Puukuitulujitteiset muovikomposiitit puunjalostusteollisuudessa

Puukuitulujitteisten muovikomposiittien käyttömäärät ovat maailmanlaajuisesti kasvaneet jatkuvasti viimeisen 15 vuoden aikana.Kasvun on ennustettu jatkuvan voimakkaana myös tulevaisuudessa. Diplomityön tavoitteena oli selvittää puukuitulujitteisten muovikomposiittimateriaalien soveltuvuus erääseen, mahdollisesti rakennusteollisuuden käyttöön tulevaan, tuotteeseen. Tutkittaviksi materiaaliyhdistelmiksi valittiin sekä kerta- että kestomuovin ja puu- jauhon seos. Puujauho oli koivupuista sahaus- ja hiontajätettä. Molemmissa tapauksissa puun osuus komposiitissa oli 30 p-%. Koekappaleiden valmistuksessakäytettiin koivupuisia muotteja, joihin materiaali annosteltiin. Kertamuovin japuujauhon seos kovettui huoneenlämmössä. Kestomuovin ja puujauhon seoksen sulatukseen käytettiin lämmitettävillä puristinlevyillä varustettua aihiopuristinta. Koekappaleille määritettiin taivutuslujuudet taivutuskokeen avulla. Koekappaleiden taivutuslujuuksia verrattiin mm. lattialastulevyn ja koivuliimalevyn arvoihin. Liimalevyn taivutuslujuus muihin verrattuna oli huomattavasti suurempi. Komposiittimateriaalista valmistettujen koekappaleiden taivutuslujuus oli lähellä lattia-lastulevyn tasoa, osittain jonkin verran parempikin. Diplomityössä saatujen tulosten perusteella voidaan todeta puukuitulujitteisilla muovikomposiiteilla olevan kehityspotentiaalia myös tutkimuskohteen tyyppisissä ratkaisuissa. Jatkotutkimusta tulisi kohdistaa ennen kaikkea kestomuovipohjaisen komposiittimateriaalinsuuntaan.

Effects of Surface Properties and Wood Modification into Direct Printing on Wood

Building industry is a high volume branch which could provide prominent markets for wood based interior decoration solutions. Competition in interior decoration markets requires versatility in appearance. Versatility in wood appearance and added value could be achieved by printing grain patterns of different species or images directly onto wood. The problem when planning wood printing’s implementing into durable applications is basically how to transfer a high quality image or print sustainably onto wood, which is porous, heterogeneous, dimensionally unstable, non-white and rough. Wood preservation or treating, and modification can provide durability against degradation but also effect to the surface properties of wood which will effect on printability. Optimal adhesion is essential into print quality, as too high ink absorbance can cause spreading and too low ink absorbance cause pale prints. Different printing techniques have different requirements on materials and production. The direct printing on wood means, that intermedias are not used. Printing techniques with flexible printing plates or in fact non-impact techniques provide the best basis for wood printing. Inkjet printing of wood with different mechanical or chemical surface treatments, and wood plastic composite material gave good results that encourage further studies of the subject. Sanding the wood surface anti-parallel to the grain gave the best overall printing quality. Spreading parallel to the grain could not be avoided totally, except in cases where wood was treated hydrophobic so adhesion of the ink was not sufficient. Grain pattern of the underlying wood stays clearly visible in the printed images. Further studies should be made to fine tune the methods that already gave good results. Also effects of moisture content of wood, different inks, and long-term exposure to UV-radiation should be tested.

