Preparation and characterization of poly(2-hydroxyethyl methacrylate) grafted bacterial cellulose using atom transfer radical polymerization

The purpose of this study is to synthesize grafted Bacterial Cellulose (BC) nanofibers using Atom Transfer Radical Polymerization (ATRP) reinforced into poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel matrix. Nanofibers grafting polymerizations were conducted in the presence of the catalyst CuCl/CuBr and the initiator 2-bromoisobutyrylbromide (2-BiBr). Degrees of substitution (DS) of BC-macroinitiators were quantified using both elemental analysis and gravimetric method. FTIR results confirmed BC nanofibers’ surface modifications of both initiator and hydroxyethyl methacrylate (HEMA) grafts. X-ray spectroscopy further confirmed the increase in carbonyl content after PHEMA-grafting polymerization. Results of the gravimetric analysis showed an increase in the weight of the grafted BC upon increasing reaction time. Furthermore, the change in the swelling ratio percentages of the reinforced composites product (BC-MI-3-g-PHEMA-1.5) was considerably higher based on reaction time. Slight increase in the swelling ratio of BC-MI-3 nanofibers was observed after 48 hours to reach 31 %. Moreover, results of thermal gravimetric analysis (TGA) demonstrated that decomposition temperature at 50 % weight loss (T₅₀) decreased to 350 °C for BC-MI-3-g-PHEMA-1.5. These characteristics demonstrate potentials for applications in the biomedical fields including drug delivery and wound care.     

Mechanical properties of semi-interpenetrating polymer network hydrogels based on poly(2-hydroxyethyl methacrylate) copolymer and chitosan

Semi-interpenetrating polymeric network (semi-IPN) hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-sodium methacrylate) [P(HEMA-co-SMA)], and chitosan with different molecular weights were prepared by crosslinking with ethylene glycol dimethacrylate (EGDMA) and poly(ethylene glycol) diacrylate (PEGDA) and their gelation time, water content, mechanical properties, and morphology were investigated. In consideration of the influence of the molecular weight of chitosan, there is no big difference in the water content, while tensile properties and compressive modulus increased as the molecular weight of chitosan increased. The water content increased and tensile properties and compressive modulus decreased with increasing SMA concentration. Considering the effect of the crosslinking agent, PEGDA had higher water content and lower tensile and compressive moduli than EGDMA. It is suggested that PHEMA/chitosan and P(HEMA-co-SMA)/chitosan semi-IPN hydrogels with different structures and physical properties can be prepared depending on the molecular weight of chitosan, the copolymerization with SMA, and the crosslinking agent type.     

Hydrophilic modification of PET fabric via continuous photografting of acrylic acid (AA) and hydroxyethyl methacrylate (HEMA)

Poly(acrylic acid) and poly(hydroxyethyl methacrylate) were introduced onto PET fabrics by UV-induced photografting to improve its hydrophilicity. Several factors affecting the photografting were studied including irradiation energy, monomer, and photoinitiator (PI) concentrations. ATR and ESCA analyses proved successful grafting of the two monomers onto PET. Morphology of fabric surface was examined using FE-SEM. Both zeta potential and water wetting time of the grafted PET fabrics decreased with increasing grafting yield. Also cationic dyeability of the grafted PET fabrics increased because of the increased electrostatic interactions between the anionic dyeing sites and cationic dyes.     

An effective and simple process for obtaining high strength silkworm (Bombyx mori) silk fiber

This article describes a new process for strengthening natural silk fibers. This process is simple yet effective for mass production of high strength silk fibers, enabled by drawing at a lower temperature and immediately heat setting at a higher temperature. The processing conditions were investigated and optimized to improve the strength. Silk fibers drawn to the maximum ratio at room temperature and then heat set at 200 °C show best tensile properties. Some salient features of the resulting fibers are tensile strength at break reaching 533±10.2 MPa and Young’s modulus attaining 12.9±0.57 GPa. These values are significantly higher than those of natural silk fibers (tensile strength increased by 44 % and Young’s modulus by 135 %). Wide-angle X-ray diffraction and FTIR confirm the transformation of silk I to silk II crystalline structure for the fiber obtained from this process. DSC and TGA data also provide support for the structural change of the silk fiber.     

