【作者】 李守海；

【导师】 储富祥；

【作者基本信息】 中国林业科学研究院 ， 林产化学加工工程， 2011， 博士

【摘要】 随着世界石油资源的日益短缺,各国科研人员开始探索可以部分替代石油制备高分子材料的其它资源。以可再生的非粮植物资源为原料开发高分子材料已受到密切关注。橡实,是泛指除板栗外的壳斗科植物果实的统称。橡实是重要的野生林业淀粉资源,全世界壳斗科植物共有900多个品种,我国约有300多个品种,年产橡实约60~70亿kg。但橡实存在各种自身缺陷,橡实淀粉支链度高难以消化吸收,橡实果仁中含有较多的单宁不易除净,由此丰富的橡实资源大量废弃,非粮橡实资源的开发具有广阔的市场前景。本文先对橡实淀粉、橡实果仁和橡实果壳三种原料进行了理化分析,对研究中所采用三种原料的各个组分的含量具有初步的认知,以期为开发橡实资源的不同用途提供依据。研究发现橡实果仁中含有69.40 %的淀粉,其中支链淀粉含量高达59.01 %,单宁含量为8.34 %;橡实淀粉原料的淀粉含量高达87.21 %,其中支链淀粉含量高达68.56 %,单宁含量为5.67 %;除此之外,橡实果仁和橡实淀粉中还含有部分可溶性糖、粗脂肪、粗纤维和蛋白质。橡实果壳中含有大量的纤维素、半纤维素、木质素和单宁,其中综纤维素含量高达56.69 %,酸不溶木素含量为32.45 %,单宁含量达到9.26 %。研究结果表明橡实果仁含有较多的淀粉,故可参照制备淀粉基材料的方法制备橡实果仁基复合材料;橡实果壳与木材的成分类似,故橡实果壳是制备木塑复合材料的良好原料;三种不同原料中均含有大量的单宁,会对其材料的综合性能产生一定影响。本文采用糊化—氧化—缩聚的方法制备了橡实淀粉基木材胶黏剂;采用挤出塑化和共混合金化技术方法分别制备了热塑性橡实淀粉和热塑性橡实淀粉/聚己内酯复合材料;采用共混合金化技术方法制备了橡实果壳/低密度聚乙烯复合材料和橡实果壳(果仁)/聚乳酸复合材料;采用三聚氰胺改性脲醛(MUF)树脂为原料制备了新型MUF阻燃泡沫材料,同时并采用共发泡技术制备了橡实果壳填充型MUF阻燃泡沫材料。论文的主要研究内容和结论如下:1.橡实淀粉基木材胶黏剂及其复合胶黏剂的研究以橡实淀粉为原料,优化制备工艺,制得缩聚氧化改性橡实淀粉胶主剂,为改善主剂的耐水性能和胶合性能,选用MDI和RW-20进行疏水增强改性,添加一定量的MDI和RW-20均可明显改善橡实淀粉胶的耐水性能和胶合干强度,虽然MDI改性的主剂耐63℃水浸时间低于60 min,但是RW-20改性主剂的耐63℃水时间大大超过180 min,胶合湿强度接近国家II类胶合板水平,文中亦对改性机理进行了分析。采用改性淀粉胶主剂/酚醛树脂复合胶制备的胶合板的胶合湿强度随酚醛树脂的含量的增加逐渐增加,当含量高于60 %时,胶合板性能达到国家II类板水平。添加一定量橡实淀粉可明显提高酚醛树脂胶的胶合湿强度,制备的橡实淀粉填充改性PF树脂亦可达到国家II类胶合板水平。2.热塑性橡实淀粉的研究以橡实淀粉和不同增塑剂为原料,采用双螺杆共挤出塑化法制备了不同热塑性橡实淀粉(TPAS)。文中分析了乙二醇、丙三醇、乙醇胺、二乙醇胺、三乙醇胺5种不同增塑剂对TPAS材料的力学性能、吸水性能、热性能影响。研究表明:TPAS材料具有较强的吸水性和吸湿性。TPAS材料的力学性能因增塑剂种类和含量的不同以及吸湿性的不同而存在较大差异。扫描电镜分析(SEM)和X射线衍射分析(XRD)分析表明:此5种增塑剂均可较好地使橡实淀粉塑化,橡实淀粉由颗粒状结构变成均一的连续相结构,增塑剂的加入使原淀粉的结晶结构完全转变。动态机械热分析(DMA)和热重分析(TGA)研究结果表明:不同增塑体系对于TPAS的增塑效果和热稳定性亦有所相同。DMA研究结果表明不同增塑体系对于TPAS的增塑效果有所相同;TGA研究结果表明不同增塑体系对于TPAS的热稳定性亦有所相同。3.热塑性橡实淀粉/聚己内酯复合材料的研究采用熔融共混合金化技术制备了热塑性橡实淀粉(TPAS)/聚己内酯(PCL)二元复合材料。研究表明,较乙醇胺和三乙醇胺三种不同增塑复合体系相比,丙三醇增塑复合体系(GTPAS)的力学性能明显优越,TPAS基复合材料的力学性能要优于热塑性橡实果仁基复合材料,橡实淀粉基复合材料的力学性能接近于玉米淀粉基复合材料,复合材料的吸湿性大大影响材料的力学性能。DMA研究结果表明,GTPAS/PCL复合材料共混物相互之间的热力学相容性较差,SEM研究结果进一步验证DMA的研究结果。复合材料具有较强的吸水性,随PCL含量的降低吸水性能逐渐增强,但丙三醇增塑复合材料表现出优异的力学性能,当PCL含量达到50 %时,复合材料的拉伸强度亦达到14 MPa,断裂伸长率达到1750 %,已接近纯PCL。土埋降解实验表明复合材料具有良好的生物可降解性能。4.橡实果壳/低密度聚乙烯复合材料采用熔融共混合金化技术制备了橡实果壳(AH)/低密度聚乙烯(LDPE)二元复合材料。随橡实果壳含量的增加复合材料的力学性能逐渐降低。文中研究了EAA、EVA和PE-g-MAH三种不同相容剂对橡实果壳基复合材料的影响。研究结果表明PE-g-MAH是一种最优良的相容剂,当PE-g-MAH用量为5 %时,复合材料的拉伸强度比未添加相容剂的提高了77.6 %,弯曲强度提高了83.8 %,抗冲击强度基本保持在5.0 kJ/m2。另外,EAA和EVA亦在不同程度上改善了复合材料的力学性能。复合材料冲击断面的SEM分析表明相容剂的添加改善了橡实果壳与LDPE基体材料的相容性。DMA和DSC测试结果亦表明相容剂的添加能有效改善两相之间的界面相容性,并从根本上改变基体材料LDPE的性质。5.橡实粉/聚乳酸复合材料的研究采用共混合金化技术制备了橡实/聚乳酸(PLA)复合材料,并采用注塑和模压法制备了两种复合材料测试样条。复合材料微观结构的SEM研究表明复合材料橡实颗粒和PLA基体之间具有较差的相容性。橡实果壳基复合材料的力学性能略微优于橡实果仁基复合材料。钢纤维网增强橡实果壳基复合材料具有优异的抗冲击性能,能达到10 kJ/m2。复合材料具有优异的疏水性能、力学行能、熔融流动性能和生物可降解性能。即使复合材料中的橡实粉含量达到70 %,复合材料仍具有优异的综合性能。当橡实果壳含量为50%时,复合材料的弯曲强度为72.21 MPa,拉伸强度为48.56 MPa,抗冲击强度为1.51 kJ/m2。当橡实果壳基复合材料中添加一定量硅烷偶联剂KH-550,4,4-二苯基甲烷二异氰酸酯(MDI)和聚乳酸接枝马来酸酐时,复合材料的综合力学性能并未得到明显改善。DSC、DMA和TG分析表明,不同橡实量的添加在不同程度上改变了基体材料的性质,使得基体材料的结晶度、玻璃化转变温度、熔融温度、熔融焓、热分解温度均发生明显变化。6.橡实果壳填充型MUF阻燃泡沫材料采用三聚氰胺改性脲醛(MUF)树脂为原料制备了新型MUF阻燃泡沫材料,调整并改善发泡工艺,确定了最佳MUF树脂中固含量、最佳表面活性剂添加量、最佳固化剂添加量和最佳发泡剂添加量。建立了MUF泡沫表观密度–力学性能模型,结果表明MUF泡沫力学性能与密度之间具有良好的指数关系。文中采用共发泡技术制备了橡实果壳填充型MUF阻燃泡沫材料,随橡实壳添加量的增加,其阻燃性有所提高,但其力学性能和耐碎性能大大降低,为改善其综合性能,文中又研究了木浆纤维增强橡实壳/MUF复合泡沫材料和J-100交联改性复合泡沫材料,这两种不同的物理增强和化学改性方式均能不同程度的增加复合泡沫的力学性能。J-100交联改性能大大提高复合泡沫的力学性能和耐碎性能,当添加极其少量的J-100型交联剂时,复合泡沫材料的力学性能可提高近10倍。其相对掉渣率降低为原来的半数,复合泡沫的阻燃性能亦略微有所提高。红外、13C-NMR核磁分析验证了交联改性反应原理的复杂性。更多还原

