Candidate Resins Research Articles

Hydrothermal in-plane-shear strength of carbon fibre/benzoxazine laminates manufactured out-of-autoclave by liquid-resin-infusion

Benzoxazine’s have recently emerged as new candidate resins for elevated temperature structural applications in the aerospace sector offering attractive attributes including infusibility under vacuum, fire-smoke-toxicity performance and room temperature storage/transport. The main objective of this study is to evaluate the hydrothermal in-plane-shear (IPS) strength of carbon-fibre (CF) based laminates manufactured using two benzoxazine (BZ) resin systems (BZ9120 and BZ9130). CF/BZ9130 was evaluated at 160 °C in the wet condition and benchmarked against two commercially available bismaleimide (BMI) resin systems – traditionally considered for wet applications at 160 °C. CF/BZ9120 was evaluated at 120 °C (just below its Tg) in the dry and wet condition and benchmarked against CF/BZ9130. BMI’s remain the benchmark for IPS strength at 160 °C (wet) with 64% retention while BZ9130 only retained 48% of IPS strength at 160 °C (wet) and also exhibited excessive elongation. CF/BZ9130 showed good retention at 120 °C (68% wet) outperforming CF/BZ9120 (48% wet). Positively, both BZ systems performed at least as well as the BMI’s under ambient conditions.

The effectiveness of ion exchange resins in separating uranium and thorium from rare earth elements in acidic aqueous sulfate media. Part 2. Chelating resins

Chelating resins with different functional groups were evaluated for their potential application in separating uranium U(VI) and thorium Th(IV) from rare earth elements, RE(III). The candidate resins included a bis-picolylamine resin, aminophosphonic resins, iminodiacetic resins, and solvent-impregnated resins. The adsorption selectivity of these resins towards U(VI) and Th(IV) in the presence of selected RE(III) was examined in sulfuric acid media of varying concentrations. It was evident that the adsorption performance of the resins was acid concentration-dependent. Most candidate resins had potentially feasible selective adsorption at or below 0.1 mol/L H2SO4 (or pH ≥ 1). Depending on their functional groups, the chelating resins displayed varying selectivity towards U(VI), Th(IV) and RE(III). It was found that the iminodiacetic resins exhibited the highest affinity for U(VI) and Th(IV) over RE(III). At 0.005 mol/L H2SO4 (or pH 2), the adsorptions of U(VI) and Th(IV) were approximately 90% while adsorption of RE(III) was less than 20%. This can be explained by considering the coordination chemistry of the resins whereby molecular ligands with N- and O-donor atoms were demonstrated to adsorb both U(VI) and Th(IV) strongly. Comparing the different O-donor groups (i.e., sulfonyl, phosphoryl and carboxyl), the carboxyl group from the iminodiacetic resin gave the best separation of U(VI) and Th(IV) from RE(III). The performance of the solvent-impregnated resins has indicated the possibility of exploiting steric effects to obtain a highly selective chelating resin for U(VI) and Th(IV) over RE(III). In addition, the potential application of these resins in an integrated process for sequential 2-stage separation of U(VI) and Th(IV) from RE(III) in sulfuric acid media is also presented.

The effectiveness of ion exchange resins in separating uranium and thorium from rare earth elements in acidic aqueous sulfate media. Part 1. Anionic and cationic resins

Conventional ion exchange resins with different functional groups were evaluated for their potential application in separating uranium U(VI) and thorium Th(IV) from rare earth elements RE(III). The resins studied comprised strong- and weak-base anion exchange resins, and strong- and weak-acid cation exchange resins. The selectivity of these resins to adsorb U(VI) and Th(IV) in the presence of selected RE(III) was examined in sulfuric acid media of varying concentrations. It was evident that the adsorption performance of the resins was acid concentration-dependent. Most candidate resins had potentially feasible selective adsorption at or below 0.1mol/L H2SO4 (pH≥0.7). Within the group of anion exchange resins, both the strong- and weak-base resins exhibited a similar selectivity with U(VI) adsorbed in preference to RE(III). The difference between them was their adsorption of Th(IV). The weak-base resin with primary amine functional group demonstrated superior separation of Th(IV) from RE(III). For this resin, 78% of U(VI) and 68% of Th(IV) were adsorbed while RE(III) co-adsorption was <5% at 0.0005mol/L H2SO4 (pH3). In the case of the strong-acid cation exchange resins, Th(IV) and RE(III) were adsorbed in preference to U(VI), i.e., RE(III)>Th(IV)>>U(VI). The weak-acid cation exchange resins, on the other hand, displayed limited adsorption of all elements.

