Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)

Response surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH₂ group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting.     

Effects of starch alkenylsuccinylation on the grafting efficiency,paste viscosity,and film properties of alkenylsuccinylated starch‐g‐poly(acrylic acid)

Commercial cornstarch was alkenylsuccinylated with alkenylsuccinic anhydride to different degrees of substitution (DS) and then the products were graft‐copolymerized with acrylic acid for investigating the effects of starch alkenylsuccinylation on the graft copolymerization with vinyl monomer, as well as on paste viscosity and film properties of alkenylsuccinylated starch‐g‐poly(acrylic acid) (ASS‐g‐PAA). The number of carbon atom of alkenyl in alkenylsuccinates considered was 8 and 12, corresponding to octenylsuccinylation and dodecenylsuccinylation of starch, respectively. The graft copolymerization was accessed by grafting efficiency, grafting ratio, and conversion of monomer to polymer, and the film properties of ASS‐g‐PAA considered included tensile strength, breaking elongation, and work‐to‐break. Experimental results demonstrated that the alkenylsuccinylation showed marked effects on the copolymerization, paste viscosity, and film properties. It resulted in increased grafting efficiency, stable paste viscosity, and strong starch film. Carbon‐chain length of the alkenyl and DS value of the alkenylsuccinates also exhibited evident effects on the copolymerization and film properties. Octenylsuccinylation of starch before the copolymerization was superior to dodecenylsuccinylation in improving the efficiency and film properties. Low levels of octenylsuccinylation could be utilized to increase the efficiency of the copolymerization and improve the properties of starch film.     

Effects of starch acryloylation on the grafting efficiency,adhesion, and film properties of acryloylated starch‐g‐poly(acrylic acid) for warp sizing

In order to enhance the grafting efficiency of graft copolymerization of granular cornstarch with acrylic acid (AA) for improving the adhesion and film properties of starch‐g‐poly(acrylic acid) used as sizing agent, the esterification of hydrolyzed starch with acryloyl chloride was applied before graft copolymerization. The influence of three common initiators on the copolymerization were also studied. The initiators included ceric ammonium nitrate [Ce(NH₄)₂(NO₃)₆], hydrogen peroxide/ferrous ammonium sulfate [H₂O₂/FeSO₄ · (NH₄)₂SO₄], and potassium persulfate/sodium bisulfite [K₂S₂O₈/NaHSO₃]. It was found that acryloylation of starch before the copolymerization was an effective method for substantially enhancing the grafting efficiency and improving the performances such as adhesion‐to‐fibers and mechanical properties of grafted starch film. The acryloylation could increase the efficiency to 67–81% when the degree of substitution (DS) of acryloylated starch ranged from 0.010 to 0.036. The adhesion to polyester and cotton fibers reached their maximum at DS = 0.010 and 0.022, respectively. Strong and tough film was obtained when the DS value was in a range of 0.010–0.022. H₂O₂/FeSO₄ · (NH₄)₂SO₄ redox system was more appropriate for initiating the copolymerization of acryloylated starch with AA.     

Synergetically Acting new Flocculants on the Basis of Starch‐graft‐Poly(acrylamide)‐co‐Sodium Xanthate

A synergetically acting new flocculant on the basis of starch‐graft‐poly(acrylamide)‐co‐sodium xanthate (CSAX) was synthesized by grafting copolymerization of crosslinked corn starch, acrylamide (AM), and sodium xanthate, using epichlorohydrin (EPI) as cross‐linking agent and ceric ammonium nitrate (CAN) as polymerization initiator in aqueous solution. The effects of some factors, such as crosslinker, initiator, AM, NaOH, on the %Tr (turbidity removal rate), %Trd (turbidity removal rate of a water sample which has both turbidity and heavy metal ions %Hr (heavy metal ion removal rate) and %Hrd (heavy metal ions removal rate of water which has both heavy metal ions and turbidity), are investigated. As proven by FTIR and elemental analysis, the CSAX can be successfully synthesized and can remove both turbidity‐causing substances and heavy metal ions from aqueous solutions. Under optimum synthesis conditions CSAX exhibits excellent performance, i.e. %Tr = 98%, %Trd = 98.4%, %Hrd = 99% and %Hr = 91.6%, respectively.     

Preparation,characterization, and water resistance of cationic acetylated starch‐g‐poly(styrene‐butyl acrylate) surfactant‐free emulsion

Cationic acetylated starch‐g‐poly(styrene‐butyl acrylate) surfactant‐free emulsion (CAS‐g‐poly(St‐BA)) was synthesized by graft copolymerization of styrene (St) and butyl acrylate (BA) onto CAS using FeSO₄–H₂O₂ redox initiator. The maximum graft of 55.68% was derived when H₂O₂ concentration, monomer concentration, and St/BA ratio were 9%, 130%, and 1:1, respectively. The results obtained from FTIR, NMR (H¹ NMR and C¹³ NMR), XRD, SEM, and thermogravimetric analysis (TGA‐DTG) confirmed graft copolymerization of St and BA onto CAS. And it was demonstrated that film‐forming properties of starch were greatly improved via grafting St and BA onto starch. It was also found that paper sized with CAS‐g‐poly(St‐BA) exhibited higher ring crush index and bursting strength than paper sized with cationic potato starch (CS) and CAS, as well as much lower water absorption, which is further verified by contact angles results.     

