糠醇树脂改性毛竹材增重率与物理力学性能的相关性

通过调控糠醇树脂处理液的质量分数,制备不同增重率(WPG)的糠醇树脂改性竹材,研究增重率对改性竹材尺寸稳定性、吸水率、表面润湿性、抗弯强度和弹性模量、热降解性能等的影响。结果表明,随着增重率的增加,改性竹材吸水率和接触角呈先快速降低、后降幅变缓的趋势;抗胀缩系数(ASE)逐渐增大,当增重率达到20%以后,增大趋势变缓;竹材抗弯强度下降,弹性模量小幅升高;改性竹材残炭率增大,且增重率与残碳率呈现较好的线性相关性。因此,可通过合理控制糠醇树脂改性竹材的增重率,调控糠醇树脂改性竹材的综合性能。     

竹材苯酚液化及胶黏剂制备工艺

采用单因素试验和正交试验研究了竹材加工剩余物的苯酚液化工艺,并进一步研究了竹材苯酚液化产物-甲醛树脂胶黏剂(BPF)的制备工艺和性能。试验结果表明:竹材苯酚液化过程中,液化温度对液化效果的影响最为显著,其次是液比和液化反应时间,催化剂用量2%~4%范围内对液化效果影响不大。竹材加工剩余物苯酚液化的优选工艺为:液固比值3.5、催化剂用量4%、液化温度145℃、液化时间60 min;在此工艺下竹材液化率为99.1%。胶黏剂制备过程中,竹材苯酚液化物与甲醛溶液(甲醛质量分数为37%)的合理质量比为100∶164.8~199.5,其中以100∶182.1较佳。BPF的固化温度低于普通酚醛树脂胶黏剂(PF),因而可在较低温度下固化良好,在130℃或140℃热压温度条件下,用其制备的胶合板的胶合强度均比较理想,热压温度为140℃时的试验结果更佳。     

酚醛树脂改性竹材的物理力学性能及其微观形貌的荧光表征

为考察低分子量酚醛树脂改性工艺对竹材性能及其微观形貌的影响,采用常压浸渍法,以低分子量酚醛树脂的固含量和浸渍时间作为变量,分析这2个因素对改性前后竹材的增重率、密度、尺寸稳定性等性能的影响;采用荧光跟踪技术表征酚醛树脂在竹材微观结构上的分布。结果表明,随着固含量和浸渍时间增加,改性后竹材增重率和密度增大,在浸渍24 h后趋于平缓;抗弯强度上升趋势与增重率相似。同未处理竹材相比,抗弯强度明显增大;抗湿胀率明显提高。微观形貌的荧光分析表明酚醛树脂在竹材上主要分布在外表面,在竹材表面形成一层连续的酚醛树脂膜。随着固含量和浸渍时间的增加,酚醛树脂在竹材界面上的平均渗透深度越大,形成的酚醛树脂膜越厚。     

丙烯酸改性松香的合成工艺研究

松香在一定的条件下与丙烯酸发生Diels-Alder双烯加成反应,本文对影响反应的各因素:反应温度、催化剂的质量用量、反应时间、原料配比等进行了系统研究;通过正交试验,确定了松香与丙烯酸的最佳反应工艺条件:反应温度230℃,催化剂的质量用量为松香质量的3.0%,反应时间3.5 h,松香与丙烯酸的质量用量配比4.5∶1.经过3次稳定性试验证明,所得反应条件为最佳合成工艺,加成物含量均在86%左右.     