Effect of Lactic Acid Supplementation on the Growth and Reproduction of Bombyx mori (Lepidopteria: Bombycidae)

Lactic acid is widely used in the food, drugs, cosmetics, and other industries to maintain the microbial stability of low-pH products. However, it is unclear whether lactic acid can affect silkworm (Bombyx mori) growth and reproduction. This study investigated the effects of lactic acid on the growth and reproduction of the silkworm. We analyzed the growth, cocoon quality, and reproductive performance of fifth instar larvae fed on mulberry leaves saturated with different concentrations (0.01, 0.1, 1, and 10%) of lactic acid and the control. Results showed that 0.01, 0.1, and 1% lactic acid supplementation positively affects growth and female cocoon quality, with increased larval weight and female cocoon shell weight compared to the control group. In contrast, 10% lactic acid was toxic to the larvae and significantly decreased growth, leading to larval death. Our study provides a basic reference for the optimal amount of preservatives. In addition, this study can be a desirable intervention for sericulturists and can play an important role in getting high return from silkworm-rearing activities.     

Identification and Characterization of Bacillus cereus SW7-1 in Bombyx mori (Lepidoptera: Bombycidae)

The bacterial diseases of silkworms cause significant reductions in sericulture and result in huge economic loss. This study aimed to identify and characterize a pathogen from diseased silkworm. SW7-1, a pathogenic bacterial strain, was isolated from the diseased silkworm. The strain was identified on the basis of its bacteriological properties and 16S rRNA gene sequence. The colony was round, slightly convex, opaque, dry, and milky on a nutrient agar medium, the colony also exhibited jagged edges. SW7-1 was Gram-positive, without parasporal crystal, and 0.8–1.2 by 2.6–3.4 µm in length, resembling long rods with rounded ends. The strain was positive to most of the physiological biochemical tests used in this study. The strain could utilize glucose, sucrose, and maltose. The results of its 16S rRNA gene sequence analysis revealed that SW7-1 shared the highest sequence identity (>99%) with Bacillus cereus strain 14. The bacterial strain was highly susceptible to gentamycin, streptomycin, erythromycin, norfloxacin, and ofloxacin and moderately susceptible to tetracycline and rifampicin. It exhibited resistance to other antibiotics. SW7-1 had hemolytic activity and could produce extracellular casease, lipase, and amylase. SW7-1 could reproduce septicemia-like symptoms with high mortality rate when re-fed to healthy silkworm. .The median lethal concentration (LC₅₀) was 5.45 × 10⁴ cfu/ml. Thus, SW7-1 was identified as B. cereus, which is a pathogen for silkworm and human infections are possible.     

Crystallization behavior,rheology, mechanical properties,and enzymatic degradation of poly(L-lactide)/poly(D-lactide)/glycidyl methacrylate grafted poly(ethylene octane) blends

Poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA)/poly(ethylene octene) grafted with glycidyl methacrylate (GPOE) were prepared by simple melt blending method at PDLA loadings from 1 to 5 wt%. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) demonstrated the formation of the stereocomplex in the blends. The addition of PDLA led to the increase of nucleation density from polarized microscope (POM) observations. Rheological measurements indicated that the blends exhibited a rheological fluid-solid transition and an enhanced elastic behavior in that ternary system as the PDLA loadings reached up to 5 wt%. By adding 1-2 wt% PDLA, the ternary system has better tensile and impact properties. Dynamic Mechanical Analysis (DMA) results showed that SC crystal formation and its effect on the enhancement of thermal stability at higher temperature. It is interesting that the enzymatic degradation rates have been enhanced clearly in the PLLA/PDLA/GPOE blends than in the PLLA/GPOE blend, which may be of great use and significance for the wider practical application of PLLA/GPOE blends.     

