Waste liquors from cellulosic industries. IV. Lignin as a component in phenol formaldehyde resol resin

The lignin separated from the spent liquor of soda pulping of rice straw can replace a part of phenol in the condensation reaction with formaldehyde in a basic medium to form phenol lignin–formaldehyde (PL–F) resol resin. The production of phenol lignin–formaldehyde resol resin was carried out in two stages: First was the formation of the adduct (lignin phenol) using different lignin percentages; second was the condensation of the adduct with formaldehyde. Reaction variables, i.e., molar ratio of formaldehyde to phenol lignin, polymerization time, amount of sodium hydroxide as a catalyst, and polymerization temperature in the polymerization step were studied. Solubility of the produced resol resin in different solvents, its viscosity, and yield were determined. Lignin could replace up to 40% of phenol in the produced resin. Infrared spectra of the prepared resin were determined. Structural similarity of phenol–formaldehyde to phenol lignin–formaldehyde resin was shown. Also, relative absorbance of characteristic bands of the resins were calculated and claimed too much on the effect of reaction parameters on the prepared resins.     

Kinetics of release of particulate solutes incorporated in cellulosic polymer matrices as a function of solute solubility and polymer swellability. III. Moderately soluble solute

Our previous investigation of the kinetics of release of simple particulate solutes of very low (CaSO₄ or SrSO₄) or very high aqueous solubility (NaCl) from cellulose acetate (CA) matrices (in the form of thin films) in contact with an eluant aqueous phase is here extended to a solute of moderate solubility (CsNO₃). Simultaneous measurement of the concurrent variation of the water content of the matrix revealed the occurrence of osmotically induced excess water uptake by the loaded matrix for all loads studied, as previously observed in the case of NaCl at lower loads. The resulting enhancement of solute release rate was considerable but much less than that generated by NaCl. Sorption and diffusion of the solute in the corresponding particle‐depleted polymer matrices was also investigated. The results exhibited a pattern qualitatively very similar to that of NaCl but greatly attenuated in quantitative terms. These observations are in keeping with the relatively weak osmotic power of CsNO₃. A mechanism for osmotically induced enhancement of solute release rate previously formulated (in terms of the growth of zones of enhanced hydration of the polymer matrix surrounding the embedded solute particles) to account for NaCl release behavior observed at lower particle loads was found to be applicable here at all loads examined. The degree of hydration of the (neat) CA polymer matrix was also varied (by varying the conditions of film preparation or by wet thermal after‐treatment of the as‐prepared films) and its effect on CsNO₃ partition and diffusion coefficients was studied. The results provided the basic information needed for interpretation of the corresponding particle‐depleted film data, in comparison with the previous ones for NaCl. It was thus shown that imbibed water was more homogeneously distributed in NaCl‐depleted, than in CsNO₃‐depleted, films. It was also observed that variation of the degree of polymer hydration affected primarily the rate, and only secondarily the kinetics, of particulate CsNO₃ release. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2028–2039, 2002; DOI 10.1002/app.10499     

Lignin gels as a medium in gel permeation chromatography

The preparation of spherical lignin gel beads, based on the crosslinking reaction between epichlorohydrin and kraft lignin (Indulin AT), is described. The lignin gels prepared were found to be an efficient resin in gel permeation chromatography. The separation of polystyrenes in dimethylformamide is described. The resin was found to separate polystyrenes with molecular weights up to 110,000. An inverse linear relationship between log M and elution volume or the partitioning coefficient was established.     

Waste Liquors from Cellulosic Industries. V. Cresol-Lignin Liquor as a Component in Polyphenol Formaldehyde Resins

Cresol–lignin liquors produced as waste from bagasse pulping, at different temperatures (160°–190°C) for 1.5 h and at 170°C for different times (0.75–3 h) were tested to evaluate their reactivity in both alkaline and acidic media toward preparation of cresol–lignin formaldehyde resins. The effects of different polymerization parameters—e.g., time, temperature, ratio of polyphenols to formaldehyde, and reaction medium (acidic or alkaline)—on the yield and properties of produced resins were detected. The yields of the resins produced in alkaline medium are higher than those produced in acidic medium.     

废纸苯酚液化及生成树脂的结构表征

首先在一定液化工艺条件下,对废纸进行了液化处理,而后对液化后的产物分别进行了傅立叶转换红外光谱(FTIR)以及电子扫描电镜(SEM)的测定分析,并对其生成树脂进行差热(DTA)分析。FTIR的结果表明,液化废纸结构发生了明显变化,而且出现了化学组分中的最基本结构单元,表明苯酚液化处理使废纸发生了降解、酚化等化学反应。SEM测定结果表明,液化后的废纸液化中依然含有废纸的未完全液化的微小废纸组织碎片,废纸纤维结构被进一步破坏。对废纸液化树脂差热(DTA)分析的结果表明,废纸液化物树脂峰顶温度低于传统酚醛树脂;废纸液化物树脂和传统酚醛树脂一样,顶峰温度随着升温速率提高。     

A highly fluorinated epoxy resin. III. Behavior in composite and fiber-coating applications

The behavior of a highly fluorinated epoxy resin used as a composite matrix material with AS-4 fibers and as an AS-4 fiber coating was studied. The composite mechanical properties were obtained, and the adhesion of the matrix to the fibers was evaluated. Comparisons of uncoated and fluoropolymer coated AS-4 fibers using single fibers embedded in an Epon 828 matrix were made. Substantial improvement in fiber critical length, and therefore fiber-matrix adhesion, was observed.     

