IPIRTI RESEARCH REPORTS

1. Development of Medium Density Fiber Board–Wheat Straw

Demand for Medium Density Fiber Board (MDF) in country is 1600-1800 cbm per day. Since wood raw material is scarce, there is a need to source raw material from other natural material. In India huge quantity of agricultural residue is generated every year and this can be used to replace wood in MDF manufacture and save valuable trees in forest. On the other side, absence of assured returns, farmers find burning is a way of managing agro waste. Burning of straw emits gases like carbon dioxide, methane, carbon monoxide, nitrogen oxide, sulphur oxide which adversely affect human health and environment. Production of MDF from agricultural waste is not new but constrains in straw characteristics, with limited technical knowledge in the manufacture of MDF has led to this investigation.

Wheat straw contains 4-6 % of silica which varies depending on the source of wheat grown. Wheat straw with alkali treatment (0.1 & 0.3 %) on the weight of wheat straw was studied for the manufacturing of MDF. Refining parameters for the manufacture of fibres was optimised with a disc gap of 0.2 mm, 6 bar pressure with a retention time of 3-4 minutes for the manufacture of Panel from wheat straw species. MDF panels of size 0.3 m x 0.3 m x 6 mm were made using (10 & 12 %) Urea formaldehyde resin, phenol formaldehyde resin and Melamine urea formaldehyde resin and tested as per IS 12406-2003 “Specification for MDF for General Purpose”. Chemical and physical characteristics of alkali treated and untreated wheat straw fibres investigations revealed that, ash content decreased with the removal of dust and increased alkali treatment. Decrease in ash content drastically reduced thickness swelling of 2 hrs in 0.1 -0.3 % alkali treated fibres for UF bonded boards. However, increase in alkali treatment reduced mechanical properties of UF bonded MDF boards. PF bonded MDF boards gave excellent results with 0.1 % alkali treated fibres. Wheat straw fibre board without alkali treatment can be successfully made using MUF resin and with 0.1% alkali treated using PF resin. Results showed that all physical & mechanical properties of the panels were above minimum requirements for MDF as specified in IS-12406-2003 standards for PF and MUF bonded boards.

The complete details are available in IPIRTI Research Report No. 201, “Development of Medium Density Fiber Board–Wheat Straw” by Mamatha B. S. and Co-workers Please contact, Indian Plywood Industries Research and Training Institute, Bengaluru for complete reports

2. Study on Acoustic and Thermal Efficiency of Particle Boards Made from Agro Residues

Limited data on agro residues boards for interior applications like acoustic and thermal properties necessitated generating data on sound absorption and thermal conductivity these boards. In this study, particleboards were made using rice straw, bagasse, wheat straw and coir. Efforts were made to collect above refereed agro residues to make low-density particleboards of different densities: 300, 400 & 500 kg/m3. The particleboards manufactured were tested for sound absorption coefficient and thermal conductivity. Above refereed agro residues targeted for density 400 kg/m3 fulfils the requirements (moisture content, modulus of rupture, swelling due to surface absorption, water absorption) of low-density particleboard standard except rice straw board in swelling due to surface absorption.

Study revealed that maximum sound absorption coefficient for all four boards were found in the frequency range of 1500 to 2500 Hz. Among four particle boards, the best sound absorption coefficient of 0.80 at frequency 3000 Hz was observed in coir particleboard with density of 300 kg/m3 and least was found in rice straw particleboard with density 500 kg/m3. Analysis of the boards showed that Noise Reduction Coefficient (NRC) of all boards decreased with increase in density. Thermal conductivity (0.098 W/m-K) was lowest in rice straw particle board with density 300 kg/m3. Results of all four boards showed that as density increases the thermal conductivity also increases.

The complete details are available in IPIRTI Research Report No. 205 “Study on acoustic and thermal efficiency of particle boards made from agro residues” by Kiran, M. C and Co-workers. Please contact, Indian Plywood Industries Research and Training Institute, Bengaluru for complete reports

IPIRTI Bulletin
Vol. V Sept. 21