Physicochemical properties of Venezuelan breadfruit (Artocarpus altilis) starch

Artocarpus altilis, seedless variety, is a fruit-producing plant which is cultived in Margarita Island, Venezuela, and is consumed by the inhabitants of the region. Its chemical composition and physical characteristics were determined. The chemical (AOAC and AACC methods), physicochemical, morphometric characteristics, viscoamylographic properties and digestibility in vitro of starch from Artocarpus were studied. The starch yield was 18.5 g/100 g (dw)w with a purity of 98.86%, 27.68 and 72.32% of amylose and amylopectin, respectively. Scanning electron microscopy showed irregular-rounded granules. Swelling power, water absorption and solubility values were determined and found to be higher than that of corn and amaranth starch. The amylographic study showed a gelatinization temperature at 73.3 degrees C, with high stability during heating and cooling cycles. Artocarpus starch could also be categorized in the group of mixed short chain branched/long chain branched glucan starches, this agrees with digestibility results that showed a high degree of digestibility in vitro. These results might be advantageous in medical and food use.     

Influence of the oxidation and acetylation of banana starch on the mechanical and water barrier properties of modified starch and modified starch/chitosan blend films

Banana starch was oxidized at three different levels and afterwards acetylated. The double‐modified starch was used for film preparation with the addition of chitosan. The physical, mechanical, and barrier properties were tested. The oxidation level increased the moisture content of the film, but the acetylation and the addition of chitosan decreased this characteristic. The oxidation level increased the whiteness of the film, but the second modification (acetylation) and the addition of chitosan to the blend did not affect this parameter. The solubility increased with the temperature and the oxidation level but decreased with the storage time of the film. The oxidation increased and the acetylation reduced the solubility with respect to the native starch film. The dual modification produced a solubility value less than that of its oxidized counterpart, and the addition of chitosan produced the highest solubility value. The addition of chitosan increased the tensile strength of the film, and the effect was higher with the oxidation level and longest storage time. The addition of chitosan produced a higher elongation value than that of its double‐modified film, but at the longest storage time, this parameter decreased. The water vapor permeability increased with the oxidation level because of the hydrophilic character, but the acetylation reduced this parameter because the acetylation increased the hydrophobic character of the starch due to the ester group. Films prepared with the double‐modified banana starch and the addition of chitosan had some improved physical, mechanical, and barrier properties, and they may be used in specific applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparative disintegrant activities of breadfruit starch and official corn starch

A Comparative evaluation of starch powder extracted from breadfruit (Artocarpus communis, Frost) as tablet disintegrant was made with corn starch BP using a 2 × 4 factorial experiment in a randomized complete block design. Two factors (type of starch: 2 i.e. breadfruit and corn) at four levels (concentrations of starch disintegrant: 4 i.e. 2.5%, 5%, 7.5% and 10%) were studied. One (1) kilogram batches of paracetamol granules containing various concentrations of endo-disintegrant or exo-disintegrant were prepared by the wet granulation method in a combined mixer-granulator, using polyvinyl pyrrolidone solution as binder. Tablets were tested for disintegration, dissolution and physical qualities following the British Pharmacopoeia (BP) compendial procedures.At the compression force of 1 tonne, corresponding to average packing fraction of 0.92, all formulations containing breadfruit and corn starch exo-disintegrants passed the official disintegration time limit of ≤ 15 min and quantity dissolved (Q₃₀) of ≥ 80% in 30 min. As endo-disintegrant however, only corn starch at 5% and 10% w/w and breadfruit at 10% passed the BP limit test. Generally, the rank order of effectiveness of disintegrant was Corn_exo ≈ Breadfruit_exo > Corn_endo > Breadfruit_endo. The observed concentration-dependent difference in disintegrant effectiveness is ascribed to the differences in their hydration capacity and effective tablet porosity. Contrary to faster disintegration suggested by its higher hydration capacity, breadfruit starch formulations showed longer disintegration time than corn, attributable to the higher density of breadfruit formulations which appears to retard entry of disintegration fluid into the tablet. However, the dissolution profiles (Q₃₀) were comparable (p > 0.05).Breadfruit starch powder appears to be a suitable substitute for official corn starch only as exo-disintegrant in paracetamol tablet formulation. In that form, it not only produced rapid tablet break-up and drug dissolution, it also improved tablet crushing strength.     

