Vikas Mittal  Gisha E. Luckachan  Boril Chernev  Nadejda B. Matsko 《Polymer Engineering and Science》2015,55(4):877-888

Biodegradable polyesters poly‐l ‐lactide (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) were reinforced with varying amount of date seed powder (DSP) with an aim to utilize the date seed waste as well as to achieve composites with improved properties. The PLA composites exhibited increase in the elastic response over the viscous response as a function of filler fraction, whereas the PBAT composites retained the viscous dominance irrespective of DSP content. The tensile modulus of the PBAT composites had enhancement of more than 300% in the composite with 40% filler content. The PLA composites also enhanced the modulus marginally till 20% filler content, however, it was still significant because of the very high modulus of PLA as compared to PBAT. Thermal analysis also indicated the stability of the composite, thus, confirming the usefulness of DSP as filler for the polymers. The TEM and light microscopy characterization revealed presence of voids in the composites which were present around the filler particles as well as dispersed in the polymer matrix. Such features were confirmed through TGA‐MS to be resulting from the escape of water vapor bound in DSP. The composites with 10% DSP content had lower extent of such voids and the morphology remained relatively unchanged with time. In the composites with 30% DSP content, in the seasoned sample, a soft and sticky phase resulting from the surface migration of date seed oil was also observed. The generation of the soft phase was also a slow process as 24 h were not enough to generate this phase. The migration of the oil to the surface was also confirmed by the IR and X‐ray diffraction studies. After embedding in compost soil, the PLA composite with 40% filler content had nine times more biodegradation after 120 days as compared to pure polymer, whereas it was 11 times for PBAT composite with same filler content. It confirmed that the addition of DSP did not lead to any thermal and mechanical degradation of the bio‐polyesters and resulted in enhanced mechanical and biodegradation behavior along with oil migration. The controlled component migration can lead to potential generation of commercially important self‐lubricating composite materials. POLYM. ENG. SCI., 55:877–888, 2015. © 2014 Society of Plastics Engineers  相似文献   

    

Pawan Kaur  Rajesh Thakur  Manju Barnela  Meenu Chopra  Anju Manuja  Ashok Chaudhury 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2015,90(5):867-873

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Vikas Mittal 《大分子材料与工程》2014,299(8):906-931

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Jasaswini Tripathy  Ashok M. Raichur 《应用聚合物科学杂志》2013,127(3):1609-1614

We report the encapsulation of optical brightening agent (OBA) into hollow microcapsules prepared by the controlled Layer‐ by‐Layer (LbL) self‐assembly process, achieved by the sequential adsorption of oppositely charged polyelectrolytes using negatively charged silica template. Loading takes place by spontaneous deposition method which was proved by confocal laser scanning microscopy (CLSM) using rhodamine 6G (Rd6G) as a fluorescent probe. The loading of the OBA into the microcapsules was found to be dependent on the feeding concentration, pH of the medium, and loading temperature. The encapsulation efficiency of OBA decreased on increasing feeding concentration. Maximum loading was observed at pH 4 and amount of OBA loaded decreased with increase in pH. The loaded OBA was released in a sustained manner for 8 h. No degradation of the OBA was observed during the process of encapsulation and release. Polyelectrolyte capsules potentially offer an innovative way of encapsulating large amounts of active materials for a variety of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

    

Mahesh Hosur  Rajib Barua  Shaik Zainuddin  Ashok Kumar  Jonathan Trovillion  Shaik Jeelani 《应用聚合物科学杂志》2013,127(6):4211-4224

The aim of this study is to investigate the optimum technique to disperse Multi‐Walled Carbon Nanotubes (MWCNTs) in SC‐1 epoxy uniformly and to evaluate the effect of processing technique on the performance of SC‐1 epoxy. To achieve better dispersion, MWCNT was mixed with SC‐1 resin directly or premixed with a solvent and then mixed with SC‐1 resin after evaporating the solvent using sonication, thinky mixing and three‐roll mill methods either in isolation or combination. Flexural tests were performed to evaluate mechanical performances and results exhibit up to 27.13, 13.51, and 21.99% improvement on flexural strength, flexural modulus, and maximum strain, respectively, over neat epoxy with only 0.2 wt % loading. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) indicated improvement in storage modulus, T_g, inflection temperature, and residue content, respectively over neat SC‐1 epoxy. Thermal and mechanical properties at higher loading conditions were seen to either reduce or not significantly improve. This was attributed to high viscosity of nanocomposites as determined by rheological analysis which prevents good dispersion of MWNCTs into epoxy system at 0.4 wt % loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

    

Sujata Pramanik  Niranjan Karak  Somik Banerjee  Ashok Kumar 《应用聚合物科学杂志》2012,126(3):830-836

