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The Preparation and Characterization of an Epoxy Polyurethane Hybrid Polymer Using Bisphenol A and Epichlorohydrin
Abstract
Epoxy polymers composed of bisphenol A (BPA) and epichlorohydrin (ECH) were grafted onto polyurethane (PU) using the graft-polymerization method to prepare the epoxy PU hybrid polymer. The main series contained the epoxy polymer grafted onto PU; however, the epoxy polymer was not bound to PU in the control series. The breaking tensile stress steeply increased at low BPA and ECH contents and then decreased as more BPA and ECH were included in the main series, whereas the control series did not display an incline in the breaking tensile stress irrespective of the BPA and ECH contents. The percent shape recovery also steeply increased after the grafting of epoxy polymer in the main series but increased at a slower rate in the control series. The flexibility of the main series at a freezing temperature was not enhanced compared with the plain PU because the grafted epoxy polymers did not effectively disrupt the molecular interaction between PUs. Therefore, the grafting of epoxy polymers noticeably enhanced the breaking tensile strength and percent shape recovery of PU.
... The idea of combining two or more materials offers the possibility to exploit intrinsic properties of the constituent materials, thus resulting in a synergistic effect on the overall performance of composites [4,5]. For instance, Ag's incorporation in the hybridization of ECA had ultimately improved the specific resistivity, along with filler distribution efficiency, weight loss, and degradation temperature compared to the ECA with the single carbon-based filler at equivalent total filler loading [6,7]. ...
This paper presents a study on Hybrid Electrically Conductive Adhesive (HECA) properties as an in-depth analysis regarding hybrid filler ratio at low filler range. It is well established that the hybridization approach exhibits excellent functional properties of HECA. Still, the highest potential ability of the proposed HECA concerning relative amounts of involving fillers is the least being discovered. In this work, silver micro-flake (AgMF) and multiwalled carbon nanotube (MWCNT) conductive fillers were incorporated from 3 to 15 wt.%, while AgMF: MWCNT filler ratio is varied between 0.006 up to 0.2 to choose the best combination. Here, a planetary centrifugal mixer with different mixing time and sequence were considered to identify the most effective mixing method. The functional properties of HECA were characterized in terms of a four-point probe electrical test and a lap shear test via tensile mode. The morphological study suggests that a shorter centrifugal mixing period allows an adequate dispersion of the micro-nano fillers in the HECA system and revealed superior interfacial bonding between the fillers at the optimum ratio. Interestingly, electrical resistivity at critical concentration showed an optimum ratio by incorporating only 2.5% AgMF in the hybrid fillers to yield a 42.62% reduction. However, the significant effects of hybridization are observed until the percolation threshold of HECA at 9 wt% only, followed by a 38.5% reduction beyond this limit. Moreover, the lap shear strength is most reliable at a total filler of 6 wt%, an indication of an excellent filler-binder load distribution.Graphic Abstract
Here the thermally catalyzed azide‐alkyne click reaction was invoked for synthesis of functional triazole. The formed triazole was invoked to engineer polyurethane as water immiscible material. The synthesized functional triazole and polyurethane were well characterized using spectroscopic techniques—nuclear magnetic resonance (NMR), electrospray ionization mass spectrum (ESI MS), and attenuated total reflectance Fourier transform infrared (ATR‐FTIR) accordingly. The N2 adsorption–desorption isotherms confirmed the material to be mesoporous in nature with a surface area of 12.89 m2/g, pore volume of 0.085 cc/g, and pore radius of 7.14 nm. The characterized triazole material can be crucial with properties related to antifungal responses and UV absorption. The polyurethane material showed adsorption of amphiphilic dye—rhodamine (RH B) and methylene blue (MB). It was selective to release of rhodamine B (RH B) quite efficiently. The recycling of polyurethane reported up to cycle four revealed efficient adsorption‐release. The metal free thermally clicked azide‐alkyne reaction was invoked for synthesis of triazole based polyurethane material, which is confirmed to be mesoporous. The polyurethane with contact angle <90° revealed its efficiency to adsorption of amphiphilic dyes—rhodamine B (RH B) and methylene blue (MB) as well as it's selectively to release of RH B.
