Lignin and Xylan as interface engineering additives for improved environmental durability of sustainable cellulose nanopapers

Cellulose materials and products are frequently affected by environmental factors such as light, temperature, and humidity. Simulated UV irradiation, heat, and moisture exposure were comprehensively used to characterize changes in cellulose nanopaper (NP) tensile properties. For the preparation of NP, high-purity cellulose from old, unused filter paper waste was used. Lignin and xylan were used as sustainable green interface engineering modifiers for NP due to their structural compatibility, low price, nontoxic nature, and abundance as a by-product of biomass processing, as well as their ability to protect cellulose fibers from UV irradiation. Nanofibrillated cellulose (NFC) suspension was obtained by microfluidizing cellulose suspension, and NP was produced by casting films from water suspensions. The use of filler from 1 to 30 wt% significantly altered NP properties. All nanopapers were tested for their sensitivity to water humidity, which reduced mechanical properties from 10 to 40% depending on the saturation level. Xylan addition showed a significant increase in the specific elastic modulus and specific strength by 1.4- and 2.8-fold, respectively. Xylan-containing NPs had remarkable resistance to UV irradiation, retaining 50 to 90% of their initial properties. Lignin-modified NPs resulted in a decreased mechanical performance due to the particle structure of the filler and the agglomeration process, but it was compensated by good property retention and enhanced elongation. The UV oxidation process of the NP interface was studied with UV-Vis and FTIR spectroscopy, which showed that the degradation of lignin and xylan preserves a cellulose fiber structure. Scanning electron microscopy images revealed the structural formation of the interface and supplemented understanding of UV aging impact on the surface and penetration depth in the cross-section. The ability to overcome premature aging in environmental factors can significantly benefit the wide adaption of NP in food packaging and functional applications

Highly loaded cellulose/poly (butylene succinate) sustainable composites for woody-like advanced materials application

We report the manufacturing and characterization of poly (butylene succinate) (PBS) and micro cellulose (MCC) woody-like composites. These composites can be applied as a sustainable woody-like composite alternative to conventional fossil polymer-based wood-plastic composites (WPC). The PBS/MCC composites were prepared by using a melt blending of 70 wt% of MCC processed from bleached softwood. MCC was modified to enhance dispersion and compatibility by way of carbodiimide (CDI), polyhydroxy amides (PHA), alkyl ester (EST), (3-Aminopropyl) trimethoxysilane (APTMS), maleic acid anhydride (MAH), and polymeric diphenylmethane diisocyanate (PMDI). The addition of filler into PBS led to a 4.5-fold improvement of Young’s modulus E for the MCC composite, in comparison to neat PBS. The 1.6-fold increase of E was obtained for CDI modified composition in comparison to the unmodified MCC composite. At room temperature, the storage modulus E′ was found to improve by almost 4-fold for the APTMS composite. The EST composite showed a pronounced enhancement in viscoelasticity properties due to the introduction of flexible long alkyl chains in comparison to other compositions. The glass transition temperature was directly affected by the composition and its value was −15 °C for PBS, −30 °C for EST, and −10 °C for MAH composites. FTIR indicated the generation of strong bonding between the polymer and cellulose components in the composite. Scanning electron microscopy analysis evidenced the agglomeration of the MCC in the PBS/MCC composites. PMDI, APTMS, and CDI composites were characterized by the uniform dispersion of MCC particles and a decrease of polymer crystallinity. MCC chemical modification induced the enhancement of the thermal stability of MCC composites

Organization of electronic commerce in Latvia.

