Maleated Elastomer Research Articles

Supramolecular semicrystalline polyolefin elastomer blends with triple‐shape memory effects

AbstractSupramolecular polyolefin elastomer blends possessing triple‐shape memory effects were prepared by melt blending of two semicrystalline maleated elastomers (maleated ethylene‐propylene‐diene rubber (mEPDM) and maleated polyethylene‐octene elastomer (mPOE)) in the presence of a small amount of 3‐amino‐1,2,4‐triazole (ATA). The amino group of ATA reacted with the maleic anhydride groups of both elastomers during melt blending to form supramolecular hydrogen‐bonded networks. Dynamic mechanical analysis of the blends showed drops in the storage modulus at two different transition temperatures (Ttrans) belonging to the crystalline melting temperatures of each phase as well as a plateau above these two Ttrans. This is an essential property for triple‐shape memory behavior. Dual‐shape memory properties of the blends were determined using one‐step programming under three different temperature ranges. When an individual crystalline phase is used for the fixing process, the switching temperature (Tsw) relates to the melting temperature of a particular phase during the recovery process. However, if both crystalline phases are used simultaneously for the fixing process, then the Tsw relates to the higher melting temperature. Cyclic two‐step programming revealed that two different shapes can be fixed, one by EPDM crystallization and the other by POE crystallization, and both programmed shapes can be recovered upon heating above a specific Tsw. © 2016 Society of Chemical Industry

Influence of maleated elastomer on filler dispersion, mechanical and antimicrobial properties of hybrid HDPE/clay/silver nanocomposites

This work analyses the effect of using ethylene-propylene-diene-monomer-grafted maleic anhydride (EPDM-g-MA) as compatibilizer to improve the interfacial properties and toughness of high-density polyethylene–organoclay–silver (HDPE/clay/silver) nanocomposites. EPDM-g-MA was reacted using ultrasound with a solution of AgNO3 0.04 M and ethylene glycol using ammonium hydroxide to obtain the silver ammonium complex. This silver-coated maleated EPDM was then melt mixed with HDPE and organoclay (Nanomer I28E) using a twin-screw extruder. Transmission electron microscopy (STEM) and X-ray diffraction (XRD) results confirmed the filler dispersion of both organoclay and silver nanoparticles into HDPE matrix when maleated EPDM was used. Both fillers were better dispersed and exfoliated by using this compatibilizer. The thermal stability enhancement of nanocomposites was confirmed using thermogravimetric analysis. Mechanical and antimicrobial properties demonstrated that better dispersed filler obtained with maleated EPDM enhanced the toughness and antimicrobial behaviour of HDPE/clay/silver hybrid nanocomposites. This confirmed that maleated EPDM was an efficient compatibilizer to obtain hybrid nanocomposites with enhanced properties to be used for several HDPE applications.

Mechanical properties and nonisothermal crystallization of polyamide 6/carbon fiber composites toughened by maleated elastomers

Polyamide 6/carbon fiber (PA6/CF) composites toughened with maleated elastomers were prepared by melt blending using twin‐screw extruder followed by injection molding. Three kinds of maleated elastomers, maleic anhydride (MAH)‐grafted ethylene‐vinyl acetate copolymer (EVA‐g‐MAH), MAH‐grafted ethylene‐propylene‐diene terpolymer (EPDM‐g‐MAH), and MAH‐grafted hydrogenated styrene‐butadiene‐styrene (SEBS‐g‐MAH), were used to toughen the PA6/CF composites. The mechanical properties, morphology, nonisothermal crystallization, and subsequent melting behavior of PA6 hybrid composites were investigated. Mechanical tests indicated that incorporation of elastomers improved the impact properties of CF‐reinforced PA composites accompanied with loss of tensile strength and modulus. It was observed from scanning electron microscope photographs that modification with maleated elastomers improved the interfacial adhesion between the CFs and PA6 matrix. Nonisothermal crystallization behavior showed that three kinds of elastomers had negative effect on crystallization and retarded crystallization of PA6. Kissinger's analysis illustrated that addition of CF slightly increased the crystallization activation energy of PA6, whereas incorporation of elastomers reversed it compared with pure PA6. Furthermore, a slight decrease in crystallinity and melting peak of the composites after incorporation of elastomers was observed compared with pure PA6. Polarizing optical microscope results showed that the transcrystallinity phenomenon seemed to be also affected when the matrix was added by the elastomers. POLYM. COMPOS., 35:2170–2179, 2014. © 2014 Society of Plastics Engineers