Recent advances in macromolecular chemistry have revolutionized the way we perceive the synthesis of polymers. Polymerization, to be modern, must be "controlled", which usually means capable of producing macromolecules of well-defined structure. The purpose of this review is to examine how the chemistry of epoxy resins, an almost century-old chemistry, is also involved in this movement.Epoxy resins are characterized by both the flexibility of implementation and the qualities of the polymers obtained. Key materials in health-, mobility- and energy related technologies, these resins are heavily present in high-performance composites, electronic boards, adhesives and coatings. Currently, a large number of resins and hardeners are available on the market or described in the literature and an interesting point is that almost any combination of the two is possible. Common to all these recipes and processes is that a liquid (or soluble) resin at some point becomes insoluble and solid. It is very important to know how to manage this transition, physically known as the gel point, as it is the point after which the shape of the object is irreversibly set. Taking into account the variety of epoxy polymerization processes - polyaddition, anionic or cationic polymerization - we detail a number of methods to program the occurrence of the gel point and how this type of control affects the structure of the growing network.
Segmented polyurethane (PU) block copolymers were synthesized using 4,4′-methylenediphenyl diisocyanate and 1,4-butanediol as hard segments and oligomeric ethoxypropyl polydimethylsiloxane (PDMS) as the soft segments, with hard segment contents ranging from 26 to 52 wt%. The microphase separated morphology, phase transitions, and degrees of phase separation of these novel copolymers were investigated using a variety of experimental methods. Like similar copolymers with mixed ethoxypropyl PDMS/poly(hexamethylene oxide) soft segments, PU copolymers containing only ethoxypropyl PDMS soft segments were found to consist of three microphases: a PDMS matrix phase, hard domains, and a mixed phase containing ethoxypropyl end group segments and dissolved short hard segments. Analysis of unlike segment demixing using small-angle X-ray scattering demonstrates that degrees of phase separation increase significantly as copolymer hard segment content increases, in keeping with findings from Fourier transform infrared spectroscopy measurements.
The bulky and rigid triphenylmethyl group was grafted onto polyurethane (PU) to reduce the molecular attractions between hard segments and to improve the mobility of the PU chain under freezing conditions. The triphenylmethyl-grafted PU exhibited improvement in the cross-link density, solution viscosity, maximum tensile stress, shape recovery at 10 °C, and low temperature flexibility compared with the plain PU. The soft segment melting was not affected by the grafted triphenylmethyl group, whereas the soft segment crystallization disappeared with the increase of the triphenylmethyl group content. The glass transition temperature (Tg) increased with the increase of the triphenylmethyl group content. The rapid increase of the tensile strength and shape recovery at 10 °C resulted from the cross-linking effect, whereas the strain at break and shape retention at -25 °C slightly decreased with the increase of the triphenylmethyl group content. The triphenylmethylgrafted PU displayed an excellent low temperature flexibility even at -50 °C due to the improved mobility of the PU chain compared to ordinary PU.
Inspired by the nature material, a crosslinked network structure of polyurethane/epoxy resin composite material was built through Diels-Alder (DA) reversible covalent bond reaction between the dienes and dienophile group on the side chain of epoxy resin and polyurethane respectively. The synthesized composite material combined the advantages of polyurethane and epoxy resin. The hard segments of polyurethane and epoxy resin were closely combined through the DA reaction and high density hydrogen bonding. The strength, hardness and toughness of the composite material were greatly enhanced. DA covalent bonds can be reversible with varying the temperature, which led to the heat reprocessing ability of the synthesized composite material. The well-established structure-property relationship shown in this paper could further provide guidance for fabrication of high performance recyclable material with precisely controllable microstructures and behaviors.
UV–Visible spectra of (a) MMA series and (b) CMMA series show the contrasting differences in their film transparency.
