Bio-degradable vegetable oil based hyperbranched poly(ester amide) as an advanced surface coating material

Vegetable oil based hyperbranched poly(ester amide) (HBPEA) has enormous importance because of its unique characteristics. Thus the synthesis of HBPEA using N,N′-bis(2-hydroxy ethyl) castor oil fatty amide, maleic anhydride, phthalic anhydride and isophthalic acid as A₂ monomers and diethanol amine, as B₃ monomer was reported for the first time. The chemical structure of the synthesized resin was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopic techniques. The degree of branching (DB) (as vouched by ¹H NMR analysis) and initial degradation temperature were found to increase with the increment in B₃ monomer content. Resins with 5 and 10 wt% of B₃ monomer showed shear thinning behavior while rheopectic nature of HBPEA with 15 wt% of B₃ content was observed. The evaluation of tensile strength, elongation at break, abrasion resistance, adhesion strength, scratch hardness, gloss, impact strength and chemical resistance complemented by microbial and lipolytic degradation forward the epoxy cured thermosets as advanced biodegradable surface coating materials.     

Synthesis,Characterization and Glass Reinforcement of Poly(Ester Amido Imide)s

Poly(ester amido imide)s (PEAI)s (IIIa–e) were prepared by the intermolecular Diels-Alder (DA) reaction of bismaleimide (II) having epoxy resin segment with various bisfurans (Ia–e) having amide bridge. The DA reaction was carried out with tetrahydrofuran as a solvent, as well as in bulk, followed by aromatization of DA polyadduct intermediates in the presence of acetic anhydride. All the resultant polymers, designated as poly(ester amido imide)s (PEAI)s, were characterized by elemental analysis, number average molecular weight, IR spectral studies and thermogravimetry. The PEAIs exhibit good thermal stability. Bismaleimide (II) and bisfurans (Ia–e) were polymerized (at 150 ± 10°C) by in situ DA intermolecular reaction into moderately thermally stable PEAIs. The glass fiber-reinforced composites (i.e., laminates) of all PEAIs were prepared and characterized by their chemical resistance and mechanical properties.     

Curable resins based on recycled poly(ethylene terephthalate) for coating applications

Poly(ethylene terephthalate) waste was depolymerised in the presence of diethylene- or tetraethylene glycol and manganese acetate as a catalyst. An epoxy resin was then prepared by the reaction of these oligomers with epichlorohydrin in presence of NaOH as a catalyst. The produced oligomers were condensed with maleic anhydride and ethylene glycol to produce unsaturated polyester. The chemical structures of the resulting epoxy and unsaturated polyester resins were confirmed by ¹HNMR. The vinyl ester resins were used as cross-linking agents for unsaturated polyester resin diluted with styrene, using free radical initiator and accelerator. The 2-amino ethyl piprazine was used as hardener for epoxy resins. The curing behaviour of the unsaturated polyester resin, vinyl ester resins and styrene was evaluated at different temperatures ranged from 25 to 55 °C to calculate the curing activation energy of the system. The cured epoxy and unsaturated polyester resins were evaluated in coating application of steel.     

Curing of epoxy resin contaminated with water

Epoxy resins used for reinforcement of bridges and buildings are explored in the light of both curing rates and mechanical properties when resins are contaminated with water in outdoor construction. The developed resin is composed of a conventional resin of bisphenol A diglycidyl ether and a hardener with a polyoxipropyldiamine base. Curing rates were obtained by time variation of the near infrared absorbance of amine groups in the hardener at various water contents. They obeyed the second‐order reaction law with respect to the hardener, of which the activation energy was 70 kJ mol⁻¹. Water increased the reaction rate. Mechanical properties such as ultimate tensile strength, adhesive shear stress, and flexural strength were measured at various water contents for the developed epoxy resin and the commercially available low‐temperature epoxy resin. The developed cured resin shows not only higher mechanical strengths but also much less deterioration by water than the conventional cured resin. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 214–220, 2001     

Tough hyperbranched epoxy/poly(amido‐amine) modified bentonite thermosetting nanocomposites

A tough and highly flexible hyperbranched epoxy and poly(amido‐amine) modified bentonite based thermosetting nanocomposite was demonstrated. The FTIR, XRD, and TGA analyses confirmed the modification of bentonite. The formation of partially exfoliated structure of the nanocomposite with good physicochemical interactions among the hyperbranched epoxy, poly(amido‐amine) hardener and modified clay was investigated by the FTIR, XRD, SEM, and TEM analyses. Significant improvements of 750% toughness, 300% elongation at break, 50% tensile strength, 300% modulus, and 250% adhesive strength of the pristine epoxy were achieved by the formation of nanocomposites with 3 wt % of modified clay. The experimental modulus values of the nanocomposites were compared with three theoretical models to account the interactions between filler and matrix. Thus, the studied epoxy nanocomposite has great potential to be used as an advanced epoxy thermoset. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40327.     

