Maleic Anhydride Treatment Research Articles

Vapor phase reaction of wood with maleic anhydride (I): dimensional stability and durability of treated wood

Reaction between maleic anhydride (MA) and wood specimens was carried out in a vapor phase reaction system. Reaction conditions such as the ratio of supplied MA to wood, initial moisture content, and reaction temperature were optimized. The MA supplied to the reaction system was effectively absorbed by the wood, and a satisfactorily high dimensional stability was achieved even at a low MA/wood ratio. The dimensional stability increased with rising initial moisture content. When the reaction was conducted at an elevated temperature (180°C), high dimensional stability was attained without remarkable weight increase and bulking. The mechanism of dimensional stabilization was discussed on the basis of the dimensional changes at high humidity and during repeated water soaking and drying. It was shown that the dimensional stabilization arises mainly from a decrease of hygroscopicity. When the reaction was conducted at 180°C, the formation of cross-links in the cell wall was apparent. Following the MA treatment, the antifungal property was remarkably enhanced and met the Japanese Industrial Standard K1571. Therefore, MA treatment in the vapor phase is an effective method to attain antifungal properties as well as high dimensional stability with a small amount of nontoxic reagent.

Effect of Treatment of Maleic Anhydride on Mechanical Properties of Natural Fiber: Polystyrene Composites

: In the present work, banana, hemp, and sisal fibers are employed as fillers for the formation of natural fiber:polystyrene composites in the ratios of 55:45, 50:50, 45:55, and 40:60 (wt/wt). The natural fibers were treated with maleic anhydride. The Young's modulus, flexural modulus, impact strength, and Shore-D hardness all decreased with increasing amounts of fibers in the natural fiber:polystyrene composites. The sisal fiber composites show the highest mechanical strength for all ratios. A maleic anhydride treatment shows significant improvement in Young's modulus, flexural modulus, impact strength, and Shore-D hardness compared with the untreated fiber composites.

Moisture adsorption isotherms of two esterified Greek hardwoods

Two Greek hardwoods (Ulmus montana and Acer pseudoplatanus), were esterified with acetic and maleic anhydride and studied for moisture adsorption behaviour. The sorption isotherms for untreated and chemically modified wood were analysed using the Hailwood-Horrobin model. The experimental analysis of the sorption isotherms showed that esterification affects both total, polymolecular and monomolecular sorption. Acetic anhydride treatment was found more effective in reducing the hygroscopicity of wood compared to maleic anhydride treatment at comparable weight percentage gain, reflecting probably the strong ester bonds between acetic anhydride and wood. Identical e.m.c values were attained in both types of sorption for maple and elm wood, at comparable weight percentage gain, not only for the unmodified samples but for the modified ones as well.

Effect of Ageing on the Mechanical Properties of Short Sisal Fibre Reinforced Polystyrene Composites

The water absorption behaviour and the effects of ageing on the mechanical properties of short sisal fibre reinforced polystyrene composites have been studied with special reference to fibre loading and fibre-matrix interface modification. The composites were subjected to different ageing conditions viz., immersion in boiling water for 24 h, immersion in cold water for 15 days and exposure to hot air at 80°C for five days. The interface modifications were performed by benzoylation, polystyrene maleic anhydride (PSMA) treatment, toluene diisocyanate treatment and silane treatment. The tensile properties and dimensions of the aged samples were measured and compared with unaged samples. The water uptake was found to increase with fibre loading and decrease with fibre modifications. However, PSMA treatment and silane treatment do not produce much variation in water uptake. The mechanical properties and dimensional stability of the treated fibre composites were found to be superior to those of untreated composites under identical ageing conditions. However, it is interesting to note that on water ageing, untreated fibre composites show minimum decrease in tensile strength compared to treated fibre composites and can be explained based on the thermal shrinkage of the polystyrene matrix. The superior properties of the treated composites were associated with the better interfacial interactions in treated fibre composites.

Filler effect of potato starch and urea on degradation of linear low density polyethylene composites

Starch and urea are used as fillers, owing to their good mechanical and degradable properties, in linear low density polyethylene matrix. Composites of varying amount of starch and urea composition are prepared. Various properties like tensile strength, elongation at break, Young's modulus, shore-D hardness, and water absorption are studied. The tensile strength, elongation at break, Young's modulus, and Shore-D hardness decrease with maleic anhydride treatment of starch and urea for polymer composites. On increasing the amount of filler in the composites, the mechanical properties decrease. The soil-burial treatment of these composites also causes reduction in these properties. The absorption of water increases for one month and decreases later during the period 2–5 months. The increase in absorption might be due to the onset of degradation of composites. The degradation of the composites is also observed by the presence of grooves and pits in optical micrographs of soil-exposed composites.

