Effect of silane monomer on the improvement of mechanical and degradable properties of photografted jute yarn with acrylamide

UV radiation was used to graft acrylamide (AA) to jute yarn in order to improve the mechanical properties. The physicomechanical properties of the grafted jute yarn were investigated. A series of solutions of different AA concentrations in methanol along with photoinitiator (Irgacure‐907, 2%) were prepared. The jute yarns were soaked in the solution for 30 min before radiation. The effect of irradiation time, concentration of monomer on polymer loading, and tensile properties of the jute yarn were studied. The highest polymer loading (22%) and tensile strength (95%) of the yarn were observed when the yarn was treated in 30% AA in methanol with 60 min of UV radiation. The surfaces of both treated and untreated jute were characterized by X‐ray photospectrometry, infrared spectroscopy, and environmental scanning electron microscopy, and it was observed that the AA reacted or deposited on the jute surface. A minute amount (1%) of silane monomer [3‐(trimethoxysilyl)‐propyl methacrylate] was used as an additive in the AA solution to further improve the mechanical properties of jute yarn. Better improvement was achieved by using 1% silane monomer. Water uptake, simulating weathering, and soil degradation tests of untreated and treated yarns were also performed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3530–3538, 2003     

A study of antimicrobial property of textile fabric treated with modified dendrimers

Dendrimers have been used as a vehicle to develop the antimicrobial properties of textile fabrics. We have taken advantage of the large number of functional groups present in the regular and highly branched three‐dimensional architecture of dendrimers. In this study, the poly(amidoamine) (PAMAM) G‐3 dendrimer was modified to provide antimicrobial properties. Following a procedure similar to what is suggested in the literature, PAMAM (G3) with primary amine end groups was converted into ammonium functionalities. The modification was then confirmed by FTIR and ¹³C‐NMR analysis. Dendrimers have unique properties owing to their globular shape and tunable cavities, this allows them to form complexes with a variety of ions and compounds; and also act as a template to fabricate metal nanoparticles. AgNO₃–PAMAM (G3) complex as well as a MesoSilver–PAMAM (G3) complex were formed and these modified dendrimers were characterized by a UV–Visible spectrophotometer to study the complex formation. Modified dendrimers were applied to the Cotton/Nylon blend fabric. SEM and EDX analysis were performed to study the dispersion of silver nanoparticles onto the fabric. An antimicrobial test of the treated‐fabric against Staphylococcus aureus exhibited significant biocidal activities for each type of modified‐dendrimer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Aureole nanofibers by electrospinning of PAMAM‐PEO solution

Poly(amido amine) (PAMAM) dendrimer‐polyethylene oxide (PEO) nanofibers as dendrimeric‐polymeric composite nanofibers were prepared via electrospinning of PEO solution containing PAMAM dendrimer. The resultant fibers were characterized by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology and thermal properties of PEO nanofibers with and without PAMAM dendrimer were compared and the effect of PAMAM concentration on morphology and thermal properties of the resultant fibers was studied. The fibers had a size range of about 400–1300 nanometer in diameter with aureole morphology in most regions. The phase change temperature, phase transition heat, and the crystallinity of the produced composite fibers were determined by DSC analyses. TGA was also used to confirm the presence of PAMAM and to determine the amount of it within the fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface modification of jute yarn by photografting of low‐glass transition temperature monomers

Jute yarns were grafted with three types of vinyl monomers of different functionalities such as methyl acrylate (MA), ethyl acrylate (EA), and 2‐hydroxyethyl acrylate (HEA) with ultraviolet radiation. The graft copolymerization reaction between the cellulose of the jute fibers and the monomer and the chemical environment of the treated fibers were confirmed by Fourier transform infrared spectroscopy. The reduction of OH groups and increment of >C?O groups in treated jute yarns were observed. DSC studies showed that the treated jute fibers were more thermally stable compared to the untreated one. The surface topography of the yarns was analyzed by an environmental scanning electron microscope. Different parameters, such as concentration of monomers and irradiation time, were optimized with the extent of mechanical properties such as tensile strength and elongation at break of the jute yarn. MA, EA, and HEA produced enhanced tensile strengths of 87, 78, and 85%, respectively. The monomers MA, EA, and HEA showed improved elongations at break of 118, 91, and 76%, respectively. The water uptake of treated and untreated jute yarns were studied. The maximum water uptake was observed of the grafted sample compared to the untreated jute yarn. The effects of additives such as urea on mechanical properties were also studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 993–1000, 2003     

