Thermal stability of substituted phenol-formaldehyde resins

A variety of crosslinked phenol-, or derivatized phenol-formaldehyde polymers have been synthesized. The phenol derivatives included o- and p-cresol, p-nonylphenol, m-pentadecylphenol, and raw and distilled cashew nutshell liquid. The derivatives were copolymerized with phenol and formaldehyde using sulfuric acid as catalyst to yield novolak-type prepolymers, which were then cured with hexamethylenetetramine. Thermogravimetric analysis was used to evaluate the thermal stability of the cured resins. It was found that the thermal stability of the resins decreased with increasing amounts of cashew nutshell liquid, with distilled cashew resins being slightly more thermally stable than raw cashew resins. The thermal stability of resins containing substituted phenols with alkyl chains was observed to increase from n-pentadecylphenol to cresol to phenol. The trend in thermal stability of the resins may be explained on the basis of alkyl groups being less thermally stable than aromatic rings. The amount of hexamethylenetetramine used to cure the prepolymers also influences the thermal stability of the resins. It appears that a level of 10 to 15% hexamethylenetetramine maximizes the thermal stability of the resin.     

Furfural-based phosphonic acid cation exchange resins from N-vinylcarbazole and its polymer. II

Thermal stabilities of the crosslinked N-vinylcarbazole/poly(N-vinylcarbazole)-furfural polymers and of the phosphonic acid resins prepared thereform were studied by thermogravimetric analysis. The overall thermal stability of the crosslinked polymers is greater than the same for poly(N-vinylcarbazole) and is further improved upon phosphorylation. The resins are stable in 5N acids and water at 100°C. Isothermal oxidative degradation studies of the resins indicate significant increase in the capacities. pH metric titration of the resins shows the presence of mono and dibasic phosphonic acid groups. The resins realize about 90% of their capacities within 2 min of equilibration.     

Pore structure and water‐swelling behavior of porous resins based on methyl acrylate and different divinylbenzene isomers

Porous resins based on divinylbenzene (DVB) and methyl acrylate (MA) were prepared with m‐DVB (98.3%) or p‐DVB (99.1%) in the presence of toluene as a porogen. The MA/DVB resins thus obtained with a wide range of pore structures were hydrophobic in nature and were swellable by direct contact with water. The behavior of m‐DVB and p‐DVB as a crosslinker in the MA/DVB monomer system was different from that in the styrene (ST)/DVB system and was influenced by the amount of MA in the MA/DVB monomer system. As a result, a larger specific surface area and pore volume were observed for MA/DVB resins derived from p‐DVB than for those derived from m‐DVB, which was opposite to that observed for resins based on DVB and ST. The different behaviors of m‐DVB and p‐DVB in the MA/DVB monomer system also resulted in different swelling abilities of the resins in water. Compared with the MA/DVB resins derived from m‐DVB, the p‐DVB derived resins swelled faster in water and were water‐swellable when the resins had a higher DVB content and, therefore, a stronger hydrophobicity and a larger specific surface area. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2071–2078, 2005     

Novel Flower-Like ZnO Hybridized with Acrylic Ester Resin for Enhanced Oil Absorption Properties

The acrylic ester resins have potential applications in for treatment of oily wastewater due to their high oil retention capacity and excellent cycle performance. Herein, a novel acrylic ester hybrid resins composed by poly(n-butylacrylate-co-styrene) resins and flower-like ZnO clusters were prepared using a combination of hydrothermal and suspension polymerization. The hybrid resins can remove a broad variety of oils from water with the maximum oil absorption performance of 30.87?g/g. More importantly, the hybrid resins are reversible and maintain high oil absorption properties after oils absorption-regeneration, making them promising candidates for treatment of oily wastewater.     

Synthesis and characterization of poly(tetramethyldisiloxane-ethynylenephenyleneethynylene) resins

Poly(tetramethyldisiloxaneethynylenephenyleneethynylene) resins were synthesized by polycondensation reactions of the bismagnesium derivative of p- or m-diethynylbenzene with 1,3-dichlorotetramethyldisiloxane. The molecular weights of the resins were determined by gel permeation chromatography. The structures of the resins were verified by ¹H, ¹³C, and ²⁹Si NMR as well as FT-IR spectroscopy. The thermal behavior of the resins was traced by differential scanning calorimetry (DSC). The resins can be thermally crosslinked through the acetylene groups to produce highly crosslinked resins which were thermally stable up to 539 °C in both nitrogen and air. Hard, black, and glassy ceramics were obtained after the sinter of the crosslinked resins at 1,450 °C. The polymers have a potential application as matrix materials for advanced composites and ceramic precursors.     