Mitochondrial Genome Architecture and Evolutionary Origin of the Yao Silkworm,a Living Fossil of the Domestic Silkworm Bombyx mori (Lepidoptera: Bombycidae)

The Yao silkworm is a unique silkworm resource producing yellow flat plate silk that has only been reared by the Baiku Yao ethnic group in Nandan County, Guangxi Province, China for a thousand years. Here, we report the mitochondrial genomes (mitogenomes) of five Yao silkworm strains and 10 local Guangxi strains of the domestic silkworm (Bombyx mori) L. (Lepidoptera: Bombycidae), and use the resulting mitogenomes and the available Bombyx mitogenomes to characterize their genome architecture and trace the evolutionary origin of the Yao silkworm. The five Yao silkworm mitogenomes exhibited genome architectures identical to typical set of 37 mitochondrial genes (13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs) and a high level of genome sequence similarity with the domestic silkworm. Mitogenome-based phylogenetic reconstruction provided solid evidence that the Yao silkworm shares a common ancestor with the domestic silkworm. Sliding window analysis uncovered a distinct variation pattern in the mitogenome between the Yao silkworm and the other domestic silkworm strains. The phylogenetic analyses revealed a basal placement of the Yao silkworm among all available domestic silkworm strains, indicating that the Yao silkworm is an ancient population of the domestic silkworm. Our data indicated that the Yao silkworm (B. mori) is a lineage of the domestic silkworm, which for the first time provides insights into the origin of the Yao silkworm.     

Dyeing properties of wool fabrics dyed with Vitis Vinifera L. (black grenache) leaves extract

In this work, water-extraction of Vitis Vinifera L. (Black Grenache) leaves and analysis of aqueous extracts for anthocyanins were investigated. Vegetable leaves were cultivated in North of Tunisia at different dates. Anthocyanins were identified as main constituents in these natural dyeing materials using high performance liquid chromatography (HPCL). Dyeability of wool and its fastness properties using Vitis Vinifera L. leaves extract were also determined. Aqueous extract of Vitis Vinifera L. leaves has markedly yielded shades with good fastness properties. Thus, affordability is a point favorable for Vitis Vinifera L. leaves. Effects of dye bath pH and temperature on dyeability and fastness proprieties of wool fabrics by aqueous extract of Vitis Vinifera L. leaves were evaluated. Experimental results showed that fastness properties of dyed fabrics ranged from average to very good. Vitis Vinifera L. leaves extracts showed potential to dyeing wool fibers under highly acidic conditions (pH ≤2). The results obtained here revealed that natural dyes extracted from Vitis Vinifera L. leaves can be cost-effective for dyeing wool fabrics.     

Preparation of high molecular weight poly(methyl methacrylate) with high yield by room temperature suspension polymerization of methyl methacrylate

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25 °C by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P_n): 30,900–36,100) and of high yield (ultimate conversion of MMA into PMMA: 83–93 %) with diminishing heat generated during polymerization. The P_n and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.     

Kinetics of two-step emulsion polymerization of poly(n-butyl methacrylate)/poly(methyl methacrylate) polymer networks

Poly(n-butyl methacrylate)/poly(methyl methacrylate) polymer networks were synthesized by two-step emulsion polymerization with sodium dodecylsulfonate and polyoxyethylene nonylphenolether as the emulsifier, distilled water as the continuous medium, and potassium persulfate as the initiator. The kinetics of two-step emulsion polymerization was studied. Effects of emulsifier concentration, initiator concentration, and polymerization temperature on monomer conversion and polymerization rate were investigated in detail. Experimental data indicate that both the steady state polymerization rate and monomer conversion increase with the augment of emulsifier concentration, initiator concentration, or reaction temperature.     

Dyeing properties of novel azo disperse dyes derived from phthalimide and color fastness on poly(lactic acid) fiber

The coloration of poly(lactic acid) (PLA) fiber with 18 carbocyclic monoazo disperse dyes bearing a hydrolyzable phthalimide ring fused to the aromatic ring of their diazo components has been investigated. The phthalimidyl nitrogen atom was substituted with either a n-butyl, sec-butyl, or isopropyl group, while the adjoining phenyl ring bore a substitution pattern typical of commercial colorants. There was a broad correlation between percentage dye exhaustion onto PLA and that onto polyester (PET) fiber, although significant differences in certain instances were apparent with no clear trends regarding dye structure. Attempts to explain the observed percentage exhaustion values by mapping them to calculated partition coefficient or solubility parameter values were unsuccessful. Wash fastness was relatively good compared to that of some conventional disperse dyes applied to PLA. As was found to be the case with PET, the wash fastness of dyes on PLA tended to be highest when their diazo ring was substituted with electron acceptors.     

