Toughening of nylon 6 with a maleated core-shell impact modifier

Super-tough nylon 6 was prepared by using maleic anhydride grafted polyethylene-octene rubber/semicrystalline polyolefin blend (TPEg) as an impact modifier. The morphology, dynamic mechanical behavior, mechanical properties, and toughening mechanism were studied. Results indicate that TPEg with a semicrystalline polyolefin core and a polyethylene-octane rubber shell, possesses not only a better processability of extruding and pelletizing with a lower cost, but also an improved toughening effect in comparison with the maleated pure polyethylene-octene rubber. The shear yielding is the main mechanism of the impact energy dissipation. In addition, the influence of melt viscosity of nylon 6 on toughening effectiveness was also investigated. High melt viscosity of matrix is advantageous to the improvement of notched Izod impact strength. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1987–1994, 1998     

Phase morphology development in PP/PA6 blends induced by a maleated thermoplastic elastomer

The effects of maleated thermoplastic elastomer (TPEg) on morphological development of polypropylene (PP)/polyamide 6 (PA6) blends with a fixed PA6 content (30 wt %) were investigated. For purpose of comparison, nonmaleated thermoplastic elastomer (TPE) was also added to the above binary blends. A comparative study of FTIR spectroscopy in above both ternary blends confirmed the formation of in situ graft copolymer in the PP/PA6/TPEg blend. Dynamic mechanical analysis (DMA) indicated that un‐like TPE, the incorporation of TPEg remarkably affected both intensity and position of loss peaks of blend components. Scanning electron microscopy (SEM) demonstrated that PP/PA6/TPE blends still exhibited poor interfacial adhesion between the dispersed phase and matrix. However, the use of TPEg induced a finer dispersion and promoted interfacial adhesion. Transmission electron microscopy (TEM) for PP/PA6/TPEg blends showed that a core‐shell structure consisting of PA6 particles encapsulated by an interlayer was formed in PP matrix. With the concentration of TPEg increasing, the dispersed core‐shell particles morphology was found to transform from discrete acorn‐type particles to agglomerate with increasing degree of encapsulation. The modified Harkin's equation was applied to illustrate the evolution of morphology with TPEg concentration. “Droplet‐sandwiched experiments” further confirmed the encapsulation morphology in PP/PA6/TPEg blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1050–1061, 2006     

Toughening of nylon‐6 with epoxy‐functionalized acrylonitrile‐butadiene‐styrene copolymer

Glycidyl methacrylate (GMA) functionalized acrylonitrile‐butadiene‐styrene (ABS) copolymers have been prepared via an emulsion polymerization process. The epoxy‐functionalized ABS (e‐ABS) particles were used to toughen nylon‐6. Molau tests and FTIR results showed the reactions between nylon‐6 and e‐ABS have taken place. Scanning electron microscopy (SEM) displayed the compatibilization reaction between epoxy groups of e‐ABS and nylon‐6 chain ends (amine or carboxyl groups), which improve disperse morphology of e‐ABS in the nylon‐6 matrix. The presence of only a small amount of GMA (1 wt %) within the e‐ABS copolymer was sufficient to induce a pronounced improvement of the impact strength of nylon‐6 blends; whereas further increase of the GMA contents in e‐ABS resulted in lower impact strength because of the crosslinking reaction between nylon‐6 and e‐ABS, resulting in agglomeration of the ABS particles. SEM results showed shear yielding of the nylon‐6 matrix and cavitation of rubber particles were the major toughening mechanisms. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2170–2180, 2005     

Effect of EVM/EVA‐g‐MAH ratio on the structure and properties of nylon 1010 blends