加压条件下制备系列松香一元醇酯

以固体酸ZnO为催化剂,在加压条件下使松香与不同碳链长度的一元醇酯化反应,制备松香甲酯、正丁酯和正辛酯,探讨反应温度、反应压力、催化剂用量、原料配比及反应时间等对酯化反应的影响。结果表明:适宜的酯化反应工艺条件:①松香甲酯化反应:反应温度220℃,反应压力5.5 MPa,催化剂用量1%,醇酸比25∶1,反应时间5 h;②松香丁酯化反应:反应温度220℃,反应压力3.5 MPa,催化剂用量1%,醇酸比8∶1,反应时间5 h;③松香辛酯化反应:反应温度210℃,反应压力2.0 MPa,催化剂用量1%,醇酸比4∶1,反应时间5 h。加压条件下可以显著促进松香与一元醇的酯化反应,反应时间比常压下大大缩短,酯化率明显提高,压力对酯化反应影响效果与一元醇的碳数成正比,即辛醇>丁醇>甲醇。工业上常用的固体酸ZnO催化剂可用于松香与系列一元醇的加压酯化反应。     

马尾松木材联苯菊酯防腐浸泡工艺研究

为探索低成本、高效率的马尾松木材联苯菊酯防腐浸泡工艺,采用正交试验法,研究浸泡工艺对马尾松锯材增重率和联苯菊酯载药量的影响。结果表明：联苯菊酯浓度对增重率和载药量的影响最大,其次为浸泡时长,最后为浸泡深度,其中联苯菊酯浓度和浸泡时间对增重率和载药量有显著性影响。综合企业实际生产,本研究以时间为优化条件,确定的较优工艺为：联苯菊酯浓度0.05%、浸泡时长6 h、浸泡深度为50 mm。以此工艺浸泡的马尾松锯材,联苯菊酯载药量为0.059%,满足AS/NZS 1604.1:2021 Preservative-treated wood-based products Part 1:Products and treatment对联苯菊酯的限值要求。     

天然苯甲醛合成新工艺

实验利用丙二醇做溶剂,NaHCO_3为催化剂,研究肉桂醛水解制苯甲醛的工艺条件。通过单因素试验和正交试验得出反应温度、催化剂用量、H_2O_2的用量和反应时间对得率有显著影响,最佳条件:反应时间2.5 h,反应温度60℃,肉桂醛和NaHCO_3的摩尔比1∶0.15,肉桂醛和H_2O_2的质量比1∶20。苯甲醛平均得率81.85%。     

不同浸渍处理方式对毛竹淀粉含量的影响

采用常压水浸渍、真空水浸渍、常压碱液浸渍3种浸渍方式对毛竹进行处理,探讨不同浸渍方式对毛竹中淀粉含量的影响。研究结果表明:竹材内淀粉含量随着浸渍处理时间的延长而减少,经过120 h浸渍后,毛竹中的淀粉含量从高到低依次为常压水浸渍、真空水浸渍、常压碱液浸渍。在相同碱液浓度的条件下,毛竹中的淀粉含量随着浸渍时间的增加而减小。经过120 h的碱液浸渍处理,碱液浓度最大(1.5%)的组溶解抽提出来的淀粉含量最多。真空水浸渍可以降低毛竹中的淀粉含量,但不同真空压力之间对淀粉含量的影响不大,真空压力对淀粉含量的影响有效时间为72 h以内,超过72 h淀粉含量减少缓慢。     

屏蔽法改性木粉制备生物基塑料的研究

以胡桑枝条木粉为原料,木粉经球磨预处理后,分散于盛有一定量蒸馏水的烧杯中,之后将配制的酒石酸铁钠(Fe TNa)溶液倒入其中,在4℃下润胀一段时间后,于捏合机中捏合5 h后烘干,最后在双螺杆挤出机中与一定量的甘油混合挤出制备生物基塑料,研究了润胀时间、球磨木粉用量和试剂用量对改性产物力学性能的影响。结果表明:以木质纤维类生物质为原料,Fe TNa络合物和甘油为屏蔽剂可制备出注塑级生物基塑料,实现木质纤维的全组分高效利用;在屏蔽改性过程中未引入新的官能团;经屏蔽改性处理后,纤维素结晶度降低,纤维素分子链间作用力降低,改性产物热稳定性下降。在较佳工艺条件下,所制备的生物基塑料的弯曲强度为20.7 MPa、拉伸强度为12.9 MPa、断裂伸长率为3.2%,热塑性和力学性能较佳。     