Microwave‐assisted Synthesis of Starch Maleate by Dry Method

Starch maleate was prepared by microwave‐assisted reactions. Microwave‐assisted esterification in a dry medium for 5 min gives a reaction efficiency of 98%. Influences of reaction time, reagent molar ratio and water content of starch on the degree of substitution (DS) of the product and reaction efficiency were investigated. The structure of starch maleate was characterized by FTIR and NMR spectroscopy. Changes in the starch granules before and after modification were studied by scanning electron microscopy (SEM). Compared with the conventional heating synthesis method, microwave‐assisted synthesis in a dry medium is rapid and energy saving with high reaction efficiency.     

Synthesis,characterization and swelling behaviour of superabsorbent polymers from cassava starch‐graft‐poly(acrylamide)

Superabsorbent polymers (SAPs) were prepared from cassava starch by graft copolymerization of acrylamide on to starch using ceric ammonium nitrate (CAN) as free radical initiator, followed by alkali saponification. The reaction parameters such as concentration of acrylamide, concentration of CAN, temperature, and duration of polymerization reaction were optimized for maximum water absorbency using a 4‐factor 3‐level Box‐Behnken design. The highest values of percentage grafting and absorbency obtained were 174.8% and 425.2 g/g, respectively. The polymers were characterized by determination of grafting efficiency, N‐content, acrylamide content, FTIR analysis, SEM and XRD analyses. Thermogravimetric analysis (TG) showed that the SAP has higher thermal stability. The rate of water absorbency and the swelling behaviour of the SAP under different conditions of pH, and different salts were determined. The de‐swelling pattern of the hydrogels over different time durations was also determined.     

Grafting of 2‐(Dimethylamino)ethyl Methacrylate onto Potato Starch Using Potassium Permanganate/Sulfuric Acid Initiation System

Graft copolymerization of 2‐(dimethylamino)ethyl methacrylate onto potato starch was carried out in an aqueous medium using a potassium permanganate/sulfuric acid initiation system. The grafting percentage and grafting efficiency were determined as functions of the concentrations of potassium permanganate, sulfuric acid and the monomer, and also polymerization temperature and time. The IR spectrum of the graft copolymer showed the peaks characteristic of the grafted chains. The grafting percentage and grafting efficiency increased and then decreased with increasing the concentrations of potassium permanganate, sulfuric acid, and the monomer, as well as polymerization temperature. The grafting reaction was characterized by an initial fast rate followed a lower rate which leveled off after a certain time. The overall activation energy for the grafting was estimated to be 66.9 kJ/mol.     

Microwave‐Assisted Synthesis and Characterization of Succinate Derivatives of Cassava (Manihot esculenta Crantz) Starch

The use of microwave heating to prepare very rapidly cassava starch succinates with high viscosity is described. A response surface design was used for the experiment and different factors affecting the succinylation of cassava starch, including concentration of succinic anhydride, reaction time, temperature and moisture content of the medium were investigated. The degrees of substitution of the modified starches increased with an increase in reaction time and were in the range 0.007 – 0.051. The products exhibited higher viscosity, lower pasting temperature, enhanced water binding capacity and reduced swelling and paste clarity than unmodified cassava starch. The results of this study indicated that succinylation of starch can be achieved in shorter reaction times, which offers a benefit to laboratories and industries involved in developing newer and more versatile uses for cassava starch.     

衣康酸/丙烯酸与聚酯织物接枝共聚性能

研究了在水溶液中以过氧化苯甲酰为引发剂,衣康酸/丙烯酸为单体与碱处理后的三叶形聚酯(PET)平纹织物接枝共聚;对共聚条件如聚合温度、时间、引发剂浓度、单体物质的量比等进行研究,得出最佳聚合条件。电子扫描电镜照片和傅里叶红外变换光谱显示衣康酸/丙烯酸共聚到聚酯大分子上。研究结果表明随着接枝率的上升,织物吸湿快干性能提高;阳离子染料上染率大幅度提高,织物色光鲜艳。     

聚丁二酸丁二醇酯的合成

以丁二酸,丁二醇为原料,采用不同催化剂,在不同的反应条件下,进行直接酯化-缩聚反应,合成了相对分子质量较高的聚丁二酸丁二醇酯（PBS）,并对酯化反应中的副反应进行了研究。结果表明,不同酯化条件对酯化率及副反应的影响较大,所合成的PBS数均摩尔质量在5.7*104-8.0*104g/mol之间。     

