【作者】 于丽丽；

【导师】 曹金珍； Paul A. Cooper；

【作者基本信息】 北京林业大学 ， 木材科学与技术， 2010， 博士

【摘要】 为了提高水载型木材防腐剂胺溶铜季胺盐-D型(ACQ-D)中有效成分铜的抗流失性,本论文采用热空气、热水、微波、蒸汽等四种后处理方法加速处理材中铜的固着,并考察了在不同的后处理过程中各种影响因素对ACQ-D杉木处理材的抗流失性、顺纹抗压强度及铜的化合价转变的作用效果。通过FTIR光谱分析及应力松弛分析等手段考察了ACQ组分在杉木处理材中的固着机理。通过野外埋桩试验,进一步考察了后处理对ACQ-D处理杉木及樟子松的野外耐久性的影响,旨在为人工林速生材杉木在防腐市场中的广泛应用提供可靠的依据。本研究结果归纳如下：1.在热空气后处理过程中,温度、处理时间、相对湿度、保持量以及通风条件下的氧气含量及风速等都会对ACQ-D杉木处理材中铜的抗流失性产生重要影响。高温高湿(如70℃、相对湿度为80%)的热空气后处理可以有效提高ACQ-D杉木处理材中铜的抗流失性,在此过程中,部分二价铜转化为一价铜,并且化合价转化率随热空气温度及处理时间的增加而升高。通风条件对铜的抗流失性的影响与氧气浓度及风速有关,氧气浓度下降会增加铜的流失率,而在氧气含量充足的条件下,风速一方面通过促进热量传递对铜的固着过程起积极作用,另一方面则由于水分的快速蒸发而使处理材的温度降低,从而不利于铜的固着。2.热水后处理过程也可以有效加速ACQ-D处理材中铜的固着,并且处理材中铜的化合价转化率随热水后处理温度及处理时间的增加而升高,较高的化合价转化率与较低的铜的流失率相对应。微波及蒸汽后处理虽然可在短时间内明显降低ACQ-D杉木处理材中铜的流失率,但仍无法有效提高处理材的抗流失性。微波强度、后处理时间的增加和包膜处理是提高铜的抗流失性的有利因素。在本研究使用的蒸汽后处理条件中,蒸汽温度、处理时间对铜的抗流失性影响均较小。在微波及蒸汽后处理过程中铜的化合价转变较低,铜的流失率与ACQ-D杉木处理材中铜的化合价转化率相关性不大。本研究中除蒸汽后处理外,其余后处理都不会明显降低处理材的顺纹抗压强度。3.从FTIR谱图中可见,木质素及半纤维素是ACQ-D组分在木材中进行固着反应的主要场所。处理材在不同组分、不同溶液温度条件下进行的应力松弛表明,ACQ组分与木材matrix区的反应分两个阶段进行：在应力松弛较快的阶段Ⅰ,ACQ组分主要与matrix区中的羟基形成氢键结合；在应力松弛较慢的阶段Ⅱ,Cu进一步渗透到不易进入的区域(如纤维素中的准结晶区)与木材形成氢键结合。极差和方差分析表明,虽然ACQ不同组分会竞争在处理材中的反应场所,但木材成分与Cu之间的反应仍然是处理材中的主要反应。4.通过比较气干(AD)、高温干燥(DO)、高温高湿(HC)、热水(HW)等后处理工艺的ACQ-D处理樟子松和杉木的野外埋桩试验结果可以发现,杉木的天然耐久性优于樟子松,不同后处理的效果受树种、试验场所及试材埋桩位置等条件的影响。但是,在两个试验场地,经HC后处理的ACQ-D处理杉木及樟子松均表现出良好的耐腐及抗白蚁能力。与土壤接触的试材中铜的流失比不接触土壤部分的高得多,广州试验场由于气候和土壤类型的影响,试材中铜的流失及腐朽等问题更为显著。另外,通过对试验20个月后试材的顺纹抗压强度的比较可知,HC和HW后处理材的顺纹抗压强度变化不大,而AD和DO的下降明显,尤其是对樟子松来说下降尤为显著。因此,与樟子松相比,杉木在野外埋桩试验中表现更好。更多还原

