Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders

Composites based on polymers with conductive fillers have been gaining more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of chosen materials can be directly used as contemporary materials by electrochemical methods. This article is concerned with the preparation characterization of the basic components: electrodeposited copper powder and lignocellulose as well as composite materials prepared by the compression molding of lignocellulose and galvanostatically obtained copper powder mixtures. Analysis of the most significant properties of individual components and prepared composites included quantitative structural analysis, morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, TGA, DSC, X-ray, FTIR, particle size distribution and conductivity measurements were used. The electrical conductivity of the composites is LT 10(-15) MS/m, unless the metal content reaches the percolation threshold of 14.4% (v/v), beyond which the conductivity increases markedly by as much as 14 orders of magnitude. It was found that this transition occurs at lower volume fractions than stated in the literature which can be due to the filler with high specific area

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders. Part II. Influence of Particle Size on Percolation Threshold

This article is concerned with synthesis and characterization of electroconductive composite materials prepared by the compression molding of mixtures of lignocellulose and electrochemically deposited copper powder under different pressures, and investigation of the influence of particle size on conductivity and percolation threshold of obtained composites. Electrodeposited copper powder content was varied from 2.0-29.8 vol%. Analysis of the most significant properties of individual components and prepared composites included structural and morphological analysis and measurements of hardness and electrical conductivity. Hardness of the investigated composites, as expected, increased with the increase of the processing pressure, as well as lowering the particle size compared to previous work. The significant increase of the electrical conductivity can be observed as the copper powder content reaches the percolation threshold. The packaging effect and more pronounced interpartical contact with smaller, highly porous, highly dendritic particles with high values of specific area lead to "movement" of percolation threshold towards lower filler content, which for the particles LT 45 mu m and highest processing pressure of 27 MPa was 7.2% (v/v). In the investigated range of electrodeposited copper powder concentrations and applied pressures the increase of the electrical conductivity of composites is as much as fourteen orders of magnitude. It was found that this transition occurs at lower volume fractions than stated in the literature which can be due to the filler with high specific area

Influence of Electrolytic Copper Powder Particle Morphology on Electrical Conductivity of Lignocellulose Composites and Formation of Conductive Pathways

Composites based on polymers with conductive fillers have been gaining more significant roles in a variety of technological domains and they are getting in the research focus of numerous studies as a part of growing research trend. Galvanostatically produced copper powder with high values of specific area was used as filler for synthesis of electroconductive composite materials prepared by the compression molding of mixtures of lignocellulose and electrochemically deposited copper powder. This article is concerned with characterization of these composites. Analysis of the most significant properties of prepared composites and its components included measurements of electrical conductivity, impedance spectroscopy (IS) behavior and structural and morphological analysis. Volume fraction of the copper powder was varied from 2.0-29.8% (v/v). The significant increase of the electrical conductivity can be observed as the copper powder content reaches the percolation threshold (PT). It was shown that PT depends on both particle shape and type of spatial distribution. IS measurements have shown that particle morphology having pronounced grain boundaries has great effect on appearance of electric conductive layers. The packaging effect and more pronounced interpartical contact with copper powder particles lead to "movement" of PT, which for the particles LT 45 mu m and highest processing pressure of 27 MPa was 7.2% (v/v). IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite

Elektroprovodni kompozitni materijali na bazi lignoceluloze i bakarnog praha

Natural polymers based on renewable materials with addition of chosen materials can be directly used as contemporary materials by electrochemical methods. This article is concerned with the preparation and characterization of composite materials prepared by the compression molding of mixtures of copper and lignocelluloses (LC) powders. Characterization of the elaborated composites involved analysis and defining of parameters that have the major influence on the electrical conductivity (σ) of the investigated composites. Morphologies of the constituents, filler and matrix as well as prepared composites were investigated. The electrical conductivity of the composites was measured in the function of mass fraction of the copper powder in the composite material. It was determined that the composites show transition conducting region between 50 mass % and 70 mass % of copper, and act as a conductive material with σ ≥ 0.935 MS/m above 70 mass % of copper fraction. Furthermore, significant increase of the electrical conductivity by as much as six orders of magnitude can be observed within the investigated region.Prirodni polimeri nа bаzi obnovljivih sirovinа mogu se elektrohemijskim metodаmа, uz dodаtаk izаbrаnih puniocа direktno koristiti kаo sаvremeni polimerni mаterijаli. U ovom radu su prikazani uslovi dobijanja kompozitnih materijala na bazi različitih smeša bakarnog praha i lignoceluloze (LC) metodom presovanja i njihova karakterizacija. Karakterizacija konstitutenata obuhvatila je analizu i definisanje parametara koji prvenstveno utiču na elektroprovodnost ispitivanih kompozita. Ispitivana je morfologija konstituenta, kao i ispitivanih kompozita. Određena je električna provodljivost (σ) kompozitnih materijala u funkciji masenog udela bakarnog praha. Utvrđeno je da se ispitivani kompoziti sa udelom bakarne frakcije između 50 i 70 mas.%, nalaze u prelaznom provodnom regionu, a kompoziti sa udelom bakarne frakcije iznad 70 mas.% se ponašaju kao provodnici sa σ ≥ 0.935 MS/m. U ispitivanom regionu, provodljivost je značajno povećana, čak i do šest redova veličine

