Toughening Agent Research Articles

Azide-alkyne 반응을 이용한 In-situ 지방족 강인화제를 적용한 광투명 강인화 에폭시 수지

투명성을 유지하면서 에폭시의 인성을 향상시키기 위해서, in-situ 방법을 이용한 새로운 지방족 구조의 폴리머를 강인화제로 사용하였다. 에폭시와 click 반응의 유사한 반응 속도를 연구하고, 이를 통해 연속적인 에폭시 경화단계를 확립하였다. 먼저 선형의 지방족 강인화제를 에폭시 수지에서 합성하였고 그 후 경화제를 첨가하여 에폭시를 경화하였다. 이를 통해 semi-interpenetrating polymer network(semi-IPN) 구조를 가지는 에폭시를 제작하였다. Semi-IPN 구조를 가지는 강인화 에폭시의 특성은 기존 에폭시 및 preformed 에폭시에 비해 물성이 현저히 향상되었다. 10 wt% 강인화 에폭시의 경우 투명성과 TSUBg/SUB의 변화를 보이지 않으면서 2.62 MPa·mSUP1/2/SUP의 향상된 파괴인성 수치BR를 보였다.

Application of bio‐based dimer acid diglycidyl ester in paper‐based copper clad laminate

ABSTRACTUsing dimer acid (DA) as raw material, DA diglycidyl ester (DADGE) was synthesized and used as reactive toughening agent to prepare paper‐based copper clad laminate (p‐CCL). The factors affecting the epoxy value of DADGE and the effect of the resin on the gelation time were studied. The effects of the epoxy value and the addition amount of DADGE on the solderleaching resistance, flammability, water absorption, bending strength, and impact strength of the p‐CCL were discussed. The results showed when the molar ratio of DA to ECH was 1:8 and the molar ratio of DA to sodium hydroxide was 1:1.6, the epoxy value of DADGE reached the maximum value of 0.23 mol/100 g. The DADGE can shorten the gelation time of the glue. The p‐CCL meets the performance of the IPC‐TM‐650 standard. And when the addition amount of DADGE is less than 12 wt %, the flammability of the p‐CCL reaches UL94V‐0 level. The p‐CCL prepared by adding 6 wt % of DADGE with 0.08 mol/100 g epoxy value has the best comprehensive performance, its toughness and rigid are comparable to those of p‐CCL with 12 wt % of commercially available high performance toughening agents and it has higher solderleaching resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47508.

Practical Technology of Toughening Epoxy Resin: Influence of Toughening Agents on Mechanical and Heat Properties

This research studies the effect of several toughening agents, such as carboxyl-terminated polyether (CTPE), carboxyl-terminated polytetrahydrofuran (CTPF), carboxyl-terminated liquid nitrile rubber (CTBN), random-base liquid nitrile-butadiene rubber (RBNR) and core-shell polymer (CSP) containing polybutadiene, on epoxy resin. These epoxy resin systems containing various toughening agents showed different viscosity, in which the viscosity of CTPE and CTPF systems nearly unchanged and the viscosity of CTBN, RNBR and CSP systems increased significantly. The impact resistance of modified epoxy systems had been improved significantly, especially the CTPF system raised by 257.2%. Meanwhile, the heat resistance of epoxy systems containing different toughening agents showed different results. Compared with the pure sample, the hardness of all toughened systems decreased. CTPE and CTBN systems decreased significantly, while CTPF and CSP remained fundamentally unchanged. Toughness modification resulted in reduction of tensile strength and the retention ratio was CSP > RNBR > CTPF > CTBN > CTPE. Toughness modification resulted in reduction of compression strength and the retention ratio was RNBR > CSP > CTPF > CTBN > CTPE. All of the toughening systems kept the shear strength basically unchanged. The shear strength of the CSP system was even improved. In terms of peel strength, all of toughening systems had improved.

