found to increase the melt viscosity at a lower concentration of DCP. The effect of temperature on melt viscosity of the blends was also studied. Finally, attempts were made to correlate the experimental data on melt viscosity and cocontinuity region with different theoretical models. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3210–3225, 2002     

Effect of fillers and plasticizers on the performance of novel heat and oil‐resistant thermoplastic elastomers from nylon‐6 and acrylate rubber blends

The effects of various fillers (SRF black, silica, and clay) and plasticizers (dibutyl phthalate and dioctyl phthalate) on the mechanical, dynamic mechanical, and rheological properties and on the heat and oil resistance of the thermoplastic elastomeric reactive blends of nylon‐6 and acrylate rubber (ACM) were investigated. The mixing torque behavior of the blends in Brabender Plasticorder shows reduced extent of interaction between the two component polymers in the presence of both fillers and plasticizers. Silica‐filled blends show the highest viscosity increment due to the possibility of reaction between its surface silanol groups and the reactive epoxy groups present in the ACM chain during melt‐blending operation. Though the addition of fillers reduces the processability of the blends, it improves the extensibility as well as the tension set properties of the blends. The mechanical integrity and the damping characteristics of the blends are also improved with the addition of fillers; the latter is evidenced from the dynamic mechanical thermal analysis of the blends. The tensile strength and hardness of the filled blends remain practically unchanged after ageing at 175°C for 72 h and, also, the oil swell does not change appreciably with the addition of fillers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1490–1501, 1999     

Coalescence in blends of thermoplastic polyurethane with polyolefins

The coalescence behavior of immiscible blends was determined by annealing the melt without shear. The kinetics and the mechanism of coalescence were observed for blends of thermoplastic polyurethane (TPU) and polyolefins. Two different types of measurements were used to observe coalescence in quiescent melt at the processing temperature. On the one hand, the blend granules were annealed in bulk. The resulting particle sizes were determined by light microscopy and by SEM on particles separated from the blend. On the other hand, thin samples were annealed on a hot stage. Coalescence was observed in situ by light microscopy or static laser light scattering. It was found that the higher viscosity and elasticity ratios between polyethylene and TPU lead to a more pronounced coarsening of the morphology of 80/20 blends than in TPU/polypropylene. It has been shown that the process of reshaping coalescence is one mechanism of coalescence that occurs in quiescent melt. Another mechanism that was directly observed is a “domino effect” where one coalescence process causes the next one.     

Extruded blends of a thermotropic liquid crystalline polymer with polyethylene terephthalate,polypropylene, and polyphenylene sulfide

Structure–property relationships were investigated for blends of a polyester-type thermotropic liquid crystalline polymer (LCP) with polyethylene terephthalate (PET), polypropylene (PP), and polyphenylene sulfide (PPS). The polymers were melt blended in a twin-screw extruder and the blends were extruded to strands of different draw ratios. Tensile properties of the blends were determined as a function of LCP content and draw ratio and compared with the results of morphological and rheological analyses. In general, the strength and stiffness of the matrix polymers were improved with increasing LCP content and draw ratio. At a draw ratio of 11, the blends of PET/30 wt % LCP exhibited a tensile strength about three times and an elastic modulus nearly four times that of pure PET. All blends exhibited a skin/core morphology with thin fibrils in the skin region. The formation and the sizes of the fibril-like LCP domains in the matrices were found to depend on LCP content and the viscosity ratio of the blend components.     

Shear flow behavior and oil distribution between phases in thermoplastic vulcanizates

The high rate shear flow behavior and the morphology of five different oil‐extended polypropylene (PP)/ethylene‐propylene‐diene monomer (EPDM) thermoplastic vulcanizate blends were investigated with the melt flow rate (MFR) of the PP varying from 0.7 to 20. The ratio of rubber to PP is 70 : 30 in three of the thermoplastic vulcanizates (TPVs) and 50 : 50 in the other two TPVs. The distribution of the high‐temperature oil between the PP melt and the rubber is a key parameter because this will affect the viscosity of the PP/oil medium. The object of this study was to estimate the matrix composition in each of the TPVs at processing temperatures and to compare the shear viscosity of the effective matrix with that of the TPV. To this end, several PP/oil mixtures were prepared and their viscosity curves were correlated with the neat PP melt viscosity curves by means of shift factors varying with oil concentration. The oil distribution between the PP and rubber phases was estimated from TEM micrographs of the TPV blends. The results show that the PPs are mixed with oil to different proportions in the different TPVs and the viscosity curves of these mixtures exhibit the same trends in magnitude as the corresponding TPV viscosity curves. Hence, the shear flow of TPVs can be understood more readily in terms of the effective PP/oil medium flow behavior than in terms of the neat PP melt flow. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 113–121, 2004     

