Immobilization of lipase on a polymeric microsphere with an epoxy group prepared by radiation‐induced polymerization

A polymeric microsphere (PM) with an epoxy group was prepared by the radiation‐induced polymerization of glycidyl methacrylate and diethylene glycol dimethacrylate in reaction conditions with variations in solvents, irradiation dose, and monomer composition. The epoxy group of the PM was analyzed by solid‐state ¹³C‐NMR, Fourier transform infrared spectroscopy (FTIR), Fourier transform Raman spectroscopy, and elemental analysis (EA) after amination. In EA after amination, the epoxy group content was in the range 0.20–0.50 mmol/g. The lipase was immobilized to the epoxy group of the PM in experimental conditions with variations in the pH and the epoxy group content. The activity of the lipase‐immobilized PM was in the range 148–342 unit/mg min. The activity of lipase‐immobilized PM increased in accordance with the epoxy group content. The lipase‐immobilized PM was also characterized by FTIR and EA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1153–1161, 2003     

Synthesis,spectral, and thermal characterization of photoreactive epoxy resin containing cycloalkanone moiety in the main chain

Dual functional epoxy resins were synthesized by solution polycondensation of 2,6‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclohexanone and 2,5‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclopentanone with epichlorohydrin. The synthesized epoxy resins were characterized systematically for their structure by UV, Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR spectroscopic techniques. Thermal characterization of synthesized epoxy resins was carried out by thermogravimetric analysis, and differential scanning calorimetry (DSC) under nitrogen atmosphere. The self extinguishing property of synthesized oligomers was studied by determining limiting oxygen index (LOI) values using Van Krevelen's equation. X‐ray analysis showed that the epoxy resins containing cyclopentanone have higher degree of crystallinity. The photoreactive property of the synthesized epoxy resins in solution and film states was investigated by UV–Vis spectroscopy. The photocross‐linking proceeds through the dimerization of olefinic chromophore present in the main chain of the oligomer via 2π + 2π cycloaddition reaction. The influence of photoacid generator on the rate of photocross‐linking of epoxy resin was studied by FTIR. UV irradiation of the epoxy resin in presence of photoacid generator produces aromatic sulfonium cation radicals and aromatic radicals which initiate the cationic ring‐opening polymerization of oxirane ring. The photoreactivity studies of the oligomers by FTIR and DSC indicated the presence of dual functionality in the synthesized epoxy resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Ring Opening of Epoxidized Soybean Oil with Compounds Containing Two Different Functional Groups

Epoxidized vegetable oils are desirable chemicals due to their eco‐friendly characteristics and their being a major source of many green products. Ring opening is one of the ways to convert these epoxidized oils to some new intermediates. The use of mono‐functional amines, alcohols, acid anhydrides and thioethers for epoxy ring opening has been reported in the literature. In this study, thioglycolic acid (TGA) bearing thiol and carboxylic acid as two different functional groups and methyl ester of thioglycolic acid (TGAME) were used. Currently, there is no reported literature describing epoxy ring opening using chemicals bearing two different functional groups simultaneously. In this way, two new polyols were synthesized, one with TGA (polyol 1) and one with TGAME (polyol 2). FTIR and ¹H‐ and ¹³C‐NMR spectroscopy confirmed that the ring was opened by the carboxylic acid group of TGA, and the thiol group was not involved in the ring opening whereas the ring was opened by the thiol group in the case of TGAME.     

Design of New Camelina Oil‐Based Hydrophilic Monomers for Novel Polymeric Materials

Triglyceride‐based monomers represent a competitive alternative to petrochemical resources in the macromolecular compounds area. In the current study, several types of hydrophilic camelina oil (CO)‐based monomers were synthesized using tunable experimental protocols that involve three different steps: first—conversion of the double bonds into epoxy rings, second—partial opening of the epoxy rings and methacrylic groups grafting and last—opening of the unreacted epoxy rings and hydrophilic units attaching. 1H‐NMR, 13C‐NMR and FTIR spectroscopy demonstrate the success of the CO functionalization with polymerizable and hydrophilic moieties—polyethylene glycol units—with different molecular weights, exhibiting self‐emulsifiable properties. Several bulk and emulsion polymerization tests were performed for the synthesized monomers and their ability to build polymer networks using different photo‐chemical procedures (using visible and UV radiations respectively) was demonstrated, without additional surfactants. FTIR spectroscopy indicates the polymerization success by the disappearance of the specific bands assigned to the double bonds from methacrylic groups and thermogravimetric analysis demonstrates that the emulsion polymerization leads to materials with an improved thermostability.     

