Combination Of PEG, Paraffin And Other Modifiers Treatment On Round Bamboo And Study On Its Antibacterial And Anti-cracking Properties

The crackability of round bamboo will bring about a series of problems.such as mildew and decay.At the same time,mildew and decay will further cause cracking.Therefore,it seems that the cracking of round bamboo is closely related to mildew and decay.so it is necessary to combine cracking prevention with mildew prevention and preservation.Aiming at problems of cracking,mildew and decay of round bamboo,polyethylene glycol with good permeability was selected as size stabilizer,borax and boric acid were used as preservative.The two protective agents were mixed to impregnate round bamboo,so as to achieve the purpose of anti-mildew and anti-cracking at the same time.After impregnation,paraffin heating treatmen not only plays a role in drying,but also further enhances the anti-mildew and anti-cracking properties of round bamboo.In the later stage,the anti-cracking and anti-mildew mechanism was analyzed by inductively coupled plasma mass spectrometer,contact angle measuring instrument,scanning electron microscope and X-ray photoelectron spectrometer.The main results were as follows:(1)Round bamboo were impregnated in the solution of different concentration and molecular weight of PEG.It showed that PEG 1000 had better permeability,and the highest weight gain rate was 8.75% when the concentration was 25%.The presence of PEG in the original bamboo can also be seen from the super-depth-of-field three-dimensional microscopy.In the first hygroscopicity-drying cycle,the swelling and shrinkage resistance of 25% PEG 1000 treated wood were 48.86% and 53.22%,respectively.In the first hygroscopicity-drying cycle,the swelling and shrinkage resistance were 30.76% and 24.41%,respectively.Although the ASE values in the water absorption-drying cycle test decreased overall,which may be caused by the loss of PEG during the blistering process,but it is undeniable that 25% PEG 1000 had improved the dimensional stability of round bamboo.(2)PEG can be used to alleviate dimension instability caused by dry shrinkage and wet swelling of bamboo,but it can easily be lost from the material in the case of high humidity.Therefore,PEG impregnation and paraffin heat treatment were combined to establish a hydrophobic barrier on the surface of round bamboo,followed by drying round bamboo.The treated bamboo was exposed outdoor for 26 weeks to evaluate the development of cracks.The results showed that the number and length of splits could be significantly reduced by the combined treatment of PEG and paraffin.SEM showed that the cell wall of treated bamboo expanded and the pits in the catheter were blocked by chemicals.The hydrophobicity test showed that the equilibrium contact angle of treated bamboo was significantly higher than that of untreated bamboo,indicating that the hydrophobicity of treated bamboo was improved.so it can reduce the cracking and deformation caused by water absorption.(3)PEG,borax and boric acid were mixed as protective agent,and the round bamboo was impregnated in the protective agent.Wet ashing method was used to determine the amount of boron absorbed by the test block increased with the increase of the concentration of boron solution,but the amount of boron absorbed by the treatment of 5% and 7% boron solution had little difference.The indoor and outdoor anti-mildew test showed that the anti-mildew effect of bamboo could be improved obviously by impregnating with boron and polyethylene glycol and then waxing.At the same time,both white rot fungi and brown rot fungi can reach grade I in the decay test.SEM showed that PEG can swell the cellwall,leading to partially blocked pits.XPS showed that boron existed in the bamboo and hemicellulose degraded significantly,which played a certain role in anti-mold and antiseptic.(4)The leaching and preservation test showed that boron solution treated alone was easy to lose and the fixation rate was low,while the fixation rate of boron was significantly increasedafter treatmen,the mixed impregnation of boron and polyethylene glycol followed by paraffinheattreatmen can still reach grade I decaying resistance.SEM showed that the untreated wood had obvious decay.The vessel was filled with hyphae and perforated around the vessel.However,no hyphae was found in the tube after mixed impregnation with boron and polyethylene glycol,and the structure was complete.Therefore,the mixed impregnation of boron and polyethylene glycol followed by paraffinheat treatment play aimportant role in improving the loss resistance of bamboo.