Study on oil adsorption/desorption kinetics and polymer network parameters of poly(lauryl methacrylate-<Emphasis Type="Italic">co</Emphasis>-hydroxyethyl methacrylate)

In the present work, oil adsorption, desorption, and resorption of poly(lauryl methacrylate-co-hydroxyethyl methacrylate) P(LMA-co-HEMA) were evaluated with different oils by a gravimetric method. Adsorption kinetics were modeled using pseudo-first-order and pseudo-second-order equations. Polymer network parameters of P(LMA-co-HEMA) regarding average molecular weight (Mc) between two crosslink piontss can be calculated by oil absorbency at equilibrium (Q _e ), the solubility parameter (δ) and polymer-solvent interaction parameter (χ) with Flory-Huggins relation. The results showed pseudo-second-order model has a better fit to the oil adsorption kinetic data The desorption can be analyzed by fitting a prediction of exponential-like decay to the deswelling curves. A typical oil desorption exhibited two stages: a burst release driven by concentration gradient, and a slow release controlled by diffusion and the elastic recovery of polymer networks. For reusability, the resorption behavior of P(LMA-co-HEMA) was also investigated. It was worth noting that oil resorption was faster than the first adsorption due to potential passages. Moreover, the adsorption capacity was not significantly changed after regeneration.     

Removal of some cationic dyes from aqueous solution by acrylamide- or 2-hydroxyethyl methacrylate-based copolymeric hydrogels

In this study, anionic hydrogels were prepared using a crosslinker (N,N′-methylenebisacrylamide) through a free radical addition reaction in aqueous solutions of neutral acrylamide or 2-hydroxyethyl methacrylate monomer and anionic monomers, mesaconic acid or aconitic acid. Cationic dyes along with safranine (azine-), nile blue (oxazine-) and methylene blue (thiazine-) were selected as models of pollutants, and adsorption of these dyes onto the hydrogels was investigated. To examine the effect of concentration on adsorption, dye solutions prepared with a concentration range of 5–50 mg l^?1 and 0.1 g hydrogel at 25 °C were exposed to the hydrogels until equilibrium was established. Dye adsorption onto the hydrogels was found to be an L type Giles adsorption isotherm. Monolayer sorption capacity and adsorption constant values were calculated from the Langmuir plots. To calculate R_L values, a non-dimensional analysis was used and they were always found to be 0<R<1. In other words, the hydrogels were favorable for adsorption of these dyes. Aqueous solutions of dyes were observed to interact with hydrogels in the following order: oxazine > azine > thiazine. Furthermore, the higher the number of carboxyl groups in the hydrogel composition, the higher the adsorbed amount of substance.     

Preparation and photochromism of poly(methyl methacrylate) microspheres containing spirooxazine

Photochromic poly(methyl methacrylate) (PMMA)/spirooxazine microspheres were prepared by in situ suspension polymerization and those photochromic behaviors were investigated. When UV irradiation was subjected to the PMMA/spirooxazine microspheres, the reflection spectra generated by photochromic reaction was clearly observed and its reversible decoloration behaviors responded rapidly in the dark. Photochromic microspheres prepared in this work, could be used to photochromic fabrics such as microcapsules for fragrant finishing of fabrics, as well as those are could be applied in sensing materials.     

Thermal performance and flammability of poly(ethylene terephthalate) fabrics grafted with different monomers followed by electron beam irradiation

Electron beam irradiation grafting of acrylic acid (AAc), acrylamide (AAm), and dimethyl vinylphosphonate (DMVP) onto poly(ethylene terephthalate) (PET) fabrics was performed using a high-energy electron accelerator. Parameters affecting the graft polymerization of PET fabrics, including absorbed dose and monomer concentration, were investigated. Fourier transform infrared spectroscopy analysis confirmed that the monomers were grafted onto the PET fabrics. The thermal behavior of the grafted PET fabrics was investigated with thermogravimetric analysis. Findings showed that grafting with AAm could improve the thermal stability of PET. The limiting oxygen index values and vertical flammability test results showed that PET fabric graft-polymerized with AAc could improve the flammability and prevent melt dripping. Grafting with AAm and DMVP could improve the flame retardation property of PET fabric. Scanning electron micrographs showed that the surface morphology of the PET fabric samples was significantly influenced by graft polymerization, and that grafting with AAc could promote the formation of residual char and impart an anti-dripping quality to PET fabrics.     