Preparation and properties of UV-autocurable BTDA-based epoxy-multiacrylate resins. Effects of the degree of polymerization and the epoxy type

A series of UV-autocurable epoxy-multiacrylate resins was synthesized, and the effects of degree of polymerization (DP) and epoxy type on their properties were investigated. These autocurable multiacrylate resins possess good pot life and are cured rapidly when exposed to ultraviolet (UV) without the addition of photoinitiator or photosensitizer. The curing rate of the autocurable resins was probably dependent on the number of abstractable hydrogen in epoxy resins. Stress-strain, differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were used to characterize the properties of cured multiacrylate resins. Increased crosslinking density of cured films improved tensile properties. Increasing the molar ratio of epoxy resin in the multiacrylate resins was found to decrease the effective acrylate concentration of resins and to depress crosslinking density of cured resins, which also resulted in an increased elongation at break but a decreased Young's modulus and breaking strength. Furthermore, the different structures of epoxy resins were used to give wide range properties of cured epoxy-multiacrylate resins with a glass transition temperature (T_g range from 74 to 102°C. The film properties of the multiacrylate resins coated on steel plates were also investigated.     

Viscoelastic characteristics of chain extended/branched and linear polyethylene terephthalate resins

Two chemically modified chain extended/branched polyethylene terephthalate (PET) resins and one unmodified resin, considered to be linear, were characterized in terms of their melt flow, die swell, and viscoelastic properties. The three resins had reportedly similar nominal intrinsic viscosities but exhibited different viscoelastic behavior. The modified resins had lower melt flow index, higher die swell, higher complex viscosity and higher storage modulus than the unmodified one. The Cole–Cole plots of the resins were independent of temperature, and the data for modified resins formed a group that lay below the data group for the unmodified PET. The distribution of relaxation times was determined. The modified resins had higher relaxation strength, G_i, especially at high relaxation times, λ_i. The mean relaxation times of the chain extended/branched resins were approximately an order of magnitude higher than that of the unmodified resin, implying pronounced elastic character. The modified resins had better foaming characteristics in extrusion foam processing than the unmodified one owing to their elastic nature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1371–1377, 2000     

Comparative study of adsorption for m-phenylenediamine in aqueous solution onto chemically modified resins

Four kinds of hypercrosslinked resins (acidic resins labeled SAMR and TAMR and heterocyclic resins IDLMR and PRLMR) were synthesized as adsorbents to remove m-phenylenediamine (MPD) from aqueous solution comparably. The Brunauer–Emmett–Teller specific surface area and pore size distribution of the two types of resins have been compared, and the infrared spectra of the resins confirm the presence of the modified groups. The adsorption isotherms illustrate that the Freundlich equation fits more appropriately than the Langmuir equation or the Temkin equation. In addition, the kinetic curves indicate that the pseudo-second-order model is a better fit than the pseudo-first-order model. The thermodynamic studies show that the isosteric adsorption enthalpy changes (ΔH) and the Gibbs free energy change (ΔG) are both negative, revealing that all of the adsorption processes are spontaneous and exothermic. All of the modified resins exhibit the best adsorption capacity at pH = 6.24. The results show that the acidic resins have better adsorption of MPD. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47378.     

Preparation and anti-microbial properties of friedel—crafts resins

Friedel-Crafts resins were prepared by reacting chloroacetyl chloride, 1,2-dichloroethane and dichloromethane with m-xylene using carbon disulfide as solvent and anhydrous AlCl₃ as catalyst. The resins were characterized by IR spectra and number average molecular weight measured by vapour pressure osmometry. The thermal properties were studied by thermogravimetry and differential scanning calorimetry. All the resins were tested for their microbial activity against Pseudomonas fluorescens, Bacillus subtilis and Aspergillus niger. The results show that most of the resins can be used as biocides.     

Structure and viscoelastic properties of epoxy resins prepared from o-cresol novolacs

The relation between the structure and viscoelastic properties of the epoxy resins prepared from o-cresol novolacs was studied. Our model epoxy resins were two kinds of epoxy compounds synthesized from three-nuclei and four-nuclei o-cresol novolacs. In addition to these models, a commercially available o-cresol novolac-type epoxy resin was also studied. Each of the three epoxy compounds was cured with one of three kinds of novolacs, which were starting materials of the above-mentioned epoxy resins. Characteristic properties of the cured resins, such as glass transition temperature (T_g), average molecular weight between crosslinking points (M¯_c), and front factor (?) were obtained. It was concluded that the number of functional groups contained in the curing system almost dominated the viscoelastic properties of the cured resins.     