Toughening of PA6 nanocomposites by reactive acrylonitrile–butadiene–styrene core–shell rubber particles

The effect of addition of organoclay and the reactive ABS‐g‐MA core‐shell particles on the mechanical properties and morphology of blends of polyamide (PA6) were reported. The reactive rubber particles with core‐shell structure were selected as modifier instead of conventional reactive bulk rubber. The microstructure of the ternary nanocomposites was characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Impact strength and stress–strain behavior of blends were measured as a function of organoclay content and core/shell ratio of ABS‐g‐MA. The organoclay plates affected the interfacial adhesion between polyamide and the core‐shell particles because of a shielding effect of organclay on the interacting of amine end groups of PA6 with the MA groups of ABS‐g‐MA. The poor dispersion behavior of ternary nanocomposites was observed when the core/shell ratio is 80/20, and with an increase of organoclay content, the core/shell dispersed phase size increased. Blends based on the maleated elastomer with the core/shell ratio 60/40 gave a more beneficial balance of toughness versus stiffness. POLYM. COMPOS., 35:864–871, 2014. © 2013 Society of Plastics Engineers

Comparison of the toughening effects of different elastomers on nylon 1010

AbstractThe toughness of three different elastomer‐toughened nylon 1010 blends was investigated via standard notched Izod impact test and single edge notched three‐point bending test. The toughness of nylon 1010 blends varies much with different elastomer types and components. All three kinds of nylon/elastomer/maleated‐elastomer blends showed high impact strength (over 50 kJ m−2) as long as at appropriate blending ratios. With increasing maleated elastomer content, brittle‐ductile transition was observed for all three kinds of elastomer‐toughened nylon 1010 blends. The number average dispersed particle size (dn) of ethylene‐1‐octene copolymers or ethylene‐vinyl acetate copolymers toughened nylon 1010 blends significantly decreased from over 1 to 0.1 μm with increasing corresponding maleated elastomer content. Investigation on the fracture toughness showed the dissipative energy density gradually increased with decreasing dn, while the limited specific fracture energy increased with increasing dn when dn was below 1 μm and then sharply decreased with further increasing dn. The energy consumed in the outer plastic zone was the main part of the whole energy dissipated during the fracture process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Morphology and Mechanical Properties of Rubber Toughened Amorphous Polyamide/MMT Nanocomposites

The effects of addition of an organoclay on the morphology and the mechanical properties of blends of an amorphous polyamide (a-PA) and an elastomer (with and without grafted maleic anhydride) prepared via melt processing are reported. Transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS) were employed to obtain a detailed quantitative analyses of the morphology of the elastomer particles for these nanocomposites containing 80 wt % a-PA and 20 wt % elastomer. Stress−strain diagrams and impact strength were measured as a function of organoclay content for blends containing maleated and unmaleated elastomer. It is clear that the addition of organoclay to blends can be an effective way for reducing elastomer particle size and enhancing stiffness when the elastomer is not maleated; however, for this system, toughness is not improved in spite of these morphological changes. Blends based on the maleated elastomer give a more beneficial balance of toughness versus stiffness.

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

AbstractPolypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Preparation and Characterisation of Polyethylene-Octene Grafted Maleic Anhydride-Toughened 70:30 PA6/PP/MMT Nanocomposites