Darba tēma – „Elektroniskās komercijas organizēšana Latvijā” izvēlēta, lai veiktu pētījumu par elektroniskās komercijas organizēšanu balstoties uz Latvijas interneta veikalu darbību, konstatētu priekšrocības un trūkumus šajā jomā, ka arī izstrādātu rekomendācijas Interneta veikalu marketinga darbības pilnveidošanai. Bakalaura darba pirmajā nodaļā tiek analizēts elektroniskās komercijas jēdziens, veidi un elektroniskās komercijas attīstība un to ietekmējošie faktori Latvijā. Otrajā nodaļā tiek veikta interneta veikalu kā elektroniskas komercijas veida darbības analīze: Latvijas interneta veikalu tirgus, interneta veikalu norēķinu sistēma un interneta veikalu darbības negatīvās puses, veidojot attiecības ar klientiem. Savukārt bakalaura darba pēdējā, trešajā nodaļā tiek noskaidroti Interneta veikalu virzīšanas pasākumi timeklī. Bakalaura darbā tiek izmantoti specializētā Latvijas un Eiropas ekonomistu, marketologu un menedžeru darbi informācijas tehnoloģijas vadībā, likumdošanas normatīvie akti, preses apskats, Valsts statistikas dati un interneta apskats. Bakalaura darbs sastāv no ievada, 3 sadaļām, secinājumiem, priekšlikumiem, izmantotās literatūras saraksta un pielikumiem. Bakalaura darbs satur: 72 lpp. (bez pielikumiem), 7 tabulas, 14 attēlus un 8 pielikumus.Topic of the work - „Organization of the electronic commerce in Latvia” is selected to research organization of the electronic commerce considering to Latvia internet shops, then establish its advantages and lacks, and also prepare recommendations to improve marketing strategy of the Internet shops. In the first chapter of the bachelor work electronic commerce is defined, its development stages and characteristics are discussed. In the second chapter, the internet shop is analyzed as a kind of an electronic commerce action: Latvia market of the internet shops, payment system of the internet shops and negative halves of the internet shops during contacts its clients. In the third chapter of the work promotion of the internet shops into the web and searching engines is discussed. In are bachelor work literature of the Latvia and European information technology field economist, marketing specialists and managers, the legislation normative acts, press reviews, data of State statistics and internet reviews are used . Bachelor work has introduction, three chapters, conclusions, proposals, literature list and appendixes. Bachelor work contains: 72 p. (without appendixes), 7 tables, 14 images and 8 appendixes

Organization of electronic commerce in Latvia

Darba tēma „Elektroniskās komercijas organizēšana Latvijā” izvēlēta, lai veiktu pētījumu par elektroniskās komercijas organizēšanu, balstoties uz Latvijas interneta veikalu darbību, konstatētu priekšrocības un trūkumus šajā jomā, kā arī izstrādātu rekomendācijas interneta veikalu mārketinga darbības pilnveidošanai. Maģistra darba pirmajā nodaļā analizēts: elektroniskās komercijas jēdziens un veidi un elektroniskās komercijas attīstība un to ietekmējošie faktori Latvijā. Otrajā nodaļā veikta interneta veikalu kā elektroniskās komercijas veida darbības analīze. Trešajā nodaļā noskaidroti interneta veikalu virzīšanas pasākumi tīmeklī. Maģistra darbs satur: 115 lpp. (bez pielikumiem), 10 tabulas, 18 attēlus un 14 pielikumus.The topic "E-commerce organization in Latvia” was chosen to carry out a study on e-commerce organization based on the Latvian Internet store operations, to identify strengths and weaknesses in this area and to develop recommendations to improve the operation for an internet store marketing. In the first chapter of Master thesis the e-commerce concept and types of e-commerce system are analyzed. In the second chapter analysis of online shop e-commerce functionality for Latvian online store market are done. The third chapter online store discusses promotion activities in the internet. Master's thesis includes: p.115 (without attachments), 10 tables, 18 pictures and 14 appendices

Polietilēna oksīda gēlu pagatavošana un izpēte

Darbā iegūti polietilēna oksīda (PEO) gēli, izmantojot ķīmiskās šķērssaistīšanas metodi. Pētīta šķērssaistīšanas aģenta koncentrācijas un nanodaļiņu pievienošanas ietekme uz gēlu uzbriešanas pakāpi, difūzijas koeficientu, gēla frakciju un gēla režģu struktūru, kā arī dielektriskajām īpašībām. Literatūras apskatā apkopota informācija par PEO, gēlu iegūšanas metodēm, superabsorbentiem un nanokompozītu gēliem. Literatūra apkopota par laika periodu no 1990. līdz 2013. gadam

Polipropilēna – titāna dioksīda daļiņu nanokompozītu izpēte

Darbā apskatīti polipropilēns, titāna dioksīds, to īpašības un struktūra, kā arī polipropilēna nanokompozītu iegūšana. Pētījumā ir iegūti un izpētīti PP/TiO2 nanokompozīti, noteikta izturība pret UV starojumu