【摘要】：聚3-羥基丁酸酯4-羥基丁酸酯（P34HB）作為最新一代的PHA生物基高分子，不僅具有生物降解性和生物來源，還擁有良好的綜合性能，已應用在生物醫(yī)藥、包裝和農(nóng)業(yè)等領域。但是P34HB在結晶性、力學性能和熱穩(wěn)定性等方面存在不足，如何克服這些缺陷是P34HB進一步發(fā)展和推廣的必經(jīng)之路。 本論文中，針對P34HB力學性能的不足而引入了天然竹纖維（BF），采用了堿處理、馬來酸酐改性和硅烷偶聯(lián)劑改性三種方法對BF進行改性。結果表明，當BF在5wt%的NaOH溶液中處理8h，添加量為10phr時，制備的P34HB/竹纖維復合材料的力學性能最佳，拉伸強度和彎曲強度分別較純P34HB提高了58.63%和46.22%。分析表明，BF經(jīng)堿處理后，直徑減小、長徑比增大、纖維素含量大幅提高，有利于提高纖維與基體的相容性。竹纖維的引入可以在基體中起到成核劑的作用，提高P34HB的結晶性能，對P34HB的熱穩(wěn)定性有一定的改善，但當竹纖維含量增大時，復合材料熱穩(wěn)定性能下降。 另一方面，本論文研究了填料種類對P34HB熱穩(wěn)定性能的影響。研究發(fā)現(xiàn)，，用具有自有知識產(chǎn)權的固相改性法改性MMT，得到含有酯基EMMT能夠大幅提高了P34HB的熱穩(wěn)定性，當EMMT的含量為5phr時，熱降解溫度從純P34HB的231.6℃提高到270.4℃，提高了近40℃，維卡軟化點也從原來的52.3℃提高至58.2℃。TGA-IR測試表明， EMMT的引入并沒有改變其降解機理，但是復合材料的比熱和導熱系數(shù)均得到增大，有利于P34HB熱穩(wěn)定性的提高。DSC測試表明，EMMT對P34HB具有成核作用，Tc從純P34HB的70.8℃提高到93.2℃，提高了22.4℃。TEM和XRD分析表明，P34HB基體能夠進一步插到EMMT層間，EMMT在基體中分散性較好，蒙脫土的分散尺度在20nm-70nm之間，達到納米級別。結合材料的力學性能，當EMMT的含量為5phr時，P34HB/EMMT納米復合材料綜合性能最佳。 降解分析表明， P34HB、P34HB/ATBF(堿處理后的BF)及P34HB/EMMT材料在pH=1.3的磷酸溶液中很穩(wěn)定，降解緩慢，但在pH=13的NaOH溶液中降解速率很快。酸降解后的試樣結晶性和熱穩(wěn)定性變化不大，而因為P34HB分子鏈上的酯基對堿敏感，在堿性條件下容易發(fā)生分子鏈斷裂，所以試樣在堿降解后結晶性能、熱穩(wěn)定性均下降。
[Abstract]:Poly (3-hydroxybutyrate) 4-hydroxybutyrate (P34HB), as the latest generation of PHA biomaterials, not only has biodegradability and biodegradability, but also has good comprehensive properties. It has been used in biomedicine, packaging and agriculture. However, there are some shortcomings in crystallization, mechanical properties and thermal stability of P34HB. How to overcome these defects is the only way to further develop and popularize P34HB. In this paper, the natural bamboo fiber (BF), was modified by alkali treatment, maleic anhydride modification and silane coupling agent modification to improve the mechanical properties of P34HB. The results showed that when BF was treated in 5 wt% NaOH solution for 8 h and the amount of 10phr was added, the mechanical properties of the P34HB/ bamboo fiber composites were the best. The tensile strength and bending strength of the P34HB/ bamboo fiber composites were increased by 58.63% and 46.2222%, respectively, compared with the pure P34HB. The analysis shows that after alkali treatment, the diameter of BF decreases, the aspect ratio increases, and the content of cellulose increases significantly, which is beneficial to improve the compatibility between fiber and matrix. The introduction of bamboo fiber can play the role of nucleating agent in the matrix, improve the crystallization property of P34HB and improve the thermal stability of P34HB to some extent, but when the content of bamboo fiber increases, the thermal stability of the composite decreases. On the other hand, the effect of filler type on the thermal stability of P34HB was studied. It is found that the thermal stability of P34HB can be greatly improved by modifying MMT, with solid phase modification with its own intellectual property rights. When the content of EMMT is 5phr, the thermal degradation temperature is raised from 231.6 鈩

本文編號：2248590