首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
用CONE法研究木材阻燃剂FRW的阻燃性能   总被引:33,自引:4,他引:29  
利用锥形量热仪 (CONE)系统地测定了新型木材阻燃剂FRW的阻燃性能 ,讨论了FRW对阻燃木材在燃烧时的热释放、质量变化及耐点燃性的影响 ,并与Dricon阻燃剂进行了对比。结果表明 ,在 5 0kW·m2 的热辐射功率下 ,FRW阻燃处理木材的热释放速率 (RHR)和总热释放量 (THR)随FRW载药率的升高而降低 ,至载药率达到 10 %左右时 ,RHR及THR降低为未处理木材的 5 0 %左右 ,并且降低的趋势明显变缓 ;FRW与Dri con阻燃木材的有效燃烧热 (EHC)曲线基本重合 ,说明二者的阻燃机理类似 ;FRW阻燃木材的质量损失速率(MLR)曲线与RHR曲线相似 ,失重和热释放主要发生在有焰燃烧阶段 ;FRW阻燃处理能显著提高木材燃烧时的成炭率 ,但对木材的点燃时间影响不大 ;FRW与Dricon的阻燃效力相当 ,属高效木材阻燃剂。  相似文献   

2.
锥形量热仪法研究FRW系列阻燃剂的抑烟性能   总被引:1,自引:0,他引:1  
采用锥形量热仪法,对FRW系列木材阻燃剂产品FRW-C1和FRW-C2的抑烟性能进行了评价。结果发现:FRW-C1和FRW-C2阻燃处理木材的烟比率、比消光面积、CO2质量分数及产生速率,均比未处理木材显著降低;二者均能有效地降低木材燃烧时的烟浓度和烟释放量,而对木材燃烧时的CO释放无显著影响。  相似文献   

3.
用CONE法研究木材阻燃剂FRW的阻燃机理   总被引:12,自引:1,他引:11  
采用锥形量热仪(CONE)法对复合木材阻燃剂FRW处理紫椴木材(FZ)、FRW的组分磷酸脒基脲(GUP)处理紫椴木材(GZ)、硼酸处理紫椴木材(BZ)和未处理的紫椴木材(UZ)的燃烧性进行了系统的测定,通过对上述试样在燃烧时的热释放、质量变化、烟气产生以及尾气成分等实验数据的综合对比分析,讨论了阻燃剂的作用机理。结果表明:1)FRW阻燃剂显著降低了木材的热释放速率(RHR)、总热释放量(1FHR)、有效燃烧热(EHC)、质量损失速率(MLR)、烟比率(SR)、比消光面积(SEA)、CO2的浓度及产率(Yco2);2)GUP与硼酸之间存在显著的阻燃协同效应;3)FRW阻燃木材的MLR曲线与RHR曲线相似,失重和热释放主要发生在有焰燃烧阶段;4)FRW阻燃处理能显著提高木材燃烧时的成炭率,说明催化成炭是FRW阻燃机理的主要方面。  相似文献   

4.
用FTIR法研究木材阻燃剂FRW的阻燃机理   总被引:3,自引:0,他引:3  
王清文  李坚  李淑君 《林业科学》2005,41(4):149-154
采用FTIR显微分析技术,对FRW阻燃处理红松木材限制燃烧固相产物的结构进行分析;采用GC_FTIR联机分析方法,对经FRW阻燃剂及其主要组分处理的紫椴木材试样的热解挥发性产物进行分析和鉴定;讨论FRW阻燃处理木材的热解炭化过程、阻燃剂的作用以及热解产物的结构特点。结果表明:FRW阻燃木材受热时,随着温度的升高,在FRW及其分解产物的催化下,木材逐步发生聚糖脱水、半纤维素脱乙酸、聚糖降解、木质素降解、木材热解产物聚合、脂肪族聚合物脱氧及芳构化等反应,最终炭化;FRW阻燃剂改变了木材的热解途径,并且显著降低了挥发性有机化合物的生成量。  相似文献   

5.
FRW阻燃刨切薄竹的阻燃特性   总被引:1,自引:0,他引:1  
采用FRW阻燃剂对刨切薄竹进行阻燃处理,用锥形量热仪(CONE)测定不同载药率下处理材与未处理材的阻燃性能。结果表明:在25kW·m-2的热辐射功率下,刨切薄竹经FRW阻燃处理后,热释放速率、总热释放量和总烟释放量随着载药率的增大而减小,处理材在燃烧过程中不会出现较高火焰的燃烧过程;处理材与未处理材相比,点燃时间延长,残余物质量增加;FRW阻燃处理刨切薄竹的阻燃和抑烟效果明显。  相似文献   