Selective removal of Pb(II) ions from aqueous solutions by acrylic acid/acrylamide comonomer grafted polypropylene fibers

Polypropylene-based chelating fibers grafted with acrylic acid and acrylamide side chains were simply synthesized, and subsequently employed as adsorbents for Pb(II) removal selectively from aqueous solutions. The assynthesized fibers were characterized by elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscope, and water contact angle. The adsorption results revealed that kinetics data were fitted by a pseudo-second order model (semi-saturation time 6.2 min), thereby suggesting chelating interaction to be the main mechanism during the adsorption process. The adsorption isotherm data fitted well with a Langmuir model. The thermodynamic study revealed the adsorption of Pb(II) as an exothermic spontaneous chemisorptive process. Coexisting Na(I), Mg(II), and Al(III) in solution showed negligible effects in the adsorption process. As confirmed by carboxyl amination, the carboxylate oxygen preferentially chelates coexisting Ca(II) over Pb(II), thereby leading to lower extents of Pb(II)-O chelate interaction. The spent fibers were effectively and repetitively (five cycles) regenerated while maintaining high performance upon treatment with 1 M hydrochloric acid solutions.     

Dyeing of cotton and polyester/cotton blend with disperse dyes using sodium 2-(2,3-dibromopropionylamino)-5-(4,6-dichloro-1,3,5-triazinylamino)-benzenesulfonate

The cotton fabrics were pretreated by sodium 2-(2,3-dibromopropionylamino)-5-(4,6-dichloro-1,3,5-triazinylamino)-benzenesulfonate (DBDCBS) at alkaline condition of room temperature and then dyed with four disperse dyes having amino groups (C.I. Disperse Yellow 9, C.I. Disperse Red 11, C.I. Disperse Blue 56 and C.I. Disperse Violet 1) at acidic condition of high temperature. A novel hetero-bifunctional bridge compound,DBDCBS, has two reactive groups such as dichloro-s-triazinyl group andα, β-dibromopropionylamido group. The first has reactivity towards hydroxy group of cellulosic fiber and the second shows reactivity towards amino groups of disperse dye containing amino groups. The results indicate that it is possible to dye polyester/cotton blend at one-bath dyeing using one kind of disperse dye containing amino groups. Therefore, two kinds of dyeing methods such as two-bath process one-bath dyeing and one-bath process one-bath dyeing were investigated and their dyeabilities were compared. The differences between these two methods were negligibly small so that perfect one-bath one-step dyeing of polyester/cotton blend by one kind of disperse dye was achieved.     

Chemical properties and water absorption kinetics of transgenic corn grain (2B587 Hx) and its conventional isoline (2B587)

In the hydration process, besides influencing processing conditions, the cultivar may also influence water absorption by the grains and, consequently, yield and quality of the milled products. Therefore, the moisture absorption kinetics of the transgenic corn grain 2B587 Hx and its conventional isoline 2B587 were studied, as well as the chemical characterization of the samples in natural conditions. The water absorption kinetics of the grains was modeled using Peleg's equation at hydration temperatures of 40, 50, 60, and 67 °C. The 2B587 Hx transgenic corn, compared with the 2B587 conventional corn, had higher carbohydrate and ash contents and lower crude fiber content. The water absorption by the grains, which was satisfactorily represented by Peleg's model, occurred more quickly as the temperature increased. Peleg's constant, k₁, which is inversely related to the initial hydration rate, varied from 405.2 to 141.5 min g/g for conventional corn and from 429.5 to 149.5 min g/g for transgenic corn at temperatures from 40 to 67 °C. The choice of the cultivar may depend on the specifications required by the industry for the main final products.