A series of nanocomposites consisting of a polyamide 6 (PA6) and polypropylene (PP) matrix (70:30) with a maleated polyethylene-octene elastomer (POEgMAH) and organophilic modified montmorillonite (MMT) were prepared by melt compounding in a co-rotating twin-screw extruder followed by injection moulding. The weight fraction of organoclay was adjusted from 2 – 10 wt% by increments of 2 wt% and the weight fraction of POEgMAH was fixed at 10 wt%. POEgMAH was used as an impact modifier as well as compatibiliser in the nanocomposites. Mechanical properties of the blends were investigated by tensile, flexural and impact testing. X-ray diffraction (XRD) was used to characterise the nanocomposites. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Addition of 4 wt% organoclay showed the highest tensile and flexural strengths for the blends. The Young's and flexural moduli were also improved with increasing the organoclay concentration but with a corresponding reduction in impact strength and elongation at break. XRD result revealed that the organoclay was dispersed uniformly (exfoliated) although the degree of exfoliation decreased with increasing organoclay content. The DSC analysis showed that the crystallinity of the blends decreased with increasing organoclay concentration. It was shown from the TGA analysis that the thermal stability of the PA6/PP nanocomposites was significantly improved in the presence of impermeable silicate layers in the blends.

The Effect of Rubber Type and Rubber Functionality on the Morphological and Mechanical Properties of Rubber-toughened Polyamide 6/Polypropylene Nanocomposites

Rubber toughened polyamide 6/polypropylene (PA6/PP) nanocomposites containing 4 wt % of organophilic modified montmorilonite (OMMT) were produced by melt compounding followed by injection moulding. Four different types of elastomer were incorporated into the blends as a toughener, i.e., ethylene-octene elastomer (POE), ethylene-propylene elastomer (EPR), maleated POE (POEgMAH) and maleated EPR (EPRgMAH). The influences of maleating on the interfacial adhesion and mechanical properties of the nanocomposites were investigated in term of mechanical testing, the X-ray diffraction (XRD) and scanning electron microscope (SEM) observation. The results showed that modulus and strength of the nanocomposites was not significantly affected by types of elastomer and their functionality. However, the toughness of the nanocomposites toughened by maleated elastomer was higher than the unmaleated elastomer. The SEM observation revealed that rubber functionality reduces the elastomer particle size in the PA6/PP matrix due to the in situ formation of graft copolymer between maleated elastomer and PA6 during melt processing. XRD revealed that the type of elastomer and functionality did not affect the dispersion of the organoclay in the system.

Comparison of the toughening behavior of nylon 6 versus an amorphous polyamide using various maleated elastomers

The toughening effect of two types of elastomers based on ethylene/α-olefin copolymers, viz, an ethylene/propylene copolymer (EPR) with its maleated version, EPR- g-MA, and an ethylene/1-octene copolymer (EOR) with its maleated versions, EOR- g-MA- X% ( X=0.35, 1.6, 2.5), for two classes of polyamides: semi-crystalline nylon 6 versus an amorphous polyamide (Zytel 330 from DuPont), designated as a-PA, was explored. The results are compared with those reported earlier based on a styrenic triblock copolymer having a hydrogenated midblock, SEBS, and its maleated version, SEBS- g-MA, elastomer system. Izod impact strength was examined as a function of rubber content, rubber particle size and temperature. All three factors influence the impact behavior considerably for the two polyamide matrices. The a-PA is found to require a somewhat lower content of rubber for toughening than nylon 6. Very similar optimum ranges of rubber particle sizes were observed for ternary blends of EOR- g-MA/EOR with each of the two polyamides while blends based on mixtures of EPR- g-MA/EPR and SEBS- g-MA/SEBS (where the total rubber content is 20% by weight) show only an upper limit for a-PA but an optimum range of particle sizes for nylon 6 for effective toughening. Higher EPR- g-MA contents lead to lower ductile–brittle transition temperatures ( T db) as expected; however, a-PA binary blends with EPR- g-MA have a much lower T db than do nylon 6 blends when the content of the maleated elastomer is not high. A minimum in plots of ductile–brittle transition temperature versus particle size appears for ternary blends of each of the matrices with EOR- g-MA/EOR; blends based on SEBS- g-MA/SEBS, in most cases, show higher ductile–brittle transition temperatures, regardless of the matrix. However, blends with EPR- g-MA/EPR show comparable T db with those based on EOR- g-MA/EOR for the amorphous polyamide but show the lowest ductile–brittle transition temperatures for nylon 6 within the range of particle sizes examined. For the blends with a bimodal size distribution, the global weight average rubber particle size is inappropriate for correlating the Izod impact strength and ductile–brittle transition temperature. In general, trends for this amorphous polyamide are rather similar to those of semi-crystalline nylon 6.