6.
木材阻燃剂FRW的阻燃机理   总被引:12,自引:2,他引:10  
王清文  李坚 《林业科学》2005,41(5):123-126
在综合分析热分析法、锥形量热仪法和FTIR法获得的FRW阻燃机理研究结果并吸收木材阻燃机理研究现有成果的基础上,推导进而提出了木材阻燃剂FRW的阻燃机理。其主要内容是:1)FRW阻燃木材受热时,阻燃剂FRW分解产生不燃性气体和不挥发的酸性熔融物质,具有降低体系温度和氧气浓度及屏蔽热辐射的作用,降低了木材的热解速度;2)FRW的组分硼酸和GUP的酸性分解产物催化木材脱水、降解,以及木材热解产物的缩合、聚合、芳构化等反应,能改变木材的热解途径并使其向着有利于炭化的方向变化,FRW显著的催化成炭作用,使阻燃木材的燃烧放热量大大降低,这是FRW阻燃机理的主要方面;3)硼酸与GUP起阻燃作用的温度和方式不同,并且有相互补充的作用,因而表现出阻燃协同效应。  相似文献   

7.
▲环保型轻质细木工板生产线建成福建省南平大展集团公司与福建林学院协作的该公司重大技改项目,总投资1300多万元,引进国内外先进的干燥室、芯条拼板机等设备的环保型轻质细木板生产线近日投产.该生产线达到90年代国内先进水平,年产2万m3,10余个品种的细木工板.该生产线生产的环保型轻质细木工板具有阻燃、无昧、无毒、防腐、质轻等特点,深受客户青睐,供不应求,产品直销深圳、广州、厦门、上海等地. ▲新型木材阻燃剂FRW通过鉴定由东北林业大学李坚教授主持的新型木材阻燃剂FRW项目,于近日通过黑龙江省科技厅组织的成果鉴定.鉴定委员会认为,新型木材阻燃剂FRW代表了木材阻燃剂的发展方向,总体技术达到国际领先水平. 阻燃剂是一类能够赋予可燃性材料以难燃性的化学物质.FRW不仅具有优异的阻燃、抑烟、防腐和防虫性能,而且具有基本不吸湿、不着色、无毒、在生产使用过程中不污染环境的优异特性.FRW可用于生产难燃B1级阻燃木质材料,尤其适用于生产有防腐要求的高阻燃、高附加值阻燃木材,其经济效益显著.  相似文献   

8.
磷酸铵盐处理人工林木材的燃烧性能   总被引:11,自引:0,他引:11  
利用锥形量热仪对磷酸铵盐处理的人工林杉木、杨木和马尾松木材的燃烧性能进行研究。结果表明 :磷酸铵盐阻燃处理木材的引燃时间与阻燃剂量有关 ,对 3种木材而言 ,阻燃剂量超过 10 0kg·m- 3,木材才不会被点燃 ;磷酸铵盐对降低木材的释热性能效果明显 ,释热速度降低 ,释热总量减少 ,气相燃烧放热降低 ,而且随着阻燃剂量的增加 ,降低程度更加明显 ;经磷酸铵盐阻燃处理 ,木材失重降低 ,这对保证结构外形的稳定性具有重要作用 ;磷酸铵盐阻燃剂的抑烟作用不理想 ,虽然降低了最强发烟过程的强度 ,但是也提高了最弱发烟过程的强度 ,而且随着阻燃剂量的增加 ,发烟量呈增加的趋势 ;在阻燃研究中 ,阻燃剂在木材内分布状态是一个不可忽视的影响因素 ,特别是木材这种非均质性材料 ,阻燃剂分布的不均匀性将会影响材料整体的耐火性能  相似文献   

9.
FRW阻燃桦木胶合板的性能研究   总被引:6,自引:0,他引:6  
选用东北林业大学木材科学与应用技术研究所研制的专利产品——新型FRW木材阻燃剂处理桦木单板,用以研制阻燃性能优异的FRW阻燃桦木胶合板,并对其各项物理力学性能和阻燃性能进行了测试。研究结果表明:FRW阻燃桦木胶合板的物理力学性能可达到国家标准GB 9846.4—88《胶合板 普通胶合板通用技术条件》的规定,阻燃性能达到日本标准JISD1322-77中规定的难燃一级品的标准和国家标准GA/T42.1《阻燃木材燃烧性能试验方法—木垛法》中的规定的阻燃木材标准。  相似文献   

10.
木材阻燃剂FRW与聚磷酸铵复配的阻燃协同效应研究   总被引:1,自引:0,他引:1  
为开发阻燃效率高、成本低的阻燃剂,将木材阻燃剂FRW与水溶性聚磷酸铵(APP)复配,进行樟子松木材处理和处理试样的热重分析,及热释放速率、总热释放量、有效燃烧热、质量损失和烟气浓度检测。结果表明,与FRW和APP单独处理试样相比,FRW和APP之间具有阻燃协同效应,复配制剂处理试样的成炭率提高,阻燃性能明显提高。  相似文献   

11.

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.  相似文献   

12.

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.  相似文献   

13.
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.  相似文献   

14.

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.  相似文献   

15.

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.  相似文献   

16.

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.  相似文献   

17.

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.  相似文献   

18.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。  相似文献   

19.

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.  相似文献   

20.
Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > TithoniaEuphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号