Accelerated ultraviolet aging study of the Vectran fiber

Aging behavior of Vectran fiber exposed to ultraviolet (UV) radiation was investigated. Vectran fiber was subjected to UV‐accelerated degradation environment. Tensile strength of Vectran fiber was determined at room temperature using a two‐parameter Weibull distribution. The average tensile strength loss was 42.75% when the irradiation time reached 186 h. The surface morphology of the degraded fiber was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). X‐ray photoelectron spectroscopy (XPS) and ¹³C‐NMR were used to provide a molecular characterization of fibers. SEM and AFM showed that UV exposure result in microvoids on the surface of fibers. The results of the XPS and ¹³C‐NMR indicated that the UV radiation could lead to chain scission of fiber surface layer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Biolignin™ based epoxy resins

Wheat straw Biolignin? was used as a substitute of bisphenol‐A in epoxy resin. Synthesis was carried out in alkaline aqueous media using polyethyleneglycol diglycidyl ether (PEGDGE) as epoxide agent. Structural study of Biolignin? and PEGDGE was performed by solid‐state ¹³C NMR and gel permeation chromatography, respectively, before epoxy resin synthesis. Biolignin? based epoxy resins were obtained with different ratios of Biolignin? : PEGDGE and their structures were analyzed by solid‐state ¹³C NMR. The crosslinking of PEGDGE with Biolignin? was highlighted in this study. Properties of Biolignin? based epoxy resins were analyzed by differential scanning calorimetry and dynamic load thermomechanical analysis as well as compared with those of a bisphenol‐A epoxy‐amine resin. Depending on the epoxy resin formulation, results confirmed the high potential of Biolignin? as a biosourced polyphenol used in epoxy resin applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Catalytic Vicinal Diacylation of Epoxidized Triglycerides in Canola Oil

The epoxy ring opening and vicinal diacylation of fatty acids in vegetable oils was found to be promising reaction to synthesize stable biolubricants and bioplasticizers. The current research investigation is emphasized on the synthesis of a value added product vicinally diacylated canola oil by sulfated‐ZrO₂. The two‐step research approach employed includes: (i) epoxidation, and (ii) epoxy ring opening and vicinal diacylation of epoxidized triglycerides in the canola oil. Sulfated‐ZrO₂ was prepared and characterized to measure the physico‐chemical properties required for the effective catalysis. The Taguchi (L16 orthogonal array) statistical design method was employed to optimize the process conditions for the maximum formation of diacylated canola oil. Sulfated‐ZrO₂ demonstrated promising activity for the epoxy ring opening and vicinal diacylation of canola oil, and 99 % conversion was achieved at the optimum process conditions of temperature 130 °C, epoxy to acetic anhydride molar ratio (1:1.25), 16 wt% of catalyst loading and reaction time of 1 h which were inferred from the Taguchi analyses. The products were characterized and confirmed with FT‐IR, ¹H NMR and sodium spray mass spectroscopy. Spectroscopic analysis also confirmed the absence of intermediate products. The statistical analyses was undertaken to determine the order, rank and interactions among the process variables. The reaction followed Langmuir–Hinshelwood–Hougen–Watson type mechanism and the kinetic data was fitted in overall second order equation. Calculated apparent activation energy was 23.1 kcal/mol.     