Toughening Studies of an Unsaturated Polyester Resin Using Maleated Elastomers

Unsaturated polyester resins are extensively used in the fibre-reinforced plastic industry. The fracture toughness and impact resistance of rigid unsaturated polyester can be improved by the incorporation of elastomers by physical and chemical methods. In the physical method, two strategies are adopted. In the first, various masticated elastomers are dissolved in styrene and blended with unsaturated polyester resin. In this study, the mechanical properties of cured blends are compared with the unmodified resin and the performance of nitrile rubber is found to be far superior to all other rubbers considered. In the second approach, elastomers are modified by grafting with maleic anhydride. These maleated elastomers are then dissolved in styrene and blended with polyester resin. Maleic anhydride modified elastomers are found to improve the mechanical properties such as toughness, impact resistance and tensile strength of the cured resin to a greater extent compared to unmodified elastomers.

Mechanical properties and morphology of impact modified polypropylene-wood flour composites

The mechanical properties and morphology of polypropylene/wood flour (PP/WF) composites with different impact modifiers and maleated polypropylene (MAPP) as a compatibilizer have been studied. Two different ethylene/propylene/diene terpolymers (EPDM) and one maleated styrene–ethylene/butylene–styrene triblock copolymer (SEBS–MA) have been used as impact modifiers in the PP/WF systems. All three elastomers increased the impact strength of the PP/WF composites but the addition of maleated EPDM and SEBS gave the greatest improvements in impact strength. Addition of MAPP did not affect the impact properties of the composites but had a positive effect on the composite unnotched impact strength when used together with elastomers. Tensile tests showed that MAPP had a negative effect on the elongation at break and a positive effect on tensile strength. The impact modifiers were found to decrease the stiffness of the composites. Scanning electron microscopy showed that maleated EPDM and SEBS had a stronger affinity for the wood surfaces than did the unmodified EPDM. The maleated elastomers are, therefore, expected to form a flexible interphase around the wood particles giving the composites better impact strength. MAPP further enhanced adhesion between WF and impact-modified PP systems. EPDM and EPDM–MA rubber domains were homogeneously dispersed in the PP matrix, the diameter of domains being between 0.1–1 μm. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1503–1513, 1998

The role of matrix molecular weight in rubber toughened nylon 6 blends: 1. Morphology

The effects of polyamide molecular weight on morphology generation in nylon 6 blends with maleated elastomers are described. The elastomers used include styrene—butadiene—styrene block copolymers with a hydrogenated mid-block, SEBS, and versions with X % grafted maleic anhydride, SEBS-g-MA- X%, and an ethylene/propylene copolymer, EPR, and a maleated version EPR-g-MA. The molecular weight of the nylon 6 phase governs the melt viscosity of the blend matrix and the number of amine end groups available for reaction with the maleic anhydride groups in the rubber phase; both of which influence the size, shape, and size distribution of the rubber phase formed during blending. In general, rubber particle size, distribution, and the amount of occluded material in the rubber phase decreases as the nylon 6 molecular weight increases. Measurement of the extent of reaction between the amine end groups and the grafted maleic anhydride revealed that a higher fraction of nylon 6 chains are grafted to the rubber matrix as the nylon 6 molecular weight increases. The weight average rubber particle size and size distribution for blends based on SEBS-g-MA- X% are smaller than corresponding blends based on SEBS/SEBS-g-MA-2% mixtures containing the same amount of maleic anhydride. EPR/EPR-g-MA mixtures produce non-spherical morphologies that are typically larger and more polydisperse than SEBS type elastomers. One reason for this difference is the fact that SEBS elastomers react more readily with nylon 6 than do EPR/EPR-g-MA mixtures as determined by extent of amine reaction and torque rheometry. The weight average rubber particle size for blends of the various rubbers and nylon 6 materials were correlated using a modified Taylor theory analysis. A master curve was generated by determining shift factors needed to superimpose the maleated rubber/nylon 6 curves onto a reference curve for the non-maleated rubber, SEBS. The overall shift factors correlate linearly with the maleic anhydride content of the rubber phase.