New Bismaleimide-Epoxy Resin System

New functional epoxy resins were prepared by the reaction of dialyldiglycicylbisphenol A (DADGBPA) with diaminodiphenylmethane. DADGBPA was prepared by reaction of o,o′-diallylbisphenol A with epichlorhydrine. By reaction of functional epoxy resins with bismaleimides, new epoxy-bismaleimide resins with good thermostability were obtained. The thermal properties of epoxy resins and epoxy-bismaleimide resins were determined by DSC and TGA measurements.     

Chemical Structure and Curing Behavior of Phenol–Urea–Formaldehyde Cocondensed Resins of High Urea Content

Phenol–urea–formaldehyde cocondensed (PUF) resins of high urea content were prepared by adding different forms of urea to the reaction system. The structure, curing behavior, and water resistance of the PUF resins were investigated, and their relations were also discussed by liquid ¹³C nuclear magnetic resonance (NMR) and different scanning calorimetry (DSC). The liquid ¹³C-NMR analysis showed that urea added in the form of methylolureas was well incorporated into the cocondensed resins by reacting with phenolic methylols to form cocondensed methylene bridges, and that the PUF resins had no free formaldehyde with any form. Unreacted urea and low molecule monosubstituted urea of PUF resins play a dominant role in the curing behavior and water resistance of resins. The peak temperature, curing time, and curing enthalpy (ΔH) value correspondingly increased, however, the water resistance of PUF resins decreased when urea content in PUF resins increased. The PUF cocondensed resin with up to 89.4 % (W _U/W _P) urea has relatively low cost, and moreover can pass the requirements of China Industry Standard for the exterior grade of structural plywood after 4-h cyclic boiling test.     

Curing behavior of epoxy resin having hydroxymethyl group and different molecular weight distribution

o-Cresol novolac-type epoxy resins having hydroxymethyl group were synthesized. These epoxy resins were cured with a mixture of 4,4′-diaminodiphenylmethane and m-phenylenediamine (molar ratio, 6:4) as a hardener. Effects of molecular weight distribution of epoxy resins on curing behavior were studied. Curing behavior of epoxy resins with hardener were examined by differential scanning calorimetery (DSC), and cure reaction parameters were obtained. Viscoelastic properties of the cured epoxy resins were studied by dynamic mechanical analyzer. It was found that the lower the average molecular weight of the epoxy resin, that is, the higher the concentration of hydroxymethyl group, the shorter the onset time of exothermal reaction, the higher the rate constant (k), and the lower the activation energy (E_a) were. It was also found that glass transition temperature (T_g) of fully cured epoxy resins was higher than those of fully cured general novolac-type epoxy resins.     

Synthesis and characterization of some novel copolymer resins. III

In continuation of our endeavor to develop synthetic resins of improved properties and performance, we report here the synthesis of mixed copolymer resins by the condensation of resorcinol, aniline, and formaldehyde with ortho-, meta-, and para-phenylenediamine separately. The resins were characterized by infrared (IR) and thermogravimetric analysis (TGA). The mixed copolymer resins were found to have superior thermal stability over conventional phenol–CH₂O and resorcinol–CH₂O resins. The solubility behavior of the resins showed that they are resistant to common solvents. However, they are soluble in concentrated H₂SO₄ and HNO₃, but insoluble in concentrated HCl. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 68: 2183–2187, 1998     

Branched and linear polyethyleneimine supports for resins with retention properties for copper and uranium. VII

Weak and strong basic resins were synthesized by crosslinking with 1,7-dibromoheptane and 1,12-dibromododecane and subsequent N-methylation reaction of branched and linear polyethyleneimine. All the resins are insoluble in water. It was found that the N-methylated resins showed the highest retention ability for uranium. The resins do not retain significatively iron (> 10%), and only two of them retain copper above 80% at optimum pH. Elution assays with sulphuric acid, sodium carbonate, and thermal stability were also carried out.     

