Synthesis,characterization, and glass fiber reinforced composites of poly(urethane-imide)s

Poly(urethane-imide)s (PUI)s were prepared by the intermolecular Diels-Alder (DA)reaction of 4-methyl-1,3-phenylene-bis(2-furanylmethylthioethylcarbamate) (MPFTC) with various bismaleimides. The DA reaction was carried out in 1,4-dioxane as a solvent as well as in bulk, followed by aromatization of tetrahydrophthalimide intermediates in the presence of acetic anhydride. All the polymers were characterized by elemental analysis, IR spectral studies and thermogravimetry. The PUIs exhibit moderate thermal stability. MPFTC and bismaleimides were polymerized (at 145 - 10°C) by an "in situ" DA intermolecular reaction into moderately thermally stable PUIs glass-fiber composite (i.e., laminates) and were characterized by their chemical resistance and mechanical properties.     

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.     

Synthesis,Characterization and Glass-Reinforced Composites of Poly(Ether-imide)s Based on Epoxy Resin: II

Abstract

Novel poly(ether-imide)s were prepared by Diels-Alder (DA) reaction of 1,1′-(1-methylethylidene)bis[4-{1-(2-furanyl-methoxy)-2-propanoloxy}] benzene with various bismaleimides. The DA reaction was carried out in solution using tetrahydrofuran (THF) as solvent, as well as in bulk. The post polymerization, involving aromatization of tetrahydrophthalimide intermediates was accomplished in the presence of acetic anhydride. All the poly(ether-imide)s were characterized by elemental analyses, infrared spectrometry and thermogravimetry. The glass reinforced composites of produced PEIs have also been prepared and characterized.     

Synthesis,Characterization, and Glass Reinforcement of Poly(Amido-Imide)s-Part-3

Poly(amido-imide)s (PAI) were prepared by the intermolecular Diels-Alder (DA) reaction of 1,1-(sulfonyldi-4,1-phenylene) bis[(2-furanyl methylamino) acetamide] (SPBFA) with various bis(maleimide)s. The DA reaction was carried out in tetrahydrofuran as a solvent, as well as in bulk, followed by aromatization of sodium acetate intermediates in the presence of acetic anhydride. All the polymers were characterized by elemental analysis, infrared (IR) spectral studies, and thermogravimetry. The PAI exhibit moderate thermal stability. The SPBFA and bis(maleimide)s were polymerized (at 145±10°C) by in situ DA intermolecular reaction into moderately thermally stable PAI-glass fiber composite laminates and were characterized by their chemical resistance and mechanical properties.     

Synthesis,Characterization, and Glass Reinforcement of Flame Retardant Acrylated Poly(Ester-Amide) and Flame Retardant Poly(Ester-Imide) Resins Based on Brominated Epoxy Resin

Bisphthalamic acids were prepared by reaction of phthalic anhydride and aliphatic diamines. Flame retardant poly(ester-amide)s were prepared by reaction of brominated epoxy resin with bisphthalamic acids and post reaction was carried out with acryloyl chloride to obtained acrylated flame retardant poly(ester-amide) resins. Bismaleimides were prepared by reaction between aromatic diamines and maleic anhydride. Carboxy terminated bismaleimides were prepared by Michael addition reaction of bismaleimides and 4-amino benzoic acid. Flame retardant poly(ester-imide)s were prepared by reaction between carboxy terminated bismaleimides and brominated epoxy resin. All the obtained products were characterized and analyzed by making composites.     

Polyimides Containing S-Triazine Ring (Part-1)

Abstract

Novel polyimides containing s-triazine nucleus were prepared via Diels-Alder (DA) intermolecular polymerization of 2,4-bis(2-furanyl methyl imino)-4-methoxy-1,3,5-triazine (1) with different bis(maleimido) compounds (2a-h). The DA reaction was carried out in tetrahydrofuran as solvent, as well as in bulk followed by dehydration on aromatization of poly(tetrahydrophthalimido)-intermediates (3a-h) in the presence of acetic anhydride. All the poly(imino s-triazine imide)s (4a-h) were characterized by elemental analysis, IR spectral studies, and thermogravimetry. 1 and 2a-h were polymerized (at 150±10°C) by in-situ Diels-Alder intermolecular reaction into poly(imino s-triazine imide)s-glass fibre reinforced composites (i.e., laminates) without evolution of bi-products. The prepared composites were characterized by chemical resistivity and mechanical properties.     