Curing of epoxy resin with poly(m‐phenylene methylphosphonate)

The mechanism and kinetics of curing of epoxy resin with poly(m‐phenylene methylphosphonate) (PMP) was studied by extraction and swelling experiments, DSC, ³¹P NMR, and FTIR. It was shown that at linear heating of 20°C/min PMP cures bisphenol A type epoxy resin at 230–300°C, whereas in the presence of catalytic amount of 2‐methyl imidazole the curing occurs at 200–230°C. Under isothermal conditions, epoxy resin was cured with PMP after 40–70 min at 150°C. An unusual mechanism of curing due to opening and insertion of epoxy into the phosphonate bond was suggested. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4011–4022, 2006     

Influence of γ‐irradiation on poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA) was γ‐irradiated (5–20 kGy) by a ¹³⁷Cs source at room temperature in air. The changes in the molecular structure attributed to γ‐irradiation were studied by mechanical testing (flexure and hardness), size‐exclusion chromatography, differential scanning calorimetry, thermal gravimetric analysis, and both Fourier transform infrared and solution ¹³C‐NMR spectroscopy. Scanning electron microscopy was used to investigate the influence of the dose of γ rays on the fracture behavior of PMMA. The experimental results confirm that the PMMA degradation process involves chain scission. It was also observed that PMMA presents a brittle fracture mechanism and modifications in the color, becoming yellowish. The mechanical property curves show a similar pattern when the γ‐radiation dose increases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 886–895, 2002     

Fabrication and characterization of the mechanical properties of multi-walled carbon nanotube-reinforced epoxy resins by e-beam irradiation

In this study, the multi-walled carbon nanotubes (MWNT) were reinforced to epoxy resin as fabrication of epoxy/MWNT nanocomposites by electron beam (e-beam) curing. An attempt is made to disperse MWNT into diglycidyl ether of bisphenol A (DGEBA) as epoxy resins, using triarylsulfonium hexafluoroantimonate (TASHFA) as an initiator. E-beam irradiation effect on the curing of the epoxy resin was investigated in oxygen and nitrogen atmospheres at room temperature. The flexural modulus was measured by a universal testing machine (UTM). Here, the flexural modulus factor exhibits an upper limit at 0.3 wt% MWNT. The dynamic mechanical and thermal properties of the irradiated epoxy resins were characterized using DMA, DSC and TGA machines. DMA curves of the storage modulus revealed an increase with an increasing MWNT content and radiation dose. However, the T_g curve decreased as a function of the increasing MWNT content and radiation dose. The thermal properties of the TGA and DSC data were improved by increasing the content of the MWNT and the radiation dose. Likewise, the thermal properties were stabilized by increasing the amount of initiator and irradiating the resins in a nitrogen atmosphere.     

Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites

Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride. The obtained resins were characterized with FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion. The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications. The cross‐linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking. The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 2.2% of unreacted epoxy groups, which was confirmed by ¹H‐NMR. The ¹³C‐NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1. The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 0.2 and 0.48 Pas, respectively, which indicates that they can be used in resin transfer molding process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,formulation, and characterization of siloxane‐modified epoxy‐based anticorrosive paints

Diglycidyl ether of bisphenol A epoxy (E) was modified with hydroxyl‐terminated polydimethylsiloxane through a ring‐opening addition polymerization reaction. The structural elucidation of the siloxane‐modified epoxy resin (ES) was carried out with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy techniques. The physicochemical characterization of the synthesized resin (ES) was performed with standard methods. E and ES were subjected to paint formulation with the help of a rutile (TiO₂) pigment. The formulated paint systems were cured at room temperature with 1,6‐diaminohexane (AH) and 1,3‐diaminopropane (AP), which were used as curatives. The E–AH, E–AP, ES–AH, and ES–AP paint systems were applied to mild steel strips. The physicomechanical and anticorrosive performance of the coated panels was evaluated with standard methods. The thermal analysis of these E–amine and ES–amine systems was carried out via thermogravimetric analysis. The effects of siloxane incorporation and amine curatives on the coating properties of the paint systems were also investigated. The ES–AP system exhibited good thermal and corrosion stability performance among all the E and ES paint systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4981–4991, 2006     

Synthesis and characterization of α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxy‐ ethylamino)propoxy]propyl}polydimethylsiloxane

A novel synthesis path for the monotelechelic polydimethylsiloxane with a diol‐end group, α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxyethylamino)propoxy]propyl}polydimethylsiloxane, is described in this article. The preparation included three steps, which were anionic ring‐opening polymerization, hydrosilylation, and epoxy addition. The structure and polydispersity index of the products were analyzed and confirmed by FTIR, ¹H NMR, ¹³C NMR, H? H, and C? H. Correlated Spectroscopy and gel permeation chromatography. The results demonstrated that each step was successfully carried out and the targeted products were accessed in all cases. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Degradation behavior of nanoreinforced epoxy systems under pulse laser