Feasibility of a Polymer Foaming Agent as a Grouting Material for Broken Coal Masses

A new soluble polymer foaming (PF) grouting material was developed by using hydrophilic amino resin as the base material and adding other cross‐linking, foam, foam stabilizing, toughening, and coupling agents. The PF material exhibited low viscosity, excellent adhesion, and strong penetration. The grouting reinforcement effect of the proposed PF material on broken coal masses was investigated and compared with that of traditional superfine cement (SC) through simulation experiments. Results showed that after grouting, fractures, joints, and other failure planes inside raw coal were filled and bonded, and the mechanical strength of the grout‐coal concretion improved relative to the residual strength of raw coal. The average uniaxial compressive strength of SC specimens was 6.16 MPa, whereas that of PF specimens was 10.85 MPa. Moreover, the PF specimens presented an obvious characteristic of plastic strengthening. Analyzing the reinforcement effect of the grouting materials on the basis of single structural plane theory revealed that at the critical state, the average σ3 value of SC specimens was 1.43 MPa, whereas that of PF specimens was 3.09 MPa. In addition, coordination between the lateral and axial deformations of the PF specimens during compression promoted the formation of a bearing structure that can adapt to deformation. This structure is crucial for the safe operation of coal mines.

Preparation and Characterization of Phenolic Foam Modified with Bio-Oil.

Bio-oil was added as a substitute for phenol for the preparation of a foaming phenolic resin (PR), which aimed to reduce the brittleness and pulverization of phenolic foam (PF). The components of bio-oil, the chemical structure of bio-oil phenolic resin (BPR), and the mechanical performances, and the morphological and thermal properties of bio-oil phenolic foam (BPF) were investigated. The bio-oil contained a number of phenols and abundant substances with long-chain alkanes. The peaks of OH groups, CH2 groups, C=O groups, and aromatic skeletal vibration on the Fourier transform infrared (FT-IR) spectrum became wider and sharper after adding bio-oil. These suggested that the bio-oil could partially replace phenol to prepare resin and had great potential for toughening resin. When the substitute rate of bio-oil to phenol (B/P substitute rate) was between 10% and 20%, the cell sizes of BPFs were smaller and more uniform than those of PF. The compressive strength and flexural strength of BPFs with a 10–20% B/P substitute rate increased by 10.5–47.4% and 25.0–50.5% respectively, and their pulverization ratios decreased by 14.5–38.6% in comparison to PF. All BPFs maintained good flame-retardant properties, thermal stability, and thermal isolation, although the limited oxygen index (LOI) and residual masses by thermogravimetric (TG) analysis of BPFs were lower and the thermal conducticity was slightly greater than those of PF. This indicated that the bio-oil could be used as a renewable toughening agent for PF.

Construction of Hierarchical Natural Fabric Surface Structure Based on Two-Dimensional Boron Nitride Nanosheets and Its Application for Preparing Biobased Toughened Unsaturated Polyester Resin Composites.

It has been a big challenge to prepare the unsaturated polyester resin (UPR) composites with good fire safety, interfacial quality, and impact strength in an environmentally friendly way. In this study, to improve interfacial performance of fabric-reinforced UPR composites, nontoxic two-dimensional hexagonal boron nitride (h-BN) nanosheets were assembled on the surface of ramie fabrics, where sodium alginate acts as a green dispersant to disperse h-BN sheets during the process. Then, the biobased phosphorus-containing toughening agent (PCTA) was synthesized to simultaneously improve the impact strength and fire safety of the composite. With application of h-BN nanosheets-assembled fabric (AF) and 20 wt % of PCTA, the AF/UPR@PCTA20 composite presented the maximum 41.2% decrease in the value of peak heat release rate and a maximum 17.8% decrease in the value of total heat release, which also reached V-0 rating in the vertical burning test. Meanwhile, the AF/UPR@PCTA20 composite showed an obvious increase in limiting oxygen index, from 24.0 to 29.5% compared with RF/UPR. The flame retardant mechanism was investigated from gas phase and condensed phase. Furthermore, compared to neat RF/UPR composite, the AF/UPR@PCTA20 composite showed a significant 68.8% improvement in impact strength, implying an extreme toughening effect of PCTA on UPR composites. The research provides a viable green method for the development of environmentally friendly UPR composites in the future.