Synthesis,Characterization and Glass/Carbon Reinforcement of Acetone-Formaldehyde-1,5-Dihydroxynaphthalene-Epoxy Resin System

Acetone-formaldehyde (AF) resin containing the methylol group (–CH₂OH) has been prepared and condensed with 1,5-dihydroxynaphthalene (DN) in the presence of an alcoholic alkali catalyst at varying ratios of AF:DN: 1:1, 1:1.5 and 1:2, respectively. The resultant AFDN resins were characterized by elemental analyses, IR spectral studies, and number average molecular weight determined by the nonaqueous conductometric titration method. Further reaction of the AFDN resins was carried out with different epoxy resins (i.e., DGEBA, DGEBC and DGEBF). The curing of these resins was monitored by differential scanning calorimeter (DSC) and their kinetic parameters have been evaluated. Based on DSC thermograms both glass and carbon fiber-reinforced composites have been laminated and characterized for chemical, mechanical and electrical properties. The unreinforced cured resins were subjected to thermogravimetric analysis (TGA).     

Re-Mendable Polyurethanes

Novel re-mendable polyurethanes were prepared by the Diels-Alder cycloaddition reaction of urethane bismaleimides to bisfuryl monomers. The urethane bismaleimides were synthesized by an addition reaction of 4-maleimidophenylisocyanate to macrodiols, such as polycaprolactone diol (M_n ? 1250 and 2000), PEA-2000 and PBA-2000. The bisfuryl monomers were obtained by the reaction of 2-furfuryl alcohol with hexamethylene diisocyanate or by open-ring reaction of the oxirane ring from diglycidyl bisphenol A with furfuryl amine.     

Fracture strength of composite resins for endodontically treated molars

Objectives: The purpose of this study was to evaluate the effect of different fabrication techniques on the fracture strength of the composite resin-based inlay restorations of endodontically treated molars. Methods: Sixty mandibular molars were divided into six groups (n = 10) designated according to the treatment as: Group-1: Control group, intact teeth; Group-2: Filtek Ultimate Universal restorative with incremental technique; Group-3: Filtek Bulk Fill Posterior restorative; Group-4: Biodentine with Filtek Ultimate Universal restorative; Group 5: everX Posterior with Filtek Ultimate Universal restorative; and Group-6: Lava Ultimate CAD/CAM restorative. The standard mesio-occluso-distal cavities were prepared and the roots filled for all the teeth, except those of the control group. Following the placement of the restorations, the fracture resistance of the specimens was measured. The data were analyzed by the one-way analysis of variance and Tukey’s post hoc test. Results: While Group-1 (2815.80 N) exhibited significantly higher fracture strength than the other groups (p < 0.05), Groups-2 (2062.20 N), 3 (2166.00 N), 5 (2355.60 N), and 6 (2340.70 N) exhibited statistically similar results (p > 0.05). The Biodentine group (1480.50 N) exhibited significantly lower fracture strength than the rest of the groups (p < 0.05). Conclusions: The CAD/CAM and manual build-up techniques exhibited statistically similar results with the exception of Biodentine, which exhibited a significantly lower in vitro performance compared to the other composites used in the study. The fiber-supported composite everX Posterior increased the fracture strength of the endodontically treated teeth.     

Synthesis and characterization of novel diimide–dinaphthols and resulting poly(urethane–imide)s

Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry     

Bond strength of fiber posts and short fiber-reinforced composite to root canal dentin following cyclic loading*

The aim of this study was to evaluate the effect of cyclic loading on the bond strength of fiber posts and short fiber-reinforced composite (FRC) to root canal. One hundred single-rooted teeth were divided into two groups according to the material used for luting fiber posts: (1) Resin-core material (Gradia Core, GC Corp.) and (2) Short FRC (EverX Posterior, GC Corp.). Then the specimens were randomly assigned into three sub-groups according to the post material and the groups are indicated as follows: (1) Short FRC (EverX Posterior) used instead of post and core, (2) Fiber post (GC post, GC Corp.) cemented with resin-core (Gradia Core), (3) Fiber post (GC post, GC Corp.) cemented with short FRC (EverX Posterior), (4) Experimental fiber post cemented with resin-core (Gradia Core, GC Corp), (5) Experimental fiber post cemented with short FRC (EverX Posterior). Then the specimens were subdivided into a further two groups in accordance with the storage condition (cyclic loading and 24 h water storage-control group) (n = 10/per group). The micropush-out bond strength between root dentin and posts was measured. Data were analyzed using three-way ANOVA and Tukey HSD tests (α = 0.05). Micropush-out bond strength of the posts to dentin was significantly affected by the type of post material (p < 0.05). However, the load cycling and the resin-based luting agent used had no effect on bond strength values (p = 0.706 and p = 0.346, respectively).     

