Elastomer Toughening Research Articles

A super-toughened polyethylene naphthalene (PEN) enabled by polyacrylate elastomer with low crosslink density and reactivity

In elastomer toughening of polyester plastics, both the particle size distribution of the elastomer and the interfacial strength between the elastomer and matrix are key factors for toughness. In this work, bi-functional polyacrylate elastomers with controllable crosslinking density and reactivity were designed for enhancing the toughness of polyethylene naphthalene (PEN) matrix. Firstly, the elastomers with crosslinked structure possess increased melt viscosity and endowed wide particle size distribution, which contribute to the construct of thin matrix ligament and make PEN matrix more susceptible to shear-yield. Secondly, the high interfacial strength between elastomer and matrix can facilitate the transfer of external stress from PEN matrix to the elastomer, protecting the matrix from destroying. The resulted PEN blends exhibit an excellent impact resistance of 45.20 kJ/m2 and a high tensile toughness of 3.586 MJ/m3, which are 21.73 times and 47.81 times higher, respectively, than the virgin PEN. The present work may provide an effective approach for designing polyester blends with enhanced impact resistance and tensile toughness.

Preparation of multistage porous polymer nanocomposites and its application in architectural design

In order to solve the problem that the toughness (impact strength) of the traditional elastomer toughening will decrease its rigidity (modulus) while improving the toughness (impact strength) of the material, the multi-porous nano-cacO3/polymer composite and its application in building plastics were proposed. In this essay, the mechanical properties of nano-caco3/PVC/CPE and nano-caco3/PP/SBS composites are studied. The results showed that the notch impact strength increased by 15.8 % from 46.8 kJ/m2 to 54.2kJ/m2 when two nano-cacO3 was added into the PP/SBS blend system, indicating that nano-cacO3 also toughened PP to some extent. ConclusionNano Ca-CO3 has remarkable toughening effect on PVC blending system, and also has certain toughening effect on PP blending system. The profile with nano-cacO3 added can ensure the impact performance of low temperature drop hammer, while the notched impact strength, tensile strength, elongation at break and flexural modulus of the simply supported beam are significantly improved compared with the profile without nano-cacO3 added. The application of nano CaCO3/PVC/CPE composites in the profile of PVC doors and Windows is studied.

Synergistic preparation of a straw fiber/polylactic acid composite with high toughness and strength through interfacial compatibility enhancement and elastomer toughening

Plant fiber-reinforced polylactic acid (PLA) composites are extensively utilized in eco-friendly packaging, sports equipment, and various other applications due to their environmental benefits and cost-effectiveness. However, PLA suffers from brittleness and poor toughness, which restricts its use in scenarios demanding high toughness. To expand the application range of plant fiber-reinforced PLA-based composites and enhance their poor toughness, this study employed a two-step process involving wheat straw fiber (WF) to improve the interfacial compatibility between WF and PLA. Additionally, four elastomeric materials—poly (butylene adipate-co-terephthalate) (PBAT), poly (butylene succinate) (PBS), polycaprolactone (PCL), and polyhydroxyalkanoate (PHA)—were incorporated to achieve a mutual reactive interface enhancement and elastomeric toughening. The results demonstrated that Fe3+/TsWF/PLA/PBS exhibited a tensile strength, elongation at break, and impact strength of 34.01 MPa, 14.23 %, and 16.2 kJ/m2, respectively. These values represented a 2.4 %, 86.7 %, and 119 % increase compared to the unmodified composites. Scanning electron microscopy analysis revealed no fiber exposure in the cross-section, indicating excellent interfacial compatibility. Furthermore, X-ray diffraction and differential scanning calorimetry tests confirmed improvements in the crystalline properties of the composites. This work introduces a novel approach for preparing fiber-reinforced PLA-based composites with exceptional toughness and strength.

Ultrahigh strength and toughness of polylactide added with EGMA elastomer of a small amount processed via pressure-induced flow above the glass transition temperature

Elastomer toughening is widely recognized as a highly effective strategy for enhancing the mechanical performance of plastics. However, the improvement in toughness generally comes at the cost of a drastic sacrifice in tensile strength. In this work, ethylene–acrylic ester-glycidyl methacrylate random terpolymer (EGMA) of a small amount of 5 % in mass was applied as a toughening agent of polylactide (PLA), with the assistance of a pressure-induced flow processing at above the glass transition temperature. The obtained PLA blend showed simultaneously improved tensile strength and impact toughness. The tensile strength and Young′s modulus maintained at a relatively high level of 58 MPa and 2.1 GPa, respectively, and the notched Izod impact strength reached up to 54 kJ/m2, which was 27 times higher than that for neat PLA (1.9 kJ/m2). The increased toughness was primarily attributed to a synergistic effect of the reduced crystal sizes, reduction in phase domain sizes and enhanced interfacial interactions. This study provided a cost-effective and feasible approach to achieving strong and super-tough PLA materials, which held a significant potential for PLA widespread applications.