Epoxy nanocomposites simultaneously strengthened and toughened by hybridization with graphene oxide and block ionomer

Epoxies are widely used in many engineering applications, however, their fracture energy remains less than desired and conventional toughening agents usually lead to compromised tensile strength. In this study, a simple one-pot blending method was used, in which both graphene oxide and a block ionomer were blended with epoxy resin. Herein, we reported that increases of ∼200% in fracture energy (GIC), 48% in uniaxial tensile strength (σt) and 340% in tensile strain could be achieved by incorporating 1.0 wt% graphene oxide into an epoxy matrix with 20 wt% sulfonated polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SSEBS). In addition, the glass transition temperature (Tg) of the nanocomposite increased with increasing graphene oxide (GO) content and the storage modulus (E′) decreased when the GO content was less than 0.50 wt% owing to the introduction of the block ionomer SSEBS. Careful examination of the nano-morphology of SSEBS revealed that it improved the dispersion of the graphene oxide in and enhanced its interaction with the epoxy matrix, hence simultaneously strengthening and toughening the epoxy resin.

Triblock Copolymer Toughening of a Carbon Fibre-Reinforced Epoxy Composite for Bonded Repair.

Epoxy resins are the most widely used systems for structural composite applications; however, they lack fracture toughness, impact strength and peel strength due to high cross-linking densities. Use of conventional toughening agents to combat this can lead to reductions in mechanical, thermal and processability properties desirable for bonded composite applications. In this work, an asymmetric triblock copolymer of poly(styrene)–b–poly(butadiene)–b–poly(methylmethacrylate) was used to modify an epoxy resin system, with the materials processed using both vacuum bag and positive pressure curing techniques. Interlaminar fracture toughness testing showed improvements in initiation fracture toughness of up to 88%, accompanied by a 6 °C increase in glass transition temperature and manageable reductions in gel-time. Shear testing resulted in a 121% increase in ultimate shear strain with only an 8% reduction in shear strength. Performance improvements were attributed to nano-structuring within the toughened resin system, giving rise to matrix cavitation and dissipation of crack front strain energy upon loading.

Study on flame retardant ABS

Flame-retardant ABS resin was prepared by adding fl ame retardant, toughening agent and dispersing silicone oilwith acrylonitrile-butadiene-styrene resin (ABS, grade 0215 A) as raw material. The results showed that in the ABSresin, fl ame retardant with tetrabromobisphenol A and antimony trioxide as the composite system (the mass ratio of2:1) was added. When the bromine content of the system was more than 10%, the flame retardant ABS meets therequirements of UL 94 V-0. The best toughening agent for flame retardant ABS resin is ABS graft powder. Whenthe amount of fl ame retardant ABS is 9% ~ 19% (mass fraction) Strength of 150-200 J / m; in the same formula andoperating conditions, brominated alkylene oxide as fl ame retardant prepared fl ame retardant ABS resin, the weatherresistance is better than tetrabromobisphenol A as fl ame retardant The Composite expansion fl ame retardant and coatedred phosphorus is an eff ective halogen-free fl ame retardant.

Antioxidant proton conductive toughening agent for the hydrocarbon based proton exchange polymer membrane for enhanced cell performance and durability in fuel cell