Shape‐memory property and characterization of epoxy resin‐modified Mesua ferrea L. seed oil‐based hyperbranched polyurethane

Modification of existing polymers leads to enhancement of many desirable properties. So, a hyperbranched polyurethane (HBPU) of monoglyceride of Mesua ferrea L. seed oil, poly(ε‐caprolactone)diol (M_n = 3000 g mol^?1), 2,4‐toluene diisocyanate, and glycerol with 30% hard segment (NCO/OH = 0.96) has been modified with different amounts of bisphenol‐A based epoxy resin. The system is cured by poly(amido amine) hardener at 120°C for specified period of time. Improvement of thermostability, scratch hardness, and impact strength are observed by this modification of HBPU. The differential scanning calorimetry (DSC) results show improvement of melting temperature of the modified systems. The enhancement of tensile strength is about 2.4 times compared with that of the unmodified one. The morphology and structural changes due to variation of epoxy content was studied by scanning electron microscopy (SEM) analysis and Fourier transform infrared (FTIR) spectroscopy. The rheological properties of the epoxy‐modified HBPU show the dependence on the amount of epoxy resin. Shape memory study of the crosslinked HBPUs shows 90–98% thermoresponsive shape recovery. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies on self cured zinc-containing Pongamia glabra oil based polyesteramide

Efforts have been made for the development of high performance protective coating materials from non drying oil such as Pongamia glabra oil and their commercialization. Zn-containing self cured Pongamia glabra oil based polyesteramide [Zn-APGPEA] resin was synthesized in situ by the reaction of Pongamia glabra fatty amide diol [HEPGA], poly(styrene-co-maleic anhydride) [SMA] and zinc acetate (different ratios) at 100 ± 5 °C in the presence of an acid catalyst. The physico-chemical characterizations of the resin were carried out by standard laboratory methods. The structural elucidation of the prepared resin was carried out by FTIR, ¹H NMR and ¹³C NMR spectral techniques. The thermal behavior was studied by TGA technique. Antibacterial activity was measured by agar diffusion method against Escherichia coli and Staphylococcus aureus. The effect of the loading of zinc on properties of Zn-APGPEA film was also investigated. The properties of Zn-APGPEA compared with reported self cured Pongamia glabra polyesteramide [APGPEA]. Physico-mechanical and chemical/corrosion resistance test of Zn-APGPEA coatings showed that the presence of zinc metal in APGPEA considerably enhances the overall film performance and also improves antibacterial activity. Therefore, Zn-APGPEA can be used as an anti-corrosive and antibacterial coatings material which may substitute polymers obtained from petroleum.     

Influence of aliphatic amine epoxy hardener on the adhesive properties of blends of mono‐carboxyl‐terminated poly(2‐ethylhexyl acrylate‐co‐methyl methacrylate) with epoxy resin

The adhesive properties have been investigated in blends of mono‐carboxyl‐terminated poly(2‐ethylhexyl acrylate‐co‐methyl methacrylate) with diglycidyl ether of bisphenol A and three different aliphatic amine epoxy hardener. The adhesives properties are evaluated in steel alloy substrate using single‐lap shear test. The copolymers are initially miscible in the stoichiometric blends of epoxy resin and hardener at room temperature. Phase separation is noted in the course of the polymerization reaction. Different morphologies are obtained according to the amine epoxy hardener. The most effective adhesive for steel–steel joints in single‐lap shear test is the blends using 1‐(2‐aminoethyl)piperazine (AEP) as hardener. This system shows the biggest lap shear strength. However, the modified adhesives show a reduction in the mechanical resistance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of comb-shaped poly(amido amine)-g-PEO via Michael addition polymerization