【Abstract】 With the growing shortage of crude oil resources in the world, considerable research efforts have been devoted to the formulation and characterization of new natural non-food resources based polymeric materials that can partly replace crude oil resources in the past decades. Acorn is an important natural starch source from wildlife forestry, and it serves as the seed for oak trees regeneration. There are about 900 known oak tree species throughout the world, of which, about 300 species can be approximately found in China, with an annual output of about 6.0-7.0 billion kg. While the content of amylopectin of acorn kernel is too high to be easily digested, furthermore, the large amount of low toxic tannin acid is difficult to be removed from acorn kernel. As a result, abundant acorn resources have being abandoned. Therefore, the development of non-food acorn resources posesses a potential marketing prospects.In the thesis,we firstly optimized the design of physical and chemical analysis of acorn starch, acorn kernel and acorn hull raw materials, and obtained a rudimentary knowledge of component content of these three kinds of raw materials to provide a basis for developing different usages. The results showed that acorn kernel contained 69.40 % starch content of which the amylopectin content was up to 59.01 %; the tannins content was 8.34 %. Acorn starch raw materials contained 87.21 % starch content of which the amylopectin content was up to 68.56 %; the tannins content of acorn starch raw materials was 5.67 %. In addition, a certain amount of soluble sugar, crude fat, crude fiber, and proteins were also included in acorn kernel and acorn starch raw materials. Acorn hull contained a large amount of cellulose, hemicellulose, lignin and tanninsof which the content of holocellulose mounted to 56.69 %; the content of acid-insoluble lignin was up to 32.45 %; the tannins content was 9.26 %. The results indicated that acorn kernel had a high content of starch, resulting in exploiting the acorn kernel-based materials according to those methods for preparation of starch-based materials. The components of acorn hull were similar to wood components so that it could be regarded as a superior materials for preparing wood plastic composites (WPC). The existence of amount of tannins in these three acorn raw materials could bring up a certain effect on acorn-based composites.Acorn starch-based wood adhesives were prepared with the method of gelatinization-oxidation-polycondensation. Thermoplastic acorn-starch (TPAS) and TPAS/Polycaprolactone (PCL) composites were prepared by utlizing a co-extrusion plasticized technique and a blending alloy technique with a twin-screw extruder.Acorn hull(AH)/Low Density Polyethylene (LDPE) composites and Acorn hull (kernel)/ Poly(1actic acid) (PLA) composites were also produced using the blending alloy technique. New foams were prepared by adopting Melamine-Urea-Formaldehyde (MUF) resin as raw materials, and acorn hull-filled type composite foams were also prepared with the co-foaming technique. Our major results and discovery were described as follows.1. Acorn starch-based adhesives and its composite adhesivesMain agents of acorn starch-based adhesives were prepared with the method of gelatinization- oxidation- polycondensation. The preparation technology was further optimized. MDI and RW-20 were added into the main agents in order to improve water resistance and mechanical properties. The results demonstrated that the addition of MDI and RW-20 could improve water resistance and tensile dry strength of plywood to varying degrees. While the water resistance time at 63 oC of main agents of adhesives modified by MDI were all below 60 min, the water resistance time with the RW-20 modification could last more than 180 min. The tensile wet strength approached to the level of national II plywood. The modifying mechanisms of MDI and RW-20 were investigated and described in this thesis. The gluing properties of composite adhesives of main agents of acorn starch-based adhesives and