دانلود رایگان مقاله لاتین پلی استر باکتریایی از سایت الزویر
عنوان فارسی مقاله:
تقویت کننده خواص پلی استر باکتریایی با نانوبلورهای سلولز مختلف از طریق تغییر پیوند هیدروژنی
عنوان انگلیسی مقاله:
Reinforcing properties of bacterial polyester with different cellulose nanocrystals via modulating hydrogen bonds
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
It is well known that uses of conventional non-biodegradable materials (especially food packaging) will cause harmful effects on environment, thus there is a growing interest in developing fully biodegradable polymer based nanocomposites (as biopackagings), especially cellulose nanoparticles (CNPs)-reinforced nanocomposites. With only a small amount of nanofiller addition, mechanical or/and thermal properties of polymer matrix are improved substantially [1e5]. For fully biodegradable nanocomposites, researchers believe that the outstanding and effective polymer reinforcement by CNPs is mainly attributed to strong intermolecular hydrogen bonds between OeH groups of CNPs and C]O groups of biodegradable polyester [poly(3ehydroxybutyrateecoe3ehydroxyvalerate) (PHBV) [6e12], polylactic acid (PLA) [13e15], polycaprolactone (PCL) [16e18]. Many studies have reported that good dispersion of CNPs in polymer matrix was bene- ficial to form more hydrogen bonding interactions between them, but relationship between surface functional groups of CNPs and hydrogen bonding interactions in nanocomposites was not clear. Recently, many attempts have been made to explain the reinforcing effect of CNPs on PHBV matrix. Ten et al. found that formation of more hydrogen bonding interactions and nucleating effect of CNPs on PHBV were responsible for significant improvement in mechanical property [10e12]. They found that solutioncast nanocomposites showed better mechanical properties than those of melt-processed nanocomposites due to severe CNP agglomeration. Although polyethylene glycol as a compatibilizer can improve the CNPs dispersion in PHBV matrix, it would restrict the formation of hydrogen bonding interactions between nano- fillers and matrix, resulting to a reduction of thermal stability [10,11]. Our study on this nanocomposite system also indicated thatat the same loading levels, the well-dispersed cellulose nanocrystals (CN) with sulfate groups (CNeS) show weaker reinforcing effects on PHBV than that of HCl-hydrolyzed CN (CNeH). By introduction 10 wt % CNeS or CNeH, tensile strength for 10% CNeS/ PHBV was improved by 149% while, the tensile strength for 10% CNeH/PHBV was increased greatly by 166% [8]. The improvement in CNeH/PHBV might be attributed to more hydroxyl groups (without substituted sulfate groups) for forming more hydrogen bonds (supported by larger hydrogen bond fraction value of 0.41 than 0.47 for 10% CNeS/PHBV) [8]. When PHBV chains were grafting on the CNs to improve their dispersion within PHBV matrix, but a decrease in increment magnitude of mechanical properties for the nanocomposite was found as compared to PHBV nanocomposites reinforced by unmodified CNs, which was attributed to decreased amounts of hydroxyl groups and resultant hydrogen bonds [6]. Besides, the graft polymerization of CN needs more complicated processes. It has been known that enhancements in the mechanical and thermal performances of biopolymer based nanocomposites can be tailored by interactions between CN functional groups and biopolymer groups. Especially, the more hydroxyl groups of CNs have, the more hydrogen bonds between nanofillers and matrix form [5e18]. Nevertheless, to the best of our knowledge, structural design of cellulose nanocrystals for modulating the formation of hydrogen bonds in nanocomposites is still poorly investigated. Therefore, the aim of this work is to endow CNs with different number of hydroxyl groups via HCOOH/HCl and C6H8O7/HCl hydrolysis of commercial microcrystalline cellulose (MCC) according to previously described method in our literature [19e21]. In order to evaluate the impact of hydrogen bonding interactions on properties of PHBV nanocomposites, CN samples with different amounts of hydroxyl groups were prepared. Bionanocomposites composed of unmodified CN, cellulose nanocrystal formates (CNeF) and cellulose nanocrystal citrates (CNeC), in a PHBV matrix were produced via simple solution casting. The microscopic structure as well as mechanical, thermal, barrier and migration properties of the nanocomposites were systematically investigated to elucidate the relationship between hydrogen bonding interactions and macroscopic performance reinforcements and thus shed some light on a fast ongoing field of high-performance food biopackagings.
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کلمات کلیدی:
Materials | Free Full-Text | Cellulose Nanocrystal Membranes as ... www.mdpi.com/1996-1944/9/12/1002/htm by AM Barbosa - 2016 - Cited by 2 - Related articles Dec 12, 2016 - In this work, cellulose nanocrystals (CNCs) were obtained from flax ... The effects of different CHX dosages on the antibacterial activity of the ... Simultaneous improvement of mechanical properties and ... - Agris agris.fao.org/agris-search/search.do?recordID=US201600051079 by HY Yu - 2012 - Cited by 59 - Related articles Related information in other data sources ... improvement of mechanical properties and thermal stability of bacterial polyester by cellulose nanocrystals [2012]. Polysaccharide-Based Nanocrystals: Chemistry and Applications https://books.google.com/books?isbn=3527336192 Jin Huang, Peter R. Chang, Alain Dufresne - 2015 - Science Lin, S. (2012) Acetylated modification of cellulose nanocrystals. ... of mechanical properties and thermal stability of bacterial polyester by cellulose nanocrystals. Reinforcing properties of bacterial polyester with different cellulose ... https://www.infona.pl/.../bwmeta1.element.elsevier-16acc673-f1a3-3a79-a567-6f4ed763... by HY Yu - 2016 - Cited by 3 - Related articles Then different nanocrystals were incorporated into bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) for tuning hydrogen bonding ... Simultaneous Improvement of Mechanical Properties and ... - NCBI https://www.ncbi.nlm.nih.gov/labs/articles/24750888/ Apr 30, 2012 - Abstract. Green nanocomposites were prepared by adding well-dispersed cellulose nanocrystals (CNCs) into bacterial polyester ... Searches related to bacterial polyester with different cellulose nanocrystals nanocellulose tunicate