Optimization-based framework for resin selection strategies in biopharmaceutical purification process development.

This work addresses rapid resin selection for integrated chromatographic separations when conducted as part of a high‐throughput screening exercise during the early stages of purification process development. An optimization‐based decision support framework is proposed to process the data generated from microscale experiments to identify the best resins to maximize key performance metrics for a biopharmaceutical manufacturing process, such as yield and purity. A multiobjective mixed integer nonlinear programming model is developed and solved using the ε‐constraint method. Dinkelbach's algorithm is used to solve the resulting mixed integer linear fractional programming model. The proposed framework is successfully applied to an industrial case study of a process to purify recombinant Fc Fusion protein from low molecular weight and high molecular weight product related impurities, involving two chromatographic steps with eight and three candidate resins for each step, respectively. The computational results show the advantage of the proposed framework in terms of computational efficiency and flexibility. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 33:1116–1126, 2017

The thermal properties and cure kinetics of polytriazole resin modified by 4,4′-bis(azidomethyl) biphenyl

4,4′-Bis(azidomethyl)biphenyl (BAMBP) was employed to modify the polytriazole resin. The thermal properties and cure kinetics of the modified polytriazole resin were investigated using differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis. Results indicate that BAMBP can promote the curing reaction and decrease the curing reaction temperature but cannot change the cure reaction mechanism. The highest glass transition temperature of modified polytriazole resin can be obtained with 5 wt% BAMBP at 213.2°C. Furthermore, the excellent solubility characteristics of BAMBP in polytriazole allows for fabricating T700 carbon fiber/polytriazole composites, which makes polytriazole one of the candidate resins cured at a lower temperature but used at a higher temperature.

Design and optimization of a chromatographic purification process for Streptococcus pneumoniae serotype 23F capsular polysaccharide by a Design of Experiments approach

Multivalent pneumococcal vaccines were used worldwide to protect human beings from pneumococcal diseases. In order to eliminate the toxic organic solutions used in the traditional vaccine purification process, an alternative chromatographic process for Streptococcus pneumoniae serotype 23F capsular polysaccharide (CPS) was proposed in this study. The strategy of Design of Experiments (DoE) was introduced into the process development to solve the complicated design procedure. An initial process analysis was given to review the whole flowchart, identify the critical factors of chromatography through FMEA and chose the flowthrough mode due to the property of the feed. A resin screening study was then followed to select candidate resins. DoE was utilized to generate a resolution IV fractional factorial design to further compare candidates and narrow down the design space. After Capto Adhere was selected, the Box-Behnken DoE was executed to model the process and characterize all effects of factors on the responses. Finally, Monte Carlo simulation was used to optimize the process, test the chosen optimal conditions and define the control limit. The results of three scale-up runs at set points verified the DoE and simulation predictions. The final results were well in accordance with the EU pharmacopeia requirements: Protein/CPS (w/w) 1.08%; DNA/CPS (w/w) 0.61%; the phosphorus content 3.1%; the nitrogen 0.315% and the Methyl-pentose percentage 47.9%. Other tests of final pure CPS also met the pharmacopeia specifications. This alternative chromatographic purification process for pneumococcal vaccine without toxic organic solvents was successfully developed by the DoE approach and proved scalability, robustness and suitability for large scale manufacturing.