Bisphenol A (BPA) is one of the most widely used synthetic compounds on the planet. Upon entering the diet, its highest concentration (1–104 ng/g of tissue) has been recorded in the placenta and fetus. This accumulation of BPA can have many health hazards ranging from the easy to repair single strand DNA breaks (SSBs) to error prone double strand DNA breaks (DSBs). Although the Human liver can efficiently metabolize BPA via glucuronidation and sulfation pathways, however the by-product Bisphenol-o-quinone has been shown to act as a DNA adduct. Low doses of BPA have also been shown to interact with various signaling pathways to disrupt normal downstream signaling. Analysis has been made on how BPA could interact with several signaling pathways such as NFκB, JNK, MAPK, ER and AR that eventually lead to disease morphology and even tumorigenesis. The role of low dose BPA is also discussed in dysregulating Ca²⁺ homeostasis of the cell by inhibiting calcium channels such as SPCA1/2 to suggest a new direction for future research in the realms of BPA induced disease morphology and mutagenicity.
A pH indicator (Bromocresol Green, Bromocresol Purple, or Thymol Blue) is grafted onto polyurethane (PU) using 2,2-dimethylolpropanoic acid (DMPA) to enhance water compatibility. The indicator-grafted, water-compatible PU is analysed for soft-segment thermal, tensile, and shape recovery properties, fast colour change depending on various pH conditions, and low-temperature flexibility. The PU surface becomes water compatible as DMPA content increases, and the characteristic UV-vis absorbance is observed for each grafted indicator. The PU series exhibits a sharp increase in tensile stress and crosslink density at low DMPA content, but a decrease with increased DMPA content. The glass transition temperature increases significantly with increased DMPA content. Shape recovery remains high, but shape retention sharply decreases after an indicator is grafted. The grafting of pH indicator onto PU improves the low-temperature flexibility and imparts an immediate colour change according to the solution pH and grafted indicator.
A novel bio-based epoxy resin was synthesized using de-polymerized hydrolysis lignin (DHL) as a feedstock under alkaline condition. The chemical functionality of DHL-based epoxy resin was studied using Fourier Transformation Infrared spectroscopy (FTIR).The curing behavior of DHL-based epoxy resin with a selective curing agent (4,4′-diaminodiphenyl methane; DDM) was also investigated using differential scanning calorimetry (DSC). The curing process was found to proceed via a ring opening reaction involving the epoxy and the amine groups followed by etherification reactions at the end. The thermal and mechanical behavior of the resulting DHL-based epoxy resin were investigated using a thermogravimetric analysis (TGA) and a universal testing machine (UTM), respectively. The cured DHL-based epoxy-DDM system demonstrated good thermal and mechanical performances, suggesting its potential of utilizing hydrolysis lignin—a byproduct/waste stream from cellulosic ethanol processes for the production of value-added bio-based materials.
Understanding and controlling the morphology of thermoplastic polyurethane (TPU) is crucial, as it is closely linked with its thermal and mechanical properties. The morphology of a TPU with a high hard segment content was investigated. When hard segment crystallisation was avoided by fast cooling, a crystallisation-induced phase separation occurred upon reheating. At higher temperatures, a second polymorph was additionally created. Cooling slowly from the melt directly induced the formation of both polymorphic forms. The complex thermal behaviour could hence be explained by the (cold) crystallisation and melting of two polymorphs. The disordered two-phase nanomorphology, revealed by AFM at room temperature after cooling slowly, was validated for both fast and slowly cooled samples at higher temperatures by fitting model SAXS patterns to time resolved synchrotron SAXS data. Annealing fast cooled samples at high temperature induced some ordered, lamellar stacks in addition. Finally, the morphology was linked to the evolution of storage modulus with increasing temperature.
