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T he highest total color difference values ( ∆E) were found in the panels produced with the similar proportions of waste paper and OCC into gypsum (A4: 6.09; B4: 5.79). These boards have also show highest CIE whiteness reduction (A4: -33.19; B4: -28.44). With the help of FTIR, some chemical groups are modified to some extent but similar functional groups were observed in surface of boards. For A- and C-type boards, similar TGA degradation trends (spectra) were observed while the B-type panels show markedly higher mass loss, especially at initial temperature stage (100-120 0 C). This is probably because of the presence of some non-cellulosic materials (i.e. starch, silica, etc.) and the high rate of lignin in sheet structure of OCC material. The flame propagation characteristic of the surfaces of all test boards shows that the flame did not reach the threshold limit of 150 mm. These indicates, even if the source of fire is not removed, flame did not reach the threshold limit that boards that could be classified as non-flammable material class according to TS EN-ISO 11925-2 standard. The heat insulation properties of the test sample were found to be lowered with addition of lignocellulosic material to the gypsum structure. It was seen that waste paper ratio in gypsum structure higher than 10% (A3 to A6 boards) show better insulation properties than counterpart OCC (B-types) and secondary fiber based (C-types) gypsum boards. In general, reduction heat transfer in average values of samples attracted attention as compared with control specimens. Interestingly, the boards are indicated best insulation properties as mentioned above, show higher mass loss too. The highest mass loss for A-type boards found to be 3.52% (A6), for B-type boards 3.46% (B6) and for C-type boards 3.28% (C8).

Aims: It was investigated to produce gypsum-based experimental composite panels with red pine wood/rice straw particles in the mixture up to 60:40 (ratio) (w/w) in gypsum-water mixture. In this case, the additives could be observed more closely. Methodology: The red pine wood chips and the rice straw (stalks) have been turned into suitable particle dimensions. The experimental boards were cut to determine the IB (Internal bond), MOE–MOR (Modulus of Elasticity and Rupture), and TS (thickness swelling after 24 hours immersion in water). A standard flame combustion test system was conducted according to TS EN-ISO 11925-2. For surface chemical analyses, FTIR was used to evaluate the chemical groups present in the board surface. The thermogravimetric analysis (TGA) was conducted for measuring changes in boards as a function of increasing temperature. The natural weathering tests were conducted that were exposed to outdoor for two months then color and surface hardness measurements conducted for determining property changes. Results: The rice straw had negative impact on thickness swelling (TS) properties of boards in water. The highest TS value of 47.66% was observed in the board that produced from 60:40 (ratio) (w/w) wood/rice straw mixture (DE4). However, the addition of rice straw to the wood/gypsum mixture has a lowering effect on the internal bond (IB) and bending strength (MOR) properties of experimental boards some level. The maximum IB strength of 0.06 N/mm2 and MOR of 2.77 N/mm2 found control sample (DE0). However, the highest MOE value of 553 N/mm2 was calculated on the DE4 board, which was produced by adding 40% rice straw to the wood/gypsum mixture. The addition of rice straw and wood particles to the gypsum structure has a positive effect on the heat transfer properties. Conclusion: It is clear that the addition of rice straw to the wood/gypsum mixture adversely affected the strength properties negatively. However, rice straw in wood chip/gypsum mixture helps to improve heat resistance (insulation) properties of panels at some level. Moreover, the addition of rice straw to wood/gypsum mixture effects on extending hardening time.

Bu calismada, kullanilarak atik/atik duruma gelmis kagit (A tipi), eski kullanilmis oluklu mukavvalar (B tipi) ve ikincil seluloz lifleri (C tipi) alci yapisina katilarak kompozit panel levhalar uretilmistir. Arastirma bulgularina gore, bu hammaddelerin alci yapisna katilmasi su icinde kalinlik artim degerlerini olumsuz etkilemistir. A, B ve C tipi levhalarda en yuksek kalinlik artim degeri sirasiyla %26,32, 12,76% ve %7,79 olarak benzer uretim sartlarindaki A6, B6 ve C6 levhalarinda gozlemlenmistir. Bu levhalarin uretim sartlari %50-50 (agirlik/agirlik) alci-selulozik atik seklindedir. Fakat en dusuk kalinlik artim degeri ise sadece alcidan uretilmis levhada (kontrol levhasi) %1,88 olarak olculmustur. Sekonder lif/alci karisimindan uetilmis C tipi levhalarda, ayni uretim sartlarinda A ve B tipi levhalardan daha yuksek ic yapisma direnc (IB) ozelligine sahip levhalar uretilmistir. En yuksek ic yapisma direnci 0.60 N/mm 2 olarak C3 tipi levhada gozlemlenmistir. Fakat %20 den daha yuksek sekonder lif eklanmesi alcidan uretilmis levhalarin direnc ozelliklerini olumusuz etkilemistir. Alci yapisina eklenen her uc tip hammadde de egilme direnc ozelliklerini (MOR) olumlu etki etttigi anlasilmistir. %10 ve %50 selulozik katki durumunda, A2 (6.59 N/mm 2 ) ve A6 (6.44 N/mm 2 ) levhalari diger B ve C tipi levhalara gore ayni uretim sartlarinda daha yuksek egilme direnc ozelligi gostermistir. Acik havada bekletilmis tum deneme levhalarinin sertlik ozellikleri, kontrol orneklerinden daha dusuk oldugu anlasilmistir.