The antioxidant toughening agent for the hydrocarbon based proton exchange polymer electrolyte membranes, cerium/organosiloxane polymer network (Ce/OSPN), is synthesized via sol-gel reaction. Ce/OSPN is introduced to the sulfonated poly(ether ether ketone) (SPEEK), a typical hydrocarbon type polymer electrolyte membrane, by formation of a semi-interpenetrating polymer network (semi-IPN) structure. As Ce/OSPN possesses superior properties to SPEEK in mechanical flexibility, proton conductivity, and oxidation stability than SPEEK, it resolves 3 inherent drawbacks of the pristine SPEEK membrane including (i) brittleness, (ii) low proton conductivity, and (iii) poor durability. Addition of 20 wt% Ce/OSPN (at Ce/silicon mol ratio = 0.10) enhances the elongation at break of the SPEEK membrane about twice. The power density of the MEA fabricated with the semi-IPN membrane is 208 mW cm−2, which is much higher than that of the pristine SPEEK membrane, 165 mW cm−2. The power density loss of the same semi-IPN membranes as determined by the Fenton's test is 4.8%, whereas those of pristine and semi-IPN membrane without cerium are 33.9% and 34.0%, respectively. This Ce/OSPN agent is expected to be applied to a variety of hydrocarbon based polymer electrolyte membranes.

Novel thermoplastic toughening agents in epoxy matrix for vacuum infusion process manufactured composites

This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

Preparation and characterizations of RTV epoxy blends using amide maleic anhydride‐g‐liquid polybutadience as both reactive toughening and curing components

ABSTRACTAmide maleic anhydride‐g‐liquid polybutadience (AMALPB) was synthesized using maleic anhydride‐g‐liquid polybutadience (MALPB) with ethylenediamine (EDA), and its structure was confirmed by FTIR and 1H‐nuclear magnetic resonance spectra, respectively. It was then used as a reactive toughening agent to make blends with diglycidyl end‐capped poly(bisphenol‐A‐co‐epichlorohydrin epoxy cured at room temperature. Their thermal decomposing behaviors did not show much difference because both EDA and AMALPB possessed similar aliphatic groups. All their glass transition temperatures (Tg) increased more than 10 °C than that of the neat epoxy, and with the addition of AMALPB, the blends were greatly strengthened upon heating as show from their storage moduli. When AMALPB was added at 10 wt %, its elongation at break increases to a maximum of 8.8% which was about two times higher than that of the neat epoxy, and its tensile strength also increased. However, the excessive addition of AMALPB resulted in an apparent decline in their tensile strength at content above 20%. The simultaneous improvements in both tensile strength and strain were attributed to the existence of well‐dispersed rubber particles in the continuous matrices performing plastic deformation that resulted from the chemical bonds of interfaces among the rubber particles and matrix, and meanwhile, inducing the deflection of the cracks. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45985.

Renewable Cardanol-Based Phosphate as a Flame Retardant Toughening Agent for Epoxy Resins

A biobased flame retardant toughening agent, phosphaphenanthrene groups-containing triscardanyl phosphate (PTCP), was successfully synthesized via debydrochlorination, epoxidation and ring opening reaction from renewable resource cardanol. The chemical structure of PTCP was confirmed by the proton and phosphorus nuclear magnetic resonance. Epoxy resins (EPs) with different contents of PTCP were prepared through a simple mixing method. Thermogravimetric analysis results indicated that the earlier degradation of PTCP catalyzed the char formation of epoxy resins that was beneficial to protecting underlying polymers from further decomposition. The flame retardant properties were enhanced with the increase of the PTCP content. The EP composite containing 30 wt % PTCP showed a limiting oxygen index of 30.5%. Meanwhile, its peak heat release rate, total heat release and average effective heat of combustion values were decreased by 50%, 27% and 32%, respectively, in comparison to those of neat EP. The enhanced fl...

