Study On The Straw Fiberboard Of Environment-friendly And High-intensity

The lack of forest resources and the free formaldehyde are the main problem ofman-made board industry at present. The production and consumption of man-madeboard is huge in China, but the traditional mode of product is based on wood as themain raw material and the adhesive glue always contains aldehyde. As the wood isserious used up, the release of free formaldehyde pose a threat to the environment andpeople’s health; To solve this problem, this study employs the crops straw as a substitutefor wood raw material, and the industrial lignin was regarded as the main adhesive toproduce a kind of high-strength and formaldehyde-free fiberboard.It systematically utilizate straw, wheat straw and other crop straw as the naturalfiber raw material, and the waste lignin comes from papermaking was used as adhesive.The straw was crushed to microns in size with supersonic air crushing technology, at thesame time the lignin was distributed to70micrometer. Afetr mixing them withaldehyde-free adhesive, the mold of fiberboard was pressed with the hot-pressingmachine. Dues to the action of high temperature, pressure and catalyst, the lignin andthe components of micron straw such as cellulose, hemicellulose reorganizate into highstrength, formaldehyde-free fiberboard. What’s more, the pressure and temperature aswell as the dosage of catalyst was optimized. With the reaserch not only the crops strawwas used effectively but also the fiberboard won’t cause formaldehyde pollution.The study identified a two pieces hot-pressing method of fiberboard, in which thefirst period of hot-pressing takes10min with140℃, and the pressure is5Mpa whilethe second period of hot-pressing time is15min, the temperature is190℃with apressure of10Mpa.The corn straw reed were made use of as the main raw material to produce fiber-board which was consist of long fiber and superfine powder. The proportion of longfibers to the superfine powder, the dosage of lignin and the consumption offormaldehyde-free glue were optimized. The result show that the corn-stalk board andreed/corn-stalk board show the ideal strength when the lignin content is30%, the ratioof the superfine powder with long fiber is3:7. At the same time its intensity increaseswith the increase of formaldehyde glue, considering all factors, the best dosage wasdetermined as6%; Under this condition, the MOR, MOE, IB and24hTS of thefiberboard reached21.3MPa、4736.5MPa、2.2MPa and7.9%respectively. In additionto the MOR, the other indicators were all beyond the national standards of mediumdensity fiberboard (MDF) and any formaldehyde was not found in the test.The effect of thickness and density on the properties of the superfine powderfiberboard were explored, it found that with the increase of average density, allperformances expect the IB improved well. On the contrary, the performances of fiberboard decreased to a certain extent with the increasing of thickness. On the other hand,this study attempts to modify lignin with free radical initiator. The result showed that the pressing temperature dropped below180℃and the performance of ultramicropowder fiberboard had improved after the modified lignin was used in the fiberboard,which will provide a new way to simplify the hot-pressing process.