phenolic resin increased with an increase of phenolic resin content. The tensile wet strength exceeded the level of national II plywood. What’s more, adding a certain amount of acorn starch into phenolic resin could improve its comprehensive properties. The product of phenolic resin filled with acorn starch can also reach the level of national type II plywood.2. Thermoplastic acorn-starch (TPAS)Thermoplastic acorn-starch(TPAS) was produced by blending acorn-starch and different plasticizers with a twin-screw co-extrusion plasticized technique.The effects of different plasticizers such as glycol, glycerol, monoethanolamine, iminobisetnanol and triethanolamine on mechanical, thermal and hydrophobic properties of TPAS were studied in this part. The results demonstrated that TPAS materials showed strong water and moisture absorption properties. The mechanical properties of TPAS materials varied with the type and content of plasticizer, content of plasticizer as well as the moisture absorption rate of TPAS. The results showed that these five different plasticizers had a better performance for plasticizing acorn starch as characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Meanwhile the native acorn starch granules were proved to transfer to a homogeneous continuous phase with the transformation of all crystalline structure. Dynamic mechanical thermal analysis (DMA) results revealed that the plasticized effect of TPAS materials also varied with different plasticized system. Thermogravimetric analysis (TGA) results showed that thermal stability of TPAS materials also varied with different plasticized system.3. Thermoplastic acorn-starch (TPAS)/Polycaprolactone (PCL) compositesThe binary composites of TPAS/ PCL were prepared by a blending alloy technique with a twin-screw extruder. The results showed that the glycerol compositing system had better mechanical properties than monoethanolamine and triethanolamine compositing system. The mechanical properties of TPAS-based were superior than thermoplastic acorn-kernel based. The mechanical properties of acorn starch-based were better than corn starch-based, while mechanical properties of TPAS/ PCL composites were greatly influenced by the moisture absorption property of composites. DMA results showed that there existed weak thermodynamic compatibility between blendings, which was further verified from SEM results. Composites had strong water absorption property, which can increase with the decrease of PCL content. But the GTPAS/PCL composites showed excellent mechanical properties. When the content of PCL reached 50 %, the composites can reach the tensile strength at 13.17 MPa, and the elongation at break at 1750 %, which was close to the pure PCL. Soil burial degradation analysis results showed the GTPAS/PCL composites had favorable biodegradation properties.4. Acorn hull(AH)/ low density polyethylene (LDPE) compositesThe binary bio-composites of acorn hull(AH)/ low density polyethylene (LDPE) were produced by a blending alloy technique with a twin-screw extruder. The mechanical properties of composites were decreased with an increase of acorn hull content. The effects of EAA, EVA and PE-g-MAH on composites were studied in this thesis. The results showed that PE-g-MAH was the best compatibilizer for AH/LDPE composite among these three compatibilizers. Compared with the mechanical properties of modifying composite without compatibilizers, the tensile strength increased by 77.6 %, flexural strength increased by 83.8 %, and anti-impact strength still remained at a level of 5.0 kJ/m2, when the content of PE-g-MAH was 5% under the condition of 50 % AH content. In addition, both