Structures and properties of low‐shrinkage polypropylene composites

ABSTRACTThe high shrinkage and the low impact strength severely limit the applications of the isotactic polypropylene (iPP). In this article, we studied the shrinkage, microstructure, and mechanical properties of the composites consisted of iPP, short glass fiber (GF), maleic anhydride grafted polypropylene (MPP), maleic anhydride grafted polypropylene/polyolefin elastomer (MPPPOE) or composite toughening agents (CTAs). The results show that the shrinkage of the composite with 40% GF reduces to 0.0754% (24 h) and 0.0893(48 h), respectively, under room temperature, which is far lower than the shrinkage [1.782% (24 h) and 1.821% (48 h)] of the pure iPP. For the composite of PP/GF/MPPPOE/CTAs (55/30/5/10), the tensile strength increases to 65.53 MPa (33.8 MPa for pure iPP), the tensile modulus is 1445 MPa which is 136% higher than pure iPP, and the izod impact strength reaches 22.72 kJ/m2 (only 5.28 kJ/m2 for pure iPP). Not only the scale stability of iPP is remarkably improved, but also the comprehensive mechanical properties are enhanced drastically. This work may generate potential opportunities for iPP in those applications demanding high scale stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44275.

Carbon nanohoops as attractive toughening and lubricant agents in TiN porous films

Hoop-shaped conjugated macrocycles (or carbon nanohoops) are eliciting significant interest from theoretical and synthetic scientists on account of their eminent physical and chemical properties. Herein, carbon nanohoops firstly fabricated by CH4 plasma treatment serve as toughening and lubricant agents in TiN porous films. The formation mechanism of carbon nanohoops is explained through a tandem Suzuki coupling/macrocyclization sequence of the charged multiple hydrocarbon molecules. The essential features of carbon nanohoops ensure that the TiN porous films with carbon nanohoops successfully possess flexible, hard, lubricant and antiwear effects.

Six‐arm star‐shaped polymer with cyclophosphazene core and poly(ε‐caprolactone) arms as modifier of epoxy thermosets

ABSTRACTA six‐arm star‐shaped poly(ε‐caprolactone) (s‐PCL) based on cyclophosphazene core was obtained by presynthesis of a hydroxy‐teminated cyclophosphazene derivative and subsequent initiation of the ring‐opening polymerization of ε‐caprolactone, and its use in different proportions as toughening modifier of diglycidylether of bisphenol A/anhydride thermosets was studied. The star‐shaped polymer was characterized to have approximately 30 caprolactone units per arm. Differential scanning calorimetry revealed a nonsignificant influence on the curing process of the epoxy‐anhydride formulation by the addition of s‐PCL. The s‐PCL‐modified epoxy thermosets exhibited a great improvement in both toughness and strength compared with the neat resin, as the result of a joint effort by the internal rigid core and the external ductile polyester chains of s‐PCL. When the addition of the modifier was 3 wt %, an optimal mechanical and thermomechanical performance was achieved. The impact resistance and tensile strength of the cured epoxy resin were enhanced by 150% and 30%, respectively. The glass transition temperature was also increased slightly. Moreover, the addition of the star‐shaped modifier had little harmful effect on the thermal stability of the material. Thus s‐PCL was proved to be a superior toughening agent without sacrificing thermal and mechanical properties of the thermosets. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44384.

Synthesis and architecture study of a reactive polybutadiene polyamine as a toughening agent for epoxy resin

ABSTRACTIn this study, a novel reactive toughener for the epoxy resin was developed and compared with traditional hydroxyl‐terminated polybutadiene (HTPB). For this purpose, the highly reactive aliphatic amine‐terminated polybutadiene (ATPB) was synthesized at ambient conditions by nucleophilic substitution amination. The characterizations of the product were provided by Fourier transform infrared and 1H NMR spectroscopy. According to the mechanical test results, incorporation of ATPB into epoxy networks can significantly toughen the epoxy matrix. The addition of 10 phr ATPB increased the critical stress intensity factor (KIC) and critical strain energy release rate (GIC) of the epoxy from 0.85 to 2.16 MPa m1/2 and from 0.38 to 3.02 kJ m−2, respectively. Furthermore, unlike HTPB, the presence of the ATPB did not deteriorate the tensile strength of the matrix. The toughening and failure mechanisms were discussed based on the epoxy network morphological characteristics. The reduction in cross‐linking density and glass transition temperature of the epoxy system upon modification with liquid rubbers was confirmed by dynamic mechanical analysis. This article opens up the possibility of utilizing reactive flexible diamines with polybutadiene backbone as effective toughening agents for thermoset polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44061.