【Abstract】 In order to improve the leaching resistance of the active ingredient of copper in alkaline copper quat-type D (ACQ-D) wood preservative, hot air, hot water, microwave and steaming post treatments were performed in this study to accelerate the fixation process of copper in ACQ-D treated Chinese fir, and investigate the different factors on copper leaching, the compression strength parallel to grain and the valence conversion of copper in treated wood during different post-treatments. The fixation mechanism of ACQ constituents in treated wood was determined with the help of FTIR analysis and tensile stress relaxation analysis. Furthermore, the effects of post-treatments on ACQ-D treated Chinese fir (Cunninghamia lanceolata Hook.) and Mongolian Scots pine (Pinus sylvestris Linn. var. mongolica Litv.) were evaluated by field test. The purpose of this study is to provide some useful information for the widely use of plantation-grown wood Chinese fir in the wood preservation market.The results of this study were summarized as follows:1. During hot air post-treatments, the important factors on copper leaching from treated wood include temperature, treatment duration, relative humidity, copper retention, the oxygen concentration and air velocity in air ventilation condition. Hot air post-treatments with higher temperature and relative humidity could improve the leaching resistance of copper in ACQ-D treated Chinese fir effectively, and part of cupic copper could convert to cuprous forms during this process. The percentage of copper conversion would increase as the temperature increased. The effects of air ventilation on copper leaching are associated with the oxygen concentration and air velocity, and more copper would be leached out as the oxygen concentration decreased. With sufficient oxygen concentration, air velocity would promote the heat transfer to accelerate the fixation process of copper, but it would also result in the fast evaporation of water from the treated wood and decrease the fixation temperature, which is a adverse effect on copper fixation.2. Hot water post-treatments could also accelerate the fixation process of copper in ACQ-D treated Chinese fir effectively, and the percentage of copper conversion would increase as the temperature and treatment duration increased. The lower copper leaching is corresponded with the higher copper valence conversion. Copper leaching from the treated wood could be reduced significantly after a short duration of microwave or steaming post-treatments, but could not be reduced effectively. The copper leaching resistance in the treated wood could be improved as the microwave power and treatment duration increased and also for the samples wrapped. The effects of steaming temperature and treatment duration on copper leaching are negligible in this study.The valence conversion of copper changed slightly during microwave and steaming post-treatments, which results in no strong correlation between the percentage of copper leaching and valence conversion of copper in treated wood. In this study, except for steaming post-treatment, the other three post-treatments could not reduce the compression strength parallel to grain of ACQ-D treated Chinese fir significantly.3. From FTIR spectra analysis, lignin and hemicellulose are the major fixation sites in ACQ-D treated wood. The stress relaxation curves obtained from treated wood impregnated in different ACQ solutions with different constituents and temperatures showed that the complex interactions between the components of ACQ solutions and wood matrix:in rapid phaseⅠ, the splitting of the easily accessible hydrogen bonds (mainly in the matrix) are prevalent by interaction with components of ACQ solution; (2) in slow phaseⅡ, Cu penetrates deeper in less accessible regions (e.g., in paracrystalline regions of cellulose) and renders possible further relaxation. The results of range and variance analysis reveal that the formation of complexes with Cu is still the major reaction in wood although the competitions among ACQ constituents for reaction sites exist.4. From the field test results of ACQ-D treated Mongolian Scots pine and Chinese fir after air drying (AD), high temperature drying (DO), high humidity and temperature condition (HC) and hot water (HW) post-treatments, it was found that the natural durability of Chinese fir is better than Mongolian Scots pine, and the effects of post-treatments would be affected by wood species, test site and the exposure locations of the treated wood. However, in these two test sites, both ACQ-D treated Mongolian Scots pine and Chinese fir displayed excellent decay and termite resistance performance after HC post-treatment. More copper has been leached out from the treated wood in-ground than from the samples above-ground and the serious copper leaching and poor biological performance were found in Guangzhou test site, which are due to its climate conditions and soil type. Additionally, after comparation of the compression strength parallel to grain after 20 months outdoor exposure, slight reduction was found in treated wood after HC and HW post-treatments, while the obvious reduction was found in treated wood after AD and DO post-treatments, especially for Mongolian Scots pine. Therefore, compare to Mongolian Scots pine, Chinese fir has better performance in field test.更多还原