碱液处理对改善竹束液体渗透性能的研究

竹材液体渗透性是影响竹材改性处理效果的重要因素。采用碱液处理(80℃,质量分数1%～4%,处理时间1～4 h)竹束,分析工艺参数对竹束质量损失率、染液质量增加率的影响,解析处理前后竹材微观构造、孔隙结构参数的变化情况,揭示碱液处理改善竹材液体渗透性的机理。结果显示,碱液质量分数及处理时间对竹束质量损失率影响显著。碱液质量分数2%、处理时间1 h条件下,可以在保证竹束液体渗透性改善效果和处理效率的同时,使竹束质量损失率较小。扫描电镜观察发现,碱液处理后竹束导管等细胞产生明显皱缩,导管壁上规则的网状孔隙结构产生破坏,竹材部分闭塞孔隙结构重新打开,竹纤维产生剥离现象。压汞测试分析发现,碱液处理后竹材显微构造变化会导致竹束内部孔体积增大;细胞壁内部孔径40 nm左右的孔隙增多,孔径增大。竹束纤维细胞剥离可增加液体渗透通道,缩短液体渗透路径,降低液体渗透压,提升液体渗透效率。孔体积的增大导致流体在竹束内部的渗透量增大,孔径增大导致流体在竹束内部渗透的效率提高。竹束细胞壁内部小尺寸孔隙的增加,使流体有更多的渗透路径向细胞壁内部渗透,易于实现深度均匀渗透。     

Potassium acetate-catalyzed acetylation of wood at low temperatures I: simplified method using a mixed reagent

Ezomatsu wood blocks were acetylated in a mixture of acetic anhydride and acetic acid containing excess potassium acetate (KAc). The mixture method enabled rapid acetylation at 120°C: a 20% weight gain (weight percent gain; WPG) was achieved within 30 min while the WPG did not exceed 18% after 120 min of conventional uncatalyzed acetylation. At 40°C, however, a satisfactory WPG was not achieved with the mixture method because both the wood swelling and KAc concentration in the reagent solution were limited at that temperature. In addition, the antiswelling efficiency attained by the mixture method was irregularly low, probably because of nonuniform reaction involving shrinkage of the cell lumina. These results suggest that the mixture method is not advantageous for low-temperature acetylation, whereas it enables simple and rapid acetylation at high temperature.     

白夹竹防护处理工艺及对力学性能的影响

以白夹竹为试验材料,采用环保防霉剂对其进行加压防护处理,分析药剂浓度、加压时间、浸渍温度对防腐防霉处理效果的影响,比较各工艺条件载药量的差别,并分析防腐防霉处理工艺对竹材力学性能的影响。结果表明:药剂浓度是影响白夹竹防腐防霉处理效果的主要因素;白夹竹较为理想的防腐防霉处理工艺为药剂浓度1.5%,加压时间30min,浸渍温度120℃;防腐防霉处理使白夹竹主要力学性能略微下降,但处理前后差异不显著。     

压缩工艺对毛白杨脲醛树脂胶浸注改性效果的影响研究

对毛白杨木材浸注脲醛树脂胶制备压缩改性木材中的主要影响因素及相关工艺参数进行初步探索与试验,并在实验结果基础上讨论了各因素对制作工艺及其性能的影响。结果表明:①影响板材性能由主到次因素的顺序为压缩率-热压时间-热压温度;②在试验参数范围内较好的工艺参数为热压温度140℃、热压时间20min、压缩率50%;③在试验参数范围内热压时间对试件增重率、含水率、树脂留存率影响显著,而热压温度对试件增重率影响显著,压缩率对试件密度、变形回复率、吸水厚度膨胀率影响显著。     

Preparation of acetylated wood meal and polypropylene composites I: acetylation of wood meal by mechanochemical processing and its characteristics

