A Fundamental Research On Enhancing The Mold Resistance Of Bamboo Scrimber

In recent years, renewable materials has been gradually accepted, used and developed in China. Bamboo is a fast-growing, renewable, high-yield and potential fibre resource with short rotation cycles for making bamboo scrimber materials. However,bamboo and products made from bamboo,are more prone to mould growth and bluestain fungi under high temperature and humidity conditions due to abundant sugar,starch and protein.Currently,one of the important methods is avail of efficient, broad-spectrum and low-toxic anti-mould chemicals treatment for bamboo has been verified as an effective preventive measure against fungi.This study evaluated the mechanical, physical and biological properties of bamboo scrimber experimental panels treated with seven different anti-mould chemicals. Bamboo bundles were prepared from the culms of Neosinocalamus affinis(Rendle)Keng f., and phenol formaldehyde(PF)resin was used as the binder. Iodopropynyl Butylcarbamate (IPBC), Didecyl dimethyl ammonium chloride(DDAC),2-(Thiocyanomethylthio)benzothiazole (TCMTB), IPBC + DDAC, Zinc borate(ZB) and Boric acid+Boric borax(SBX)were selected as anti-mould chemicals, Na-PCP as a control chemical. Each of seven anti-mould chemicals was sprayed at three loading levels onto the dipped glue bambo bundles. Through evaluated for the properties of bamboo scrimber panels including thickness swelling after 24-hour water soaking, modulus of rupture, modulus of elasticity, shear strength, mold-resistant properties and effects of seven anti-mould chemicals on the leaching resistance of bamboo scrimber, to seek the reasonable anti-mold chemicals and loading level of Neosinocalamus affinis bamboo scrimber for future basic research provide important theoretic value and practical significance. The mail reseach findings were summarized are as follows:Physical mechanical properties and durability of Bambusa emeiensis bamboo scrimber with 1 to 6 years old: 1)The basic density increased with the age increment, three years later tend to be stable,basic density keep the range 0.856g/cm3 to 0.863g/cm3. 2)The 1 to 6 years old bamboo scrimber mechanical properties increased with the age increment, but not by much. 3)Bamboo of different ages had not significant influences on the natural mold-resistant performance of bamboo scrimber. the 1 to 6 years old all bamboo scrimber test materials entire surface were inspected for mold growth after 4 weeks of incubation at 28℃, and 95% relative humidity. This phenomenon show that untreated bamboo scrimber was more prone to mildew. 4)Natural decay resistance of Bambusa emeiensis bamboo scrimber was inspected decay fungi after 16 weeks of incubation at 28℃, and 85% relative humidity, the ratio of all materies lose weight were less than 5%,still reached the strong anti-decay level, bamboo of different ages had not significant influences on the natural decay resistance of bamboo scrimber.Quick choise of anti-mold chemicals: 1)fungicide type and loading level have a significantly iMPact on anti-fungi performance, that is, the mold-resistant efficacy increased with the increase in the loading levels. 2)The results showed from finhibition zone experiment, IPBC, DDAC, TCMTB, IPBC + DDAC, ZB, SBX and Na-PCP were potention anti-mold chemicals that were manufactured Neosinocalamus affinis bamboo scrimber.The anti-fungal technology study on the bamboo scrimber: 1)Different anti-mold chemicals and loading level have a significantly iMPact on physical mechanical and anti-fungi performance. different moulds has a remarkable affected on anti-fungi performance. 2)IPBC have a positive effect on Penicillium citrintim. The bamboo scrimber treated with IPBC at loading level 0.35%～0.65%(dried bamboo stress)that have not a significantly weaken on physical and mechanical performance. 3)DDAC have not an adverse iMPact on physical and mechanical performance of bamboo scrimber at loading level 0.35%～0.65%, 0.65%DDAC was tested to be effective against the growth of Trichoderma viride, average killed value less than 1. 4)TCMTB have not a significantly iMPact on mechanical strength at loading level 0.18%～0.25%, and showed protection against Aspergillus niger better than Penicillium citrintim and Trichoderma viride. 5)IPBC + DDAC have not a significantly weaken on mechanical strength at loading level 0.35%～0.65%, and was found to be effective against the growth of Trichoderma lignoru at loading level 0.65%. 6)The loading level to 0.70% ZB fully protected the panels from the infection of three molds with efficacy up to 100%, but yielded adverse effects on physical and mechanical properties of bamboo scrimber. 7)The SBX tested adverse effects on physical and mechanical properties of bamboo scrimber. The TS24h values were much higher than the control, and at the highest loading level(0.90%), it showed satisfactory inhibition on Aspergillus niger, Penicillium citrintim and Trichoderma viride growth. 8)Bamboo scrimber containing Na-PCP presented full protection against three molds after the 4 weeks period of incubation at the loading level of 1%. total protection against bluestain fungi(Botryodiplodia theobromea)at the loading level of 1.30%. 9)Based on comprehensive consideration of the physical mechanical and anti-mold properties, ZB, IPBC, IPBC + DDAC were promising anti-mold chemicals.The leaching resistance study of treated bamboo scrimber by anti-mold chemicals: 1)The leaching resistance rate of anti-mold chemicals affected by anti-mold chemicals type and loading level. 2)The leaching resistance rate of anti-mold chemicals with low retention level is less than thoes with higher retention level. 3)The leaching resistance rate of bamboo scrimber with Na-PCP is highest, The leaching resistance rate of bamboo scrimber with IPBC,IPBC + DDAC and TCMTB were lower than bamboo scrimber with SBX and ZB, the leaching resistance rate of anti-mold chemicals with DDAC was lowest. 4)The bamboo scrimber with IPBC of washing process after had little resistant to Penicillium citrintim infection, and showed no protection from Aspergillus niger and Trichoderma viride; The bamboo scrimber with 0.65% DDAC gave an average rating scale of 3.07 toward Trichoderma viride, But, it had no protection against two molds at all;The bamboo scrimber with TCMTB of washing process after only had little resistant to Aspergillus niger infection; The bamboo scrimber with 0.65% IPBC + DDAC respectively gave an average rating scale of 2.88 and 1.68 toward Aspergillus niger and Penicillium citrintim, But, it had no protection against Trichoderma viride at all. The bamboo scrimber with 0.70%SBX still showed great protection from all three experimental molds; The bamboo scrimber with ZB yielded adverse effects on Aspergillus niger and Penicillium citrintim,but,it provided bamboo scrimber panels full protection against Trichoderma viride after the 4 weeks period of incubation; The fungi-resistant efficacy of treated bamboo scrimber with Na-PCP by after washing was not change at a loading level 1.30%. Of the 7 anti-mold chemicals, in addition to Na-PCP,The panels containing ZB and SBX had the excellent mold-resistant properties by washing before and after, But ZB and SBX were tested to have detrimental effects on the quality of physical and mechanical performance. According to this phenomenon, Future anti-mould study is needed to keep the loading level of ZB within the 0.70%, SBX within the 0.90%. The panels containing IPBC and IPBC + DDAC were proven to have favourable average performance at their corresponding highest loading levels(0.65%), the physical and mechanical performance of panels nearly close to blank board, The mold resistant efficacy of panels containing IPBC and IPBC + DDAC can be achieved respectively 72.33% and 77.17% at their corresponding highest loading levels, which in the future can be study the proper loading levels. The leaching resistance of panels containing IPBC and IPBC + DDAC were poorer, So advised panels treated with IPBC and IPBC + DDAC used for above ground.