The nylon 1010/ethylene‐vinyl acetate rubber (EVM)/maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) ternary blends were prepared. The effect of EVM/EVA‐g‐MAH ratio on the toughness of blends was examined. A super tough nylon 1010 blends were obtained by the incorporation of both EVM and EVA‐g‐MAH. Impact essential work of fracture (EWF) model was used to characterize the fracture behavior of the blends. The nylon/EVM/EVA‐g‐MAH (80/15/5) blend had the highest total fracture energy at a given ligament length (5 mm) and the highest dissipative energy density among all the studied blends. Scanning electron microscopy images showed the EVM and EVA‐g‐MAH existed as spherical particles in nylon 1010 matrix and their size decreased gradually with increasing EVA‐g‐MAH content. Large plastic deformation was observed on the impact fracture surface of the nylon/EVM/EVA‐g‐MAH (80/15/5) blend and related to its high impact strength. Then with increasing EVA‐g‐MAH proportion, the matrix shear yielding of nylon/EVM/EVA‐g‐MAH blends became less obvious. EVM and EVA‐g‐MAH greatly increased the apparent viscosity of nylon 1010, especially at low shear rates. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 877–887, 2009     

Toughening effect of ethylene‐vinyl acetate rubber on nylon 1010 compatibilized by maleated ethylene‐vinyl acetate copolymers

The toughening effect of ethylene‐vinyl acetate rubbers (EVM) with maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) on the nylon 1010 was investigated. The addition of 5 phr (per hundred nylon 1010) EVM increased the elongation at break of nylon 1010 to a great extent. The notched Izod impact strength of nylon/EVM blends increased with increasing EVM content. Scanning electron microscope showed that the EVM particle size was around 0.5 μm when the EVM content was 5 phr and increased with increasing EVM content. After the addition of EVA‐g‐MAH to nylon/EVM (100/20) blend, the average diameter of EVM particles decreased from more than 1 μm to 0.5–0.6 μm. EVA‐g‐MAH could improve the adhesion between nylon 1010 and EVM. A sharp brittle‐ductile transition (BDT) was observed when the interparticle distance was about 0.2 μm, independent of the addition of EVA‐g‐MAH. The notched Izod impact strength of nylon/EVM blends at low temperatures was measured and the BDT shifted toward low temperatures with increasing EVM or EVA‐g‐MAH content. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 434–444, 2009     

Synergistically toughening high‐density polyethylene with calcium carbonate and elastomer

The microstructure, impact strength, and rheological properties of blends consisting of high‐density polyethylene (HDPE) and maleated poly (ethylene‐octene) (POEg) and/or calcium carbonate (CaCO₃) were investigated. The improvement of impact strength of HDPE/POEg was limited due to the high miscibility between them. The introduction of CaCO₃ had a negative impact on the toughness of the matrix because of the poor interfacial adhesion. In ternary blends of HDPE/POEg/CaCO₃, an elastomer layer was formed around CaCO₃ particles due to the strong interaction between POEg and CaCO₃, which improves the HDPE‐CaCO₃ interfacial strength and the toughness of the blends. A significant enhancement of dynamic viscosity, storage modulus, and the low‐shear viscosity were observed as the results of the high miscibility of HDPE with POEg and strong interaction between POEg and CaCO₃. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3213–3221, 2005     

混合方式对增容尼龙-6/聚苯醚体系的影响

研究了三种混合方式对于Nylon 6 PPO TPEg共混体系的影响 .混合是在双螺杆挤出机上进行的 .即(A)尼龙 6、聚苯醚和TPEg的混合物直接进行熔融挤出 ;(B)尼龙 6与TPEg的混合物预挤出 ,然后与聚苯醚熔融挤出 ;(C)聚苯醚和TPEg的混合物预挤出 ,然后与尼龙 6熔融挤出 .实验结果表明 ,混合方式不仅会影响共混物的形貌结构 ,而且会影响复合材料的最终性能 ,如力学性能、热性能和尺寸稳定性 .采用混合方式C所得的尼龙 6 聚苯醚复合材料的抗冲击强度高于用混合方式A和B所制备的复合材料 .这是因为聚苯醚和TPEg预共混时 ,聚苯醚上的OH基团和TPEg上的一部分马来酸酐发生化学反应 .然后预混物和尼龙 6熔融挤出时 ,剩下的马来酸酐再与尼龙分子上的NH2 基团反应 .这样就会形成一个好的界面层 ,它使复合材料的抗冲击强度大幅度提高 ,材料达到了超高韧性     