Wood meals of Sugi (Cryptomeria japonica D.Don) passing 2.0 mm and retained on 1.0 mm mesh screens were milled along with acetic anhydride (AA) and pyridine as a catalyst in a high-speed vibration rod mill at ambient temperature. The weight percent gain (WPG) of the chemically modified wood was calculated based on the yield after washing with deionized water. The effects of amounts of AA and catalyst added, pulverization time, and saponification of the acetylated wood on WPG were examined. In addition, FT-IR analysis, and water vapor adsorption and desorption tests were performed as functions of the WPG. Increases in WPG, the acetyl contents of the acetylated wood after saponification, changes in the FT-IR spectra after pulverization, and the water vapor sorption isotherms showed that the one-step acetylation systematically modified the hydroxyl groups of the wood into acetyl groups. Up to 38 % WPG was obtained at 100 phr AA and 15 phr catalyst, and 120 min pulverization. Pulverization time and the amounts of AA and catalyst added to the wood meals could be adjusted to obtain acetylated wood meal with the desired WPG. These demonstrated that the mechanochemical acetylation is a method to prepare acetylated wood meals with high WPG at less reaction time and required AA addition.     

超声-抗菌石蜡处理对竹材防霉性能的影响

为增强竹材的防霉性能,以毛竹作为研究材料,先对竹材进行超声预处理,制备了抗菌石蜡乳液对竹材进行浸渍改性处理,并对改性后竹材的含水率、吸水率、防水效率和防霉性能进行了测试。选用天然植物中的2-羟基-1,4萘醌作为防霉剂,选用司班80(Span80)和吐温80(Tween80)作为58号食品级石蜡的复配乳化剂,考虑了亲水亲油平衡(HLB)值对石蜡乳化的影响,制得稳定的抗菌石蜡乳液。利用抗菌石蜡乳液对超声处理后的竹片进行浸渍处理,采用L₉(3³)正交试验设计,以石蜡乳液固含量、干燥温度和干燥时间为因子,以含水率和浸泡768 h后的防水效率为测试指标。结果表明,当Span80和Tween80的质量比为2∶3、HLB值为10.72时,石蜡乳液的稳定性最好。对改性后竹材含水率的影响从大到小依次是石蜡乳液固含量、干燥温度、干燥时间。当石蜡乳液固含量为5%、干燥温度为70℃、干燥时间为1.5 h时,试件含水率最低为4.11%。浸泡768 h后对竹材防水效率影响从大到小依次是干燥温度、石蜡乳液固含量、干燥时间;当石蜡乳液固含量为15%、干燥温度为40℃、干燥时间为1.5 h时,试件防水效率最高为32.15%。超声处理并不能有效阻止竹材的霉变,超声联合抗菌石蜡乳液改性后的竹材防霉性能有明显提高,改性竹材在28 d霉变试验后表面无菌丝、霉点。     

苯甲基化木材溶液制备聚氨酯树脂工艺条件的研究

用苯甲基化木材溶液与甲苯二异氰酸酯(TDI)反应制备聚氨酯树脂。通过考察TDI的加入量、增塑剂种类、催化剂用量和木粉增重率等因素对制得的聚氨酯涂膜性能的影响，得出了用苯甲基化木材制备聚氨酯树脂的最佳工艺条件：增重率为63％～80％的改性木粉8g、TDI 14～16mL、二月桂酸二丁基锡0．4％、分子质量为400的增塑剂。在此条件下，涂膜的干燥时间、铅笔硬度、附着力等参数基本可以满足聚氨酯涂料国家标准(GB 1986)的要求。     