Nanocomposites using EPON 824 as their matrix were exposed to pulse laser at 532 nm for various time intervals. The developed nanomaterials used for this study were manufactured using EPON 824 with multiwalled carbon nanotubes (MWCNTs) at a loading rate of 0.15% by weight and nanoclays at a loading rate of 2% by weight as reinforcements. The effect of laser irradiation on polymer composites has been investigated. The degradation mechanism for the epoxy was of a laser induced burning nature. Of all specimens tested, the ultimate strength of the MWCNT‐reinforced specimens decreased the most as a function of radiation time; the nanoclay‐reinforced epoxy retained the most strength after 2 min of laser radiation. In addition, the threshold fluence for decomposition indicated that less energy was required to initiate decomposition in the MWCNT‐reinforced epoxy than in the nanoclay‐reinforced epoxy. This can be attributed to the high thermal conductivity of the carbon nanotubes. Measurement of surface damage in the material was observed via electron microscopy. Fourier transform infrared spectroscopy was used to investigate changes to the molecular structure as a function of exposure time. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,cationic polymerization and curing reaction with epoxy resin of 3,9‐di(p‐methoxybenzyl)‐1,5,7,11‐tetra‐oxaspiro(5,5)undecane

A new spiro ortho carbonate, 3,9‐di(p‐methoxybenzyl)‐1,5,7,11‐tetra‐oxaspiro(5,5)undecane was prepared by the reaction of 2‐methoxybenzyl‐1,3‐propanediol with di(n‐butyl)tin oxide, following with carbon disulfide. Its cationic polymerization was carried out in dichloromethane using BF₃‐OEt₂ as catalyst. The [¹H], [¹³C]NMR and IR data as well as elementary analysis of the polymers obtained indicated that it underwent double ring‐opening polymerization. The polymerization mechanism is discussed. The curing reaction of bisphenol A type epoxy resin in the presence of the monomer and a curing agent was investigated. DSC measurements were used to follow the curing process. In the case of boron trifluoride‐o‐phenylenediamine (BF₃‐OPDA) as curing agent, two peaks were found on the DSC curves, one of which was attributed to the polymerization of the epoxy group, and the other to the copolymerization of the monomer with the isolated epoxy groups or homopolymerization. However, when BF₃‐H₂NEt was used as curing agent, only one peak was present. IR measurement of the modified epoxy resin with various weight ratios of epoxy resin/monomer was performed in the presence of BF₃‐H₂NEt as curing agent. The results demonstrate that the conversion of epoxy group increases as the content of monomer increases. The curing process and the structure of the epoxy resin network are discussed. © 2000 Society of Chemical Industry     

Study of glycidyl ether as a new kind of modifier for urea‐formaldehyde wood adhesives

In this work, the multiepoxy functional glycidyl ether (GE) modified urea‐formaldehyde (UF) resins were synthesized via a traditional alkaline‐acid process under low formaldehyde/urea (F/U) molar ratio. The synthesized resins were characterized by ¹³C magnetic resonance spectroscopy (¹³C‐NMR), indicating that GE can effectively react with UF resins via the ring‐opening reaction of epoxy groups. Moreover, the residual epoxy groups of GE could also participate in the curing reaction of UF resins, which was verified by Fourier transform infrared spectroscopy. The storage stability of GE‐modified UF resins and the thermal degradation behavior of the synthesized resins were evaluated by using optical microrheology and thermogravimetric analysis, respectively. Meanwhile, the synthesized resins were further employed to prepare the plywood with the veneers glued. For the modification on bonding strength and formaldehyde emission of the plywood, the influences of addition method, type, and amount of GE were systematically investigated. The performance of UF adhesives were remarkably improved by the modification of GE around 20–30% (weight percentage of total urea) in the acidic condensation stage during the resin synthesis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

(η6‐N‐alkylcarbazole) (η5‐cyclopentadienyl) iron hexafluorophosphate salts in photoinitiated and thermal epoxy polymerization