Oriented monofilaments from blends of poly(ethylene terephthalate) and polypropylene

Poly(ethylene terephthalate) and polypropylene are considered, to be incompatible by the usual criteria for polymer blends. Sheath/core filaments of these polymers could not be oriented because of poor adhesion of the base polymers. Melt blends of the two polymers with 30 and 50 weight percent polypropylene produced useful, oriented monofilaments. Tensile and dynamic mechanical properties of these filaments indicate that the structures consist of interlocked microfibrillar domains of the polyester and polyolefim. The glass transition region of poly(ethylene terephthalate) is not affected by admixture with polypropylene. A fine mutual dispersion of the two polymers was possible because the melt viscosities of the ingredients were reasonably well matched under the conditions of mixing. The melt viscosity and elasticity of blends were lower than those of either component as expected if the two polymers are immiscible. Monofilament extrusion and melt flow measurements were made with a one-half inch single screw extruder.     

Phase behavior and properties of in situ‐reinforcing elastomer composites based on thermoplastic elastomers and thermotropic liquid crystalline copolyester

In situ reinforcing composites based on two elastomer matrices very different in melt viscosity, styrene–(ethylene butylene)–styrene triblock copolymer (Kraton G1650) and styrene–(ethylene propylene) diblock copolymer (Kraton G1701), and a thermotropic liquid crystalline polymer (TLCP), Rodrun LC3000, were prepared using a twin‐screw extruder. The rheological behavior, morphology, mechanical and thermal properties of the blends containing various LC3000 contents were investigated. G1650 was found to have much higher shear viscosity than G1701. All neat components and their blends exhibited shear thinning behavior. Melt viscosity of the blends gradually decreased with increasing LC3000 contents. Despite a large difference in melt viscosity of the two matrices, the results showed that the fibrillar morphology was obtained for both as‐extruded strands of LC3000/G1650 and LC3000/G1701 with up to 30 wt % LC3000. At 40 wt % LC3000 or more, the lamellar structure was observed for both types of blends because of the coalescence of liquid TLCP threads that occurred during extrusion. The addition of LC3000 into both elastomer matrices enhanced the tensile modulus considerably whereas the extensibility remarkably decreased. The results obtained from thermogravimetric analysis suggested that an addition of LC3000 into both elastomer matrices improved the thermal resistance significantly in air, but not in nitrogen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1610–1619, 2006     

聚丙烯／无规共聚聚丙烯共混物的流变行为与力学性能研究

以毛细管流变仪研究了聚丙烯(PP)／无规共聚聚丙烯(PP-R)共混物熔体的流变行为。讨论了共混物的组成、剪切应力和剪切速率以及温度对熔体流变行为、熔体粘度的影响。测定了不同配比共混物熔体的非牛顿指数和膨胀比。结果表明：PP／PP-R共混物熔体属假塑性流体，其熔体粘度随PP-R含量的增加而迅速增大。力学性能测试结果表明，PP-R对PP有很好的增韧改性作用。另外，也用偏光显微镜研究了PP-R对共混物结晶形态的影响。     

Morphology and properties of blends with different thermoplastic polyurethanes and polyolefines

Unmodified blends of two thermoplastic polyurethanes (TPU) and six polyolefines were used to study the influence of the component viscosities on the blend morphology and mechanical properties. Blends were produced by melt mixing using a twin screw extruder. Interactions between the blend components could not be detected by DSC, DMA, selective extraction, and SEM micrographs of cryofractures. The variation in tensile strength with blend composition produce a U-shaped curve with the minimum between 40 and 60 wt % of polyolefine. At similar viscosity ratios (η_d/η_m), blends with polyether based TPU (TPU-eth) have a finer morphology than blends with polyester based TPU (TPU-est). This is due to the lower surface free energy of the polyether soft segments compared to the polyester soft segments. Different morphologies also lead to changes in mechanical behavior. Blends with TPU-eth show a lower decrease in tensile strength with blend composition than blends with TPU-est. The viscosity ratio between TPU and polyolefines can be directly correlated to the blend morphology obtained under similar blending conditions. TPU/PE blends show a lower dispersity than TPU/PP blends, due to the higher viscosity ratios of TPU/PE blends. This results in a greater reduction in tensile strength with the disperse phase content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 749–762, 1997     