The changes of structure and properties of nanofibers were studied as a function of solubility parameters of the organic solvents that are used in interfacial polymerization of polyaniline (PAni) nanofibers. The presence of UV–visible absorbance at 340, 440, and 800 nm confirmed the formation of emeraldine salt structure of the prepared PAni nanofibers. Fourier transform infrared spectral results indicate an increasing trend of benzenoid to quinoid ratio with the decrease of interaction of the solvents with aniline. This can be correlated to the increase in the degree of conjugation of the polymer chain. Photoluminescence study revealed an increase in the density of defect state with the decrease of interaction. Single‐line approximation technique was used to analyze the broadening of the most intense X‐ray reflection peak corresponding to (110) plane of the nanofibers. The greater the solvent–monomer interaction, the lesser was the domain length and π‐stacking of the PAni chains. The study of this interaction is instrumental to precisely control the internal conformation of the PAni nanofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

    

Saheli Roy  Suneel Kumar Srivastava  Jürgen Pionteck  Vikas Mittal 《大分子材料与工程》2015,300(3):346-357

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Suresh P Deshmukh  Mahindra B Parmar  Ashok C Rao  Varinder Wadhwa 《Coloration Technology》2010,126(4):189-193

Over the past few decades, masterbatch production has been increasing year by year. Pigments are used primarily in masterbatches because of their ability to impart colour or opacity to a matrix. The effectiveness of pigments depends not only on their intrinsic ability to absorb or scatter light, but also, importantly, on the dispersiblity and distribution of the pigments that can be achieved in plastics. Nowadays, stringent environmental as well as excellent quality controls are making inevitable the use of non‐dusty monoconcentrated predispersed pigments for the production of masterbatches for the colouring of plastics. Commercially, for the most part, two types of monoconcentrated predispersed pigments are being used for the colouring of thermoplastic masterbatches. These are polymer‐ and wax‐based predispersed pigments. This study has been undertaken to provide a comparison of the colouring properties of polymer‐ and wax‐based monoconcentrated predispersed pigments. Four commercially used organic pigments have been selected. Both types of monoconcentrate predispersed pigments have been developed on a co‐rotating twin‐screw compounding extruder with a length/diameter ratio of 44. A detailed analysis on the comparison of the colouring properties is presented. Results indicate that good colour properties are achieved when operating conditions are optimised.  相似文献   

    

Ritesh Gupta;Gaurav Mittal;Gajendra Kumar Nhaichaniya;Krishna Kumar;Upender Pandel; 《应用聚合物科学杂志》2024,141(46):e56233

The research conducts a comparative analysis of epoxy/bi-directional (twill) carbon fiber three-phase shape memory hybrid composites modified with MWCNT and GnP, examining their mechanical, thermomechanical, and shape memory properties. Fabrication involves preparing nanoparticle-modified epoxy nanocomposites through ultrasonication followed by hand layup technique. The findings revealed that the modified composites achieved their optimal performance at a 0.6 wt% concentration of nanoparticle, with the tensile strength and modulus increasing by 33.59% and 23.47% for 0.6 wt% MWCNT composite and by 45.94% and 25.61% for 0.6 wt% GnP composite. GnP-modified composites outperformed MWCNT ones due to GnP's sheet structure aligning parallel to the load and larger surface area facilitating enhanced interaction with the matrix. Despite polymer modification, the shape recovery ratio values remained high, with 98.92% for unmodified composite, 97.72% for 0.6 wt% MWCNT composites, and 97.12% for 0.6 wt% GnP modified composites, all exceeding 90%, indicating no compromise in performance.  相似文献   

    

Neeraj Mittal  Gurpreet Kaur 《应用聚合物科学杂志》2014,131(2)

Designing a drug delivery system to target the eye is an interesting and challenging endeavor faced by scientists because of the critical and pharmacokinetically‐specific environment that exists in the eye. Topical administration of ophthalmic drugs is used to alleviate the symptoms and signs caused by ocular surface inflammatory disorders, to treat infections, for glaucoma or intraocular inflammation (uveitis). However, the responsiveness toward the conventionally developed drug delivery system is limited because of the presence of several types of barriers in the eye that impede the effective passage of many drugs leading to minimal dose absorption. Ion activated in situ gelling ocular systems undergo phase transition in the presence of cations (present in the tear fluid), thus enhancing the residence time of drug in the cornea. In the present study natural polysaccharides (pectin alone or in combination with sodium alginate) or a pectin derivative (thiolated pectin [TP] alone or in combination with sodium alginate) were used to formulate in situ gelling eye drops. The formulations were evaluated for their gelling capacity, rheological studies, spreadability, bioadhesion strength, and in vitro drug release. Thiolation of pectin was observed to result in an increase in the gelling behavior, viscosity, and bioadhesive strength. The formulations comprising pectin alone (P₇), combination of pectin and sodium alginate (P₅SA₁) or TP₆ demonstrated good in vitro release characteristics. The optimized formulations displayed a significant decrease in the intraocular pressure as compared to the marketed formulation upon instillation in rabbit eye. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39788.  相似文献