Nonisothermal curing kinetics of epoxy resin composite utilizing Ga (III) xanthate as a latent catalyst

Cure kinetics and curing mechanism of epoxy resin composite utilizing gallium (III) xanthate as a latent catalyst was investigated and compared with the commercial latent catalyst UCAT3512T formulation. Nonisothermal differential scanning calorimetric technique at different heating rates was employed to investigate the kinetic parameters. Activation energy was determined using Kissinger's and Flynn‐Wall‐Ozawa methods. Ga (III) xanthate was found to possess superior latent properties compared with UCAT3512T since the activation energy value obtained was higher for epoxy resin composite consisting of Ga (III) xanthate than UCAT3512T. Friedman's isoconversional method was utlizied to for kinetic modeling. An autocatalytic model was found to be successful in describing the curing reaction for both of the formulations. The calculated conversion rate as a function of temperature obtained by solving the autocatalytic equation showed a very good fit with experimental values. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42149.     

Photochemical investigations into cellulosic materials III. Photografting vinyl monomers onto cotton in the presence of various photo-initiators

UV-light induced grafting onto cotton is reported for a large variety of vinyl monomers. The reaction was generally initiated by free radical initiators such as phenylacetophenone derivatives, substituted benzophenone compounds, quantacure SKS, saccharides and so on. % grafting-time conversion curves were determined. The rate of grafting was lying in the range 0.15–1.3% grafting min^-1. In some cases, the amount of homopolymer was quite low. The efficiency of the initiator is strongly dependent upon the monomer used.     

AC impedance spectroscopy as a technique for investigating corrosion of iron in hot flowing Bayer liquors

The flow-induced corrosion of iron, in spent Bayer liquor at high temperatures, was investigated using a rotating cylinder electrode (RCE) in an autoclave facility. A temperature range of 100–230 °C and equivalent pipe velocities in the range 0.84–3 m s^–1 were used. AC impedance technique was applied to monitor in situ the entire corrosion process. Corrosion rates measured by a.c. impedance expressed as average 1/R _p were in good agreement with those obtained by weight loss measurements. The results suggest that a.c. impedance is a suitable method to monitor the corrosion process of steels exposed to flowing Bayer liquor at higher temperatures.     

Formation and Structure of Lignin in Monocotyledons. III. Heterogeneity of Sugarcane (Saccharum officinarum L.) Lignin with Respect to the Composition of Structural Units in Different Morphological Regions

Heterogeneity of sugarcane lignin with respect to the composition of structural units in different morphological regions was studied by microautoradiography and some degradative analyses. Structure of the lignin differs among fiber, vessel and parenchyma. The lignin in the secondary wall of fiber is composed of syringyl (S)-, guaiacyl (G)- and p-hydroxyphenyl (H)-propane units with accompanying phenolic acid residues, and the proportion of these monolignols is S > G > H. The lignin in vessels of protoxylem contains more G and H units than S units, and that in vessels of metaxylem is similar to that in fibers. Phenolic acid constituent in sugarcane cell wall includes sinapic acid in addition to p-coumaric and ferulic acids. Ferulic acid deposits at the very early stage of lignification, and p-coumaric and sinapic acids increasingly deposit with the progress of lignification. Therefore, the ratio of p-coumaric acid or sinapic acid to ferulic acid increases with lignification. Parenchyma wall involves larger amount of phenolic acids than vascular bundle does. The lignin in parenchyma is difficult to isolate by Björkman procedure, because there is greater possibility to form cross-linkage among cell wall polymers through phenolic acids. The cross linkages involving phenolic acid ester also explains why the sugarcane lignin is easily degraded.     