ArkWood-case puumuovitalo

Rakennusalalla kehitetään uusia materiaaleja ja rakennuslainsäädäntö muuttuu kiivaaseen tahtiin. Kilpailu alalla kiristyy ja tarvitaan uusia toimintatapoja rakentamisen kaikissa vaiheissa aina suunnittelusta toteutukseen. Puumuovikomposiitti on Suomessa uudehko rakennusmateriaali. Tässä työssä selvitetään tällä hetkellä voimassa olevien rakennusmääräysten ja standardien asettamia vaatimuksia puumuovikomposiittien käytölle rakentamisessa Suomessa sekä kehitetään omaa yritystoimintaa laatimalla oman yrityksen liiketoimintasuunnitelma. Tässä diplomityössä on laadittu puumuovikomposiittitalon rakennuslupapiirustukset ja selvitetty, kuinka Lappeenrannan rakennusvalvonta suhtautuu puumuovikomposiitin käyttöön kyseessä olevassa kohteessa rakennuslupahakemusvaiheessa. Suunnitellusta puumuovitalosta on pyydetty tarjoukset talotoimittajilta ja arvioitu puumuovikomposiitin käytön vaikutusta rakentamisen kokonaiskustannuksiin. Liiketoimintasuunnitelman laadinnassa on hyödynnetty aihealueeseen liittyvää kirjallisuutta ja julkaisuja yhdistäen niihin omia näkemyksiä ja ideoita.

Kytkentäaineet puumuovikomposiiteissa

Puumuovikomposiittien valmistuksessa yhdistetään kaksi toisistaan eroavaa materiaalia jolloin saadaan aikaan materiaalien ominaisuuksien ainutlaatuinen yhdistelmä. Polymeerimateriaaleina käytetään pääasiassa erilaisia kestomuoveja. Kuitumateriaaleina voidaan käyttää puujauhetta, sahanpurua, paperin- ja kartongin valmistuksessa käytettävää sellua, nanoselluloosaa tai muita puukuitumateriaaleja. Polaarisen puukuidun ja polaarittoman muovimateriaalin välinen materiaalien rajapinnan adheesio on yleensä riittämätöntä, mikä vaikuttaa lopputuotteen ominaisuuksien heikkenemiseen. Kyseinen ongelma on pyritty ratkaisemaan käyttämällä erilaisia kytkentäaineita. Tässä työssä keskitytään käsittelemään erilaisia puumuovikomposiittien kytkentäaineita, niiden toimintaa sekä vaikutuksia lopputuotteeseen. Lisäksi työssä esitellään myös puumuovikomposiittien valmistusmateriaaleja ja valmistusprosesseja.

Kaupallisten komposiittituotteiden materiaaliominaisuuksien määritys ja vertailu

Tässä kandidaatintyössä tutkittiin viiden kaupallisen puu-muovikomposiittituotteen säänkestävyyttä kolmen eri materiaaliominaisuuden avulla. Tuotteet olivat Suomessa markkinoilla olevia terassirakentamisen tuotteita ja niiltä mitattiin Charpy -iskulujuutta, veden absorptiokykyä ja värinmuutosta. Tuloksia verrattiin sekä keskenään, että muualla maailmassa tutkittujen kaupallisten tuotteiden kanssa. Tulosten perusteella havaittiin, että Suomen markkinoilla olevien tuotteiden säänkestävyys on erinomainen.

Impact of mineral fillers on the properties of extruded wood-polypropylene composites

The main aim of this thesis is to study the effect of mineral fillers on the properties of extruded wood-polypropylene composites (WPC). The studied minerals are Talc, Calcite (CaCO3), two quantities of Wollastonite and Soapstone, and the level of mineral addition is 20 w-%. The study shows that mineral fillers can be used to modify and improve the properties of woodplastic composites. Especially the moisture-related properties of WPCs were found to be improved significantly by mineral addition. As the WPCs of the studied type are commonly used in outdoor applications, this is of importance in terms of usability. In machining, the addition of two minerals retained the surface roughness at same level throughout the test, indicating a favorable effect on machinability. The use of hard minerals shortened the tool life in machining. In general, a modest increase in density was observed. In many of the studied properties, no apparent influence of mineral addition was found, indicating that the properties were not weakened. An overall result was that talc showed the best overall performance, indicating that it can be used as an active filler improving most of the studied properties, especially moisture resistance. Calcite was found to have nearly similar performance. According to the findings, mineral addition to wood-plastic composites appears to be beneficial; especially moisture resistance can be enhanced without diminishing the other properties or usability in general.