Linear pH-sensitive poly(amido amine)s were synthesized via Michael addition polymerization of N-aminoethyl piperazine (AEPZ) or 4-aminomethyl piperidine (AMPD) with 1,12-dodecylene diacrylamide (DDA). Successive Michael addition reaction of acryl-terminated poly(ethylene oxide) (A-PEO) with the secondary amine of linear poly(DDA-AEPZ) that has one secondary amine in every repeating unit afforded PEO-grafted poly(amido amine). Variation of grafting degree could be obtained conveniently via tuning the feed molar ratio of acryl/secondary amine. When this ratio equals to 1.2, all the secondary amines on the backbone of poly(DDA-AEPZ) (or poly(DDA-AMPD)) were consumed and the comb-shaped polymers were formed. The amphiphilic comb-shaped poly(DDA-AEPZ)-g-PEO was molecularly dissolved in water at pH 2.0 (w/v=0.25%), and micelles were formed when pH value of aqueous solution was adjusted to 6.5. ¹H NMR data verify the formation of micelles due to the disappearance of signals attributed to poly(DDA-AEPZ). The formation of micelles can be confirmed further by TEM photos, they show that all the particles are approximately spherical and their number-average diameter is around 95 nm.     

Studies on self cured zinc-containing Pongamia glabra oil based polyesteramide

Efforts have been made for the development of high performance protective coating materials from non drying oil such as Pongamia glabra oil and their commercialization. Zn-containing self cured Pongamia glabra oil based polyesteramide [Zn-APGPEA] resin was synthesized in situ by the reaction of Pongamia glabra fatty amide diol [HEPGA], poly(styrene-co-maleic anhydride) [SMA] and zinc acetate (different ratios) at 100 ± 5 °C in the presence of an acid catalyst. The physico-chemical characterizations of the resin were carried out by standard laboratory methods. The structural elucidation of the prepared resin was carried out by FTIR, ¹H NMR and ¹³C NMR spectral techniques. The thermal behavior was studied by TGA technique. Antibacterial activity was measured by agar diffusion method against Escherichia coli and Staphylococcus aureus. The effect of the loading of zinc on properties of Zn-APGPEA film was also investigated. The properties of Zn-APGPEA compared with reported self cured Pongamia glabra polyesteramide [APGPEA]. Physico-mechanical and chemical/corrosion resistance test of Zn-APGPEA coatings showed that the presence of zinc metal in APGPEA considerably enhances the overall film performance and also improves antibacterial activity. Therefore, Zn-APGPEA can be used as an anti-corrosive and antibacterial coatings material which may substitute polymers obtained from petroleum.     

Modification of epoxy–anhydride thermosets with a hyperbranched poly(ester amide). II. Thermal,dynamic mechanical,and dielectric properties and thermal reworkability

An epoxy–anhydride formulation used for the coating electrical devices was modified with a commercially available hyperbranched poly(ester amide), Hybrane S2200, to improve the thermal degradability of the resulting thermoset and, thus, facilitate the recovery of substrate materials after the service life of the component. The thermomechanical, mechanical, and dielectric properties and thermal degradability were studied and interpreted in terms of the composition and network structure of the cured thermosets. Although the crosslinking density was significantly reduced with the incorporation of S2200, the glass transition temperature of the fully cured material (T_g∞) of the modified thermoset was hardly affected because of the enhancement of H‐bonding interactions in the presence of S2200. Despite the different network structures, the combined dielectric and dynamic mechanical analysis revealed that the relaxation dynamics of both networks were very similar. In terms of application, improvements in the dielectric and mechanical properties were observed. The incorporation of S2200 accelerated the thermal decomposition of the material and, thus, facilitated the recovery of the valuable parts from the substrate at the end of the service life of the apparatus. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Curing of DGEBA epoxy resin by low generation amino‐group‐terminated dendrimers

Low generation amino‐group‐terminated poly(ester‐amine) dendrimers PEA1.0 (NH₂)₃ and PEA1.5 (NH₂)₈, and poly(amido‐amine) dendrimer PAMAM1.0 (NH₂)₄ were used as diglycidyl ether of bisphenol A (DGEBA) epoxy resin hardeners. Thermal behavior and curing kinetics of dendrimer/DGEBA systems were investigated by means of differential scanning calorimetry (DSC). Compared with ethylene diamine (EDA)/DGEBA system, the dendrimer/DGEBA systems gradually liberated heat in two stages during the curing process, and the total heat liberated was less. Apparent activation energy and curing reaction rate constants for dendrimer and EDA/DGEBA systems were estimated. Thermal stabilities and mechanical properties of cured thermosetting systems were examined as well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3902–3906, 2006     