Polyurethane (PU) was graft polymerized with poly(acrylic acid) (PA) to form a PA-grafted PU (UA) series, and a control PU (C) series containing free PA was also prepared for comparison. The grafted PA could be ionized, and an ionized PA-grafted PU (IUA) series was separately prepared. The spectroscopic, thermal, tensile, shape memory, low-temperature flexibility, and water permeability properties of the polymer series were compared. With an increase in the PA content, the T
m did not change, but ΔH
m decreased for the UA, IUA, and C series. The T
g did not significantly change with the increase in PA content for the UA, IUA, and C series. The tensile strengths of the UA and IUA series sharply increased with the PA content, whereas that of the C series did not. The breaking strain of the UA, IUA, and C series remained the same with the increase in PA content. The shape recovery and shape retention of the PU–PA series remained high after four repeated tests. Finally, the IUA series PU demonstrated better low-temperature flexibility and water compatibility than the unmodified PU.
A series of polyurethanes (PUs) containing grafted cholesterol (UA series) and a control series blended with free cholesterol (UB series) were prepared: the spectroscopic, thermal, tensile, shape memory, and low temperature flexibility properties of these series were compared with those of unmodified PU. For both the UA and UB series, the soft segment melting temperature (T
m
) was not affected by the cholesterol content. Differential scanning calorimetry (DSC) results showed that the crystallization of the hard segment of the UA series was completely inhibited as the grafted cholesterol content increased, which were supported by dynamic mechanical analysis (DMA) results for the storage modulus. As the cholesterol content increased, the glass transition temperature (T
g
) of the UA series increased and remained the same for the UB series. The tensile strength in the UA series sharply increased with the cholesterol content, unlike that of the UB series. The strain at break in the UA series remained the same as the cholesterol content increased, whereas that of the UB series decreased significantly. As the cholesterol content increased, the shape recovery of the UA series remained above 90% at 45 °C and sharply increased at 0 °C. Finally, the UA series containing grafted cholesterol demonstrated excellent low temperature flexibilities compared to the UB series and unmodified PU.
A series of polyurethanes (PUs) grafted with poly(isobornyl acrylate) (PIBA) was prepared to form a series (denoted the I series), which was compared with the PUs containing free PIBA (denoted the C series). The bulky and rigid bicyclic isobornyl groups attached to the PIBA chains were intended to hinder the molecular interactions between PU chains and improve the low temperature flexibility of the PUs. The soft segment melting temperature (Tm) was not changed by the increase of the isobornyl acrylate (IBA) content; however, the enthalpy change of melting (ΔHm) sharply decreased. The C series PUs did not exhibit similar differences in response to the IBA content change. The tensile strength of the I series sharply increased at low IBA content due to the physical crosslinking and decreased at high IBA content due to the repulsion between PU chains. The I series demonstrated an improved low temperature flexibility compared with the unmodified and the C series PUs.
Polyurethane was linked to graphite modified with a phenol or 4-phenylethanol group on its surface, and the composite polymer was characterized regarding its thermal, spectroscopic, mechanical, and shape-memory properties as well as its electric conductivity. Graphite as a filler was covalently linked to a polyurethane backbone composed of 4,4′-methylenebis(phenylisocyanate) and 1,4-butanediol as hard segments and poly(tetramethyleneglycol) as a soft segment. The two different polyurethane series, differing in their modifying spacer, show similar structural characteristics and exhibit a small degree of cross-linking due to the agent used for the covalent linking of graphite to the polyurethane frame. The tensile mechanical strength and shape-recovery characteristics remain high as the graphite content is increased when compared to the linear polyurethane polymer without the linked graphite. Regarding the tensile mechanical properties, the maximum stress increases up to 436% compared to the linear polyurethane, and the maximum strain goes up to 1744%. Shape recovery reaches values as high as 93%, and shape retention gradually decreases as the graphite content increases. The electric conductivity of graphite-linked polyurethane exhibits a sharp increase as the graphite content increases, but the blended graphite polyurethane has very poor electric conductivity at higher graphite contents. The implication of this finding is discussed, and the synthesized polymers are compared with other conductive polymer composite.