Sorption of ethyl acetate and d‐limonene in poly(lactide) polymers

Poly(lactide) (PLA) polymers have garnered increased attention in the last few years as food packaging materials because they are environmentally friendly polymers. As the production of PLA increases and price per pound drops, PLA is becoming a growing alternative as a green food packaging material. In this research, the organic vapor barrier properties of commercially available PLA polymers were studied. Gravimetric sorption tests in PLA films were carried out, and the diffusion (D), solubility (S) and permeability (P) coefficients for ethyl acetate and d‐limonene in PLA were determined. For ethyl acetate, values of P = 1.22 × 10^?17 kg m m^?2 s^?1 Pa^?1, D = 2.63 × 10^?15 m² s^?1, and S = 4.62 × 10^?3 kg m^?3 Pa^?1) at 45 °C and a partial pressure of 12 654 Pa were obtained. For d‐limonene, no trace was detected after 21 days of testing at 45 °C and 258 Pa, which indicates a permeability coefficient lower than 9.96 × 10^?21 kg m m^?2 s^?1 Pa^?1. Poly(lactide) polymers demonstrated good aroma barrier to ethyl acetate and d‐limonene, and will most likely be good aroma barriers. PLA is not likely to promote flavor loss by either permeation or scalping. Copyright © 2005 Society of Chemical Industry     

芳香族多氨基甲酰磺酸盐羊毛防毡缩整理剂的制备和应用

采用3种聚醚多元醇与2,4-甲苯二异氰酸酯进行加成反应，然后用亚硫酸氢钠进行封端反应，再加入HCl调pH2-3制得芳香族多氨基甲酰磺酸盐(PCS)，探讨了具体封端条件和应用性能随其结构不同的差异，用PCS在不同羊毛织物上作防毡缩试验，其抗弯刚度较小，毡缩率较小，该产品与进口产品相比尚好．     

Microwave‐assisted extraction of bioactive saponins from chickpea (Cicer arietinum L)

Growing interest in plant secondary metabolites has brought with it the need for economical, rapid and efficient extraction protocols. Microwave‐assisted extraction (MAE) was used to extract saponins from chickpea (Cicer arietinum). Several MAE conditions were tested, and the method proved to be superior to Soxhlet extraction with regard to amounts of solvents required, time and energy expended. The use of a butanol/H₂O mixture showed selectivity towards saponin extraction. Using TLC, two distinct saponins were observed in the various chickpea extracts. The identification of the major saponin as a DDMP‐conjugated saponin was verified using ¹H and ¹³C NMR, for the first time in chickpea. The MAE procedure most likely contributed to the conservation of the heat‐sensitive DDMP moiety. The pure chickpea saponin exhibited significant inhibitory activity against Penicillium digitatum and additional filamentous fungi. Two Fusarium strains tested were highly tolerant to the saponin. The potential for using MAE for the efficient extraction of natural products may assist in expediting the chemical analysis and characterization of the biological activities of such compounds. Copyright © 2004 Society of Chemical Industry     

Chemical Acylation of Water‐Soluble Antioxidant of Bamboo Leaves (AOB‐w) and Functional Evaluation of Oil‐Soluble AOB (cAOB‐o)

Antioxidant of bamboo leaves (AOB) is a novel natural food antioxidant approved in China since 2004. Natural phenolics contained in the current AOB are usually polyhydroxy derivatives exhibiting hydrophilic character, which has been marked as water‐soluble AOB (AOB‐w). In order to broaden the application fields, oil‐soluble AOB (cAOB‐o) was obtained by chemical acylation of AOB‐w with different chain‐length fatty acids varying from C8 to C18. Results indicated that the yield and solubility of cAOB‐o in 1‐octanol solvent depended on the carbon chain length of acyl donor, and cAOB‐o derived from C12 fatty acid exhibited the more powerful antioxidant activity evaluated by β‐carotene/linoleic acid bleaching assay. Total phenolic content decreased by Folin–Ciocalteu assay. Fourier transform infrared spectra showed the increase of a carbonyl (C = O) peak at 1701 cm^?1 and a decrease in the intensity of the absorption at 3400 cm^?1 (O‐H stretching) in cAOB‐o. Acylation was inferred to mainly occur on the hydroxyl groups of flavones C‐glycosides according to the change of high‐performance liquid chromatography spectra and the contents of total flavonoids and phenolic acids. cAOB‐o with the addition of 0.02% significantly increased oxidative stability of palm oil 1.59 times, lard 3.74 times, and fried potato chips 2.08 times, which was better than the effect of oil‐soluble tea polyphenol (P < 0.01). Moreover, cAOB‐o was identified to be actually nontoxicity by an acute oral toxicity test. All the above results indicated that cAOB‐o could be used as a novel and effective oil‐soluble antioxidant in the food industry.