Role of Amino Acids on In Situ Photografting of Jute Yarn with Acrylamide Using Ultraviolet Radiation

Abstract

To improve the mechanical performance of jute yarn, grafting with acrylamide (AM) monomer has been performed on in situ UV radiation and optimized; the monomer concentration (30%) and irradiation time (60 min) attained 195% tensile strength with 22% polymer loading (PL). The effect of amino acids (1%) as additives in AM with photografted jute yarn at optimized system has been studied. The PL and tensile properties, such as tensile strength (TS) and elongation at break (Eb), of treated samples were enhanced by incorporation of amino acids, and the highest TS value (270%) and Eb value (300%) with 27% PL value were achieved by the sample treated with L‐arginine (Arg). Weak acid [3% acetic acid (Ace)] and strong acid [1% sulfuric acid (Sul)] were also incorporated in the optimized system of AM grafting to investigate their effect on the mechanical properties of photografted jute yarn. Water absorption and weathering resistance of treated untreated samples (TS₀) were also studied.     

Dendrimer–Palladium Complex Catalyzed Oxidation of Terminal Alkenes to Methyl Ketones

Silica‐supported polyamidoamine (PAMAM) dendrimers with different spacer lengths were prepared. After the introduction of diphenylphosphino groups, complexation to dibenzylidenepalladium(0) gave the desired silica‐supported dendrimer–palladium catalyst complexes G0 to G4‐C2‐Pd. These catalysts showed activity towards the oxidation of terminal alkenes to methyl ketones. A dependence of catalytic activity on the spacer length of the diamine in PAMAM was observed.     

Binding properties of polyamidoamine dendrimers

Dendrimers are globular, hyperbranched polymers possessing a high concentration of surface functional groups and internal cavities. These unique features make them good host molecules for small ligands. To reveal relationships between dendrimer size and its encapsulating properties, the interactions of the fourth and the sixth generations of polyamidoamine dendrimers (PAMAM G4 and PAMAM G6) with a fluorescent dye 1‐anilinonaphthalene‐8‐sulfonate (ANS) were studied. Because ANS is a fluorescent molecule and its fluorescence is very sensitive to changes in its microenvironment, it was possible to use spectrofluorometric methods to evaluate the interactions with dendrimers. A double fluorometric titration method was used to estimate a binding constant and the number of binding centers. There were two types of dendrimer binding centers characterized by different affinity towards ANS. For PAMAM G4, the values of K_b and n for low‐affinity and high‐affinity sites equaled to 2.6 × 10⁵, 0.60 and 3.70 × 10⁶, 0.34, respectively, whereas in the case of PAMAM G6, these values equaled to 1.2 × 10⁵, 76.34 and 1.38 × 10⁶, 22.73. It was observed that the size of the dendrimer had a strong impact on the number of ANS molecules that interacted with dendrimers and their location within the macromolecule. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2036–2040, 2007     

Improvement of physico-mechanical properties of jute yarn by photografting with 3-(trimethoxysilyl) propylmethacrylate

Jute yarns were treated with an alkoxy silane monomer 3-(trimethoxysilyl) propylmethacrylate under UV radiation. The monomer concentration and radiation intensity were optimized with respect to the extent of grafting and mechanical properties of the grafted (silanized) jute yarn. The enhanced tensile strength by 159%, elongation-at-break (237%) and polymer grafting (26.2%) were observed when the yarn was treated at 30 wt% silane in methanol under UV radiation for 30 min. The surfaces of both treated and untreated jute yarns were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-Transform Infrared Spectroscopy (FTIR) and Environmental Scanning Electron Microscopy (ESEM) and it was concluded that the silane reacted or deposited on jute surface as a result of UV radiation. Water uptake and degradation properties of untreated and silanized jute yarn were studied in various conditions such as simulated weathering and in soil containing 25% water. The silanized jute yarn showed lesser water uptake as well as less weight loss and mechanical properties as compared to virgin samples.     