(η6‐Carbazole)(η5‐cyclopentadienyl) iron hexafluorophosphate salts (CFS PF₆) are capable of photoinitiating cationic polymerization of epoxy monomers directly upon irradiation with long‐wavelength UV light. To improve the solubility of CFS ferrocenium salts in epoxides, two CFS photoinitiators have been prepared: [cyclopentadiene‐Fe‐N‐buylcarbazole] hexafluorophosphate (C4‐CFS PF₆) and [cyclopentadiene‐Fe‐N‐octylcarbazole] hexafluorophosphate (C8‐CFS PF₆), bearing C4 and C8 alkyl chains, respectively, on the nitrogen atom. Studies with real‐time infrared spectroscopy have shown that C4‐CFS and C8‐CFS photoinitiators exhibit high efficiency in polymerization of 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexane carboxylate (ERL‐4221) epoxy monomer, but lower efficiency in polymerization of di(2,3‐epoxypropyl)‐3,4‐epoxy‐1,2‐cyclohexanedioate (TDE‐85) epoxy monomer. Benzoyl peroxide (BPO) sensitizer was very effective in improving the photoinitiating activities of CFS in polymerization of both ERL‐4221 and TDE‐85. DSC studies have shown that C4‐CFS and C8‐CFS photoinitiators can also be employed as thermal initiators for the cationic ring‐opening polymerization of epoxides at moderate temperatures. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Nanocomposite coatings via simultaneous organic–inorganic photo‐induced polymerization: synthesis,structural investigation and mechanical characterization

Hybrid sol–gel films were prepared via a simultaneous organic‐inorganic UV‐curing process using a diaryliodonium salt as a superacid photogenerator. In this single‐step procedure, an epoxy functionalized reactive resin mixed with a variable amount of either of two epoxy trialkoxysilane precursors was UV‐irradiated, causing both the initiation of epoxy ring‐opening copolymerization and the catalysis of trialkoxysilyl sol–gel reactions. The concomitant photo‐induced sol–gel process was found to have a significant effect on the two related propagation mechanisms in competition for the oxirane ring‐opening—the active chain‐end and the activated monomer mechanisms—as proved by a systematic examination of the hybrid material microstructure through ²⁹Si and ¹³C solid‐state NMR spectroscopy. The effect of the oxo‐silica network generation on the epoxy reaction kinetics was also evaluated using real‐time Fourier transform infrared spectroscopy upon varying the epoxysilane structure and its concentration. Thermal and dynamic mechanical analyses were systematically performed on these hybrids, by studying thoroughly their structure–property interdependence. Other mechanical characterizations through tribological and scratch tests suggested that the present photopolymer–silica hybrid material provides a powerful tool to tailor mechanical property profiles. Copyright © 2010 Society of Chemical Industry     

Reactions of palm oil‐based mcl‐PHAs with epoxidized natural rubber

A palm oil‐based medium‐chain‐length polyhydroxyalkanoate (mcl‐PHA) was allowed to react with epoxidized natural rubber (ENR). There was no noticeable reaction at ambient temperature for short reaction times. However, after 30 min at 170°C, the mcl‐PHA underwent thermal degradation to generate carboxylic terminal groups that attacked the epoxy groups of the ENR. Evidence of the ring‐opening reaction was provided by both FTIR and ¹H‐NMR. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Radiation grafting/crosslinking of silk using electron‐beam irradiation

The radiation grafting of silk with methacrylamide (MAA) was studied using an electron‐beam (EB) irradiation technique. Two irradiation processes, preirradiation and coirradiation, were compared, and some factors affecting the degree of grafting were investigated. The radiation crosslinking of silk with dimethyloldihydroxyethylene urea (DMDHEU) was preliminarily studied. The physical and mechanical properties such as whiteness, breaking strength, and resilience of the radiation‐grafted/crosslinked silk fabrics were examined. The radiation grafting of silk with MAA increases the silk weight, while the radiation crosslinking of silk with DMDHEU imparts improved crease resistance to silk. X‐ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) analysis indicate the formation of peroxy and free‐radical species on the EB‐irradiated silk. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2028–2034, 2004