Micron and nanostructured rubber toughened epoxy: A direct comparison of mechanical, thermomechanical and fracture properties

Phase separating rubbers are a well-documented toughening additive to epoxies. However, their effectiveness begins to plateau as the loading approaches 10 phr. To better understand this phenomenon, we directly compared the mechanical, thermomechanical, fracture properties and toughening mechanisms of the diglycidyl ether of bisphenol-A (DGEBA)/m-phenylenediamine (mPDA) system (Tg = 154 °C) toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN) and the triblock copolymer poly(styrene)-block-poly(butadiene)-block-poly(methylmethacrylate) (SBM), respectively. The SBM formed a nanostructured thermoset and thus was a more efficient toughening agent than CTBN, which forms micron scale, rubbery inclusions in the epoxy. At 10 phr SBM, the fracture toughness (MPa*m1/2) was increased by 220%, while the 10 phr CTBN modified epoxy containing 18 and 26% acrylonitrile showed 60 and 80% increases, respectively. Unlike the CTBN modified epoxy, SBM increased the fracture toughness with increasing concentration. Fracture surface analysis of the SBM modified epoxy via scanning electron microscopy identified the toughening mechanism as cavitation of ∼100 nm spherical micelles, void growth of the epoxy and concomitant matrix shear yielding. While both the CTBN and SBM modified epoxy exhibit similar toughening mechanisms, the nanoscopic SBM particles had an interparticle distance one order of magnitude smaller than that of the CTBN modified epoxy. Thus, a finer dispersion of nanoscopic, spherical micelles resulted in massive plastic deformation of the epoxy upon activation of cavitation, void growth and matrix shear yielding toughening mechanisms. Finally, dynamic mechanical analysis indicated that SBM did not decrease epoxy Tg, while the Tg of CTBN modified epoxy decreased with both increasing concentration and acrylonitrile content.

Mechanical bulk properties and fracture toughness of composite-to-composite joints of an elastomer-toughened ethyl cyanoacrylate adhesive

The bulk mechanical and fracture characterisation of an elastomer-toughened ethyl cyanoacrylate adhesive were investigated using thin film and standard double cantilever beam specimens, respectively. It is shown that these properties are strongly dependent on the prevailing curing conditions. These in turn are influenced by factors such as surface chemistry, curing time, the use of initiators, and the concentration of stabilizing acids in the system which have a profound effect on the polymerisation reaction. The curing conditions in turn have been shown to greatly influence the phase separation of the elastomeric toughening agent and the effectiveness of its associated toughening mechanism.

A novel hybrid linear–hyperbranched poly(butylene adipate) copolymer as an epoxy resin modifier with toughening effect

AbstractA study was carried out on the effect of a hybrid linear–hyperbranched poly(butylene adipate) copolymer on the properties of a commercial epoxy resin. First, the synthesis of the hyperbranched systems was optimized. These systems were obtained by reacting linear oligomers with 1,1,1‐tris(hydroxymethyl)propane used as branching agent and varying the reaction times from 16 to 44 h. The synthesized samples were characterized through matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, differential scanning calorimetry and thermogravimetric analysis. Results showed that for reaction times of 30 h a highly branched system, namely 5HB30, was obtained. This system was chosen as toughening agent for a commercial high‐performance epoxy resin. A kinetics analysis of epoxy/5HB30 blends indicated that the hyperbranched system had no accelerator or catalytic effect on the crosslinking reaction in the resin. Furthermore, it was demonstrated that 5HB30 acted as an excellent toughening agent, increasing significantly impact resistance up to 90% with respect to neat epoxy resin. The toughness behaviours of epoxy‐based blends were explained by investigating the fracture surface after impact tests through scanning electron microscopy before and after solvent etching. It was observed that the globular‐like hyperbranch‐rich domains, dispersed throughout the continuous epoxy resin, were able to absorb the impact energy without affecting thermal stability. © 2015 Society of Chemical Industry