Rosin acid oligomers were modified and utilized in order to prepare thermosets based on epoxy resins. Epoxide groups were incorporated into this acidic precursor by various synthetic strategies and the corresponding thermosets were obtained thanks to an amino curing agent. Endocyclic epoxidized materials were firstly prepared and used as an additive to diglycidyl ether of bisphenol A (DGEBA) in the presence of isophorone diamine. In a second approach, glycidyl esters of rosin acid oligomers were synthesized and thus utilized for the preparation of DGEBA-free thermosets. Some thermo-mechanical properties of the resulting epoxy resins were explored by DSC and DMA analytical techniques.
Polyurethane (PU) copolymer is laterally linked with three kinds of metal ion indicator (calcein, calmagite, or eriochrome black T), with which free metal ion in aqueous solution is intended to be detected by PU color change. Metal ion detection by the indicator-PU fails due to the poor permeation of hydrophilic metal ion into hydrophobic PU layer. Instead, three surfactants with different ionic head groups, aerosol OT (AOT), cetyltrimethylammonium bromide (CTAB), and sodium dodecylsulfate (SDS), are tested for metal ion. Cationic CTAB exhibits an instant PU color change, but anionic AOT and SDS do not respond at all. Reason for the selective detection of cationic surfactant is the complex formation between cationic surfactant and indicator. Molecular interactions between PUs are affected by the laterally linked indicators based on the results by infrared spectra and differential thermal analysis. UV-vis spectra reveal that extra peak arising from the linked indicator appears compared to plain PU. The lateral linking of indicator to PU demonstrates, as well as the selective surfactant detection, a 454 % increase in tensile strength and reproducible shape recovery as high as 99 % compared to plain PU.
The utilization of renewable resources such as vegetable oils [VO] for the development of environment friendly waterborne [WB] materials is encouraged worldwide. The preparation of WB materials from VO is a challenging task due to their hydrophobic nature. The present work describes the synthesis of WB epoxy from VO [WBOE]. WBOE was characterized for its structural and physico-chemical attributes. The cured material was subjected to physico-mechanical, chemical resistance tests, and thermal analyses. The coatings of WBOE showed good physico-mechanical, chemical resistance as well as thermal stability and may find application as eco-friendly WB coatings with safe usage up to 220 °C.
Polyurethanes are the only class of polymers that display thermoplastic, elastomeric, and thermoset behavior depending on their chemical and morphological makeup. In addition to compact polyurethanes, foamed variations in particular are very widespread, and they achieve their targeted properties at very low weights. The simple production of sandwich structures and material composites in a single processing step is a key advantage of polyurethane technology. The requirement of energy and resource efficiency increasingly demands lightweight structures. Polyurethanes can serve this requirement by acting as matrix materials or as flexible adhesives for composites. Polyurethanes are indispensable when it comes to high-quality decorative coatings or maintaining the value of numerous objects. They are extremely adaptable and sustainable problem solvers for today's challenges facing our society, all of which impose special demands on materials.
This work study is the compatibility, phase structure, and component interaction of poly(lactic acid) (PLA) and glycidyl methacrylate grafted poly(ethylene octane) (GMA-g-POE denoted as mPOE) blend by Fourier transform infrared (FTIR) spectra, dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and wide-angle X-ray diffraction (WAXD), respectively. All the binary blend compositions exhibit two distinct glass transition temperatures corresponding to the mPOE-rich and PLA-rich phases, respectively. Moreover, these two peaks approach each other with increasing mPOE content, indicating partial compatibility between the PLA and mPOE. Chemical reactions between the end carboxyl groups of the PLA and epoxy groups of the mPOE are considered as the driving force of the enhanced compatibility. They lead to an increase in viscosity of the blends and a decrease in the structural symmetry of PLA. This result brings about a decrease in the spherulite growth rate and the degree of crystallinity. Glass transition temperature (Tg) depression of mPOE is attributed to the negative pressure imposed on the dispersed rubber phase, resulting from differential contraction due to the thermal shrinkage mismatch upon cooling from the melt state. The negative pressure in the dispersed particles, in turn, would cause a dilational effect for the matrix ligament between the particles, and therefore increases the ductility and toughness of PLA.