共聚聚丙烯／茂金属线形低密度聚乙烯共混体系的流变行为与结晶行为

用毛细管流变仪研究了冲击性能相对优良的共聚聚丙烯(cPP)与茂金属低密度聚乙烯(m-PE—LLD)共混物熔体的流变行为。讨论了共混物的组成、剪切应力和剪切速率对熔体流变行为、熔体粘度的影响。测定了不同cPP及m—PE—LLD配比的共混物熔体的非牛顿指数。结果表明：共混物熔体属假塑性流体，但其粘度随m—PE—LLD加入量的增加变化不大。DSC分析及微观形态分析表明，m-PE—LLD的加入使cPP的结晶温度提高，具有异相成核作用。m-PE—LLD对cPP有明显的增韧作用，当m—PE—LLD含量为15％时，共混物的冲击强度明显提高，增幅在75％左右，而拉伸强度保持率为85％以上。     

Bio‐based thermoplastic polyurethane and polyamide 11 bioalloys with excellent shape memory behavior

Bio‐based blends of commercially available polyester based bio thermoplastic polyurethane (TPU) and castor oil based polyamide 11 (PA11) of different ratios are prepared by melt processing. The blends properties such as shape memory behavior through unconstrained and constrained recovery, interfacial interaction, morphology, dynamic mechanical, rheological, and mechanical behavior are studied. A strong interface between the two polymeric phases due to hydrogen bonding observed through morphology indicates that TPU and PA11 are well compatible. The complex viscosity of blends ranges between that of neat PA11 and TPU. Thermal analysis shows that higher the TPU content lower the melting point (T_m ) corresponding to PA11 and the crystallization temperature (T_c ) remains unaltered. Adding TPU to PA11 ductility and impact strength of the blends increases significantly with the small reduction in their tensile strength. Shape memory behavior investigation reveals that, blends recover almost 95% of the applied deformation when heated at zero load and they recovered a stress of 1.8–3.2 MPa in constrained recovery during three consecutive thermomechanical cycles. The reported results on bioalloys promotes the usage in multidisciplinary field of intelligent devices, such as ergonomic grips and sports shields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44794.     

Prediction of polymer processing characteristics using the C. W. Brabender plasti-corder torque rheometer

The Brabender Plasti-Corder is shown to be an effective tool for predicting the processing characteristics of thermoplastic polymers. Procedures for determining the molding temperature range, the relative melt viscosity over a continuous temperature range, and the stability of molding and experimental curtain coating materials are presented. Molding temperature ranges can be determined by first establishing the Brabender torque which corresponds to the maximum viscosity at which a material will just fill the cavity in a particular injection system under full injection pressure and maximum injection rate. This torque is constant for any material to be molded in this system. A Brabender torque-temperature curve is then obtained on the pertinent resin and the temperature which corresponds to the torque associated with the maximum viscosity is the minimum molding temperature. Maximum molding temperature is the temperature at which the log of the torque deviates from a linear dependence on temperature. The stability of thermoplastic compositions can be shown by a Brabender torque-time curve at constant temperature. An unstable polymer shows decreasing torque with time if the decomposition predominantly consists of chain scission.     

Studies on binary and ternary blends of polypropylene with SEBS,PS, and HDPE. I. Melt rheological behavior

Studies are reported on melt rheological behavior of some binary and ternary blends of polypropylene (PP) with one or two of the following polymers: styrene–b-ethylene butylene–b-styrene triblock copolymer (SEBS), polystyrene (PS), and high-density polyethylene (HDPE). Blend composition of the binary blends PP/X or ternary blends PP/X/Y were so chosen that the former represent addition of 10 wt % X to PP while the latter represent 10 wt % addition of X or Y to the PP/Y or PP/X blend of constant composition 90:10 by weight, X/Y being SEBS, PS, or HDPE. Measurements were made on a capillary rheometer using both temperature elevation and constant temperature methods to study the behaviors prior to flow and in the flow region. Flow behavior, measured at a constant temperature (200°C) and varying shear stress (from 1.0 to 5.0 × 10⁶ dyn/cm²) to evaluate melt viscosity and melt elasticity parameters, is discussed for its dependence on the nature of the blend. Extrudate distortion, studied as a function of shear stress to evaluate the critical shear stress for the onset of extrudate distortion, showed differences in the tendency for extrudate distortion or melt fracture of these different blends. Also discussed is the effect of melt viscosity and melt elasticity on extrudate distortion behavior at the critical condition, which showed a unique critical value of the ratio (melt elasticity parameter)^1/2 (melt viscosity) for all these blends. Blend morphologies before and after the flow through the capillary are investigated through scanning electron microscopy, and their correlations with rheological parameters of the melt are discussed.