耐候型竹塑复合材料的制备及性能

发布时间：2018-06-03 09:08

  本文选题：竹塑复合材料 + 抗氧化剂　； 参考：《中国林业科学研究院》2017年博士论文

【摘要】：与木材、竹材等实体天然材料相比,木塑复合材料(WPC)的耐候性能相对优异,但在温度和湿度较高的地区,WPC的老化现象也非常严重。WPC耐候性能的优劣对其广泛应用起着重要作用。竹塑复合材料(BPC)以竹材碎料为增强相或填料,是WPC的重要组成部分。本文以BPC为研究对象,系统研究抗氧化剂的组合、配比及含量对BPC抗热氧老化及其他物理力学性能的影响;采用喷雾施加技术将稳定的TiO_2溶胶负载到竹粉或者聚丙烯(PP)表面,重点研究施加工艺和纳米TiO_2添加量对BPC氙灯加速老化和自然老化性能的影响。作为对比试验,还研究了几种商业抗老化剂对BPC性能的影响;采用直接添加表面改性商业纳米颗粒或者以喷雾施加技术将改性纳米颗粒悬浮液负载到竹粉表面,研究了不同施加工艺及纳米颗粒含量对BPC氙灯加速老化性能的影响;提出一种简单快速分离竹材中纤维与薄壁细胞的物理方法,研究了不同细胞单元对BPC氙灯加速老化和自然老化性能的影响。论文主要结论如下:(1)氧化诱导时间(OIT)可作为WPC抗氧化剂快速筛选的重要指标。添加少量的抗氧化剂可显著提高BPC的OIT,是改善BPC抗热氧老化能力的有效途径。添加抗氧化剂可显著提高BPC在热烘箱老化过程中的抗光变色能力、表面抗侵蚀性能以及弯曲性能保留率,同时降低质量损失率。主要原因是抗氧化剂可有效抑制BPC的表面发生热氧老化。添加抗氧化剂对BPC的吸水性能、动态力学性能以及热性能影响较小。基于成本考虑,本研究提出的抗氧化剂体系的优化组合参数为:主抗氧化剂1076与辅抗氧化剂硫代二丙酸二月桂酯(DLTP)组合,配比为2:1,总含量占PP的0.2 wt%。(2)虽然原位合成纳米TiO_2的施加工艺可以保证纳米TiO_2在BPC中具有良好的分散性,但未能改善BPC在氙灯加速老化和自然老化过程中的抗光变色能力,并且加剧了老化过程中BPC的表面侵蚀现象。上述不利影响通常随着纳米TiO_2含量的增加而更加明显。主要原因是作为催化剂的无机酸加速了BPC在老化过程中的降解。改性竹粉和低温干燥改性PP工艺均略增加了BPC在老化过程中的力学损耗,但高温干燥改性PP工艺则在一定程度上降低了BPC在老化过程中的力学损耗。(3)在竹粉表面原位合成纳米TiO_2对BPC的初始物理力学性能起着负面作用,而在PP表面原位合成纳米TiO_2则对BPC的初始物理力学性能无不利影响或起到显著改善作用。低温干燥改性PP工艺在纳米TiO_2含量仅为0.2%和0.5%时,BPC的弯曲强度和模量分别提高近21%和18%,24 h吸水率和吸水厚度膨胀率分别下降近40%和45%。因此,采用低温干燥工艺在PP表面原位合成纳米TiO_2,并且合理控制纳米TiO_2的含量,可显著改善BPC的界面结合性能。(4)施加少量的商业抗老化剂,可轻微提高BPC的初始弯曲强度和模量,其中主抗氧化剂1076与辅抗氧化DLTP组合和有机光稳定剂GW-327的效果要优于表面未经改性的商业纳米ZnO和Ti O_2。同时,抗老化剂对BPC的吸水性能影响较小。商业抗老化剂可提高BPC在氙灯加速老化和自然老化过程中的抗光变色性能,其中抗氧化剂和有机光稳定剂组合的效果最好。同时抗老化剂可降低BPC在老化过程的表面侵蚀和力学性能损失,其中商业纳米Zn O的效果最显著,但是商业纳米TiO_2的改善作用不明显。(5)KH-570硅烷和超声分散协同作用改性可显著降低商业纳米TiO_2和ZnO的粒径分布,并改善纳米颗粒在BPC中的分散性。改性纳米TiO_2和ZnO的加入显著提高了BPC的弯曲强度和模量,降低了BPC的吸水性能。当纳米TiO_2和ZnO含量仅为0.1%并采用喷雾施加方式,BPC的弯曲强度和模量分别提高了23.3%和36.8%,以及28.6%和26.5%。同时,24 h吸水率和吸水厚度膨胀率分别下降了59.7%和66.7%,以及85.2%和52.8%。此外,表面改性商业纳米TiO_2和ZnO还可提高BPC的抗光变色能力,并且在老化初期改性效果更显著。然而,改性纳米颗粒未能显著改善BPC表面的抗侵蚀性能。虽然老化后,含改性纳米颗粒复合材料的弯曲强度和模量下降率高于对照样,但是其绝对平均值依然高于后者。(6)不同细胞单元对BPC的增强作用存在显著差异,其增强作用大小为:竹纤维杨木纤维(竹纤维+薄壁细胞)薄壁细胞。与竹薄壁细胞/PP复合材料相比,竹纤维/PP复合材料的弯曲强度和模量分别提高了26.5%和50.3%,24 h吸水率和吸水厚度膨胀率分别降低了32.8%和24.1%。不同细胞单元填充PP复合材料经氙灯加速老化和自然老化后,表面颜色均发生显著褪色,并且出现一定数量的裂纹,弯曲性能和储存模量降低。竹纤维/PP复合材料在老化过程中弯曲性能的损失远低于竹薄壁细胞/PP复合材料。但是后者在老化过程中的抗光变色性能优于前者。因此,合理调控BPC中竹纤维与薄壁细胞的比例可改善BPC的耐候性能。综上所述,通过施加优选抗氧化剂组合不仅可显著改善BPC的抗热氧老化性能,同时还提高了BPC光氧老化过程中的抗光变色和表面抗侵蚀性能;此外,施加表面改性商业纳米TiO_2和ZnO颗粒可以显著提高BPC的力学性能,降低吸水性;添加有机光稳定剂和合理调控BPC中竹纤维与薄壁细胞的比例,也可一定程度上改善BPC的抗光氧老化性能。
[Abstract]:Compared with solid natural materials such as wood and bamboo, wood plastic composite material (WPC) has relatively excellent weatherability, but in areas with high temperature and humidity, the aging phenomenon of WPC is very serious and it plays an important role in the wide application of.WPC weather resistance. Bamboo plastic composite material (BPC) with bamboo material as reinforced phase or filler is the weight of WPC. In this paper, the effects of combination, ratio and content of antioxidants on thermal oxygen aging and other physical and mechanical properties of BPC are systematically studied with BPC as the research object. The stable TiO_2 sol is loaded onto the bamboo powder or polypropylene (PP) surface by spray application technology, and the application process and the TiO_2 addition of nano TiO_2 to the BPC xenon lamp are studied. The influence of accelerated aging and natural aging properties. As a comparative test, the effects of several commercial antiaging agents on the performance of BPC were also studied. Using direct addition of surface modified commercial nanoparticles or spraying technology to load the modified