Synthesis and properties of graft oxidation starch sizing agent

In this article, a graft, oxidation starch sizing agent was synthesized and its structure and surface morphology were analyzed by infrared (IR) spectroscopy and scanning electron microscopy (SEM). The results show that the synthesized graft oxidation starch has good gelatinizing ability, good film properties, good desizing ability, and lower hygroscopic properties. The sized yarns (T/C65/35, 13.5tex), sized with graft oxidation starch and emulsive copolymer size EM, exhibit good tensile strength and elongation at break, good abrasion resistance, and lower counts of fluff when poly (vinyl alcohol) (PVA) is substituted by ≤ 80% with graft oxidation starch. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1563–1566, 2003     

Effect of graft-copolymerization with poly(acrylamide) on rheological and thermal properties of cassava starch

Graft copolymers of different grafting levels were synthesised by the free radical initiated reaction of cassava starch with acrylamide in presence of ceric ammonium nitrate. The viscosity properties of the native granular starch and the grafted starches were determined using a Rapid visco analyzer (RVA) and rheological properties by frequency sweep test under different conditions using a rheometer. Some of the grafted starches exhibited significantly higher and some others exhibited drastically reduced peak viscosity values irrespective of the percentage grafting. All the grafted starches exhibited very good viscosity stability as evidenced from the highly reduced breakdown and higher final viscosity values in comparison to native cassava starch. Thermal analysis of the pure granular cassava starch and grafted starches was carried out using a differential scanning calorimetry (DSC) and thermogravimetry. DSC studies showed that in comparison to native starch, the grafted starches showed lower temperatures of transition. The thermal stability of cassava starch was enhanced by grafting as observed from the thermogravimetric data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal and viscoelastic properties of some commercial starch products

Three commercial starch products for polyolefins, marketed under the Mater‐Bi, Cornplast, and Bioefect trademarks, were subjected to an accelerated soil burial test. Their thermal and viscoelastic behaviors were studied by differential scanning calorimetry (DSC) and dynamic mechanical spectroscopy. Degradation in soil leads to more significant changes both in the DSC thermogram and the mechanical relaxation spectrum of Mater‐Bi. The relaxation spectra of Cornplast and Bioefect, two products containing polyethylene, basically coincide with that of pure low density polyethylene. The α‐relaxation zone of these starch products is the most affected by the degradation process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1242–1251, 2003     

The acetylation and enzymatic degradation of starch films

The preparation of films from starch and their degradation by amylase enzymes is described. Starch acetate was prepared by acetylation of starch with a pyridine/acetic anhydride mixture. The resulting polymer was cast into films from solutions of 90% formic acid. A series of films with a range of acetyl content were then exposed to buffered amylase solutions and the retained tensile strength measured. It was found that with a sufficient acetyl content the wet strength of the films was maintained in the aqueous solutions, but that the acetyl content was sufficiently low enough to permit degradation by a mixture of alpha and beta amylases within a period of 1 h. These films could be useful as membranes in bioreactors, which could be degraded at will by the addition of enzymes to the system. © 1993 John Wiley & Sons, Inc.     

氧化-接枝双重改性淀粉胶粘剂的制备与性能研究

以玉米淀粉为原料、过硫酸铵(APS)为氧化剂、APS-亚硫酸氢钠为引发剂、苯乙烯(St)和丙烯酸丁酯(BA)为接枝共聚单体,制得氧化-接枝双重改性淀粉胶粘剂。采用单因素试验法和正交试验法优选出制备改性淀粉胶粘剂的最佳工艺条件。结果表明:当w(APS)=0.6%、w(总单体)=20%、w(引发剂)=0.6%、反应时间为2.0 h和反应温度为65℃时,改性淀粉胶粘剂的综合性能良好,其耐水时间为200 h、吸水率为60%和黏度为850 mPa.s。     

Effect of oxidation under accelerated conditions on fuel properties of methyl soyate (biodiesel)

Biodiesel derived from transesterification of soybean oil and methanol is an attractive alternative fuel for combustion in direct-injection compression ignition (diesel) engines. During long-term storage, oxidation due to contact with air (autoxidation) presents a legitimate concern with respect to maintaining fuel quality of biodiesel. This work examines the effects of oxidation under controlled accelerated conditions on fuel properties of methyl soyate (SME). SME samples from four separate sources with varying storage histories were oxidized at elevated temperature under a 0.5 standard cm³/min air purge and with continuous stirring. Results showed that reaction time significantly affects kinematic viscosity (ν). With respect to increasing reaction temperature, ν, acid value (AV), PV, and specific gravity (SG) increased significantly, whereas cold flow properties were minimally affected for temperatures up to 150°C. Antioxidants TBHQ and α-tocopherol showed beneficial effects on retarding oxidative degradation of SME under conditions of this study. Results indicated that ν and AV have the best potential as parameters for timely and easy monitoring of biodiesel fuel quality during storage.     

