Bamboo grows fast, produces a large quantity and soon becomes a material and widely applied. Compared to wood, there are some differences in structure and properties, shown in high stiffness, high flexure, physical and mechanical properties can be compared with broadleaf wood, with the potential to be used as materials. structural work. But in bamboo there are many nutrients, protein accounts for 1.5 – 6%, the sugar (glucose) solubility is about 2%, starch is about 2.02 – 5.18%, fat and wax make up about 2.18 – 3.55%. Bamboo and products made from bamboo are susceptible to decay, termites and termites in hot and humid environments, so it is important to prevent termites..
1. Anatomy and treatment properties of bamboo.
The anatomical characteristics of bamboo have the characteristics of the bamboo itself, organizing the cells between the bamboo eyes arranged in a vertical direction, unlike radial distribution (parenchyma). cell) and ray cells, so the treatment and water cannot penetrate in the direction of the ray. After bamboo maturation, due to sedimentation of resins, the accumulation of baits (thylose) makes the pipes (catherer) and filter tube (sieve tube) no longer permeable. Horizontal. The outer surface of the bamboo is covered with a thin layer (hard) made of silicon and wax, so the treatment chemicals cannot penetrate in the radial direction (radial). Due to the structural differences, bamboo treatment is more difficult than wood treatment. Viewed vertically, the organization of the bamboo cells is made up of parenchymal cells and vascular bundles – consisting of sclerenchyma and sclerenchyma – formed from the head to the top of the tree. so the vertical flow is very fast. However, the vascular bundles are unevenly distributed in the trunk of the bamboo, in the outer ring the bamboo distributes many small vascular bundles, the middle distributes a few large vascular bundles. The further away from the pipe, the less the permeability level, this creates the uneven distribution of the treatment chemicals in the bamboo. The pipe accounts for 10% of the volume of the bamboo tube, so the chemicals for osmotic treatment to other organizations around the pipe are weak. A treatment that cannot penetrate to the parenchymal organization will provide an opportunity for early invasion of the fungus.
2. Treatment method against termites for bamboo
The treatment of termite-resistant bamboos is becoming increasingly important, so many countries conduct research. According to a Japanese report, the use of phenol and formaldehyde is condensed into A-stage resin or resol, which is a low-molecular, soluble substance with low adhesion. Good permeability for bamboo materials. After this substance penetrates the bamboo material, it is further processed by heat or acid, it will produce a compound on the polymeric compound (triad –structure), odorless, non-toxic and non-toxic. Reverse osmosis and non-dispersing, has a long antimicrobial feature. Bamboo material after being treated with this substance will no longer be invaded by fungi or antibacterial losses whether used outdoors or buried in the ground, antibacterial properties are superior to treatment. wood, but high cost due to the use of phenolic resin. Nanjing Forestry University (China) soak products made of bamboo in phoxim solution (chemical formula is C12H15N2O3PS) 3% for 3 minutes, then after 2-3 days of bamboo borer die, effect of the drug maintained over 1 year. The drug is less toxic, has a long-lasting effect, and is a relatively ideal antifungal agent for products made from bamboo. Adding 1% catalyst (borax: boric acid in 1: 1 ratio) to bromo-geramine solution (full Dodecyl dimethyl benzyl ammonium bromide) 5% for mold prevention is also relatively good. In addition, Nanjing Forestry University (China) also conducted an acetylation liquid phase treatment, resulting in a weight percentage gain of acetyl radical (WPG). 12.97%, while the weight reduction rate of the sample is 0, the antibacterial effect is very good, but this method is complicated and expensive.
(Further explanation of weight increase / decrease ratio: is the increase or decrease ratio of the material after processing compared to the original weight x 100%).
3. Using antibacterial agents for bamboo.
Antibacterial agents for bamboo are divided into four categories according to usage: those used for fumigation, those used for irrigation, those that are oil-soluble and those that are water-soluble.
The type used for smoking such as Ammonium water (formula is NH3 · H2O), sulfur is only effective at the surface, hard to work with the fungus inside, easy to pollute the air; The most widely used irrigating type is creosote oil (Creosote), but because it contains polycyclic aromatic hydrocarbons, which can cause cancer, it has been eliminated. Water-soluble type such as chlor-phenolic acid (pentachlorophenol: pcp) is both expensive and toxic to health, while water-soluble type has low toxicity, good effect, no strange smell, so it should be used. More and more, it can also be used in combination.
4. Some antibacterial agents for bamboo.
The International Association of Bamboo and Rattan (INBAR) proposed 10 recipes for combining antibacterial agents for bamboo in 1994 (mainly based on Indian standards), in 1998 American Wood Conservation Association (AWPA) Identify 17 standard antibacterial formulas for wood including water and oil based. But there are some chemicals that are seriously polluting to the environment, so it has been banned or restricted in many countries, such as sodium pentachlorophenol (PCP-Na) which has been banned in most countries. not containing arsenic (As chemical formula), the US and the European Union have issued a ban on its use in the public since 2004.
5. New antibacterial drugs.
Since water-based antimicrobial agents are less toxic, they should be focused on research. Currently, low-toxic but highly effective antibacterial drugs include: AAC – alkyl ammonium (Alkyl ammonium compounds), ACQ – fourth-class copper ammonic ( Ammoniacal copper quaternary), boride, CDDC – Copper dimethyl dithiocarbamate. Oil-based antibacterial drugs are copper / zinc naphthenate (copper / zinc naphthenate), CTL – chlorothalonil or Daconil, IPBC – organic iodine compound (Iodopropynyl butylcarbamate), synthetic pyrethroids …
6. Development trend of antibacterial techniques for bamboo.
The antibacterial technique for bamboo has made strides in addition to techniques for wood, focusing on research:
– Develop effective but less toxic drugs suitable for the characteristics of bamboo.
– Find out the proper treatment for bamboo.
– Going into researching the reliance of medicine.
There is also a further direction is to change the properties of bamboo to conduct treatment, for example, for low molecular condensation such as phenolic, melamine glue penetrates the bamboo and then condenser condenser, or conducting liquid phase acetylation process, although at a high cost but very high efficiency.
Note: the articles are collected and for reference only, do not advise readers to arbitrarily apply to production.
The term “antibacterial” in English is Antiseptic or 防腐剂 in Chinese. Due to the limitations of its Vietnamese vocabulary, it sometimes appears as “anti-repellent”, “anti-termite”, “antibacterial drug”.….