Waste natural gum as a multifunctional additive in rubber

Bahera gum, extracted from the bark of Terminalia bellerica, is a waste material. The present study involves the use of this natural gum as a multifunctional additive in natural rubber (NR) and brominated isobutylene‐co‐paramethyl styrene (BIMS). Fourier transform infrared (FTIR) analysis was employed to study the functional groups present in the gum. It was found that fatty acids/esters in the gum act as accelerator activator and can replace stearic acid in rubber formulations. Polyphenols in the gum act as antioxidant and the action is comparable with the commercial antioxidant 2,2,4‐trimethyl‐1,2‐dihydroquinoline (TQ) in natural rubber. The gum improves the tack strength of the rubbers (21% at 2.5 phr loading for NR and 54% at 10 phr loading for BIMS). The gum imparts plasticization effect which is reflected in the reduction in k and enhancement in n values, the exponents in the power law equation, with increasing gum concentration. The activation energy of flow is also reduced with the addition of the gum. Moreover, it decreases the elastic memory of the system which causes reduction in die swell. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4897–4907, 2006     

Water-soluble polymers as retention aids in a model papermaking system. III. Modified polyacrylamides

The pigment retention efficiency, in a model papermaking system, of anionically and cationically modified polyacrylamides was compared to that of the unmodified homopolymer. The anionic polyacrylamide is a much less efficient retention aid, especially at high pH's; the nonionic and cationic polymers perform similarly and without any marked pH dependence. However, it is the nonionic and anionic polyacrylamides which are similarly poor at fiber flocculation, at pH's between 4.5 and 7.5, whereas the cationic polymer is a good fiber flocculant. All three polymers stabilize pigment suspensions. The anionic polymer is not effective in heteroflocculation of mixed dispersions of fibers and pigment, whereas both the nonionic and cationic are good flocculants, the latter being less susceptible to overdosing. Equilibrium adsorption isotherms were determined; the cationic polymers is, unlike the other modified polyacrylamide, very well adsorbed by cellulose fibers. Onto titanium dioxide, polymers adsorbed in the order anionic < nonionic < cationic. A further differentiation of the cationic polymer is that it gives high pigment retention in sheet formation without markedly increasing the resistance to fluid flow through the forming sheet. Although a process of heteroflocculation is postulated for both nonionic and cationic polymers, in the former case it is thought that the primary adsorption is onto titanium dioxide, whereas with the latter it is onto cellulose.     

Electrodeposition from a fluidized bed electrolyte. III. Electrodeposit structure

Copper electrodeposits grown from a fluidized bed electrolyte appear to be unaffected by mechanical action of the inert particles. Additions of thiourea to the electrolyte caused some improvement in levelling at lower current densities but, at the limiting value, additions of up to 10^?2 M gave no improvement. Micrographic evidence is presented to suggest that a simultaneous dissolution process may account for the transition from nodular to powder growths at the limiting current density.     

Resin. III. Synthesis,characterization, and ion-exchange properties of a 2,2′-dihydroxybiphenyl–formaldehyde copolymer resin

A 2,2′-dihydroxybiphenyl–formaldehyde copolymer, synthesized by the condensation of 2,2′-dihydroxybiphenyl with CH₂O in the presence of an acid catalyst, proved to be a selective chelating ion-exchange copolymer for certain metals. The chelating ion-exchange properties of this copolymer were studied for Fe(III), Cu(II), Ni(II), Zn(II), Cd(II), and Pb(II) ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake, involving the measurements of the distribution of a given metal ion between the copolymer sample and the solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for Fe(III), Cu(II), and Ni(II) ions than for Co(II), Zn(II), Cd(II), and Pb(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Bromine chloride as a cathode component in lithium inorganic cells

Investigations were conducted on a Li inorganic battery system using BrCl and SOCl₂ as co-depolarizers. The Li/BrCl, SOCl₂ cell exhibited an open-circuit voltage of 3.90±0.02 V at room temperature. The discharge results of cells of various sizes showed that an energy density of l W h cm^–3 is possible at low discharge rates at room temperature. The storage tests showed no significant capacity loss after a storage period of 15 months at ambient temperature or three months at 72° C. The cells were subjected to abuses such as short circuiting, forced overdischarge and charge. No hazard of any kind was encountered during these tests. In view of these results, we concluded that Li/BrCl, SOCl₂ is a practical system for high energy density batteries.     

Particle distribution from in‐plane resin flow in a resin transfer molding process

In liquid composite molding (LCM) processes such as resin transfer molding (RTM), particle distribution can be problematic as the particle fillers can be filtered by the reinforcement fibers during the resin infusion process. In this paper, the filtration of alumina and silica nanoparticles in the production of aramid fiber epoxy composites is characterized. The laminates are produced by in‐plane RTM and the effects of selected process variables on the laminate particle distribution are investigated. The objective is to evaluate the assumption that nanoparticles due to their small physical size inherently do not filter in resin infusion processes. The nanosilica particles are found to effectively not filter, while the nanoalumina particles are much more sensitive to filtration as they formed micro‐scale agglomerates as small as a few microns in size prior to injection. The filtration behavior follows a simple theoretical model for micro‐scale particle filtration, already existing in the literature. For the filtration sensitive particles, it was found that the filtration is influenced by the preform fiber volume content. Other common process variables such as resin viscosity, particle concentration in the injected resin, and saturated resin flow time (resin overflow volume) are found to be filtration independent and do not change the filtration behavior. POLYM. ENG. SCI., 59:22–34, 2019. © 2018 Society of Plastics Engineers