Effect of moisture content on tensile properties of starch/poly(hydroxyester ether) composite materials

The effect of moisture content on the mechanical properties of starch/poly(hydroxyester ether) (PHEE) composite materials has been characterized. Cornstarch with either 1 or 10% moisture content was extruded with PHEE. Total moisture content (TMC) during subsequent injection molding ranged from 1.0 to 10% (total solids basis). Starch granule structure, determined by X-ray diffraction and scanning electron microscopy, was progressively disrupted but not completely destroyed (as in thermoplastic starch) as TMC during molding increased. Tensile strength and modulus values were not significantly impacted when the TMC was 6% or less. As TMC increased above 6%, both properties decreased rapidly, while strain to break increased. Tensile strength increased when samples prepared at high TMC were equilibrated to a lower value. Changes in weight average molecular weight of the PHEE during processing were not significant as measured by gel permeation chromatography, even at the highest moisture contents. The effects of TMC on mechanical properties of starch/PHEE materials are shown to be due to changes in the viscoelastic response of the PHEE matrix, by comparison of starch/PHEE results to those of neat PHEE [Polymer 42 (2001) 5643].     

Effect of unmodified and modified sago starch on properties of (sago starch)/silica/PVA plastic films

Sago starch was modified by crosslinking with sodium trimetaphosphate (STMP). Different formulations of films were prepared by a blending process and a casting method. A suitable plasticizer was added to the blend. Mechanical properties of plastic films with unmodified and modified sago starch were compared. From the results obtained, films with modified sago starch had better compatibility and interaction with polyvinyl alcohol than unmodified sago starch films. Thus, the tensile strength of modified films was higher, but lower in elongation at break than unmodified sago starch plastic films. Films with modified sago starch also showed lower water absorption, water vapor transmission, and degradation than unmodified sago starch plastic films. Chosen were 1 wt% and 2 wt% of silica as the optimum formulation that produced the best tensile properties for modified and unmodified sago starch plastic films. J. VINYL ADDIT. TECHNOL., 20:185–192, 2014. © 2014 Society of Plastics Engineers     

Effect of oxidation level on the dual modification of banana starch: The mechanical and barrier properties of its films

Banana starch was oxidized at three different levels and then acetylated. The double‐modified starch was used for film preparation. The physical, mechanical, and barrier properties were tested. The oxidation level increased the whiteness of the film, and the second modification (acetylation) did not affect this parameter. The solubility increased with temperature and oxidation level. However, acetylation decreased the solubility value. At the longest storage times, the solubility decreased because of starch reorganization inside the polymeric matrix. In general, oxidation increased the tensile strength of the films, and a slight increase was observed when the oxidized starch was acetylated. This effect was more noticeable at the longest storage time. The oxidation level decreased the percentage elongation at break, and a slight effect due to acetylation was observed. The film of oxidized–acetylated starch showed a higher elastic modulus value than its oxidized counterpart. The water vapor permeability increased with oxidation level, but the acetylation decreased this parameter. The oxidation increased the hydrophilic character of the starch because of the formation of carbonyl and carboxyl groups that showed more affinity for water molecules. When the oxidized banana starch was acetylated, a decrease in the water vapor permeability was found because the acetylation increased the hydrophobic character of the starch due to the ester group. Films prepared with the double‐modified banana starch had some improved physical, mechanical, and barrier properties, and they may be used in specific applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

氧化条件对淀粉/丙烯酸共聚物粘接性能的影响

以双氧水(H2O2)为氧化剂、硫酸铜(CuSO4)为氧化催化剂,玉米淀粉经氧化、糊化和AA(丙烯酸)接枝改性后,制得淀粉/AA接枝共聚物;然后以此为瓦楞纸板生产用淀粉胶粘剂的载体,以淀粉氧化过程中的pH、催化剂含量、氧化剂含量、氧化时间和氧化温度为试验因素,以接枝淀粉胶粘剂/瓦楞纸板的粘接强度和边压强度为考核指标,采用单因素试验法优选出制备该胶粘剂的最佳工艺条件。结果表明:当pH=10、V(0.1 mol/L CuSO4)=0.6 mL、w(H2O2)=0.6%、氧化时间为20 min和氧化温度为30℃时,接枝淀粉胶粘剂具有相对最好的粘接性能,相应接枝淀粉胶粘剂/瓦楞纸板的粘接强度和边压强度相对最大。     

生物油对生物油基淀粉胶黏剂性能的影响

我国的生物质资源丰富,将其快速热解成生物油,作为优质化工原料应用,可实现其高值高效应用。本文对以生物油制备的环境友好型生物油淀粉胶黏剂基本性能进行研究,结果表明,其湿胶合强度可达到国标Ⅱ类胶合板标准,其黏度可以满足胶合板工业化生产需求;生物油淀粉胶黏剂流变行为呈现出明显的剪切变稀特征,是典型的假塑性流体,流动活化能△E_η为9.67 kJ·mol^-1,表明其具有良好的流动性和应用潜力;通过对比不同生物油加入量的BOS胶黏剂湿胶合强度、流变性和热稳定性的研究发现,生物油的加入可改善BOS胶黏剂的耐水性,促进其固化,并增强其热稳定性。     