Toughening of a copolyester with a maleated core‐shell toughener

A reactive extrusion process was developed to toughen an amorphous copolyester (PETG) of ethylene glycol, terephthalic acid and 1,4‐cyclohexanedimethanol using either a maleic anhydride grafted polyethylene–octene elastomer (POEg), or a maleic anhydride grafted mixture (TPEg) of the polyethylene–octene elastomer and a semicrystalline polyolefin plastic as the impact modifier. TPEg showed an important toughening effect on the PETG. A sharp ductile‐brittle transition was observed when the TPEg content was about 10 wt %. For POEg toughened PETG, the ductile–brittle transition required a higher content in POEg, ∼15 wt %. Evolution of the topography and morphology of the blends and the relationship between impact strength and topography were discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2801–2809, 2000     

马来酸酐接枝热塑性弹性体在PP/PA6共混物中的作用

研究了马来酸酐接枝热塑性弹性体 (TPEg )作为增容剂对聚丙烯 (PP) 尼龙 6 (PA6 )共混体系的相容性、相态以及物理力学性能的影响 .研究结果表明TPEg的加入大大改善了PP PA6共混体系的相容性 ,且随TPEg含量的增大分散相粒径明显降低 ,共混物的韧性以及延展性大大提高 ,同时拉伸强度及模量仍保持较好的水平 .TPEg增容的PP PA6共混物的非等温结晶行为的研究表明 ,共混物中PP和PA6的结晶行为不同于各自纯的聚合物 ,PA6作为成核剂使PP的结晶温度提高 ;而PA6由于TPEg的加入 ,出现分级结晶现象 ,一级结晶温度略低于纯PA6的结晶温度 ,且随TPEg含量增大结晶受阻 ,二级结晶温度与PP的接近 .由于PP、PA 6以及TPEg之间存在较强的相互作用 ,三元共混物中PP及PA6的玻璃化转变温度分别较其纯聚合物升高 .基于上述结果 ,提出了本共混体系的结构模型     

Preparation of core‐shell structured particle and its application in toughening PA6/PBT blends

Combining the excellent mechanical strengths of polyamide 6 (PA6) with the low water absorption of poly(butylene terephthalate) (PBT) was supposed to be a feasible way to prepare a high comprehensive performance material. However, the poor compatibility between PA6 and PBT resulted in low‐notched impact strength of PA6/PBT blends. Poly(n‐butyl acrylate)/poly(methyl methacrylate‐co‐methacrylic acid) (PBMMA), a core‐shell structured modifier with controlled particle sizes, was prepared by seed emulsion polymerization and confirmed by Transmission electron microscope (TEM). The PBMMA particles as toughening modifier and compatilizer were employed to toughen PA6/PBT blends. The notched impact strength of the PA6/PBT blends was significantly increased and the water absorption was reduced with the addition of PBMMA particles. With 23.0 wt% modifier loading, the notched impact strength of the blends was 25.66 kJ/m², which was 4.04 times higher than that of pure PA6/PBT. Meanwhile, the water absorption of the blends was only 1.3%, dropping 53.6% compared with pure PA6 and reducing by 26.6% than PA6/PBT. Scanning electron microscope results showed that the PBMMA particles were dispersed in the PA6/PBT blends homogeneously, and the toughening mechanism was the cavitation of rubber particles and shear yielding of the matrix. Thermo‐gravimetric analysis analysis demonstrated that the compatibility between PA6 and PBT was improved with the addition of core‐shell PBMMA particles. The core‐shell particles could be used as an effective modifier to achieve the high toughness and low water absorption for PA6/PBT blends. Copyright © 2016 John Wiley & Sons, Ltd.     