木聚糖改性类荷叶纳米结构超疏水竹材尺寸稳定性研究

从玉米芯中提取的木聚糖用于改性竹材,提高竹材的尺寸稳定性;然后以新鲜荷叶和聚二甲基硅氧烷（PDMS）为模板,在改性的竹材表面利用软印刷法制备类荷叶竹材表面。采用抗胀（缩）率（ASE）,阻湿率（MEE）,增重率（WPG）和增容率（B）对竹材的尺寸稳定性进行了测试,并通过水接触角（WCA）、扫描电镜（SEM）和原子力显微镜（AFM）分析了类荷叶竹表面的超疏水性能和微观结构。研究发现,随着木聚糖含量的增加,改性后竹材的抗溶胀性和WPG相应增加,木聚糖对材竹的增容效果更好。木聚糖在一定程度上改善了竹子的尺寸稳定性。此外,木聚糖处理改性后的类荷叶竹各向异性和超疏水性得到显著改善。本研究为竹材尺寸稳定性及竹材疏水性改良机理的研究奠定了基础。     

Effects of previous solvent exchange on acetylation of wood

Wood specimens were prepared in a swollen state using solvent exchange (PS) treatment. The swollen wood specimens were acetylated using acetic anhydride by heating at 80–120°C. At the beginning of heating, the weight percent gain (WPG) of PS-treated wood was greater than that of conventionally acetylated wood. This acceleration effect of the PS treatment was explained by the introduction of treating reagent into the wood polymers where the intermolecular hydrogen bonds were previously broken. On the other hand, the PS treatment had no influence on the final WPG and moisture sorption characteristics of acetylated wood. This indicated that the intrinsic reactivity of wood constituents was unaffected by the PS treatment. The acetylation of PS-treated wood produced greater bulking and slightly higher dimensional stability than that in the case of conventional acetylation at the same WPG. It was speculated that the expansion of cell lumina due to the PS treatment resulted in greater bulking on acetylation and lesser swelling of acetylated wood with moisture sorption.     

Non-uniform reaction of solid wood in vapor-phase acetylation

To clarify the non-uniform reaction of wood during vapor-phase acetylation, spruce wood blocks were exposed to acetic anhydride vapor at 120°C. Weight percent gain (WPG) due to the acetylation was estimated from the equilibrium moisture content at 25°C and 60% relative humidity. The diffusion of reagent vapor was much faster along the longitudinal direction than along the tangential direction. When the end surface was exposed to the reagent vapor for 48?h, 20% WPG, which was known to have sufficient stability and durability, was achieved to a depth of 42.5?mm. However, this depth was only 6.5?mm when the straight-grain surface was exposed. The reaction profiles were successfully approximated using reaction time (t), reaction rate (k′), delay time (t _d′), and a parameter n reflecting the diffusion-controlled reaction. The t _d′ value increased almost linearly as the depth increased from the surface. The k′ value ranged from 0.02 to 0.03?h^?1, regardless of the depth and direction of diffusion. The n value decreased with an increase in the depth and approached 1–2. These values enabled the prediction of the degree of acetylation at any reaction time and positions of wood during vapor-phase acetylation.     

Fe3+/TiO2改性竹炭催化降解甲醛

以竹炭为载体,采用溶胶-凝胶法制备TiO2溶胶,并掺杂Fe3+,经浸渍过滤和高温焙烧制备Fe3+/TiO2改性竹炭,并用SEM和XRD进行表征.采用单因素和正交组合试验探究焙烧温度、Fe3+掺杂量、负载层数三因子对改性竹炭去除甲醛效果的影响,从而确定制备Fe3 +/TiO2改性竹炭的最优工艺.从SEM和XRD图谱表征可知,竹炭、TiO2溶胶和Fe3+三者之间能够较好地复合在一起.三因子中焙烧温度因子最为显著,其次是负载层数和Fe3+掺杂量.制备Fe3+/TiO2改性竹炭最佳工艺参数为焙烧温度450℃、负载层数2层、Fe3+掺杂量1％,其对甲醛的去除率达到61％,均高于单一竹炭或TiO2/竹炭复合对甲醛的去除率,表明三者复合具有协同促进作用.