Simultaneously strong and tough continuous nanofibers for next generation structural supernanocomposites

Modern advanced composites and fibers are strong but brittle. Optimization of damage progression in composites has led only to moderate toughening. The advent of novel nanomaterials such as CNT and graphene has raised hopes for the development of strong and tough structural materials. However, problems with dispersion, alignment, achieving high volume fraction of discontinuous nanoreinforcement, and interfacial stress transfer proved to be more difficult than was initially thought. Recently, a different class of nanomaterials, i.e. continuous nanofibers, has been shown to possess unusual mechanical properties. This presentation will review recent breakthroughs on ultra-high-performance continuous nanofibers and their composites. Controlled nanofiber manufacturing, characterization, and mechanical testing will be discussed. Examples of pioneering high-performance polymer, carbon, and ceramic nanofibers will be presented. Highly ordered 2D/3D macroscopic nanofiber assemblies produced by potentially low-cost integrated (one-step) nanofabrication processes will be reviewed. Unique, recently discovered dramatic simultaneous increases in strength, modulus, and toughness in nanofibers with their diameter decrease will be presented and analyzed for the first time. Unconventional mechanisms of superplasticity in the strong and stiff nanofibers will be elucidated and experimentally verified. Possibilities of further significant improvements in properties by judicial, mechanism-guided control of polymer chemistry and crystalline structure of nanofibers will be demonstrated. Prospects of supertough continuous nanofibers with strength and energy to failure several times higher than the strength and toughness of the best commercial fibers will be demonstrated for the first time. Recent progress on nanofiber-reinforced supernanocomposites (defined by the author as nanocomposites exceeding the properties of conventional advanced composites such as carbon-epoxy) will be also discussed. Finally, possibilities for the ultrastrong and tough continuous nanofibers to enhance or even replace carbon as a new reinforcement for the next generation strong AND TOUGH structural composites will be evaluated

SOCIOETHNIC GROUPS OF LATGALE IN 16-18th CENTURIES ACCORDING TO RĒZEKNE DISTRICT INVENTORY AND SOUL AUDIT DATA

One of the most sustainable constituents of Latgalian culture is historically socioethnic groups. A socioethnic group is a community of residents determined by specific ethnic and historical circumstances and a more or less fixed place in social hierarchy. Until now, few studies have used the written sources dated 1599, 1712, 1738 and 1765 the Rzecpospolita estate Rzezyca (Rēzekne) district country manor inventory, written in Polish, stating the names of the hosts of peasants’ houses which reflects the dynamics of socioethnic group formation. Souls audit legislation written in autumn 1772 in Russian is the oldest source of information related to the relatively wide range of kinds of Latgale population concerning age, place of residence and kinship ties. The inventory by parishes and villages included host names, which made it possible to create an inventory of the names of Latvians living in Latgale, Jewish names, people with Slavic and Old Believers’ specific names, which made it possible to determine the trends of population and ethnic composition. Following a long period of war and political chaos in 1599 Rēzekne district inventory list of seven parishes recorded only 104 farms. The foreign ethnic group indicates the presence of certain non-Latvian peasant family names – Litvil, Hanekenon, Gadpian, which in subsequent documents do not occur. The document recorded seven Latgalian Latvian names of specific locations referred to in later centuries – for example, Kemp in Makašāni (Makaszany) parish, Laizan, Greidan, Stylba, and Spungian. The 1712 inventory recorded 232 village farms. This number after the Great Northern War and pest is considered as relatively high. In the same year, in Krīvāni (Kryvan), Rāzna (Razien) and Osyune (Osyn) parish were listed individuals with Polish surnames – Dukalski, Borkevicz, Lipski, Harasimowicz. For the first time there are some Jewish names listed. 1738 for Latgale is a peaceful and politically stable period. The number of farms has increased to 291. Among these, 34 farms in Krīvāni, Lobuordi (Loborsky), Rāzna and Osyune parishes were inhabited by Poles. Most of them were public service people – the so-called bojary or personally free landowners. There were mentioned only two hosts called moskal – strangers from Russia. It should be noted that in 1712 and 1738 inventories there were mentioned some Latvian landowner families in Nautrani parish: Laizan, Rudborz, and Jurdz. The biggest number of Russian Old Believers was in 1765. In that year, 119 villages with an average of five farms within each already recorded 20 villages inhabited by Russians and Poles. In addition, there were 10 Russian and Latvian mixed populated villages and eight villages populated by Latvians and Poles. Year 1772 souls audit shows that many of the Old Believers have not come from Russia, but from Rzecpospolita territory, modern time Belarus. Souls audit provides information on the crown and 42 private manors. For the first time both sexes and all nationalities are represented in the audit. This source provides a very good opportunity to study the ethnic composition, age and kinship with mathematical methods. Most of the farmers were Latvians. The second largest ethnic group of farmers was Russian Old Believers, the third – the Belarussians. The Russians, the Poles and Latvians inhabited villages and free villages – sloboda. Socially most diverse ethnic group was Poles, among which there were large and small landlords, village residents, farmers, and manor servants. In 34 estates Jews were listed – a socially homogenous and well-organized group. All Jews in Rēzekne district belonged to the Kahal in Kruoslova (Kreslaw), which was a Jewish self-government body with judicial functions. In 3 manors were mentioned Gypsies engaged in agriculture. Social groups in Rēzekne district consisted of three religious and spatially demarcated ethnic groups: Latvians, Russian Old Believers, and Belarussians. All ethnic groups of farmers in year 1772 lived in big families in which three generations lived together – parents, unmarried children and several married children, grandchildren and foster children. The servants mostly were close relatives. Latvian villages were mostly inhabited by one family and the names of these villages were derived from the surname of that family. From 1772 souls audit data it can be inferred that every ethnic group was a closed living space. Latvians, Russians and Belarusians lived in villages and sloboda, Poles – in manors and sloboda, Jews – in manors. Up to the 20th century the living space was maintained as a cultural space. Ethnic group-specific traditions were passed on to future generations. Belonging of a social group to a distinct ethnicity was not a strict criterion. Diversity of ethnic groups is most prominently seen in farmers’ social group