Rheological properties and the interface in polycarbonate/impact modifier blends: Effect of modifier shell molecular weight

Core-shell impact modifiers are used to enhance the impact strength of thermoplastics such as polycarbonate. The shell of the modifier is designed specifically to interact with the matrix polymer because interfacial adhesion between the modifier and matrix is important in improving the impact strength. Several methods have been proposed to study the interactions at the modifier/matrix interface. One measure of this interaction is the strength of lap joints. The degree of interactions at the interface can be characterized as the thickness of the interfacial region where the chains of the two polymers mix. Yet another aspect is related to the effect of interfacial interactions on the dynamic mechanical properties of the blend. Previous studies have shown that the viscoelastic properties of these blends deviate from the emulsion models that have been proposed for such blends. The deviation of the measured viscoelastic behavior of these blends compared to that predicted by the models has been attributed to the formation of network structure of particles in the blend. The formation of the network structure is a consequence of larger effective volumes of the particles due to interactions at the interface with the matrix. This study provides a means of using rheological properties and the emulsion models to estimate the extent of interaction at the modifier/matrix interface. In blends used in this study it can be shown that the interactions between the modifier and matrix extend far beyond the boundary between the two and the estimated effective volume fraction of modifier is much larger than the actual modifier content in the blend. The effective volume fraction is frequency dependent and decreases with increasing frequency. The data suggest that beyond certain frequencies the modifier no longer interacts with the matrix and the system has properties similar to the matrix with holes. The data are presented which indicate that, within the range studied, lower modifier shell molecular weight results in a higher level of interaction with polycarbonate. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1095–1105, 1998     

Toughening of poly(2,6-dimethyl-1,4-phenylene oxide)/nylon 6 alloys with functionalized elastomers via reactive compatibilization: morphology, mechanical properties, and rheology

Blends of poly(2,6-dimethyl-1,4-phenylene oxide)/nylon 6 alloys based on ethylene-propylene-diene elastomer (EPDM) grafted with maleic anhydride (MA) (EPDM-g-MA), EPDM grafted with glycidyl methacrylate (EPDM-g-GMA), and styrene-ethylene-butadiene-styrene block copolymer grafted with MA (SEBS-g-MA) were prepared via melt extruction, and morphology, mechanical properties, and rheology were studied. The compatibilizing effects of functionalized elastomers on the PPO/nylon 6 alloys were proved by DSC analysis and confirmed by the significant improvement in the notched Izod impact strength. Toughening was resulted from the smaller particle size and finer dispersion of EPDM in the PPO/nylon 6 matrix as well as a novel network structure of SEBS-g-MA domain in matrix. The notched Izod impact strength of the blends exhibited an optimum value when the extent of MA or GMA graft ratio of EPDM varied, which was an order of magnitude higher than the non-toughened alloys. The morphology revealed that the size of EPDM particles decreased with an increase in graft ratio of MA or GMA onto EPDM. Rheology investigation indicated that the MA or GMA moieties on EPDM reacted with the amine groups of nylon 6, which increased the molecular weight and the degree of branching, and thus resulted in an increase in the viscosity of the blends. This proved the reactive compatibilization between functionalized EPDM and PPO/nylon 6 matrix.     

Mutual influence of the morphology and capillary rheological properties in nylon/glass‐fiber/liquid‐crystalline‐polymer blends

Nylon‐6/glass‐fiber (GF)/liquid‐crystalline‐polymer (LCP) ternary blends with different viscosity ratios were prepared with three kinds of nylon‐6 with different viscosities as matrices. The rheological behaviors of these blends were characterized with capillary rheometry. The morphology was observed with scanning electron microscopy and polarizing optical microscopy. This study showed that although LCP did not fibrillate in binary nylon‐6/LCP blends, LCP fibrillated to a large aspect ratio in some ternary blends after GF was added. The addition of 5 wt % LCP significantly reduced the melt viscosity of nylon‐6/GF blends to such an extent that some nylon‐6/GF/LCP blends had quite low viscosities, not only lower than those of neat resins and nylon‐6/GF blends but also lower than those of corresponding nylon‐6/LCP blends. The mutual influence of the morphology and rheological properties was examined. The great reduction of the melt viscosity was considered the result of LCP fibrillation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1619–1627, 2004     