Room temperature‐curable VARTM epoxy resins: Promising alternative to vinyl ester resins

AbstractThe objective of this investigation is to characterize various room temperature (RT)‐curable epoxies for vacuum‐assisted resin transfer molding (VARTM) of large structure manufacturing. Six epoxy candidate resins: X‐40, 780‐33, 780‐35, 8601/8602, 8602, 8603, and two vinyl ester resins (VE), 411‐350 and 411‐510A, are physically and thermochemically characterized. All the resins are cured at RT with extended period of time. The degree of cure for 24‐h RT‐cured samples ranges from 70 to 85% for epoxies and is comparable with the baseline VE systems (75%). After 1 year at RT, the degree of cure increases from 90 to 98%. Most of the epoxies show a single transition in dynamic mechanical analysis and differential scanning calorimetry. However, two heterogeneous transitions are observed for the VE systems. The glass transition temperature increases monotonically with exposure time, except X‐40, that rapidly achieves a plateau and remains constant. The degree of cure for the majority of the systems increases logarithmically with RT curing time with excellent fitting (R2 varies from 0.92 to 1). Consistent with the increase in degree of cure, the storage modulus increases and (tan δ)max decreases with time of exposure. A negative correlation between the curing temperature range and the total heat of reaction is observed among the epoxy systems. However, the VE systems show the reverse trend. RT curing epoxy resin (X‐40) shows promising overall result to VE system and can be a viable alternative to VE for VARTM processing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Direct imprint of conductive silver patterns using nanosilver particles and UV curable resin

The direct nanoimprinting of device patterns on functional resist has attracted increasing attention since it has the potential to extend nanoimprinting applications and improve productivity. Considerations of device-oriented functional resins are currently limited to optical or optoelectronic applications where the optical properties of the imprint resin can be selectively controlled. Either nanosilver particle dispersions or conductive polymers are candidate resins for the direct imprinting of electrode line patterns. In this paper, we describe direct ultraviolet (UV) imprinting using acrylate-based resin incorporating nanosilver colloid, with optimized post-imprinting steps involving heat treatment and wet etching. Resin mixtures with 40, 50, and 60 wt% of nanosilver loading were prepared, and UV imprinting was performed on the dispensed resin mixtures, followed by heat treatment to sinter the nanosilver particles and wet etching of the imprint residues. The pattern shrinkage that occurred during the post-imprinting steps reached 25–35%, and was strongly dependant on the nanosilver concentration. The electrical resistivity for 60 wt% Ag loading was roughly 2.5 times higher than that of bulk silver. In addition, surface texturing effects on the imprinted patterns were investigated using selective oxygen plasma etching.

Assessment of commercial low viscosity resins as binders in the wood composite material Vintorg

Vintorg is a composite product made from wood modified by high intensity microwave energy (named Torgvin) and then impregnated with resin. Four commercial resins were cured as resin stakes and their properties assessed. Based upon these results, Vintorg composites were prepared using the candidate resins and their properties tested. One trial resin exhibited superior performance and has been recommended as a phenol formaldehyde benchmark resin for Vintorg production trials.

Towards rapid screening of new composite matrix resins

A study to test the correlations among neat-resin and composite properties was performed, to identify possible ways of reducing the number of tests necessary to screen candidate resins for use in aerospace structures. Neat-resin and composite tests were conducted for four different resin matrices, whose neat properties varied over a wide range, allowing reasonably strong tests of correlations. Since different fiber architectures and fiber types are often of interest to a designer, tested correlations included those between composite coupons containing the same resin but with different fibers and lay-up. Composite structural properties were represented by unnotched tension, open-hole tension, unnotched compression, and open-hole compression. Correlations were sought between these and neat-resin properties, composite shear strength, and Mode I composite delamination toughness. Strong linear correlations, which are proposed to be the most useful because they discriminate best between different resin systems, were found in certain cases, but not others. Most significantly, an Iosipescu shear test for a [0°/90°] composite of one fiber type was shown to be a good predictor, for the tested resins, of open-hole compression and unnotched compression in composites with different fibers and architecture; and a fair predictor of open-hole tension. Open-hole tension strength was shown to correlate better with neat-resin fracture toughness, but neat-resin properties were otherwise inferior indicators of most composite properties. While data for further resins are needed to enrich the statistical base, some rationalizations can be found for the presence of the stronger correlations that were observed. The correlations described here suggest that reduced test matrices, containing tests for only Iosipescu composite shear and either neat-resin toughness or Mode I delamination toughness, may suffice to evaluate the likely structural performance of composites containing new candidate resins. The tests could be performed on a standard fiber type and architecture, yet be predictors for other fiber types and architecture.