Building and origin of bio‐based bismaleimide resins with good processability,high thermal,and mechanical properties

Bio‐based high performance thermosetting resins have been urgently required by cutting‐edge fields for meeting sustainable development. A new kind of high performance thermosetting resins (BA‐n) with good processability, high thermal resistance, and mechanical properties was developed based on 4,4′‐bismaleimidodiphenylmethane (BDM) and renewable bis(5‐allyloxy)‐4‐methoxy‐2‐methylphenyl)methane (ABE) from bio‐based lignin derivative. The effect of the molar ratio of allyl to imide (n) on structures and properties of BA resins were systematically researched. BA‐n resins have much better processability, thermal, and mechanical properties than their petroleum‐based counterparts, 2,2′‐diallylbisphenol A‐modified BDM (BD‐n) resins. Compared with BD‐0.86, the best available bismaleimide (BMI) resin, BA‐0.86 not only has 6 h longer process window and 13.7 °C higher glass transition temperature, but also owns the highest flexural strength and modulus among all bio‐based allyl compound‐modified BMI resins reported. The origin behind these attractive performances of BA resins is revealed by discussing the unique crosslinked structure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45947.     

Comprehensive study of metal on the characteristic properties of epoxy resins

A series of different type of epoxy resins containing metal(s) have been prepared by the using cobalt acrylate (CoA₂), nickel acrylate(NiA₂),bismuth acrylate (BiA₃) during resinification. The values of epoxide equivalent weight, chlorine content increases whereas hydroxyl content, refractive index decreases in the presence of metal acrylate(s). The influence of complex formation of metal acrylate with ether linkage of epoxy resins were investigated by spectroscopy. Epoxy resins containing cobalt acrylate which was cured by p‐acetylbenzilidinetriphenylarsoniumylide (p‐ABTAY) shows better conducting properties in comparison to NiA₂ and BiA₃ containing epoxy resins. The dispersion of metal(s) in epoxy resins matrix was confirmed by scanning electron microscope (SEM). The glass transition temperature of epoxy resins containing CoA₂ is lower than that of blank epoxy resins and epoxy resins containing bismuth and nickel acrylate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of biscyanamide resins containing o-substituted groups or phenyl–ether linkage

New biscyanamides containing o-substituted groups or a phenyl-ether linkage were synthesized. The curing reaction behaviors of the biscyanamides were investigated. All the prepared biscyanamides began to polymerize as soon as they melted after being put on a heated plate beyond a certain temperature. The cured resins of each biscyanamides were prepared on the optimal conditions. Optimal conditions for cured resins were obtained from the curing reaction behaviors of each biscyanamide by differential scanning calorimetry (DSC). The effect of chemical structures of the biscyanamides on the thermal and mechanical properties of the cured resins such as seen by thermal gravimetric analysis (TGA), density, and flexural strength were studied. The introduction of alkyl groups into the ortho position decreased intermolecular interactions. The introduction of a long phenyl-ether linkage into the structure gave a broad exothermal peak in the DSC and good workability for the preparation of the cured resins. Moreover, the extension between cross-linkings improved the flexibility of the cured resins. The cured resins with fluorine-containing substituent groups also had better thermal stability in the air compared with hydrocarbon group resins.     

Ortho-Substituted Ortho-Cresol Novolac Resins as an Epoxy Resin Curing Agent

A series of ortho-substituted ortho-cresol novolac resins were synthesized and used as curing agents for epoxy resins. The chemical structures of different ortho-substituted ortho-cresol novolac resins were investigated by many measurements, such as FT-IR, ¹H NMR, and ¹³C NMR. The results indicated that the ortho-cresol novolac resin with the needed proportion of ortho-substitution was synthesized through the adjustment of the reaction conditions. The studies on the curing kinetics of ortho-cresol novolac epoxy resin cured by different ortho-cresol novolac resins showed that the activation energy was reduced with an increase in the proportion of ortho-ortho methylene bridges.     

Polycarbonate resins

An outline of the history and manufacture of polycarbonate resins is followed by a discussion about resin product types anal their processing. The key properties of flex modulus, deflection temperature, and impact are those that make polycarbonate resins premier engineering resins. Like most other engineering plastics, polycarbonate resins' early commercial history was characterized by substitutions of polycarbonate resins for traditional materials, particularly metal and glass. Examples of applications are presented, More recently application developments involve ab initio selection of polycarbonate resins and article designs based on polycarbonate resin properties. In addition, “tailored” resins such as poly (estercarbonate) resins and polycarbonate resin blends have evolved to meet specific applications. The future growth of polycarbonate resins is predicted to feature few new resins, many new blends, and application developments using computer techniques.