Ultrarobust self-healing elastomers with hydrogen bonding connected MXene network for actuator applications

Self-healing ability is highly desired for flexible actuators that operate in dynamic and real-world environments, as these machines are vulnerable to mechanical damage. However, self-healing properties and mechanical strength are often difficult to combine at the same time. We report a synergistic enhancement strategy based on the ordered micro-nano structure and interfacial hydrogen bonding aggregation to achieve self-healing elastomer toughening. The hydrogen bonding interaction drives the MXene nanosheet to self-assemble into an interconnected network around the PU latex microsphere. Thanks to the synergy of dynamic physical networks and high-density interfacial hydrogen bonding, the composites with controllable room temperature self-healing efficiency (76.5–95.9%) and tensile strength (17.7–42.6 MPa). Furthermore, the MXene network structure of the composite endows the actuator with an efficient photothermal conversion efficiency, fast responsiveness, and even functional recovery. It is an effective strategy to achieve high-strength self-healing materials through hydrogen bonding connected MXene network and interfacial hydrogen bonding aggregation, which is expected to be applied to other flexible devices, such as flexible sensors and electromagnetic shielding.

Bifunctional linear polyphosphazene decorated by allyl groups: Synthesis and application as efficient flame-retardant and toughening agent of bismaleimide

As known, the poor toughness and low fire safety of bismaleimide resin (BMI) has become a problem which restricts its further application in advanced high-performance field. Therefore, a novel allyl-functionalized linear polyphosphazene (PMAP) was designed and synthesized. With inclusion of 3wt% PMAP , the peak heat release rate (PHRR) and total smoke production (TSP) of BMI/PMAP-3 are reduced by 51.3% and 17.8%, respectively. And the residual char of BMI/PMAP increases significantly as well. Furthermore, the flame-retardant mechanism of BMI/PMAP is proposed. In condensed phase, PMAP can participate in the formation of residual char of BMI/PMAP and the char layer is with an excellent physical barrier effect by the existence of phosphorus oxygen and phosphorus nitrogen cross-linking substances. In gas phase, phosphorous oxygen free radical is also generated from PMAP, which can capture gas-phase chain free radicals and inhibit gas-phase combustion. Moreover, the impact strength of BMI/PMAP-3 increases by 85.3%, which indicates that the toughness of BMI/PMAP is effectively enhanced. The toughening mechanism of PMAP on BMI can be assigned to elastomer toughening. Therefore, with modification of PMAP, BMI/PMAP is indeed of better comprehensive performance, which is in line with expectation and provides inspiration for the simultaneous flame-retardant and toughening modification of BMI. • Innovation: bifunctional allyl functionalized linear polyphosphazene was firstly synthesized. • High-efficiency: the PHRR and impact strength of BMI/PMAP-3 is reduced by 51.3% and increased by 85.3%. • Mechanism: the flame retardant and toughening mechanism is proposed.

Effect of the elastomer viscosity on the morphology and impact behavior of injection molded foams based on blends of polypropylene and polyolefin elastomers

AbstractThe impact resistance of injection‐molded polypropylene (PP) parts is severely reduced when they are foamed. It is necessary to implement strategies, such as elastomer toughening, to increase the impact behavior of foamed parts. However, the knowledge on the effect of elastomer addition on the morphology, cellular structure, and impact of injection‐molded cellular parts is very limited. In this work, foamed parts based on blends of PP and polyolefin elastomers have been produced and characterized. A high and a low viscosity octene‐ethylene copolymer (EOC) and a high viscosity butene‐ethylene copolymer (EBC) were employed. The blends have been thermally and rheological characterized. Solids materials and foams (relative density 0.76) were injection‐molded. The solid phase and cellular structure morphologies were studied using scanning electron microscopy. The results showed that elastomer toughening has been successful to obtain an improvement of the impact behavior in solid and cellular polymers. In this case, EOC materials provide an appropriate interfacial adhesion and optimized cellular structure which results in high impact resistance. The optimum elastomer to improve the properties is the EOC with a higher viscosity which provides impact resistance with n values below 3 due to the toughening of polymer matrix, thick skin thickness, and low cell size.

