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Wpływ obróbki chemicznej wodnym roztworem Mg(OH)2 na strukturę oraz właściwości wytrzymałościowe włókien juty przeznaczonych do wytwarzania kompozytów polimerowych

Bogdan A., Myalski J., Wieczorek J., Kozioł M.

Kompozyty

2009

R. 9, nr 4

358-362

W ostatnich latach zwrócono szczególną uwagę na materiały przyjazne dla środowiska. W przypadku materiałów kompozytowych zbrojonych włóknem szklanym alternatywę mogą stanowić włókna naturalne, które posiadają wiele zalet, takich jak: niska gęstość, niska cena, dostępność, degradowalność oraz w miarę dobre właściwości wytrzymałościowe. Na właściwości włókien, a tym samym na właściwości gotowego kompozytu, ma wpływ ich budowa oraz udział składników strukturalnych. Wzrost właściwości wytrzymałościowych można uzyskać na drodze modyfikacji powierzchni włókien metodami fizycznymi lub chemicznymi. Praca dotyczy analizy zmian zachodzących w włóknie juty pod wpływem obróbki chemicznej. Wpływ modyfikacji został określony na podstawie zmian wytrzymałości pojedynczego włókna oraz zmian kąta skręcenia włókien w przędzy. W badaniach zastosowano obróbkę chemiczną włókien wodnym roztworem wodorotlenku magnezu o stężeniach 5, 15 i 30%. Włókna przetrzymywano w roztworze od 0,5 do 8 h. Na podstawie uzyskanych wyników stwierdzono, że zastosowana obróbka korzystnie wpływa na właściwości wytrzymałościowe włókien oraz powoduje wzrost ich kąta skręcenia w przędzy. Najlepsze rezultaty uzyskano podczas trawienia włókna 15% roztworem Mg(OH)2 przez 1 h.

Nowadays polymer-matrix composites play essential rule as structural materials, what leads to increase in waste products. Exploitet composite materials create serious problem for natural environment. Environment protection against wasted composites contains an improvement of their removal process. In recent years particular attention is paid to materials friendly for natural environment. In composite materials glass fibers can be replaced by natural fibers because of their advantages such as: low density, low price, good mechanical properties, accessibility and degradation. Properties of natural fibers, and properties of their composites, depend on their structure and volume fraction of structural phase. Increase in mechanical properties of the fibers can be achieved as effect of surface modification. This paper apply to analysis of changes proceeded in jute fiber as effect of chemical treatment. In order to enhance mechanical properties physical and chemical treatment were applied. Physical methods, such as stretching, calandering, thermo-treatment, and the production of hybrid yarns do not change the chemical composition of the fibres. Physical treatments change structural and surface properties of the fibre and thereby influence the mechanical bondings to polymers. Chemical modification method are mercerization, graft copolymerization or treatment with isocyanates. Chemical methods lead to occurring of new compounds, which increase an adhesion between fibres and polymer matrix. Influence of chemical treatment was determined on the basis of changes of mechanical properties of single fibers and variation of spiral angle of jute yarn. In this research jute fibers were treated with alkaline solution Mg(OH)2, concentration 5%, 15% and 30%. The fibers were treated with each alkaline solution for 0.5, 1, 2, 3, 4, 6, and 8 hours. The mechanical properties of jute fibers were tested on ZWICK/ Z 2,5 machine. Profilograph MICRO PROF FRT was used to investigate the changes of spiral angle in jute fibers. This study proves that the process of alkalization improves mechanical properties of jute fibers. Chemical treatment have an effect on changes of spiral angle of jute fibers too. During mercerization, swelling of native cellulosic materials in the alkali solution, which is the main polymorphic modification of cellulose, causes a rearrangement of the crystal packing of chains from native cellulose I to cellulose II. The best result has been received for 15% Mg(OH)2 solution for one hour. The investigations are only a part of a research concerning manufacture technology of polymer-matrix composite materials.

Morphology diversity and mechanical response of injection moulded polymer nano-composites and polymer-polymer composites

Bilewicz M., Viana J. C., Cunha A. M., Dobrzański L. A.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 15, nr 1-2

159--165

Purpose: This work was performed in the aim of exploring non-conventional injection moulding technique and to study the effect of processing thermomechanical treatment on the morphology and properties of polymer-polymer composites. Design/methodology/approach: Multilayered highly oriented skin regions induced by high shearing of the melt were obtained during non-conventional injection moulding process. Structure development has been observed in the polarized light microscope and by scanning electron microscopy. The fracture energy has been calculated from notched bar specimens. Findings: The processing variables (melt temperature, stroke time and number) are determinant of the fracture energy of the neat PP. Higher setting of these processing variables gives enhanced fracture energy (25% higher). Immiscible polymer blend of PP/PC processed by melt manipulation techniques show improved fracture toughness compared to neat PP. Addition of MAP to PP/PC did not affect the fracture energy for low setting of the processing variables, but significantly decreased it for high adjustments. The fracture energy of nanoclay reinforced PP is the double of the neat PP, for both melt temperature settings. Lower values of fracture energy have been obtained for polymer-polymer composite of PP/PC reinforced with nanoparticles (3-fold lower). Research limitations/implications: Further work contains research of different materials’ ratio, as well different polymer-polymer compositions (e.g., PP/PS and PP/LCP). Other mechanical properties will be assessed. Practical implications: The improvement of mechanical response is sharply apparent by use of SCORIM technique and by the use of nanoparticles reinforcement. Originality/value: This polymer processing technology is promising route for morphology manipulation and improvement on the mechanical properties of polymer systems. Research studies on processing-structure-properties relationships of polymer-polymer composites and nanocomposites moulded by melt manipulation techniques are scarce.