Effect of maleic anhydride treatment on steam and water absorption of wood polymer composites prepared from wheat straw, cane bagasse, and teak wood sawdust using Novolac as matrix

Wheat straw, cane bagasse, and teak sawdust (agrowaste) were sieved up to a 425-μm mesh size and employed for sheet preparation with and without maleic anhydride (MA) treatment using Novolac resin in a 50 : 50 (w/w) ratio. The shore D hardness of MA treated and untreated wood polymer composites (WPCs) was measured. The MA treated WPCs showed 2–3 times more hardness than that of the untreated respective WPCs. Moisture absorption had a detrimental effect on the mechanical properties of the WPCs. MA treatment restricted swelling and water and steam absorption in the agrowaste. Teak sawdust showed the best results in all respects among the three WPCs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2963–2967, 2000

Effect of maleic anhydride treatment on steam and water absorption of wood polymer composites prepared from wheat straw, cane bagasse, and teak wood sawdust using Novolac as matrix

Wheat straw, cane bagasse, and teak sawdust (agrowaste) were sieved up to a 425-μm mesh size and employed for sheet preparation with and without maleic anhydride (MA) treatment using Novolac resin in a 50 : 50 (w/w) ratio. The shore D hardness of MA treated and untreated wood polymer composites (WPCs) was measured. The MA treated WPCs showed 2–3 times more hardness than that of the untreated respective WPCs. Moisture absorption had a detrimental effect on the mechanical properties of the WPCs. MA treatment restricted swelling and water and steam absorption in the agrowaste. Teak sawdust showed the best results in all respects among the three WPCs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2963–2967, 2000

Studies on Swelling Behavior of Wood-Polymer Composites Based on Agro-Waste and Hdpe in Steam and Water at Ambient Temperature

The polymer composites of HDPE and banana, hemp, and agave fibers (50 : 50, w/w) were prepared separately with and without treatment of maleic anhydride. The swelling phenomenon in terms of absorption of water and steam was studied and it was found that the steam penetrates more within a smaller period of time than the water at ambient temperature. The maleic anhydride treatment on these fibers showed the ester-ification of fibers, and because of that, the absorption (swelling) of steam and water is less than the untreated respective fibers composites.

Albondin-mediated capillary permeability to albumin. Differential role of receptors in endothelial transcytosis and endocytosis of native and modified albumins.

Specific albumin binding to the surface of endothelium initiates its transcytosis across continuous endothelium via noncoated plasmalemmal vesicles. Past work has identified several putative albumin-binding proteins (SPARC, gp60, gp30, and gp18). In this study, we examined the specific role of these proteins in the binding of bovine serum albumin (BSA) to endothelium. The 60-kDa albumin-binding protein (gp60, now called albondin) was purified from cultured rat microvascular endothelial cells for antibody production. Anti-albondin antibodies (alpha gp60) specifically recognized albondin expressed by rat, bovine, and human endothelial cells (EC). alpha gp60 and unlabeled native BSA inhibited 125I-BSA binding to confluent EC monolayers and to both albondin and SPARC extracts immobilized on filters. Modification of BSA by maleic anhydride treatment (Mal-BSA) or by surface adsorption to colloidal gold particles (A-Au) renders the ligand specific for gp30 and gp18 while eliminating its ability to inhibit 125I-BSA binding to EC and to both albondin and SPARC extracts. Mal-BSA and A-Au interacted with EC via distinct binding sites not recognizing native BSA. EC internalization of 125I-BSA is inhibited by unlabeled BSA and alpha gp60 IgG but not nonimmune IgG, Mal-BSA, or A-Au. Conversely, internalization of modified BSA is inhibited by unlabeled modified BSA but not BSA or alpha gp60 IgG. Specific 125I-BSA transendothelial transport in rat lungs perfused in situ and for EC monolayers in vitro is inhibited (> or = 90%) by unlabeled BSA and alpha gp60 IgG but not nonimmune IgG and Mal-BSA. No specific transport of 125I-Mal-BSA is detected across bovine lung microvascular endothelial cell monolayers, only paracellular and/or fluid-phase transport. Low temperatures reduce BSA transport by 5-fold and Mal-BSA by 2-fold. Interestingly, 3-fold more native BSA is transported than Mal-BSA at 37 degrees C, whereas at 8-10 degrees C they are nearly equal, suggesting facilitation of BSA transport. Cumulatively, it appears that gp30 and gp18 mediate the binding, endocytosis, and degradation of modified albumins, whereas albondin mediates native albumin binding which significantly enhances its transcytosis and capillary permeability.

ATP-independent proteolysis of globin cyanogen bromide peptides in rabbit reticulocyte cell-free extracts.