New Resin Systems for 157nm Lithography.

The development of sufficiently transparent resin systems is one of the key elements required for a successful and timely introduction of 157nm lithography. This paper reports on the Simple Transmission Understanding and Prediction by Incremental Dilution (STUPID) model, a quick back-of-the-envelope increment scheme to estimate the absorption of polymers at 157nm. A number of promising candidate resins based on norbornenes are discussed, and results with a first 157nm resin system developed at the University of Austin are presented. The new system is based on copolymers of norbomene-5-methylenehexafluoroisopropanol (NMHFA) and t-butyl norbornene carboxylate (BNC), formulated with an acetal additive obtained by copolymerization oftbutyl norbomene-5-trifluoromethyl-5-carboxylate (BNTC) with carbon monoxide. Lithographic performance of this system extends to 110nm dense features using standard illumination and a binary mask, or 80nm semi-dense and 60nm isolated features with a strong phase shift mas . The dry etch resistance of this resist is found to be slightly lower than APEX-E DUV resist for polysilicon but superior to it for oxide etches.

The Use of FRP with Alcohol-Containing Fuels

There will be increasing use of alcohols and other oxygenated compounds, such as MTBE and TAME, for enhancing the octane value of gasoline. In some cases, alcohols, such as methanol, may be used as a direct fuel. In recognition of this, many standards relating to the storage, handling, or containment of petroleum products contain ing oxygenates have been adopted, such as UL 1361. FRP has had a long history of suc cessful use in containment of gasoline, but introduction of alcohols coupled with increased levels of reformates makes the fuels more aggressive toward FRP. Designing resins for this purpose is now very demanding, especially in view of stringent standards required to pre vent leaking from underground tanks and secondary containment vessels. This article dis cusses the trends in gasoline production as well as recently completed testing for candidate resins. Of special interest is the good performance observed for novolac-based vinyl esters and high-crosslink-density polyesters.

Composite implants for orthopedic applications: in vivo evaluation of candidate resins.

Three resins which include poly (methyl methacrylate), surgical Simplex P, and ultrahigh molecular weight polyethylene were selected to be evaluated as candidate systems for a polymer based composite for hard tissue prosthesis. Characterization of the mechanical behavior of these polymers in different environments including in vitro and in vivo storage was accomplished. As a result, conclusions were made as to which material maintained the least amount of mechanical variance as influenced by environmental effects. In vivo studies of implanted materials provided for a study of soft tissue response to each material. Conclusions were then developed as to the varying degrees of tissue reaction initiated by each material, and which resin generated the greatest tissue response with respect to the others.

BEACH PROTECTION BY A DEGRADABLE, SPRAYED FILM

ABSTRACT The feasibility of beach protection against off-shore oil spills by means of a sprayed-on polymeric film is reported. The concept involves the spraying of a threatened beach area with a water-soluble polymer which forms a protective film on drying. The film prevents the adsorption and absorption of oil by sand, rocks, and wood and thus facilitates clean-up. Ideally, the film should degrade and dissolve within 2 to 3 weeks of application. Eighteen candidate resins systems were screened initially for their solution and film properties. Five were selected for further testing, and two were chosen for small-scale, mock-beach protection tests. One coat of 55% polyvinyl acetate provides good protection against oil permeation of sand and against staining of wood and rocks. The film is nontoxic and clear; it does not adversely affect a beach site. However, under laboratory conditions, the film is quite slow to degrade.