Toughening Biosourced Poly(lactic acid) and Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Blends by a Renewable Poly(epichlorohydrin-co-ethylene oxide) Elastomer.

A series of sustainable polymer blends from renewable poly(lactic acid) (PLA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3,4HB), and poly(epichlorohydrin-co-ethylene oxide) (ECO) elastomer were fabricated via a melt blending method to gain balanced physical performance. The interplay of the composition, mutual miscibility, and viscosity ratio of the pristine PLA, P3,4HB, and ECO elastomer resulted in diverse phase structures of the ternary blends. An excellent flexibility at an elongation of 270% was achieved for the PLA/P3,4HB/ECO (70/20/10) blend with a core–shell structure. The PLA/P3,4HB/ECO (70/10/20) blend with a phase-separated structure exhibited a high impact strength of 54 KJ/m2, which is 25 times over that of the neat PLA. The relationship between the phase structure and physical performance of the blend was analyzed based on the compositions, surface tension, and physical characteristics of the neat components. Combining the compatibilization of the P3,4HB phase and ECO elastomer toughening played a crucial role in enhancing the mechanical properties of the blends.

Pseudo‐ductile behavior of poly(vinyl alcohol) fiber‐reinforced polypropylene

Composites based on two different polypropylene (PP) grades reinforced with poly (vinyl alcohol) (PVA) fibers were prepared by compounding and injection molding. Very high residual fiber length values of up to 2,500 μm were achieved. The impact performance of a PP homopolymer can be improved dramatically by reinforcement with the PVA fibers, even below the glass transition temperature of the matrix. For a high impact PP heterophasic copolymer, the fiber reinforcement interferes with the elastomer toughening. Scanning electron microscopy and X‐ray computer‐tomography analysis indicate that the specific composite microstructure has very long, entangled fibers and a low fiber matrix interaction allowing for pseudo‐ductility. Analysis of the micromechanical deformations by volume strain and acoustic emission measurements during tensile testing supports this hypothesis. POLYM. COMPOS., 40:4067–4078, 2019. © 2019 Society of Plastics Engineers

Loss of thermoplastic elastomer toughening in polylactide after weathering

ABSTRACTIt has been already pointed out that one of the best ways to increase toughness of the inherently brittle polylactide (PLA) without sacrificing strength and modulus is the use of thermoplastic elastomer toughening approach; but what happens under outdoor conditions was not explored. Therefore, the objective of this study was to explore the degree of losses especially in fracture toughness of PLA when blended with thermoplastic polyurethane (TPU) elastomer or thermoplastic polyester elastomer (TPE) after weathering. For this purpose, neat PLA, its 10 phr TPU and TPE blends were exposed to accelerated weathering conditions of both ultraviolet‐irradiation cycles and moisture cycles as described in the standard of ISO 4892‐3 for various periods. In general, due to the significant molecular weight reduction via chain scission reactions, drastic losses in the strength and toughness of the specimens were observed. On the other hand, in terms of %retention in the properties after weathering periods, it could be suggested that, rather than use of neat PLA, the use of its TPU or TPE blends would be still advantageous for both “indoor use” and also for “outdoor use.” © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47177.

Inherently Flame Retardant Nylon 6 Nanocomposite Fibers

In this study, inherently flame retardant nanocomposite nylon 6 fibers infused with nanoclay and intumescent additives were compounded and melt-spun. Two approaches were adopted to mitigate the loss of mechanical properties typically observed nanocomposite fiber systems: (a) additive particle size reduction; and (b) elastomer toughening of the nanocomposite system. As a result, the ductility of the FR nanocomposite formulations was improved significantly. Structural and morphological characterization of the melt-spun fibers using TEM and XRD demonstrated good dispersion of the additives and exfoliation of the nanoclay platelets. Microscale Combustion Calorimetry analysis demonstrated effective reduction of heat release capacity and thus significant enhancement of flame retardant performance of the compounded fibers.