The effect of polyamide end‐group configuration on morphology and toughness of blends with maleated elastomers

The effect of polyamide end-group configuration on morphology generation and toughness of blends with maleated elastomers was investigated. Two difunctional polyamides, a copolymer containing 15% nylon 6,6 and an amine enriched nylon 6, were compared to monofunctional nylon 6 materials of equivalent molecular weight and melt viscosity. Difunctional polyamides have some chains with amine groups on both ends capable of reacting with the maleated rubber phase resulting in crosslinking-type effects. The elastomers used included styrene-butadiene-styrene block copolymers with a hydrogenated midblock, SEBS, and versions with X% grafted maleic anhydride, SEBS-g-MA-X%, and a maleated ethylene/propylene random copolymer, EPR-g-MA. Blends based on difunctional polyamides form large, complex rubber particles when compounded in a single-screw extruder; however, by compounding with an appropriate twin-screw extruder, the size and complexity of the particles can be reduced to levels similar to blends with the monofunctional nylon 6 controls. Measurement of the extent of reaction between the amine end groups and the grafted maleic anhydride revealed that a larger number of amine groups are consumed for the difunctional polyamides than for their monofunctional controls. The room-temperature Izod impact strength of blends with the difunctional polyamides is greater than are the corresponding blends with the controls; however, subambient toughness depends mainly on the inherent ductility of the polyamide matrix. © 1996 John Wiley & Sons, Inc.

The effect of polyamide end-group configuration on morphology and toughness of blends with maleated elastomers

The effect of polyamide end-group configuration on morphology generation and toughness of blends with maleated elastomers was investigated. Two difunctional polyamides, a copolymer containing 15% nylon 6,6 and an amine enriched nylon 6, were compared to monofunctional nylon 6 materials of equivalent molecular weight and melt viscosity. Difunctional polyamides have some chains with amine groups on both ends capable of reacting with the maleated rubber phase resulting in crosslinking-type effects. The elastomers used included styrene-butadiene-styrene block copolymers with a hydrogenated midblock, SEBS, and versions with X% grafted maleic anhydride, SEBS-g-MA-X%, and a maleated ethylene/propylene random copolymer, EPR-g-MA. Blends based on difunctional polyamides form large, complex rubber particles when compounded in a single-screw extruder; however, by compounding with an appropriate twin-screw extruder, the size and complexity of the particles can be reduced to levels similar to blends with the monofunctional nylon 6 controls. Measurement of the extent of reaction between the amine end groups and the grafted maleic anhydride revealed that a larger number of amine groups are consumed for the difunctional polyamides than for their monofunctional controls. The room-temperature Izod impact strength of blends with the difunctional polyamides is greater than are the corresponding blends with the controls; however, subambient toughness depends mainly on the inherent ductility of the polyamide matrix. © 1996 John Wiley & Sons, Inc.

Mechanical behaviour and morphology of toughened aliphatic polyamides

The mechanical properties of a series of polyamide materials (nylon 6,12, nylon 11, nylon 12 and nylon 12,12) were investigated using triblock copolymers of the type styrene-(ethylene- co-butene)-styrene (SEBS) and a maleic anhydride (MA) functionalized version (SEBS- g-MA). The results have been compared with the behaviour reported for nylon 6 and nylon 6,6 in our previous work. A much lower concentration of the maleated elastomer (SEBS- g-MA) was required for effective toughening of these polyamides with higher CH 2 NHCO ratios. This is believed to be a consequence of the inherently more ductile polyamide matrix as the methylene content of the nylon material increases. Further evidence of this was given by the trends in the ductile-brittle transition temperature of the various binary blends of these polyamides with SEBS- g-MA. Transmission electron microscopy techniques used for investigating the morphology generated in these blends showed that ternary blends of nylon x (monofunctional) materials (nylon 11 and nylon 12) yielded regular, spherical rubber particles with a continuously varying particle size as the proportion of SEBS and SEBS- g-MA in the rubber phase was changed, while ternary blends of nylon x, y (diffunctional) materials (nylon 6,12 and nylon 12,12) yielded rubber particles with varying levels of complexity and size depending on the SEBS-g- MA SEBS ratio. Such differences in the blend morphology between nylon x and nylon x, y materials have been attributed to differences in the basic chemical structure of these polyamides. The existence of critical limits on the rubber particle size for toughening these blends was also explored.