壳-核结构增韧剂超高增韧非晶共聚酯的形貌和形态

研究了马来酸酐接枝的壳核结构增韧剂 (TPEg)对非晶热塑共聚酯 (PETG)的增韧和增强效果 ,并与马来酸酐接枝的纯橡胶类增韧剂 (POEg)作了对比 .TPEg对PETG具有显著的增韧效果 ,当TPEg含量由 5%增加到 1 0 %时 ,共混物就可以发生由脆性到超高韧性的快速转变 .而POEg虽然也可以使PETG发生由脆性到韧性的快速转变 ,但转变是在较高的增韧剂含量下发生的 ,这意味着共混物的抗张强度和模量损失更多 .利用扫描电镜观察、分析了随增韧剂含量的增加 ,共混物的形貌、形态的演化过程 .共混物的缺口冲击韧性与其形貌、形态之间存在很好的对应关系 .     

Morphology and fracture behavior of toughening‐modified poly(vinyl chloride)/organophilic montmorillonite composites

Toughening‐modified poly(vinyl chloride) (PVC)/organophilic montmorillonite (OMMT) composites with an impact‐modifier resin (Blendex 338) were prepared by melt intercalation, and their microstructures were investigated with wide‐angle X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. The mechanical properties of the PVC composites were examined in terms of the content of Blendex and OMMT, and the fracture toughness was analyzed with a modified essential work of fracture model. Intercalated structures were found in the PVC/OMMT composites with or without Blendex. Either Blendex or OMMT could improve the elongation at break and notched impact strength of PVC at proper contents. With the addition of 30 phr or more of Blendex, supertough behavior was observed for PVC/Blendex blends, and their notched impact strength was increased more than 3319% compared with that of pristine PVC. Furthermore, the addition of OMMT greatly improved both the toughness and strength of PVC/Blendex blends, and the toughening effect of OMMT on PVC/Blendex blends was much larger than that on pristine PVC. Blendex and OMMT synergistically improved the mechanical properties of PVC. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 286–295, 2004     

Influence of structure on the impact behaviour of nylon-rubber blends

Blends of nylon-6 and EPDM rubber were prepared by reaction blending to study the influence of rubber concentration, rubber particle size and interfacial adhesion on the impact strength. Rubber particles induce a sharp brittle-tough transition which is independent of the glass transition of the nylon matrix. Increasing the rubber concentration or decreasing the particle diameter shifts the brittle-tough transition temperature for notched Izod impact tests to lower values. A toughening mechanism is proposed in which the interparticle distance, the rubber modulus and the temperature play crucial roles.     

Fracture toughness of nylon‐6 blends with maleated rubbers

The fracture toughness of blends of nylon‐6 with maleated ethylene–propylene rubber and maleated styrene/hydrogenated butadiene/styrene triblock copolymer was investigated with a single‐edge‐notched three‐point‐bending instrumented Dynatup test. The blends for which the rubber particle size was less than 0.7 μm fractured in a ductile manner over the whole range of ligament lengths, whereas the blends with particles larger than 0.7 μm showed a ductile‐to‐brittle transition with the ligament length. In this regime, ductile fracture was observed for specimens with short ligaments, whereas brittle fracture was seen for those with long ligaments. The ductile fracture behavior was analyzed with the essential‐work‐of‐fracture model, whereas linear elastic fracture mechanics techniques were used to analyze the brittle fracture behavior. The fact that the ductile fracture energy was larger for the blends with the styrene/hydrogenated butadiene/styrene triblock copolymer than for those with ethylene–propylene rubber was due to the larger dissipative energy density of the blends based on the styrene/hydrogenated butadiene/styrene triblock copolymer. Both the critical strain energy release rate (G_IC) and the plane‐strain critical stress intensity factor (K_IC) increased as the rubber particle size decreased for both blend systems. The G_IC and K_IC parameters had similar values, regardless of the rubber type, when the rubber particle size was fixed. The transition ligament length was near the size criterion for plane‐strain conditions for both blend systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1739–1758, 2004     