Effect of dehulling methods and desolventizing temperatures on proximate composition and some functional properties of sesame (Sesamum indicum L.) seed flour

Sesame seeds were dehulled mechanically and in 10% sodium chloride solution before oil extraction and drying to obtain the flour. The effect of these dehulling methods on the proximate composition, oil and water absorption, emulsification, and foaming properties of the flour was investigated. The effect of desolventizing temperatures (80, 90, and 100°C) on these properties was also investigated. Protein contents of seeds, dehulled mechanically (MDSF) and in 10% NaCl solution (SDSF), were 58.5 and 52.1%, respectively. Carbohydrate and ash contents of both flours also varied. The oil and water absorption capacities of the flours were 268 and 252% for MDSF and 370 and 410% for SDSF, respectively. The emulsion capacity of the MDSF sample was slightly lower (20.0 mL oil/g sample) but more stable than the SDSF sample, whose value was 20.4 mL oil/g sample. The foam capacity of MDSF was, however, higher (48.5%) but less stable than SDSF (33.7%). An increase in desolventizing temperatures of the meal led to increases in oil and water absorption capacities of the flours. Foam and emulsion capacities, on the other hand, decreased with increase in temperature. Desolventizing temperatures had no effect on the stability of the formed emulsion but had a decreasing effect on the stability of the foam.     

Effect of starch predrying on the mechanical properties of starch/poly(ε‐caprolactone) composites

This study describes the effect of predrying sago starch, a tropical starch, on the resultant mechanical properties of starch/poly(ε‐caprolactone) composite materials. Sago starch was dried to less than a 1% moisture level in a vacuum oven and dispersed into a polycaprolactone matrix with an internal mixer at 90°C. The mechanical properties of the composite were studied according to methods of the Association for Standards, Testing, and Measurement, whereas the morphology was monitored with scanning electron microscopy. The properties were compared with a composite obtained with native starch containing 12% moisture. The results indicated that predrying the starch led to a lower property drop rate in the composite as the starch content increased. The elastic modulus, tensile strength, and elongation at break were higher than those obtained when starch was used without predrying. The morphology observed during scanning electron microscopy studies was used to explain the observed trends in the mechanical properties. In this way, a relatively simple and cost‐effective method was devised to increase the starch loading in the polycaprolactone matrix to obtain properties within the useful range of mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 877–884, 2003     

Effect of concentration and type of plasticizer on some physical properties of poly(vinyl chloride)

The effect of four different types and concentrations of plasticizers on some physical properties of poly(vinyl chloride) (PVC) has been studied. DOP, DOA, TTP, and Hex were used as plasticizers in concentration levels of up to 24% of PVC weight. The plasticized and unplasticized PVC were processed into sheets by compression molding. The sheets were tested for their vicat softening point, shore D hardness, flexural properties, and dynamic fatigue. It was found that the vicat softening point, shore D hardness, flexural yield strength, and flexural modulus decrease with increase in plasticizer concentration, though in some cases a threshold concentration must be passed before these effects can be observed. Close similarities were always found in the behavior of DOP and DOA and also between TTP and Hex. It was found in the study of flexural fatigue properties of PVC plasticized by DOP that an increase in plasticizer concentration led to a decrease in load bearing ability only at stress levels above 20 MPa.     

Effect of filler type and concentration on some mechanical and electrical properties of poly(methyl methacrylate)

Polymer composites of poly(methyl methacrylate) (PMMA) and cuprous oxide (Cu₂O), magnesium oxide (MgO), copper biphthalocyanine, iron (II) chloride (FeCl₂), and iron metal were prepared by different filler-to-polymer percentages of 10, 20, 30, 40, and 50%. With increasing filler concentration, brinell hardness increases. Copper biphthalocyanine resulted in the highest hardness, and iron metal resulted in the lowest one. The electrical conductivity was found to increase with increasing filler concentration. The iron metal composite gave the highest effect, while the magnesium oxide composite resulted in the lowest one. The 50% concentration samples were subjected to electrical conductivity measurements at temperatures ranging from 25 to 100°C. The electrical conductivity was found to increase with increasing the temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 637–641, 1998     

Studies on some properties of poly(phenylene sulphide)

Poly(phenylene sulphide) was synthesized by a direct method. Benzene and elemental sulphur were used as substrates, and aluminium chloride as a catalyst. The obtained final product was characterized by IR, VIS-UV, wide angle X-ray and mass spectroscopy, thermal, and elemental analyses. On the base of the analytical methods the molecular structure of the obtained polymer was discussed.