Interacting Blends of Flame-Retardant Acrylated Poly(Ester-Amide) Resins Based on Brominated Epoxy Resin with Methyl Methacrylate and Styrene

Bisphthalamic acids were prepared by reaction between phthalic anhydride and diamines. Flame-retardant poly(ester-amide)s (FR-PEAs) were prepared by reaction between bisphthalamic acids and brominated epoxy resin. Acrylation of FR-PEAs gives flame retardant acrylated poly(ester-amide)s (FR-APEAs). FR-PEAs and FR-APEAs were characterized by IR spectra, elemental analysis and number average molecular weight. Blending of FR-APEAs with methyl methacrylate and styrene was carried out. Curing study of these blends was monitored by Differential Scanning Calorimeter (DSC). Based on DSC data, glass and carbon reinforced composites have been laminated and characterized. The unreinforced cured samples were subjected to thermogravimetric analysis.     

Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand(SCOD)systems previously based on aliphatic bismaleimides.These SCOD systems are based on Diels-Alder(DA)/retro-DA reactions.The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented.These maleimides have been protected using DA reaction and characterized by 1H NMR analysis to determine protection rate and diastereomer ratios.The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied.Kinetic analysis was monitored by 1H NMR and compared to model study.Finally,both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared.The glass transition temperature values ranged from–20°C to 14°C and very good thermal stabilities were observed(up to 300°C).     

Synthesis and characterization of poly(ester-urethane-imide)s by Diels–Alder polyaddition

Poly(ester-urethane-imide)s were prepared by Diels–Alder polyaddition of 1,6-hexamethylene-bis(2-furanylmethylcarbamate) with various bismaleimides containing ester groups in the backbone. The Diels–Alder reaction was carried out in m-cresol, at 110°C, followed by thermal and chemical aromatization of tetrahydrophthalimide intermediates. The monomers and polymers were characterized by IR, ¹H-NMR spectroscopy and elemental analysis. Thermal properties of the polymers were investigated by differential scanning calorimetry and dynamic thermogravimetric analysis.     

Novel Semi-Interpenetrating Polyimide Network Based on Acryl End Capped Oligoimides

Amino terminated oligoimides (AOIs) were prepared by the Michael addition reaction of various bismaleimides(1a–c) with excess of 4,4′-diamino diphenyl methane (DDM). These AOIs were characterized by elemental analysis, FT-IR spectral studies and number average molecular weight estimated by non-aqueous conductometric titrations. AOIs were then reacted with acrylol chloride and resultant acryl end capped oligoimides (AcOIs) sample were also characterized thermogravimetrically. Each of these AcOI was then combined with the commercially available thermoplastic polyamic acid solution in various proportions. The resultant suspensions were then heated in the presence of azobisisobutyronitrile (AIBN) as a initiator. The AcOI polymerized through double bond and polyamic acid is cyclized to form SEMI-IPN polymides, which were analyzed thermogravimetrically. The glass fibre reinforced composites were fabricated by using the suspensions of the AcOI and polyamic acid solution. The composites of SEMI IPN polymides were analyzed for their mechanical, chemical and electrical properties.     

Sustainable conducting polymer composites: study of mechanical and tribological properties of natural fiber reinforced PVA composites with carbon nanofillers

ABSTRACT

Ball milled jute fiber (JF) was added to Polyvinyl Alcohol (PVA)/20 wt.% multi-layer graphene (MLG) composites in various proportions (0, 5, 10, 15 and 20 wt.%) to prepare sustainable and biodegradable conducting polymer composites. Also, PVA/17.5wt.%MLG/2.5wt.%MWCNT/20wt.% JF composite was prepared for comparison purpose. A dynamic mechanical analysis of the composites was conducted to analyze their viscoelastic nature. The electrical conductivity of the composites was measured to study their suitability for various applications. Jute reinforcement increased the electrical conductivity of PVA/MLG nanocomposites. The PVA/20wt.%JF/17.5wt.%MLG/2.5wt.%MWCNT hybrid composite had the highest electrical conductivity of 3.64 × 10^?4 S/cm among all the composites prepared. Multilayered structures of the hybrid composite films were made by hot-pressing, and their effectiveness in electromagnetic interference shielding was tested. The shielding effectiveness of the composites decreased with jute addition. The wear resistance of PVA/MLG/JF composites increased with an increase in the jute content up to an optimum value of 10 wt.%, and then it started deteriorating.     