LATGOLYS ETNOSOCIALŪS GRUPU VEIDUOŠONUOS PIEC RĒZEKNIS STARASTEJIS 16.–18. G. S. INVENTARU I DVIESEĻU REVIZEJIS ZIŅOM

Vīns nu nūtureiguokajim Latgolys kūpejuos kulturvidis komponentim ir viesturiski izaveidovušuos socialetniskuos grupys. Pietejumūs leidz šam moz izmontuoti 1590., 1712., 1738. i 1765. goda Rēzeknis starastejis krūņa muižu inventari ar tymūs aizraksteitim saiminīku vuordim i uzskaitis īspiejom, kas labi paruoda etnosocialūs grupu veiduošonuos dinamiku. Savukuort 1772. goda rudinī veiktuos Rēzeknis starastejis dvieseļu revizejis akti ir vacuokais olūts, kurā snāgtys zinis par kuruos naviņ Latgolys plotuokys dalis vysim dzeivuotuojim, jūs vacumu, dzeivis vītom i radnīceibys saitom. Mynātuo olūta informaceja raksturoj jau izaveidovušuos, ilgtspiejeigys etnosocialūs grupu kulturtelpys i jūs strukturu. Piec garūs karu i politiskūs juku perioda 1590. godā Rēzeknis starastejis inventarā septeņūs pogostūs fiksātys tikai 104 saimisteibys. Par sveša etnosa kluotbyutni līcynoj atseviški zemnīku nalatvyskī uzvuordi – Litvils, Hanekenons, Gadpians, kas vāluokūs dokumentūs vaira napasaruoda. Nu latvīšu zemnīku uzvuordu fiksāti septeni, kas konkretajuos vītuos aizraksteiti i vāluokūs godu symtūs – pīmāram, Laizāns, Greidāns, Stylba, Špuņģāns. 1712. goda inventarā fiksātys 232 apdzeivuotys saimisteibys. Itaids skaits piec Zīmeļu kara i Leluo miera pūstejumu viertejams kai augsts. Šymā godā Krīvānu, Rāznys i Osyunis voitistēs aba pogostūs mynātys atseviškys personys ar pūliskim uzvuordim – Dukaļskis, Borkevičs, Lipskis, Harasimovičs. Pyrmūreiz nūsaukts nazcik žeidu – krūgu rentnīki. 1738. godā jau beja pastuojs mīra i politiskuos stabilitatis laiks. Saimisteibu skaits beja pīaudzs da 291. Apmāram 34 saimisteibys Krīvānu, Lobuoržu, Rāznys i Osyuna pogostūs apdzeivuojuši pūli. Jūs leluokuo daļa bejuši vaļsts dīnasts ļauds – tai sauktī Bruņu bojuori ci personiski breivī zemis eipašnīki. Pīmynāti i divi saiminīki ar apzeimiejumu „moskali“. Juoatzeimej, ka 1712. i 1738. godā registrātys ari atseviškys latvīšu leimaņu i zemis eipašnīku saimis: Laizāni, Rudbuorži, Jūrdži. Krīvu staraveru leluoka īceļuošona ir nūtykuse leidz 1765. godam. Itymā godā nu vysu 119 cīmu ar videji pīcom saimisteibom kotrā jau fiksāts 20 krīvu i pūļu apdzeivuotu cīmu. Svešūs etnosu dzeivis vītys koncentrējuos nūteiktuos teritorejuos: pīci krīvu cīmi Rāznys pogostā, ostoni – Cyskoda pogostā. Bez jūs beja vēļ desmit krīvu i latvīšu jaukti apdzeivuotu cīmu. Teirī pūļu – Bruņu bojuoru i zemis eipašnīku cīmi beja septeni Krīvānu pogostā, seši Osyuna pogostā, jaukti pūļu i latvīšu – ostoni cīmi Osyuna, Rāznys i Krīvānu pogostūs. 