發(fā)布時間：2019-02-26 13:53

【摘要】：支架材料作為承載組織工程細(xì)胞外基質(zhì)功能的載體,其結(jié)構(gòu)與性能直接決定了細(xì)胞培育、繁殖與分化及組織再生情況。研究和開發(fā)具有理想結(jié)構(gòu)特征并能有效滿足性能需求的支架材料,對推動組織工程研究的深化具有重要的研究和工程應(yīng)用價值。生物可降解高分子材料PHBV以其優(yōu)異的力學(xué)性能和生物相容性受到了研究學(xué)者和產(chǎn)業(yè)界的廣泛重視,并成為聚合物成型加工工程領(lǐng)域的一個研究熱點。然而,脆性、低熱穩(wěn)定性和成型加工窗口較窄等問題限制了其進(jìn)一步的廣泛應(yīng)用。本文擬采用熔融共混法、通過復(fù)合工業(yè)化生產(chǎn)的低成本生物降解高分子材料,系統(tǒng)研究PHBV基共混/復(fù)合材料體系的形態(tài)結(jié)構(gòu)、結(jié)晶性能、力學(xué)性能、熱性能、流變特性和發(fā)泡性能等,探究具有優(yōu)異綜合性能PHBV基可完全生物降解材料的制備方法,及在拉伸形變下的結(jié)構(gòu)與性能演變規(guī)律。據(jù)此,本文做了以下四個方面的研究工作:(1)采用熔融共混法制備了不同配比的PHBV/PBAT共混材料,系統(tǒng)表征和研究了其微觀結(jié)構(gòu)與性能。研究發(fā)現(xiàn),PBAT的加入抑制了 PHBV的結(jié)晶,提高了 PHBV基體的熱穩(wěn)定性;隨著PBAT含量的增加,共混體系的儲能模量、損耗模量及復(fù)數(shù)黏度均有所提高;PHBV與PBAT兩相互不相容,當(dāng)兩相的占比均等時,呈現(xiàn)出共連續(xù)相結(jié)構(gòu);PHBV/PBAT共混物的彈性模量及拉伸強(qiáng)度隨著PBAT含量的增加呈現(xiàn)下降趨勢,但斷裂應(yīng)變明顯改善,當(dāng)PHBV含量達(dá)到75%時,PHBV/PBAT共混物的應(yīng)變高達(dá)1000%仍未斷裂。(2)開展了無機(jī)納米粒子羥基磷灰石(HA)增強(qiáng)PHBV/PBAT共混體系的制備及性能研究。研究結(jié)果表明,HA的加入使得共混物的晶粒尺寸呈現(xiàn)減小趨勢;HA的增強(qiáng)效果取決于其在PHBV/PBAT基體中的分散情況,在PHBV/PBAT/HA(50/50/HA)試樣中,HA聚集在相界面處,加劇了兩相分離;復(fù)合HA后共混體系的彈性模量增加,但拉伸強(qiáng)度和斷裂應(yīng)變有所降低;較好的分散于PBAT相中的HA在間歇發(fā)泡過程中起到成核劑作用,促進(jìn)泡孔成核。(3)在PHBV/PBAT(50/50)二元共混物的基礎(chǔ)上,引入生物可降解材料PLA,探究PHBV/PBAT/PLA三元共混體系的性能變化規(guī)律及大形變條件。結(jié)果表明,隨著體系中PLA含量的增加,共混物的熱穩(wěn)定性能提高,各相的分散更加均勻,力學(xué)性能提升。PHBV/PBAT/PLA(35/35/30)試樣在室溫下的彈性模量達(dá)645MPa,屈服強(qiáng)度28MPa,斷裂應(yīng)變達(dá)到13%。在60℃條件下,(35/35/30)試樣具有單軸拉伸下的大變形能力。(4)系統(tǒng)研究了 PHBV/PBAT/PLA(35/35/30)共混物在不同拉伸速率及拉伸比下的應(yīng)力應(yīng)變行為及結(jié)構(gòu)演變。拉伸過程中,試樣經(jīng)歷裂紋、孔洞的形成與擴(kuò)展,最后演變?yōu)楦叨热∠虻睦w維狀單相體結(jié)構(gòu)。試樣的結(jié)晶度在總體上隨著應(yīng)變的增加呈現(xiàn)先增大后降低的現(xiàn)象。研究發(fā)現(xiàn),在低應(yīng)變速率下材料出現(xiàn)應(yīng)力波動現(xiàn)象,并隨著拉伸速率的增加逐漸消失。
[Abstract]:As a carrier of extracellular matrix function in tissue engineering, the structure and properties of scaffolds directly determine cell culture, reproduction, differentiation and tissue regeneration. The research and development of scaffolds which have ideal structural characteristics and can effectively meet the needs of performance have important research and engineering application value in promoting the deepening of tissue engineering research. Because of its excellent mechanical properties and biocompatibility, biodegradable polymer material PHBV has been paid more and more attention by researchers and industry, and has become a research hotspot in the field of polymer molding engineering. However, brittleness, low thermal stability and narrow forming window limit its further application. In this paper, the morphology, crystallization, mechanical properties and thermal properties of PHBV-based blends / composites were systematically studied by means of melt blending method and low-cost biodegradable polymer materials. The rheological properties and foaming properties of PHBV-based biodegradable materials with excellent comprehensive properties were investigated. The evolution of structure and properties under tensile deformation was also investigated. Accordingly, the following four aspects of research work have been done in this paper: (1) PHBV/PBAT blends with different ratios were prepared by melt blending method, and their microstructure and properties were characterized and studied systematically. It was found that the addition of PBAT inhibited the crystallization of PHBV and improved the thermal stability of PHBV matrix, and the storage modulus, loss modulus and complex viscosity of the blend increased with the increase of PBAT content. PHBV and PBAT are incompatible with each other. When the proportion of the two phases is equal, they show the structure of co-continuous phase. The elastic modulus and tensile strength of PHBV/PBAT blends decreased with the increase of PBAT content, but the fracture strain improved obviously. When the content of PHBV reached 75%, the tensile strength of the blends decreased. The strain of PHBV/PBAT blends was as high as 1000%. (2) the preparation and properties of inorganic nano-hydroxyapatite (HA) reinforced PHBV/PBAT blends were studied. The results show that the grain size of the blend decreases with the addition of HA. The strengthening effect of HA depends on its dispersion in PHBV/PBAT matrix. In PHBV/PBAT/HA (50/50/HA) samples, HA aggregates at the interface of phase, which aggravates the two-phase separation. After composite HA, the elastic modulus of the blend increased, but the tensile strength and fracture strain decreased. The better dispersed HA in PBAT phase plays the role of nucleating agent in intermittent foaming process, and promotes cellular nucleation. (3) on the basis of PHBV/PBAT (50 / 50) binary blend, biodegradable material PLA, is introduced. The property change rule and large deformation condition of PHBV/PBAT/ PLA ternary blend system were studied. The results show that with the increase of PLA content, the thermal stability of the blends increases, the dispersion of each phase is more uniform, and the mechanical properties of the blends are improved. The elastic modulus of PHBV / PBAT/PLA (35-35-30) samples reaches 645 MPA at room temperature. The yield strength is 28 MPA and the fracture strain is 13%. At 60 鈩，

本文編號：2430835