Effect of Epoxy Resin on the Thermal,Mechanical and Rheological Properties of Polybutylene Terephthalate/Glycidyl Methacrylate Functionalized Methyl Methacrylate-butadiene Blend

Epoxy resin was used to modify polybutylene terephthalate(PBT) and glycidyl methacrylate functionalized methyl methacrylate-butadiene(MB-g-GMA) blend. Results show that MB-g-GMA dispersed in PBT matrix uniformly and PBT/MB-g-GMA/epoxy blends reveal good compatibility. However, the added epoxy resin restricted the mobility of PBT macromolecular chains during the growth process of the crystal, which reduced the final crystallinity of PBT. The PBT/MB-g-GMA blend containing 1%(mass fraction) epoxy resin exhibited good mechanical properties. For example, the notched impact strength of the PBT/MB-g-GMA blend with 1%(mass fraction) epoxy resin was about 2 times that of PBT/MB-g-GMA blend. Sanning electron microscope(SEM) results show that the shear yielding of the PBT matrix and the cavitations of rubber particles were the major toughening mechanisms. The chemical reaction between PBT and epoxy resin induced the high complex viscosity and storage modulus of PBT/MB-g-GMA blend.     

Use of a dye‐labeled ethylene‐butene copolymer as a tracer in laser scanning confocal fluorescence microscopy studies of thermoplastic olefins

A benzothioxanthene‐labeled ethylene‐butene rubber has been synthesized and tested as a potential fluorescent tracer for the impact modifier (IM) phase in laser scanning confocal fluorescence microscopy (LSCFM) studies of thermoplastic olefin (TPO) morphology. The amino‐functional Hostasol Yellow derivative HY‐DP reacts with maleated EBR‐28 to give a good labeling yield (ca. 70%) and a dye concentration of 0.051 mmol/g, when the maleated rubber is first refluxed over molecular sieves and the reaction purged with N₂. Without pretreatment of the rubber and N₂ purging, a lower labeling yield (0.036 mmol dye/g) is obtained and the labeled product tends to undergo crosslinking at 240 °C and subsequent dye detachment when the crosslinked gel is hydrolyzed. LSCFM studies reveal HY‐labeled EBR to be completely miscible and evenly dispersed in the unlabeled EBR‐9 of model TPO blends. Moreover, the HY‐labeled EBR provides good fluorescence contrast between the IM droplets and the PP matrix in the TPO blend PP/EBR (80/20) (w/w) + 3 wt % labeled polymer with respect to EBR. Imaging of IM droplets down to 40 μm below the film surface of this blend has been demonstrated. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 239–252, 2001     

The influence of partial emulsification on coalescence suppression and interfacial tension reduction in PP/PET blends

This study examines how the relative role of coalescence suppression and interfacial tension reduction influence the particle size at various levels of in situ compatibilization. The polymers studied are polyethylene terephthalate (PET) as matrix and a polypropylene (PP) as dispersed phase compatibilized by a triblock copolymer of poly(styrene–hydrogenated butadiene–styrene) (SEBS) grafted with maleic anhydride. The interfacial tension was studied by the breaking‐thread method, and it was used along with the morphology to characterize the emulsification efficacy of the copolymers. By modifying the concentration of MA grafted on the SEBS, different levels of emulsification of the blends were obtained. A comparison of 1/99 and 10/90 PP/PET blends compatibilized by SEBS‐g‐MA allows one to distinguish the relative role of interfacial tension and coalescence suppression in diminishing particle size. It is shown that varying degrees of residual coalescence remain, depending on the level of %MA in the copolymer. A detailed study of the 2%MA system below interfacial saturation was carried out to shed further light on the dependence of coalescence suppression on emulsification level and interfacial coverage. After separating out the contribution of interfacial tension on particle size reduction, it is shown that coalescence suppression for this system increases gradually with areal density of modifier at the interface right up to the region of interfacial saturation. Finally, the interfacial and morphological data were used to test the ability of the Lee and Park model to describe coalescence in polymer blends. Reasonable agreement was found between the parameter c₁, describing the coalescence in that model, and the trends related to residual coalescence from this study. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 939–951, 1999