1772. godā dvieseļu revizejis dokumenti aproksta 42 krūņa i pryvatuos muižys. Kotrā nu jom beja 7–38 cīmi. Leluokuos dzeivis vītys beja seši mīsti i slobodys, storp tim Rēzekne, Varakļuoni, Viļāni, Tiskādu sloboda, Latvīšu Sloboda natuoli nu Tiskādim, Sloboda natuoli nu Osyuna. Vairums dzeivuotuoju beja krīvi i pūli – īguojieji nu Krīvejis, Boltkrīvejis i Reigys. Leluokys pūļu – zemis eipašnīku – grupys aizraksteitys divejuos krūņa muižuos, seikūs šļahtiču grupys – četruos muižuos. Pūli beja sociali vysdaudzveideiguokuo grupa – i lelī muižnīki, i mīstu dzeivuotuoji, i seikī zemis eipašnīki, taipat kolpuotuoji muižuos. Žeidi, kas beja krūgu rentnīki ci tierguotuoji, atrūnami 34 muižuos. Tei beja sociali vysorganizātuokuo etniskuo grupa. Vysi Rēzeknis starastejis žeidi pīdarēja pi Kruoslovys kahala, kas beja jūs pošpuorvaļdis vīneiba ar religiskom, fiskalom i tīsys funkcejom. Žeidim 1772. godā rakstureigys mozuos saimis – pracātais puors i bārni. Rēzeknis starastejis zemnīku socialū grupu veidova treis nūrūbežuotys etniskuos grupys: latvīši, staraveri (krīvi), boltkrīvi. Cīš bīži pi krīvu i boltkrīvu zemnīku vuordim ci cīmu nūsaukumim pīmynāts, ka tī ir īguojieji voi aizbāgušī zemnīki nu Boltkrīvejis ci Krīvejis. Zemnīku cīmūs dzeivova videji 2–10 saiminīki. Vysu etniskūs grupu zemnīkim 1772. godā rakstureigys leluos saimis, kuruos dzeivova treju paaudžu pīdareigī: vacuoki, napracātī bārni, 1–2 pracātūs bārnu puori ar mozbārnim i audžubārnim. Saimē īguoja i bobuļnīki – kolpi, kas struodova par dzeivis vītu. Tikai ratūs gadejumūs tī nabeja saiminīka tyvi radinīki. Kūpumā viertejūt, cīmi beja vīnys dzymtys dzeivis vītys, i jūs nūsaukumi beja identiski ar dzeivuotuoju uzvuordu. 1772. goda dvieseļu revizeja atkluoj kotrys etniskuos grupys nūslāgtu dzeivis telpu pastuoviešonys faktu. Latvīšim, krīvim i boltkrīvim tuos beja atseviški cīmi i slobodys, pūlim – muižys i slobodys, žeidim – muižys. Šuos dzeivis telpys leidz pat 20. godu symtam izaglobuoja i kai kulturtelpys, kuramuos tyka praktizātys i nūdūtys tuoļuok kotram etnosam rakstureiguos tradicejis

METHOD OF FABRICATING A CONTINUOUS NANOFIBER

A method of fabricating a continuous nanofiber is described . The method includes preparing a solution of one or more polymers and one or more solvents and electrospinning the solution by discharging the solution through one or more liquid jets into an electric field to yield one or more continuous nanofibers . The electrospinning process ( i ) highly orients one or more polymer chains in the one or more continuous nanofibers along a fiber axis of the one or more continuous nanofibers , and ( ii ) suppresses polymer crystallization in the one or more continuous nanofibers . The one or more continuous nanofibers can have diameters below about 250 nanometers and exhibit an increase in fiber strength and modulus while maintaining strain at failure , resulting in an increase in fiber toughness

