【作者】 王莉；

【导师】 刘盛全； 郭勇；

【作者基本信息】 安徽农业大学 ， 木材科学与技术， 2019， 硕士

【摘要】 环保与创新印刻了新时代的主题。竹材以其丰富的资源储量和优异的天然性能,正在逐步代替木材在绿色经济,绿色产业等方面创造出巨大的潜能及利用空间。当下中国,正在朝着美丽中国、乡村振兴地长河涌动,为推动竹材的高效及细化利用,振兴竹产区经济发展,竹材和竹基复合材料的研究成为很重要的一环。本文以浙江新昌的毛竹为原料,通过对毛竹顺纹抗弯强度测试后数据的分析,按照弯曲模量不同将竹纤维分为三个模量级,并对不同模量等级的竹纤维及其与聚（3-羟基丁酸酯和3-羟基戊酸酯）（PHBV）混合制备的复合材料的性能进行了研究。另外,为了改善竹纤维/PHBV复合材料的界面结合,提高复合材料各项性能,使用稻壳酸预处理--热解后制备稻壳基SiO₂作为增强材料,利用硅烷偶联剂及稀土偶联剂处理竹纤维及稻壳基SiO₂,探究竹纤维、稻壳基SiO₂和PHBV三元复合材料性能的变化。本文主要从三个方面展开研究:首先,对模量分级竹纤维的各项性能进行分析,探究模量对竹纤维的化学组分,纤维形态,解剖特征及热解性能等的影响。其次,利用竹纤维与PHBV制备复合材料,探究竹纤维含量、模量分级及偶联剂种类对复合材料力学性能、吸水性能及热稳定性等的影响;最后,向竹纤维/PHBV复合材料中添加稻壳基SiO₂,探究稻壳基SiO₂含量、偶联剂处理对不同模量等级竹纤维/PHBV复合材料的影响。通过研究可以得到以下结论:（1）不同模量等级的竹材原料的化学组成存在差异,其中,综纤维素和a-纤维素含量随模量增加而增加,木质素含量则不断降低;竹材原料的气干密度和含水率也随着模量的增加逐渐提高。竹纤维的长度、直径、长宽比和结晶度均随着模量增加不断增加,模量大于13GPa竹纤维（LMBF）的纤维长径比和结晶度分别为228.89和58.89%;随着模量增大,竹纤维的微纤丝角不断减小。竹纤维的热解性能也存在较大的差异,其中,小于11GPa竹纤维（SMBF）的热稳定性最差,这可能是因为SMBF中不稳定的半纤维素含量最高,热解时,在较低温度就能够最先分解。（2）力学性能测试结果表明,纯PHBV的拉伸强度和拉伸模量为17.74MPa和420.16MPa,弯曲强度和弯曲模量为43.61MPa和669.76MPa。竹纤维/PHBV复合材料拉伸强度随着竹纤维含量先提升后降低,在竹纤维含量为10%时,拉伸强度最大为20.37MPa;复合材料的弯曲强度随着竹纤维含量增加不断减小;复合材料的拉伸模量和弯曲模量随着竹纤维含量增加均不断提高。不同模量等级的竹纤维/PHBV的拉伸性能和弯曲性能均随着竹纤维模量的提高而增强。扫面电镜观察发现,利用硅烷偶联剂及稀土偶联剂处理竹纤维,能有效的改善复合材料中纤维与基体的界面结合。与纯PHBV和为处理前的复合材料相比,偶联剂处理后的竹纤维/PHBV复合材料力学性能、吸水性能和热稳定性均有一定程度的改善。（3）傅立叶红外图谱（FTIR）和X射线衍射图（XRD）分析表明,采用酸预处理-550℃热解制备的稻壳基SiO₂为非结晶态的无定形结构的纳米SiO₂,有少量的微米SiO₂存在。稻壳基纳米SiO₂为均匀的球状颗粒,多数聚集成较大的球状簇,只有少数为单个的SiO₂纳米粒子。向竹纤维/PHBV复合材料中添加稻壳基SiO₂,能够有效的提高复合材料的力学性能。当稻壳基SiO₂含量为1.5%时,LMBPC10复合材料力学性能最好,拉伸强度和拉伸模量分别为22.20MPa和624.76MPa;弯曲强度和弯曲模量分别为43.72MPa和1492.39MPa。与纯PHBV和未添加稻壳基SiO₂相比,力学性能均提高,且不同模量等级的竹纤维/PHBV复合材料中添加稻壳基SiO₂,力学性能均提高。（4）利用硅烷偶联剂及稀土偶联剂改性竹纤维及稻壳基SiO₂,复合材料中竹纤维、稻壳基SiO₂与基体PHBV的结合性能明显改善。复合材料的拉伸强度和弯曲强度达到最大值,分别为22.42MPa和47.61MPa。复合材料初始降解温度均高于未处理前的稻壳基SiO₂增强竹纤维/PHBV复合材料,最大降解温度也有提高,复合材料的热稳定性得到了增强。复合材料的吸水率较未处理前的稻壳基SiO₂增强竹纤维/PHBV复合材料也得到了改善。更多还原