Polyurethane networks containing allophanate groups, based on hydroxyl terminated polybutadiene and various diisocyanates, such as toluene diisocyanate, 4,4′ di(isocyanatocyclohexyl) methane and isophorone diisocyanate were synthesized at various NCO/OH equivalence ratios (r-values) ranging from 1.0 to 1.5. Mechanical properties such as tensile strength, stress at 100% elongation, equilibrium relaxation modulus increase and % elongation at break decreases with r-value. Crosslink density (νe) for the networks was determined using swell methods. Crosslink density values calculated from equilibrium relaxation modulus were found to be close to those obtained from swell data. Crosslink density (νt) was theoretically calculated assuming complete reaction between the functional groups. The ratio, νe/νt decreases with r-value. Linear fits with good correlation coefficients were obtained between network parameters and mechanical properties. Dynamic mechanical studies show that the r-value does not influence the glass transition temperature. Thermal decomposition studies using thermogravimetric technique indicate that the decomposition is in multiple stages.
Aqueous dispersions of nonionic grafted polyurethane (PU) were prepared by reaction of polytetrahydrofuran (PTHF), toluene diisocyanate (TDI) and 1,4-butane diol (BDO). Then N-substituted with poly(ethylene glycol monomethyl ether) (PEGMME) pendant group by generation of active anion sites on the polymer back bone, followed by treating with corresponding chlorinated PEGMME. The prepared polymers were analyzed by contact angle measurement, Fourier transform infrared (FT-IR) and H NMR spectroscopy and the effect of various molecular weight of PEGMME on particle size and viscosity were studied. Particle size decreased and emulsion Viscosity increased with increase in PEGMME molecular weight. The decrease in particle size and increase in viscosity are due to increased chain flexibility and or hydrophilicity of grafted PU.
Alcoholysis and kraft lignin-based polycaprolactones (LigPCL) were synthesized by the polymerization of ε-caprolactone which was initiated by the hydroxyl (OH) group in lignin. LigPCL-based polyurethanes were also prepared from LigPCL. The caprolactone (CL)/OH ratio of the CAPCLs was changed from 1 to 25 mol mol−1. Thermal properties of the LigPCL and LigPCL-based polyurethane (PU) sheets were studied by differential scanning calorimetry (DSC). Glass transition temperature (Tg), heat capacity difference at Tg (ΔCp) cold crystallization temperature (Tcc) and melting temperature (Tm), were determined by DSC. The main chain motion of lignin is observed in the whole CL/OH ratio. When CL/OH ratio exceeds 5 mol mol−1 in the LigPCL samples and 10 mol mol−1 in the LigPCL-based PU samples, the crystalline region which is organized by the PCL chain association is observed. It was found that PCL chain association is controlled by both chain length and chemical cross linking.
Novel highly functional biobased epoxy compounds, epoxidized sucrose esters of fatty acids (ESEFAs), were cross-linked with a liquid cycloaliphatic anhydride to prepare polyester thermosets. The degree of cure or conversion was studied using differential scanning calorimetry (DSC), and the sol content of the thermosets was determined using solvent extraction. The mechanical properties were studied using tensile testing to determine Young's modulus, tensile stress, and elongation at break. Dynamic mechanical analysis (DMA) was used to determine glass-transition temperature, storage modulus, and cross-link density. The nanomechanical properties of the surfaces were studied using nanoindentation to determine reduced modulus and indentation hardness. The properties of coatings on steel substrates were studied to determine coating hardness, adhesion, solvent resistance, and mechanical durability. Compared with the control, epoxidized soybean oil, the anhydride-cured ESEFAs have high modulus and are hard and ductile, high-performance thermoset materials while maintaining a high biobased content (71-77% in theory). The exceptional performance of the ESEFAs is attributed to the unique structure of these macromolecules: well-defined compact structures with high epoxide functionality. These biobased thermosets have potential uses in applications such as composites, adhesives, and coatings.
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