Strukturne karakteristike kompozitnih materijala lignoceluloze i bakra

In recent years, composites based on polymers with conductive fillers have been gaining more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of chosen materials can be directly used as contemporary materials by electrochemical methods. This article is concerned with the characterization of the basic components: copper powder and lignocellulose (LC) as well as composite materials prepared by the compression molding of mixtures with 50-90mass% of copper powder. Analysis of the most significant properties of individual components and prepared composites included morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, TGA, light microscopy and conductivity measurements were used.U novije vreme, kompozitni matirajali bazirani na polimerima sa provodnim puniocima nalaze sve značajniju primenu u brojnim tehnološko-tehničkim oblastima i predmet su istraživačkog fokusa čiji je trend u permanentnoj ekspanziji. Prirodni polimeri na bazi obnovljivih sirovina mogu se elektrohemijskim metodama, uz dodatak izabranih punioca, direktno koristiti kao savremeni polimerni materijali. Prezentovan rad obuhvata deo eksperimntalnih rezultata istraživanja svojstava kompozitnih materijala na bazi bakarnog praha dispergovanog u matrici od linoceluloze (LC), za udeo bakarnog praha u opsegu 50-90 mas.%, dobijenih metodom presovanja. Analiza i karakterizacija najznačajnijih karakteristika konstituenata i ispitivanih kompozita obuhvatila je mikrostrukturna ispitivanja, određivanje gustine i poroznosti kao i merenje elektriþne provodljivosti. U eksperimentalnom delu za analizu i karakterizaciju konstituenata i ispitivanih kompozita korisüene su razliþite eksperimentalne metode: SEM, TGA, optiþka mikroskopija, merenje električne provodljivosti

Struktura i svojstva elektroprovodnih kompozitanih materijala na bazi lignoceluloze i bakarnog praha

Composite materials are gaining ever larger industrial applications in the world. None the less, composites based on polymers with conductive fillers are having more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of electrochemically obtained conductive materials can be directly used as contemporary materials. This article is concerned with the experimental results of the investigation and characterization of the copper powder and lignocellulose (LC) composite materials. The content of copper powder was varied from 2-30 vol%, and the samples were prepared by the compression molding. Analysis and characterization of the most significant properties of individual components and prepared composites included morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, light microscopy and conductivity measurements were used.Kompozitni materijali dobijaju sve veću industrijsku primenu u svetu. Kompoziti bazirani na polimerima sa provodnim puniocima su u novije vreme u širem istraživačkom fokusu pre svega zbog njihovog rastućeg značaja sa gledišta primene. Prirodni polimeri na bazi obnovljivih sirovina mogu se dodatkom elektrohemijski dobijenih provodnih punioca direktno koristiti kao savremeni kompozitni materijali. U ovom radu prikazan je deo eksperimentalnih rezultata istraživanja svojstava kompozitnih materijala na bazi lignocelulozne matrice (LC) i bakarnog praha dobijenog elektrohemijskim putem. Udeo bakarnog praha u ispitnim uzorcima variran je u opsegu od 2-30 vol%, a uzorci su pripremljeni kompaktiranjem-presovanjem. U eksperimentalnom delu za analizu i karakterizaciju polaznih konstituenata i istraživanih kompozita korišćene su različite eksperimentalne metode i tehnike: mikrostrukturna i morfološka analiza vršena je primenom skening elektronske mikroskopije (SEM) i optičke mikroskopije. Određena je veličina i distribucija čestica konstituenata kao i gustina, poroznost i električna provodljivost kompozita u zavisnosti od udela bakarnog praha

Електрична проводљивост лигноцелулозних композита пуњених електролитичким бакарним прахом