nanoparticle suspension on the surface of bamboo powder, the different application process and nano particle content were studied for B. The effect of the accelerated aging performance of PC xenon lamp, a simple and rapid physical method for separating fiber and parenchyma cells in bamboo is proposed, and the effects of different cell units on the accelerated aging and natural aging properties of the BPC xenon lamp are studied. The main conclusions are as follows: (1) the oxidation induction time (OIT) can be used as an important index for the rapid screening of WPC antioxidants. Adding a small amount of antioxidants can significantly improve the OIT of BPC and is an effective way to improve the ability of BPC to resist heat and oxygen aging. The addition of antioxidants can significantly improve the anti photochromic ability of BPC in the aging process of hot oven, the surface erosion resistance and the retention of flexural properties, and reduce the quality loss rate. The main reason is that the antioxidant can be effective. The addition of antioxidants has little effect on the water absorption, dynamic mechanical properties and thermal properties of BPC. Based on the cost, the optimum combination parameters of the antioxidant system proposed in this study are: the combination of the main antioxidant 1076 and the auxiliary antioxidant thiopropionic acid two propionate (DLTP), with a ratio of 2:1, and the total content of the antioxidant 1076. The amount of 0.2 wt%. (2) of PP (2), although the application process of in situ synthesis of nano TiO_2, can guarantee the good dispersibility of nano TiO_2 in BPC, but it can not improve the anti photochromic ability of the xenon lamp in accelerated aging and natural aging process, and aggravate the surface erosion of BPC during the aging process. The adverse effects are usually along with nanoscale. The increase of TiO_2 content is more obvious. The main reason is that the inorganic acid as the catalyst accelerates the degradation of BPC during the aging process. The modified bamboo powder and the low temperature drying modified PP process have slightly increased the mechanical loss of BPC during the aging process, but the high temperature drying modified PP process reduces the force of BPC in the aging process to a certain extent. (3) in situ synthesis of nano TiO_2 on the surface of bamboo powder has a negative effect on the initial physical and mechanical properties of BPC, while the in-situ synthesis of nano TiO_2 on the PP surface has no adverse effect or significant improvement on the initial physical and mechanical properties of BPC. The low temperature drying modified PP process is bent when the nano TiO_2 content is only 0.2% and 0.5%, the bending of BPC. The strength and modulus increased by nearly 21% and 18%, 24 h water absorption and water absorption thickness decreased by nearly 40% and 45%., respectively. Therefore, nano TiO_2 was synthesized by low temperature drying technology on PP surface, and the content of nano TiO_2 could be controlled reasonably. (4) a small amount of commercial anti aging agent could be applied slightly. The initial bending strength and modulus of BPC, including the combination of the main antioxidant 1076 with the auxiliary antioxidant DLTP and the organic light stabilizer GW-327, is better than the surface unmodified commercial nanoscale ZnO and Ti O_2., while the anti aging agent has little effect on the water