【Abstract】 Environmental protection and innovation have engraved the theme of the new era.Bamboo,with its abundant resource reserves and excellent natural properties,is gradually replacing wood to create tremendous potential and utilization space in green economy and green industry.Nowadays,China is moving towards a beautiful country and a prosperous countryside.In order to promote the efficient and refined utilization of bamboo,and promote the economic development of bamboo producing areas,the research of bamboo and bamboo matrix composites has become an important part.In this paper,bamboo fibers from Xinchang,Zhejiang Province were divided into three modulus levels according to their bending modulus,and the properties of bamboo fibers with different modulus levels and their composites mixed with poly（3-hydroxybutyrate and 3-hydroxy valerate）（PHBV）were studied.In addition,in order to improve the interfacial bonding of bamboo fiber/PHBV composites and the properties of the composites,rice husk-based SiO₂ was prepared by pyrolysis of rice husk acid as reinforcing material.Then,bamboo fiber and rice husk based-SiO₂ were treated by silane coupling agent and rare earth coupling agent.The changes of properties of bamboo fiber,rice husk-based SiO₂ and PHBV ternary composites were investigated.This paper mainly studies from three aspects.Firstly,the properties of modulus graded bamboo fibers are analyzed,and the effects of modulus on the chemical composition,morphology,anatomical characteristics and pyrolysis properties of bamboo fibers are explored.Secondly,bamboo fiber and PHBV were used to prepare composite materials.The effects of bamboo fiber content,modulus grading and types of coupling agents on mechanical properties,water absorption and thermal stability of the composite materials were investigated.Finally,rice husk based-SiO₂ was added to bamboo fiber/PHBV composites to explore the effect of content of rice husk-based SiO₂ and the treatment of coupling agents on different modes composites.The following conclusions can be drawn from the study:（1）The chemical compositions of bamboo raw materials with different modulus grades are different.The contents of holocellulose and a-cellulose increase with modulus increasing,while the lignin content decreases.The air-dry density and moisture content of bamboo raw materials also increase with modulus increasing.The length,diameter,aspect ratio and crystallinity of bamboo fibers increase with the increase of modulus.The length-diameter ratio and crystallinity of bamboo fibers with modulus greater than 13 GPa（LMBF）are 228.89%and 58.89%respectively.With the increase of modulus,the microfibril angle of bamboo fibers decreases.The thermal stability of bamboo fibers less than 11 GPa（SMBF）is the worst,which may be due to the highest content of unstable hemicellulose in SMBF,which can be decomposed first at lower temperature during pyrolysis.（2）The results of mechanical properties test show that the tensile strength and modulus of pure PHBV are 17.74 MPa and 420.16 MPa,while the flexural strength and modulus are 43.61 MPa and 669.76 MPa.The tensile strength of bamboo fiber/PHBV composites increases first and then decreases with the increase of bamboo fiber content.When the bamboo fiber content is 10%,the maximum tensile strength is 20.37 MPa;the flexural strength of the composites decreases with the increase of bamboo fiber content;the tensile modulus and flexural modulus of the composites increase with the increase of bamboo fiber content.The tensile and flexural properties of bamboo fibers/PHBV with different modulus grades increased with the increase of modulus of bamboo fibers.Scanning electron microscopy showed that bamboo fibers treated with silane coupling agent and rare earth coupling agent could effectively improve the interface bonding between fibers and matrix.Compared with pure PHBV and pre-treated composites,the mechanical properties,water absorption and thermal stability of bamboo fiber/PHBV composites treated with coupling agent were improved to a certain extent.（3）Fourier infrared spectroscopy（FTIR）and X-ray diffraction（XRD）analysis showed that rice husk-based SiO₂ prepared by acid pretreatment-pyrolysis at 550℃ was amorphous nano-SiO₂ with amorphous structure,and a small amount of micro-SiO₂ existed.Rice husk based nano-SiO₂ is uniform spherical particles,most of which aggregate into larger spherical clusters,and only a few are single SiO₂ nanoparticles.Adding rice husk based-SiO₂ to bamboo fiber/PHBV composites can effectively improve the mechanical properties of the composites.When the content of SiO₂ in rice husk was 1.5%,the mechanical properties of LMBPC10 composites were the best,the tensile strength and modulus were 22.20 MPa and 624.76MPa,respectively,and the flexural strength and modulus were 43.72 MPa and 1492.39 MPa,respectively.Compared with pure PHBV and without rice husk-based SiO₂,the mechanical properties of bamboo fiber/PHBV composites with different modulus grades were improved by adding rice husk-based SiO₂.（4）Bamboo fibers and rice husk-based SiO₂ were modified by silane coupling agent and rare earth coupling agent.The binding properties of bamboo fibers,rice husk-based SiO₂ and PHBV were improved significantly.The tensile strength and flexural strength of the composites reached the maximum,22.42 MPa and 47.61 MPa,respectively.The initial degradation temperature of the composites was higher than that of the untreated rice husk-based SiO₂ reinforced bamboo fiber/PHBV composites.The maximum degradation temperature was also increased,and the thermal stability of the composites was enhanced.The water absorption of the composites was also improved compared with that of the untreated rice husk-based SiO₂ reinforced bamboo fiber/PHBV composites.更多还原