Improved crystallizability and processability of ultra high molecular weight polyethylene modified by poly(amido amine) dendrimers

Ultrahigh molecular weight polyethylene (UHMWPE) is usually difficult to be melt processed due to severe intermolecular entanglement in its melt. In this work, we reported the development of a poly(amido amine) (PAMAM) dendrimer (G1) and its derivatives with different terminal groups which showed promising feasibility for aiding UHMWPE melt processing. The rheological, crystalline, and mechanical properties of the blends were investigated comprehensively. The addition of the dendritic modifiers to the UHMWPE matrix resulted in a significant decrease in melt viscosity, thus an obvious enhancement of the processability. The dynamic analysis of the mechanical properties and rotation‐rheological test indicated a disentanglement effect of the UHMWPE melt molecules was generated by the PAMAM dendrimer (G1) and its derivatives. Furthermore, the PAMAM dendrimer (G1), as an internal lubricant, was uniformly distributed in the UHMWPE matrix. The heteronucleation effect of the PAMAM dendrimer (G1) with its derivatives led to a higher degree of crystallinity, smaller crystallites in the matrix and enhanced tensile strength in the UHMWPE blends. POLYM. ENG. SCI., 57:153–160, 2017. © 2016 Society of Plastics Engineers     

Jute composite with MMA by gamma and UV radiations in the presence of additives

Jute yarns treated with MMA + MeOH solutions were irradiated either with Co‐60 gamma source or with UV radiation. In gamma radiation, polymer loading of MMA (methyl methacrylate) onto jute increased quite substantially, but the strength of the composite decreases sharply after 15% polymer loading. The gamma‐treated jute samples were very brittle. On the other hand, jute yarns irradiated in situ under UV radiation was found to be grafted with MMA. The tensile strength of the UV‐cured jute yarn composite increases with an increase of grafting level, in contrast to the behavior observed with the gamma‐irradiated jute composite samples. The tensile properties of the composites can be further enhanced by the incorporation of certain additives and coadditives into MMA + MeOH solutions. This opens diverse applications for jute materials. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 900–906, 1999     

Effect of alkali and ultraviolet (UV) radiation pretreatment on physical and mechanical properties of 1,6‐hexanediol diacrylate–grafted jute yarn by UV radiation

To improve the physicomechanical properties of jute yarn, grafting with 1,6‐hexanediol diacrylate (HDDA) monomer was performed by a UV radiation technique. A series of HDDA solutions of various concentrations in methanol were prepared. A small quantity of photoinitiator (Darocur‐1664) was also added to HDDA solutions. To optimize the conditions for grafting, the effects of monomer concentration, soaking time, and radiation doses were studied by varying the number of soaking times along with variation of monomer concentrations and UV radiation intensities. The extent of polymer loading and the mechanical properties like tensile strength (TS), elongation at break (Eb), and tensile modulus of both treated and untreated jute were investigated. The highest tensile strength, polymer loading, and modulus were achieved with 5% HDDA concentration, 5 min soaking time, and the 4th pass of UV radiation. This set of conditions was selected as optimum and produced enhanced tensile strength (67%), modulus (108%), and polymer loading (11%) over those of virgin fiber. To further improve the mechanical properties the jute yarns were pretreated with alkali (5% NaOH) solution and after that the alkali‐treated yarn were treated under UV radiation of various intensities. The pretreated samples were grafted with optimized monomer concentration (5% HDDA). Increased properties of alkali + UV‐pretreated and grafted samples such as polymer loading (12%), tensile strength (103%), elongation at break (46%), and modulus (114%) were achieved over those of virgin jute yarn. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 18–24, 2004     

Long jute fiber‐reinforced polypropylene composite: Effects of jute fiber bundle and glass fiber hybridization

Two types of long jute fiber pellet consisting of twisted‐jute yarn (LFT‐JF/PP) and untwisted‐jute yarn (UT‐JF/PP) pellets are used to prepare jute fiber–reinforced polypropylene (JF/PP) composites. The mechanical properties of both long fiber composites are compared with that of re‐pelletized pellet (RP‐JF/PP) of LFT‐JF/PP pellet, which is re‐compounded by extrusion compounding. High stiffness and high impact strength of JF/PP composites are as a result of using long fiber. However, the longer fiber bundle consequently affects the distribution of jute fiber. The incorporation of 10 wt % glass fibers is found to improve mechanical properties of JF/PP composites. Increasing mechanical properties of hybrid composites is dependent on the type of JF/PP pellets, which directly affect the fiber length and fiber orientation of glass fiber within hybrid composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41819.     