This article deals with the synthesis and characterization of electroconductive composite materials prepared by the compression molding of mixtures of lignocellulose and electrochemically deposited copper powder under different pressures, as well as with the investigation of the influence of particle morphology on conductivity and the percolation threshold of obtained composites. Electrodeposited copper powder content varied from 1.9-29.4 vol%. The analysis of the most significant properties of prepared composites and its components included impedance spectroscopy (IS) behavior, the measurements of electrical conductivity, scanning electron microscopy (SEM) and structural analysis. It has been shown that the percolation threshold (PT) depends on both particle shape and the type of spatial distribution. IS measurements and SEM analysis have shown that particles that have pronounced grain boundaries have a bit effect on the appearance of electric conductive pathways thus on the composite conductivity. The packaging effect and more pronounced interparticle contact with copper powder particles lead to the “movement” of PT, which, for the particles <45 μm and the highest processing pressure of 27 MPa, was 7.2% (v/v).У овом раду приказана је синтеза и карактеризација електропроводних композитних материјала на бази лигноцелулoзе и електрохемијски добијеног бакарног праха добијених хладним пресовањем на различитим притисцима, као и испитивање утицаја морфологије праха на проводност и перколациони праг добијених композита. Запремински удео бакарног праха је варирао 1.9−29.4% (v/v). Анализа најзначајнијих особина припремљених композита обухватала је импедансну спектроскопију (IS), скенирајућу електронску микроскопију (SEM), мерења електричне проводности и структурну анализу. Показано је да перколациони праг (PP) зависи како од облика честица тако и од њиховог просторног уређења. IS мерења и SEM анализе су показали да морфологија честица са изражено великом границом зрна има велики утицај на појаву електричних проводних слојева. Ефекат паковања и израженији међучестични контакт са честицама бакарног праха доводи до „померања” PP, који је за честице <45 μm и највеćи притисак од 27 MPa износио 7.2% (v/v)

Electrical Conductivity of Lignocellulose Composites Loaded with Electrodeposited Copper Powders

Composites based on polymers with conductive fillers have been gaining more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of chosen materials can be directly used as contemporary materials by electrochemical methods. This article is concerned with the preparation characterization of the basic components: electrodeposited copper powder and lignocellulose as well as composite materials prepared by the compression molding of lignocellulose and galvanostatically obtained copper powder mixtures. Analysis of the most significant properties of individual components and prepared composites included quantitative structural analysis, morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, TGA, DSC, X-ray, FTIR, particle size distribution and conductivity measurements were used. The electrical conductivity of the composites is LT 10(-15) MS/m, unless the metal content reaches the percolation threshold of 14.4% (v/v), beyond which the conductivity increases markedly by as much as 14 orders of magnitude. It was found that this transition occurs at lower volume fractions than stated in the literature which can be due to the filler with high specific area

Struktura i svojstva elektroprovodnih kompozitanih materijala na bazi lignoceluloze i bakarnog praha

Composite materials are gaining ever larger industrial applications in the world. None the less, composites based on polymers with conductive fillers are having more and more significant roles in a variety of technological domains and are in the research focus of numerous studies as a part of growing research trend. Natural polymers based on renewable materials with addition of electrochemically obtained conductive materials can be directly used as contemporary materials. This article is concerned with the experimental results of the investigation and characterization of the copper powder and lignocellulose (LC) composite materials. The content of copper powder was varied from 2-30 vol%, and the samples were prepared by the compression molding. Analysis and characterization of the most significant properties of individual components and prepared composites included morphological analysis, determination of density and porosity and measurements of electrical conductivity. Different investigation techniques including SEM, light microscopy and conductivity measurements were used.Kompozitni materijali dobijaju sve veću industrijsku primenu u svetu. Kompoziti bazirani na polimerima sa provodnim puniocima su u novije vreme u širem istraživačkom fokusu pre svega zbog njihovog rastućeg značaja sa gledišta primene. Prirodni polimeri na bazi obnovljivih sirovina mogu se dodatkom elektrohemijski dobijenih provodnih punioca direktno koristiti kao savremeni kompozitni materijali. U ovom radu prikazan je deo eksperimentalnih rezultata istraživanja svojstava kompozitnih materijala na bazi lignocelulozne matrice (LC) i bakarnog praha dobijenog elektrohemijskim putem. Udeo bakarnog praha u ispitnim uzorcima variran je u opsegu od 2-30 vol%, a uzorci su pripremljeni kompaktiranjem-presovanjem. U eksperimentalnom delu za analizu i karakterizaciju polaznih konstituenata i istraživanih kompozita korišćene su različite eksperimentalne metode i tehnike: mikrostrukturna i morfološka analiza vršena je primenom skening elektronske mikroskopije (SEM) i optičke mikroskopije. Određena je veličina i distribucija čestica konstituenata kao i gustina, poroznost i električna provodljivost kompozita u zavisnosti od udela bakarnog praha