On the mechanical,thermophysical and dielectric properties of Nextel™ 440 fiber reinforced nitride matrix (N440/Nitride) composites

The Nextel? 440 fiber reinforced nitride matrix (N440/Nitride) composites were fabricated by precursor infiltration and pyrolysis (PIP) route. The results demonstrated that the original N440 fiber had a phase composition of amorphous SiO₂ and γ-Al₂O₃. Its single filament tensile strength was 3.03 GPa (at room temperature), while it dropped to 72.6% and 35.1% at 1200 °C and 1400 °C, respectively. The phase content of N440/Ntride composites was mainly γ-Al₂O₃ and amorphous BN, as well as mullite phase (formed at > 1100 °C). The composites owned a flexural strength up to 76.0 MPa at room temperature. The stair-stepping decrease in the load-displacement curve and fiber pull-outs in the fracture surface indicated a good fiber/matrix interface and toughness. By heating at 1400 °C, the composites still possessed 67.4% of original bending strength. It was found that the high temperatures caused strong fiber-matrix bonding and severe fiber degradation. The specific heat, CTE and thermal conductivity of the composites were 0.325–0.586 J g^?1 K^?1, (3.2–4.0) × 10^?6 K^?1 and 0.78–3.47 W m^?1 K^?1, respectively. The composites possessed a dielectric constant of 4.25–4.35 and loss tangent of 0.004–0.01 at 8–12 GHz. The good overall performances enabled the N440/Nitride composites advanced high-temperature wave-transparent applications.     

Preparation and Characterization of Functionalized Masterbatch of Montmorillonite and Its Application in Preparing ABS Nanocomposite

The functionalized masterbatch of montmorillonite (FMMT) was prepared when monomer acrylic amide (AM), organic-MMT (OMMT) and initiator dibenzoyl peroxide (BPO) were added to acrylonitrile-butadiene-styrene (ABS) carrier which has been dissolved by 1,2-dichloroethane. The influences of AM and BPO amount, reaction time, and reaction temperature on grafting degree were investigated by the orthogonal experimental design. The range analysis showed that optimal conditions for preparing FMMT are AM (1.6 g), BPO (0.4 g), reaction temperature 90°C and reaction time 2 h. The structure of FMMT was characterized by the test of infrared (IR), x-ray diffraction (XRD) and transmission electron microscope (TEM). The results confirmed that AM was successfully grafted onto ABS, the masterbatch was a kind of intercalculated nanocomposite and the gallery height of nanocomposite was 3.42 nm. When montmorillonite was blended with ABS in the form of masterbatch, ABS/FMMT composite was a kind of exfoliated nanocomposite compared to the ABS/Montmorillonite (MMT), ABS/OMMT composites.     

Preparation and properties of flame retardant poly(urethane‐imide)s containing phosphine oxide moiety

The preparation of new poly(urethane‐imide)s (PUIs) having acceptable thermal stability and higher flame resistance was aimed. Two new aromatic diisocyanate‐containing methyldiphenylphosphine oxide and triphenylphosphine oxide moieties were synthesized via Curtius rearrangement in situ and polymerized by various prepared diols. Four aliphatic hydroxy terminated aromatic based diols were synthesized by the reaction between ethylene carbonate and various diphenolic substances. Chemical structures of monomers and polymers were characterized by FTIR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. Thermal stabilities and decomposition behaviors of the PUIs were tested by DSC and TGA. Thermal measurements indicate that the polymers have high thermal stability and produce high char. Polymers exhibit quite high fire resistance, evaluated by fire test UL‐94. The films of the polymers were prepared by casting the solution. Inherent viscosities, solubilities, and water absorbtion behaviors of the polymers were reported in. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009