Improving the usability of extruded wood-plastic composites by using modification technology

Using cellulosic reinforcement to produce plastic composites is a globally growing trend. One of such materials are wood-plastic composites, which are an extensively studied group of materials for which the global industry is looking for new applications. Issues such as bondability, durability and fire resistance still require development to improve the usability of the wood-plastic composite material. Improvement of the usability of wood-plastic composites is studied in this thesis through the effects of using selected modification technology in wood and plastic industry. The applied modification methods are surface by mechanical abrasion and plasma, chemical impregnation of wood flour, and structural modification by the co-extrusion process. The study shows that the properties of WPC can be influenced by the selected modification methods. The selected methods are also found to be able to result as improvement in the properties of the material. The may also affect other than just the targeted properties of the end-product, either in a positive or a negative manner. Therefore modification as performance improvement should be considered as a caseby- case study. Introducing WPC materials for new applications can be done by using modification technology. Structuralmodification can possibly be used to reduce material costs of the modified WPC material.

Ultraviolet light protection and weathering properties of wood-polypropylene composites

The main aim of this thesis is to study the effect of pigments on the weathering properties of wood-polypropylene composites (WPC). The studied properties are color change, water absorption, thickness swelling and Charpy impact strength. The impact of weathering and UV exposure on WPCs was studied by using pigments and minerals as protective agents. The study shows that the pigments and/or mineral fillers can be used to improve the weathering properties of WPCs. The effect of pigments was found to vary with the type of pigment and the method of weathering. The black pigment, an inorganic carbon black master-batch, was found to be the most effective one in reduction of the discoloration of WPCs. By preventing discoloration, and further reducing the degradation of the surface of the WPC, the pigments were found to reduce the decrease in the impact strength after weathering. As well as UV protection, the moisture resistance is a significant factor affecting the durability of WPCs. The addition of mineral fillers was found to improve the moisture-related properties, such as water absorption and thickness swelling, of WPC significantly. According to the findings, addition of pigments and mineral fillers to wood-polypropylene composites appears to be beneficial: color stability and moisture resistance can be enhanced especially in outdoor weathering. The combined effect of black pigment (carbon black master-batch) and wollastonite as a mineral filler was found to bring about the most effective properties against weathering.

Improving the fire retardancy of extruded/coextruded wood-plastic composites

The main objective of this thesis is to study the impact of different mineral fillers and fire retardants on the reaction-to-fire properties of extruded/coextruded wood-plastic composites (WPCs). The impact of additives on the flammability properties of WPCs is studied by cone calorimetry. The studied properties are ignition time, peak heat release rate, total heat release, total smoke production, and mass loss rate. The effects of mineral fillers and fire retardants were found to vary with the type of additive, the type of additive combinations, the amount of additives, as well as the production method of the WPCs. The study shows that talc can be used to improve the properties of extruded WPCs. Especially ignition time, peak heat release rate and mass loss rate were found to be improved significantly by talc. The most significant improvement in the fire retardancy of coextruded WPCs was achieved in combinations of natural graphite and melamine. Ignition time, peak heat release rate and total smoke production were improved essentially. High increase in smoke production was found in samples where the amount of ammonium polyphosphate was 10% or higher. Coextrusion as a structural modification was found as a promising way to improve the flammability properties of composite materials in a cost-effective way.

Research progress in wood-plastic composites: A review

The interest towards wood-plastic composites (WPCs) is growing due to growing interest in materials with novel properties, which can replace more traditional materials, such as wood and plastic. The use of recycled materials in manufacture is also a bonus. However, the application ofWPCs has been limited because of their often poor mechanical and barrier properties, which can be improved by incorporation of the reinforcing fillers. Nanosized fillers, having a large surface area, can significantly increase interfacial interactions in the composite on molecular level, leading to materials with new properties. The review summarizes the development trends in the use on nanofillers for WPC design, which were reported in accessible literature during the last decade. The effect of the nanofillers on the mechanical properties, thermal stability, flammability and wettability ofWPC is discussed.