absorption of BPC. The commercial antiaging agent can increase the accelerated aging and natural aging of the xenon lamp in BPC. The anti photochromic performance of the process is the best combination of antioxidants and organic light stabilizers. At the same time, anti aging agent can reduce the surface erosion and mechanical properties loss of BPC in aging process, of which commercial nano Zn O has the most significant effect, but the improvement of commercial nano TiO_2 is not obvious. (5) KH-570 silane and ultrasonic dispersion synergy. The modification can significantly reduce the particle size distribution of commercial nanoscale TiO_2 and ZnO and improve the dispersion of nano particles in BPC. The addition of modified nano TiO_2 and ZnO significantly improves the bending strength and modulus of BPC and reduces the water absorption properties of BPC. When the nano TiO_2 and ZnO content is only 0.1% and the spray is applied, the bending strength and modulus of BPC can be obtained. The increase of 23.3% and 36.8%, as well as 28.6% and 26.5%., 24 h water absorption and water absorption thickness expansion rate decreased by 59.7% and 66.7% respectively, as well as 85.2% and 52.8%.. The surface modified commercial nano TiO_2 and ZnO can also improve the anti photochromic ability of BPC, and in the early aging, the modification effect is more significant. However, the modified nano particles can not be used. The corrosion resistance of BPC surface was significantly improved. Although the bending strength and modulus of the modified nano particle composite were higher than the same after aging, the absolute mean value of the composite was still higher than that of the latter. (6) there were significant differences in the enhancement of BPC by different cell units. The enhancement effect was bamboo fiber poplar fiber (bamboo fiber +). Parenchyma cells) parenchyma cells. Compared with bamboo parenchyma /PP composites, the flexural strength and modulus of bamboo fiber /PP composites increased by 26.5% and 50.3% respectively. The water absorption and water absorption thickness of 24 h decreased by 32.8% and 24.1%., respectively, of PP composites filled with the xenon lamp to accelerate aging and natural aging after xenon lamp accelerated aging and natural aging. In the aging process, the loss of flexural properties of bamboo fiber /PP composites is much lower than that of bamboo parenchyma cell /PP composites. However, the photochromic properties of the latter in the aging process are better than those of the former. Therefore, the rational control of bamboo fiber and thinning in BPC is made. The ratio of parietal cells can improve the weatherability of BPC. To sum up, the application of optimal antioxidant combination not only significantly improves the anti thermal oxygen aging properties of BPC, but also improves the anti photochromic and surface anti-corrosion properties of BPC in the light oxygen aging process. Furthermore, the application of surface modified commercial nanoscale TiO_2 and ZnO particles can significantly improve B The mechanical properties of PC reduce water absorption, adding organic light stabilizer and reasonably regulating the proportion of bamboo fiber and parenchyma cells in BPC can also improve the anti photooxidation aging performance of BPC to a certain extent.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB332
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本文编号：1972234