Toughness augmentation by fibrillation and yielding in nanostructured blends with recycled polyurethane as a modifier

In the present paper, we have carefully investigated the morphology and fracture mechanism of the recycled polyurethane (RPU)/epoxy blend system. The second phase (RPU) added to the epoxy resin has a positive effect on the overall mechanical properties. Interestingly, the recycled polymer has a remarkable effect on the fracture toughness of epoxy resin. The mechanism behind the fracture toughness improvement up on the addition of RPU was found to be very similar to that of the incorporation of hyperbranched polymers in epoxy resin. Brittle to ductile fracture was clear in the case of higher loadings such as 20 and 40 phr of RPU in the epoxy resin. The mechanism behind improvement of fracture toughness was found to fibrillation of the RPU phase which was evidenced by the fracture morphology. In fact the force applied to the epoxy matrix was effectively transferred to the added RPU phase due to its strong interaction with the epoxy phase. This effective transfer of force to the RPU phase protects the epoxy matrix without catastrophic failure and we observed 44% increase in G1C values at an addition of 40 phr RPU. This results in the extensive fibrillation of RPU which causes the generation of new surfaces. Thus the impact energy has been fully utilized by the RPU phase. The mechanism is termed as simultaneous reinforcing and toughening and normally reported as a result of cavitations and yielding. SEM, HRTEM and AFM analyses clearly demonstrated the fibrillated morphology of the fracture surface and the formation of nanostructures. This report is first of its kind in the case of both epoxy modification and the elastomer toughening.

Rubber (SEBS-g-MA) Toughened Flame-Retardant Polyamide 6: Microstructure, Combustion, Extension, and Izod Impact Behavior

ABSTRACTIn this study, elastomer toughening is explored as a means of recovering ductility of polyamide 6/intumescent flame-retardant composite systems. This was achieved using a maleic anhydride modified SEBS elastomer incorporated into the system by twin-screw melt extrusion. TEM micrographs show an even distribution of both flame retardant and elastomer particles. The effects of elastomer content on mechanical properties, Izod impact behavior, and flammability of the polymer system were investigated. The incorporation of flame retardant significantly degraded the elongation and ductility of the polymer system. The addition of the elastomer succeeded in significantly enhancing the Izod impact strength and partially recovering the elongation at break without compromising the flame-retardant performance. Micro-scale Combustion Calorimeter (MCC) tests show that samples containing both elastomer and FR additives exhibit slightly improved combustion properties compared to the original polyamide 6/intumescent flame-retardant system. Rubber loadings of up to 15 wt% were possible while still achieving the highest UL-94 V0 flame exposure rating indicating a self-extinguishing and non-drip behavior.

Generalization of the sacrificial bond principle for gel and elastomer toughening

Although conventional polymer gels are known as mechanically weak materials, their fracture toughness can be effectively improved by introducing weak and brittle bonds into soft and stretchy polymer networks. This toughening method, denoted as the ‘sacrificial bond principle’, has been recently proposed. In this focus review, I describe some extremely tough gels prepared using this principle, e.g., double- or multiple-network gels with high water content featuring covalent sacrificial bonds, self-healing polyampholyte gels containing ionic sacrificial bonds and PDGI/PAAm gels based on hydrophobic sacrificial bonds exhibiting stress-responsive structural colors.

Simultaneous toughening of PPO/HIPS/Glass fiber reinforced composites with thermoplastic rubbers

ABSTRACTSimultaneously reinforced and toughened PPO/HIPS/SEBS/glass fiber (GF) 60/40/5/30 composites were successfully prepared with GF as reinforcing agent and SEBS as toughener. The formulation of PPO/HIPS/SEBS/GF quaternary composites was stepwise optimized by evaluating the effect of GF and SEBS on the processing, mechanical and thermal properties of the composites. The synergistic effects of GF reinforcement and elastomer toughening are attributed to high performance PPO/HIPS/SEBS/GF composites. Among the four elastomers studied, SEBS exhibited as effective toughener for PPO/HIPS matrix and the resulted PPO/HIPS/SEBS/GF composites presented a good combination of mechanical and thermal properties. The optimized PPO/HIPS/SEBS/GF 60/40/5/30 quaternary composites displayed a tensile strength of 123.6 MPa, a bending strength of 149.7 MPa, an unnotched impact strength of 46.6 KJ/m2 and a heat distortion temperature of 148.9°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40299.

Reactive Compatibilization and Elastomer Toughening of Poly(2,6-dimethyl-1,4-phenylene oxide)/Polyamide 6 Blends

Poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 (PPO/PA6) blends were reactively compatibilized by maleic anhydride (MA) grafted PPO (PPO- g-MA) and toughened by MA grafted styrene-ethylene-butadiene-styrene block copolymer (SEBS) (SEBS- g-MA) via melt extrusion. The compatibilizing effect of PPO- g-MA on the PPO/PA6 blends was studied by using scanning electronic microscopy, differential scanning calorimetry and mechanical properties tests. The notched impact strength of PPO- g-MA/PPO/PA6/SEBS- g-MA blends increased with increasing SEBS- g-MA content, leading to blends having super-tough behaviour. The fracture behaviour of the PPO/PA6 blends was studied using a modified essential work of fracture model (EWF), which showed that plastic deformation related to SEBS- g-MA was the crucial factor for the toughening.