Preparation of novel soluble poly(ester imide)s containing a trimellitimide moiety and their use as modifiers for aromatic diamine‐cured epoxy resin

Poly(ester imide)s, prepared by the reaction of phthalic anhydride, N‐(4‐carboxyphenyl) trimellitimide and 1,2‐ethanediol, were used to improve the toughness of bisphenol‐A diglycidyl ether epoxy resin cured with 4,4′‐diaminodiphenyl sulfone (DDS). The poly(ester imide)s include poly(ethylene phthalate‐co‐ethylene N‐(1,4‐phenylene) trimellitimide dicarboxylate)s (PESIs) having 10, 20 and 30 mol% trimellitimide (TI) units, respectively. PESIs having 10 and 20 mol% TI units were effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt% of PESI (20 mol% TI unit, M _W 19300 g mol^?1) led to a 55% increase in the fracture toughness (K_IC) of the cured resin (with an increase in flexural strength and modulus) and the modified resin had a particulate morphology. PESI having 30 mol% TI units was not effective because of degradation of the modifier by DDS. The toughening mechanism is discussed in terms of morphological and dynamic viscoelastic behaviour of the modified epoxy resin system. © 2001 Society of Chemical Industry     

Preparation of intercross-linked poly(L-lactide) and epoxy resin using N-benzyl pyrazine hexafluoroantimonate

The overall goal of our study was to prepare the intercross-linked poly(l-lactide) (PLA) and epoxy polymer by using N-benzyl pyrazine hexafluoroantimonate (BPH) as a latent hardener. First, the glycidol end-functionalized PLA (Gly-PLA) polymer was prepared at quantitative yields by the polymerization of l-lactide (LA) with glycidol as an initiator in the presence of stannous octoate. Gly-PLA showed the predicted PLA molecular weight. The epoxide group in the chain end of the PLA segments was observed using ¹H nuclear magnetic resonance (NMR). The ring-opening polymerization of the epoxy group in Gly-PLA in the presence of BPH as a latent initiator yielded the polyether-g-PLA (PE-g-PLA), which was confirmed using ¹H NMR and gel permeation chromatography (GPC). We confirmed that BPH acted as a latent initiator for the polymerization of epoxide in the Gly-PLA polymer. The curing of the epoxy resin (bisphenol-A-type epoxide oligomers, DGEBA) and Gly-PLA was carried out with BPH as a latent hardener. The curing reaction quantitatively generated a solvent-insoluble gelled epoxy resin. The curing process of the DGEBA and Gly-PLA in the presence of BPH was monitored using differential scanning calorimetry (DSC), and the cured materials were characterized with infrared (IR) spectroscopy. The results indicated that the intercross-linked Gly-PLA and epoxy resin could be prepared using BPH as a latent hardener.

Toughness and strength improvement of diglycidyl ether of bisphenol‐A by low viscosity liquid hyperbranched epoxy resin

This article reports on the use of low viscosity liquid thermosetting hyperbranched poly(trimellitic anhydride‐diethylene glycol) ester epoxy resin (HTDE) as an additive to an epoxy amine resin system. Four kinds of variety molecular weight and epoxy equivalent weight HTDE as modifiers in the diglycidyl ether of bisphenol‐A (DGEBA) amine systems are discussed in detail. It has been shown that the content and molecular weight of HTDE have important effect on the performance of the cured system, and the performance of the HTDE/DGEBA blends has been maximum with the increase of content and molecular weight or generation of HTDE. The impact strength and fracture toughness of the cured systems with 9 wt % second generation of HTDE are 58.2 kJ/m² and 3.20 MPa m^1/2, which are almost three and two times, respectively, of DGEBA performance. Furthermore, the tensile and flexural strength can be enhanced about 20%. The glass transition temperature and Vicat temperature, however, are found to decrease to some extent. The fracture surfaces are evaluated by using scanning electron microscopy, which showed that the homogeneous phase structure of the HTDE blends facilitates an enhanced interaction with the polymer matrix to achieve excellent toughness and strength enhancement of the cured systems, and the “protonema” phenomenon in SEM has been explained by in situ reinforcing and toughening mechanism and molecular simulation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2504–2511, 2006     

ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C₁₄H₇O⁺, CHO⁺, CH₃O⁺, and C₂₁H₂₄O₄⁺ showed variance related to the completion of the curing reaction. Relative intensities of C_xH_yN_z⁺ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Silica/poly(styrene-alt-maleic anhydride) hybrid particles as a reactive toughener for epoxy resin

Amino-modified silica nanoparticles (SiO₂─NH₂) were first prepared by hydrolytic condensation of tetraethyl orthosilicate and 3-aminopropylmethyldiethoxysilane. Then, organic–inorganic hybrid particles (SiO₂─SMA) were prepared by the amidation reaction between SiO₂─NH₂ and poly(styrene-alt-maleic anhydride) (SMA). Subsequently, SiO₂─SMA particles were employed for modifying bisphenol-A epoxy/anhydride thermoset. Compared with pure cured epoxy, the modified epoxy thermosets with only 1 wt % of SiO₂─SMA particles could achieve a simultaneous toughening and reinforcing performance. The tensile strength, impact strength, and fracture toughness of epoxy thermoset were increased by 14.1, 44.3, and 114.4%, respectively. Moreover, the modification also improved the thermal stability of epoxy thermosets, and the modulus and glass transition temperature of cured resin were not sacrificed. It can be attributed to the rigid structure of SiO₂, as well as the anhydride and carboxyl groups onto the surface of SiO₂─SMA particles participating in the epoxy curing reaction and effectively enhancing the crosslinking density of epoxy thermoset.     

Composites of Poly(Keto-Sulfide)–Epoxy Resin Systems and Their Thermal and Mechanical Properties

A novel matrix resin system, poly(keto-sulfide)–epoxy resin, has been developed. The poly(keto-sulfide)s (PKS), based on various ketones, formaldehyde, and sodium hydrogen sulfide (NaSH), were prepared by the reported process. These (PKS) having terminal thiol (–SH) groups were used for curing commercial epoxy resin (i.e., diglycidyl ether of bisphenol A – DGEBA), to fabricate crosslinked epoxy-poly(keto-sulfide) resin glass fiber-reinforced composites (GRC). Various epoxy/hardener (PKS) mixing ratios were used, and the curing of epoxy-PKS has been monitored using differential scanning calorimetry (DSC) in dynamic mode. Based on DSC parameters the GRC of epoxy-PKS were prepared and characterized by thermal and mechanical methods. The variation in resin/hardener ratio led to variations in thermal and mechanical properties.     

Synthesis and characterization of unsaturated polyesters based on the aminolysis of poly(ethylene terephthalate)

The depolymerization of poly(ethylene terephthalate) via an aminolysis process was studied. An excess of ethanol amine in the presence of sodium acetate as a catalyst was used to produce bis(2‐hydroxyl ethylene) terephthalamide (BHETA). Unsaturated polyester (UP) resins were obtained by the reaction of BHETA with different long‐chain dibasic acids such as decanedioic acid, tetradecanoic acid, and octadecanoic acid in conjunction with maleic anhydride as a source of unsaturation. The chemical structure of the UP resins was confirmed by ¹H‐NMR. The vinyl ester resins were used as crosslinking agents for UP. The curing behavior and mechanical properties of the UP resins with vinyl ester were evaluated at different temperatures ranging from 25 to 55°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

硫醇固化剂的合成和应用

硫醇固化剂与环氧树脂的配合物可低温快速固化,广泛应用于胶粘剂领域,目前尚依赖进口。为促进硫醇固化剂的国产化,对硫醇固化剂的制备方法和应用进行了研究。实验表明,选用β-巯基丙酸与季戊四醇在酸性催化剂存在下酯化,然后再与环氧树脂进行扩链反应,可以制得黏度和使用配比均适用的硫醇固化剂,总产率为95%以上。用此固化剂与环氧树脂及叔胺混合后,能在5℃以下数分钟内固化。该合成方法工艺简单,易于控制,制得的硫醇固化剂黏度适中,与环氧树脂相溶性好,低温固化快,固化物无色透明等超过了进口产品。