树状分子PAMAM接枝改性纳米SiO2与尼龙6的原位复合

将树状分子PAMAM接枝改性的纳米Si02与尼龙6进行原位复合，测试了复合材料的各项性能，对树状分子改性无机纳米粒子进行了初步的探索。结果表明：PAMAM接枝改性纳米SiO2可以提高尼龙6的强度、刚性和非等温结晶能力，但材料的韧性在接枝PAMAM代数较高的情况下趋于降低，同时，基体的摩尔质量显著下降。     

酯端基型聚酰胺胺树形高分子对聚(3-羟基丁酸戊酸共聚酯)结晶性能的影响

采用不同比例G3.5酯端基类型的聚酰胺胺(PAMAM)树形高分子氯仿溶液与聚(3-羟基丁酸酯-co-3-羟基戊酸酯)(PHBV)树脂氯仿溶液进行共混并流延成膜,采用差示扫描量热分析、偏光显微镜以及拉伸和直角撕裂等方式对制备的PHBV/PAMAM复合膜进行表征。结果表明,随着PAMAM树形高分子的加入,PHBV/PAMAM复合膜的玻璃化转变温度（Tg）越来越明显,初步表明其韧性增强; G3.5 PAMAM树形高分子的加入,可使PHBV的结晶度由61.70 %先下降至24.02 %,并逐渐下降,最后至结晶消失; PAMAM树形高分子的加入可使PHBV的直角撕裂强度大幅度提高,最高可由8.90 kN/m提高到22.10 kN/m;当PAMAM树形高分子含量为2.0份时,增韧效果最好。     

Synthesis and characterization of stearyl‐group‐terminated dendrimers and thermosensitivity of their toluene solutions

Stearyl‐group‐terminated poly(ester amide) dendrimers [PEAD (R)₃ and PEAD (R)₈] and a poly(amino amide) dendrimer [PAMAM (R)₄] were synthesized by the amidation of three, eight, and four terminated primary amino groups in poly(ester amine) dendrimers and a poly(amino amide) dendrimer with stearyl chloride. The dendrimer structures were characterized with IR and elemental analysis. The toluene solutions of the stearyl‐group‐terminated dendrimers were thermosensitive. Not only did gels form in PEAD (R)₃–, PEAD (R)₈–, and PAMAM (R)₄–toluene solutions below 57.5, 60, and 49°C, respectively, but the content of toluene in the gels depended on the temperature, and a break existed at about 30°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 341–346, 2005     

PAMAM树状大分子在水处理中的应用研究进展

PAMAM树状大分子具有特殊结构与性能,应用于水处理中,具有无毒和高效的特点。本文综述了PAMAM树状大分子在含重金属离子废水、染料废水、高硅水等水处理中的应用研究。PAMAM树状大分子在水处理中的处理效果受溶液的pH值、作用时间、树状大分子的代数等因素的影响,且在含重金属离子废水处理中可再生。最后探讨了PAMAM树状大分子在水处理应用中存在的问题,预测未来将通过改性PAMAM树状大分子或合成新树状大分子扩大其在水处理中的应用范围。     

Gadolinium‐conjugated FA‐PEG‐PAMAM‐COOH nanoparticles as potential tumor‐targeted circulation‐prolonged macromolecular MRI contrast agents