EAA and EVA could improve the mechanical properties of composites at different levels. The SEM study of composites proved that the addition of compatibilizers improved the compatibility of AH powder with LDPE matrix. The testing results of DMA and DSC further confirmed that the addition of compatibilizers could significantly improv the compatibility between two phases and chang the properties of LDPE matrix materials.5. Acorn powder/ poly(lactic acid)(PLA) compositesThe composites were prepared with acorn powder and poly(lactic acid)(PLA) by using a blending alloy technique with a twin-screw extruder, followed by an injection molding processing or a hot-compression molding processing. The study of the composites microstructures showed poor adhesion between acorn powder and PLA matrix. The mechanical properties of acorn hull-based composites were slightly better than the acorn kernel-based composites. The impact resistance strength of reinforced acorn hull-based composites with steel fiber webs improved greatly in comparison with those without steel fiber webs. It reached at 1.51 kJ/m2. The hygroscopicity, mechanical properties, melt flow property and biological degradation property of composites were promising even though the composites had a 70 % content of acorn powder. AH-based composites showed flexural strength of 72.21 MPa, tensile strength of 48.56 MPa and impact resistance strength of 1.51 kJ/m2 when the content of acorn hull was 50 % Silane coupling agent KH-550, 4,4’- Methylenebis(phenyl isocyanate)(MDI) and PLA grafted with maleic anhydride (PLA-g-MAH) did not show obvious effect on mechanical properties of acorn hull-based composites. Results on thermal properties characterized by DSC, DMA and TGA showed that the addition of acorn powder significantly changed the properties of PLA matrix materials and affected the crystallinity (Xc%), crystallization temperature (Tc), glass transition temperature (Tg), melting temperature (Tm) and thermal decomposition temperature of PLA matrix.6. Acorn hull-filled type composite foamsNew flame-retardant foam materials were prepared by using Melamine-Urea- Formaldehyde (MUF) resin as raw materials. We then finely tuned and optimized a foaming technology, optimum solid content of MUF resin, optimum addition of surfactant, curing agent and foaming agent were determined, MUF foam apparent density– mechanical properties models were established. The results showed that there existed an exponential relation between mechanical properties and apparent density of MUF foam. Acorn hull-filled type composite foams were also prepared with a co-foaming technique. The flame-retardant property increased with an increase of addition of acorn hull, but the mechanical and anti-brittleness properties decreased greatly. Wood pulp fiber and J-100 crosslinking agent were added into pre-foaming system in order to improve the comprehensive properties of acorn hull-filled type composite MUF foams. The results showed that these two different physically and chemically modified foams improved the mechanical properties of composite foam at different levels. J-100 crosslinking modification improved the mechanical and anti-brittleness properties greatly. It was found that the mechanical properties of composite foam enhanced more than 10 times than the system without modification when little J-100 crosslinking agent was added into the pre-foaming system, and the relative loss powder rate has been 50 % lower, furthermore, the flame-retardant property slightly improved with the addition of J-100. FTIR and 13C-NMR analysis results showed the complexity of J-100 crosslinking modification mechanism.更多还原