Spinning Continuous Fibers for Nanotechnology

Nanotubes of carbon and other materials are arguably the most fascinating materials playing an important role in nanotechnology today. Their unique mechanical, electronic, and other properties are expected to result in revolutionary new materials and devices. However, these nanomaterials, produced mostly by synthetic bottom-up methods, are discontinuous objects, and this leads to difficulties with their alignment, assembly, and processing into applications. Partly because of this, and despite considerable effort, a viable carbon nanotube–reinforced supernanocomposite is yet to be demonstrated. Advanced continuous fibers produced a revolution in the field of structural materials and composites in the last few decades as a result of their high strength, stiffness, and continuity, which, in turn, meant processing and alignment that were economically feasible. Fiber mechanical properties are known to substantially improve with a decrease in the fiber diameter. Hence, there is a considerable interest in the development of advanced continuous fibers with nanoscale diameters. However, conventional mechanical fiber spinning techniques cannot produce fibers with diameters smaller than about 2 μm robustly. Most commercial fibers are several times that diameter, owing to the trade-offs between the techno¬logical and economic factors

Structural Nanocomposites

Materials scientists predict that composites made with nanoscale reinforcing materials such as nanotubes, platelets, and nanofibers will have exceptional mechanical properties. However, the results obtained so far are disappointing, particularly when compared to advanced composites reinforced with high-performance continuous fibers (1–4). The reasons include inadequate dispersion and alignment of the nanoreinforcement, low nanoreinforcement volume fraction, and poor bonding and load transfer at interfaces. Intensive work is under way, but the prospect of bulk structural supernanocomposites appears more remote now than it did just a few years ago. However, recent work shows that some applications in reinforcement of small structures may have a near-term payoff that can foster longer-term work on nanocomposites. Most of the work on structural nanocomposites has relied on ultrastrong nanoreinforcement such as single- walled carbon nanotubes (SWCNTs) (1–3). However, the high SWCNT strength has not yet translated into bulk strength, and it is not even clear whether such translation is possible: Any attempt to create strong interfacial bonds will introduce defects into the SWCNTs that reduce their intrinsic strength. Still, multifunctional applications not relying solely on the mechanical superproperties will benefit (4, 5). Tailorability and controlled anisotropy are other useful special features of nanocomposites. Multiscale modeling (6) will help us achieve the desired balance between various functions

Analysis of the Effects of the Residual Charge and Gap Size on Electrospun Nanofiber Alignment in a Gap Method

In this paper, the effects of residual charges on nanofiber alignment in a gap method are studied and presented. The gap method was presented by Li and Xia (2003 Nano Lett. 3 1167); in it, a gap is introduced into a traditional collector. Due to the non-perfect conductivity of electrospun nanofibers, they carry residual charges after deposition across the gap. These residual charges will interact with the charges carried by the upcoming jet/fiber, that will also deposit across the gap. The effects of these charge interactions on nanofiber alignment were studied numerically at various gap sizes. Results showed that alignments of nanofibers improve substantially with the gap size increasing from 3 to 8 mm. Numerical studies on the effect of residual charges in already deposited nanofibers on the alignment of nanofibers deposited afterwards were also conducted. Studies showed that the residual charges result in worse alignment, with a 10%–25% decrease in orientation parameters

Antiplane surface acoustic waves propagating in elastic half-space coated with an anisotropic laminate

Dispersion relation of antiplane surface acoustic waves (SAWs) propagating in elastic half-space coated with an anisotropic laminate was determined explicitly by means of Stroh\u27s formalism within the subsonic range, where is no energy leakage into the substrate. During the procedure, the governing dynamic equation in each anisotropic layer and the displacement–traction continuity at interfaces were exactly satisfied by Stroh\u27s functions. Explicit algebraic equation was derived for determining the dispersion relation. As an example, the wave number vs. phase velocity diagram for steel half-space coated with a graphite-fiber/epoxy laminate with a [± 45°/0°2] lay-up was demonstrated. The given method can be used for the study of SAW properties of anisotropic coating systems and non-destructive evaluation based on surface/guided wave methods

Nanofiller Aggregation as Reinforcing Mechanism in Nanocomposites

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