The aim of research is to develop potential tumor‐targeted circulation‐prolonged macromolecular magnetic resonance imaging (MRI) contrast agents without the use of low molecular gadolinium (Gd) ligands. The contrast agents were based on polymer–metal complex nanoparticles with controllable particle size to achieve the active and passive tumor‐targeted potential. In particular, poly (amidoamine) (PAMAM) dendrimer with 32 carboxylic groups was modified with folate‐conjugated poly (ethyleneglycol) amine (FA‐PEG‐NH₂, M_w: 2 k and 4 kDa). FA‐PEG‐PAMAM‐Gd macromolecular MRI contrast agents were prepared by the complex reaction between the carboxylic groups in PAMAM and GdCl₃. The structure of FA‐PEG‐PAMAM‐COOH was confirmed by nuclear magnetic resonance (¹H‐NMR), Fourier transform infrared (FTIR) spectra, and electrospray ionization mass spectra (ESI‐MS). The mass percentage content of Gd (III) in FA‐PEG‐PAMAM‐Gd was measured by inductively coupled plasma‐atomic emission spectrometer (ICP‐AES). The sizes of these nanoparticles were about 70 nm measured by transmission electron microscopy, suggestion of their passive targeting potential to tumor tissue. In comparison with clinically available small molecular Gadopentetate dimeglumine, FA‐PEG‐PAMAM‐Gd showed comparable cytotoxicity and higher relaxation rate, suggestion of their great potential as tumor‐targeted nanosized macromolecular MRI contrast agents due to the overexpressed FA receptor in human tumor cell surfaces. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of CaCO3/polymer composite films via interaction of anionic starburst dendrimer with poly(ethylenimine)

Summary The CaCO₃/poly(ethylenimine) composite film was obtained in the presence of anionic poly(amidoamine) (PAMAM) dendrimer (G=3.5), whereas the formation of composite film was not observed without PAMAM dendrimer or with PAMAM dendrimer (G=1.5) judging from the results of scanning electron micrographs (SEM). The crystal phase of the CaCO₃ film formed was found to be calcite by FT-IR and XRD analysis. The adsorption of PAMAM dendrimer on poly(ethylenimine) film might cause local high concentration of calcium ion and induce a formation of the CaCO₃ film. Received: 23 October 2000/Accepted: 10 November 2000     

Spectroelectrochemical analysis of ion-transfer and adsorption of the PAMAM dendrimer at a polarized liquid|liquid interface

The interfacial behavior of the fourth generation polyamidoamine (G4 PAMAM) dendrimer at a water|1,2-dichloroethane (DCE) interface was studied by cyclic voltammetry and potential modulated fluorescence (PMF) spectroscopy. Irregular voltammetric responses were observed at positively polarized interfaces. The cyclic voltammogram was strongly dependent on pH and on the concentrations of the G4 PAMAM dendrimer and the organic supporting electrolyte. PMF spectroscopy was successfully used to analyze the interfacial mechanism of the dendrimer by adding an anionic porphyrin derivative as a fluorescent probe. The results of the PMF measurements demonstrated that the G4 PAMAM dendrimer was transferred across the interface, a process that was accompanied by an adsorption step at pH 7. In contrast, under alkaline conditions, the adsorption process did not seem to be involved in the interfacial behavior.     

Effect of dendrimer‐like PAMAM grafted attapulgite on the microstructure and morphology of Nylon‐6

The effect of dendrimer‐like polyamidoamine grafted attapulgite (ATP‐PAMAM) on the microstructure and morphology of Nylon‐6 (PA6) was investigated. The ATP‐PAMAM nanoparticles were prepared by treating attapulgite (ATP) with heat and acid followed by grafting with polyamidoamine (PAMAM) molecules, which was confirmed by Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and dispersion state in formic acid. The X‐ray diffraction (XRD) analysis result indicated that the grafting modification was occurred on the surface of fibrous crystals and did not shift the crystal structure of ATP. PA6/ATP‐PAMAM (G_2.0) nanocomposites with different modified ATP content were prepared by melt compounding in a twin screw extruder. XRD measurements suggested that the intensity of diffraction peak of α crystalline form of PA6 decreased gradually as the inclusion of ATP‐PAMAM(G_2.0) into the PA6 matrix, while that of γ crystalline form increased gradually. The results of molau experiment and scanning electron microscopy (SEM) observation showed not only a uniform dispersion of ATP‐PAMAM(G_2.0) in the PA6 matrix but also a strong interfacial adhesion between them. Mechanical investigation (by tensile test) showed an obvious improvement in the presence of surface modified ATP. POLYM. COMPOS., 35:627–635, 2014. © 2013 Society of Plastics Engineers