Toughened nylon66/nylon6 ternary nanocomposites by elastomers

The elastomer toughening of PA66/PA6 nanocomposites prepared from the organic modified montmorillonite (OMMT) was examined as a means of balancing stiffness/strength versus toughness/ductility. Several different formulations varying in OMMT content were made by mixing of PA6 and OMMT as a master-batch and then blending it with PA66 and different elastomers in a twin screw extruder. In this sequence, the OMMT layers were well exfoliated in the nylon alloy matrix. The introduction of silicate layers with PA6 induced the appearance of the γ crystal phase in the nanocomposites, which is unstable and seldom appears in PA66 at room temperature and it further affected the morphology and dispersion of rubber phase resulting in much smaller rubber particles. The incorporation of POE-g-MA particles toughened the nanocomposites markedly, but the tensile modulus and strength were both reduced. Conversely, the use of OMMT increased the modulus but decreased the fracture toughness. The nanocomposites exhibited balanced stiffness and toughness. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Impact fracture toughness of polyamide‐6/montmorillonite nanocomposites toughened with a maleated styrene/ethylene butylene/styrene elastomer

AbstractPolyamide‐6 (PA6)/montmorillonite (MMT) nanocomposites toughened with maleated styrene/ethylene butylene/styrene (SEBS‐g‐MA) were prepared via melt compounding. Before melt intercalation, MMT was treated with an organic surfactant agent. Tensile and impact tests revealed that the PA6/4% MMT nanocomposite fractured in a brittle mode. The effects of SEBS‐g‐MA addition on the static tensile and impact properties of PA6/4% MMT were investigated. The results showed that the SEBS‐g‐MA addition improved the tensile ductility and impact strength of the PA6/4% MMT nanocomposite at the expenses of its tensile strength and stiffness. Accordingly, elastomer toughening represents an attractive route to novel characteristics for brittle clay‐reinforced polymer nanocomposites. The essential work of fracture (EWF) approach under impact drop‐weight conditions was used to evaluate the impact fracture toughness of nanocomposites toughened with an elastomer. Impact EWF measurements indicated that the SEBS‐g‐MA addition increased the fracture toughness of the PA6/4% MMT nanocomposite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 585–595, 2005

Brittle–tough transition in elastomer toughening thermoplastics: effects of the elastomer stiffness

The effect of the elastomer stiffness on brittle–tough transition in elastomer toughening thermoplastics was quantitatively studied. A correlation between brittle–tough transition temperature and the elastomer stiffness was obtained. The calculation from this correlation showed that the brittle–tough transition temperature ( T bt) of elastomer toughening thermoplastics slowly increased up to one tenth of the modulus of matrix, thereafter it increased rapidly with increasing the modulus of elastomer. The results indicated that the modulus of the elastomer must be one-tenth or less of that of the matrix in order to be effective at low temperature.

Toughened polypropylene with balanced rigidity (I): preparation and chemical structure of toughening master batch

The title toughening master batch (TMB) was synthesized in a low-viscosity reaction system by using dynamic vulcanization technique starting from polypropylene (PP) as the matrix resin and ethylene–propylene or butadiene–styrene elastomer as the toughening agent through a polymer–bridge conjunction derived from a monomer containing a carbonate group in the presence of a free radical initiator. The chemical structure of the TMBs and the effects of technological conditions on structural parameters were investigated using fractional extraction and infrared spectroscopy. The prepared TMBs consisted of unreacted PP, unreacted elastomers, graft copolymer of PP and/or elastomers containing branched chains formed by bridging agent, and crosslinked copolymer of PP and/or elastomers in conjunction with polymer bridge chains derived from bridging agent. Results showed that the PP existed in graft and crosslinked forms was in the range of 3–21 wt% and that of the elastomer toughening agent was in the range of 50–70 wt%, grafting and bridging efficiency of bridging agent was in the range of 62–88 wt%, graft copolymer content in the total TMB was in the range of 0.18–3.65 wt% and crosslinked copolymer content was in the range of 22–42 wt%. Copyright © 2000 John Wiley & Sons, Ltd.