The catabolism of two rabbit globin cyanogen bromide peptides in cell-free extracts of ATP-depleted rabbit reticulocytes has been studied. Proteolysis of the peptides (3533 and 5957 molecular weight) proceeded rapidly in the absence of ATP, had a pH optimum of approximately 7.8, and was inhibited by omicron-phenanthroline, N-ethylmaleimide, cystamine zinc and cobalt ions, and puromycin peptide high-molecular-weight aggregates. Proteolysis of puromycin peptides was inhibited by the rabbit globin cyanogen bromide peptides. The ability of cell-free extracts of degrade the globin cyanogen bromide peptides decreased with the reticulocyte maturity. Blocking the globin cyanogen bromide peptide amino groups by succinic and maleic anhydride treatment decreased susceptibility to degradation. It is suggested that the globin cyanogen bromide peptides might provide model substrates, replacing puromycin peptides, for the investigation of ATP-independent proteolytic events.

Analysis of Fat-Soluble Vitamins. XXII. High Performance Liquid Chromatographic Determination of Vitamin D in Concentrates. Collaborative Study1

A collaborative study was carried out which compared the official chemical method (43.B14-43.B24), the HPLC method according to Hofsass et al. including maleic anhydride treatment, and the HLPC procedure according to De Vries et al. for vitamin D concentrates. A total of 396 samples were distributed to 33 collaborators for analysis. Five laboratories performed both the chemical and the HPLC methods. Five laboratories performed the Hofsass method and 16 laboratories performed the De Vries method. The results for the chemical method agreed with the theoretical values for the samples, and the standard deviation was comparable to that obtained in previous AOAC collaborative studies. Collaborative results for the Hofsass method were low. In addition, incorrect use of a fixed conversion factor (1/0.586) and necessity of a double chromatogrpahic system on a non-treated and a treated vitamin D sample reduce the effectiveness of the method. There were no adverse reactions to the DE Vries HPLC method. It is recommended that the method be adopted official first action as an alternative procedure for determining vitamin D in concentrates, excluding powders containing irradiated 7-dehydrocholesterol.

Analysis of Fat-Soluble Vitamins. XIX. Collaborative Studies on the Chemical Assay for Vitamin D Concentrates

In 1971, a chemical method for the assay of vitamin D in concentrates containing only vitamin D was collaboratively studied by 14 laboratories, using 6 different samples from 2 European manufacturers. On the basis of these results, the laboratories were divided into 2 groups: 5 with significant laboratory biases of greater than or equal to 2%, and 9 laboratories with nonsignificant bias. The 9 laboratories were subdivided into 2 groups which differed significantly as to reproducibility within laboratories. The reproducibility between laboratories, expressed as a standard deviation in per cent with 95% confidence limits, was 1.2% (confidence range 0.6-7.3) and 4.7% (confidence range 2.4-29.3) for 3 and 6 laboratories, respectively. A second collaborative test was performed in 1974, using 12 vitamin D resin samples in oil from 3 United States manufacturers, to compare 2 chemical vitamin D assay methods (with and without maleic anhydride) and to compare results from the chemical and biological methods; 9 laboratories participated in the chemical method study and 3 in the rat bioassay study. The correlation of results of the chemical method including maleic anhydride treatment and the rat bioassays was satisfactory. The reproducibility of the chemical method was about the same as that in the first collaborative test.

The subunits of human hexosaminidase A.

Previous studies of the subunit structure of hexosaminidase gave ambiguous results, but suggested that the enzyme was composed of six equally sized subunits. Dissociation of hexosaminidase A with p-chloromercuribenzoate produces an alkylated fragment with mol.wt. approx. 50000, which is converted into hexosaminidase S by treatment with dithiothreitol. Treatment of native hexosaminidase A with sodium dodecylsulphate results in the formation of a large and a small fragment. However, although the native enzyme has a sedimentation coefficient of 5.8S, dissociation by S-carboxymethylation and maleic anhydride treatment results in subunits exhibiting a single schlieren boundary on analytical ultracentrifugation with a sedimentation coefficient of 2.18S. These results indicate that the enzyme is composed of four subunits, each with molwt. approx. 25000-27000. The mol.wt. of the native enzymes is calculated to be approx. 110000. Our data are consistent with the subunit structures of hexosaminidases A, B and S as being alpha2beta2, beta4 and alpha4 respectively.

Report of Ad Hoc Committee on Vitamin D Methodology, AOAC

Abstract In a collaborative study 6 samples of vitamin D3 resins were analyzed chemically by 9 laboratories and tested biologically by 3 laboratories to determine whether there exists a discrepancy between chemical and biological methods of measuring potency of these materials. The chemical methods employed saponification with and without subsequent maleic anhydride treatment. The biological method was the AOAC official final action rat assay, 39.149–39.162. The results showed good agreement between laboratories in the chemical analysis and relatively poor agreement in the biological tests. However, based upon the mean values as reported by the different laboratories, the chemical method employing saponification alone consistently overestimated biopotency, whereas the chemical method including maleic anhydride treatment gave results which averaged much closer to the mean biopotency values. There was no evidence that maleic anhydride treatment reduced values significantly below biopotency values.