發(fā)布時(shí)間：2018-08-14 12:26

【摘要】：為了克服聚乳酸或鎂合金作為骨固定材料單獨(dú)使用時(shí)的不足,本文采用熱壓成型方法制備了一種以鎂合金薄片為增強(qiáng)體、以聚乳酸為基體的可吸收骨內(nèi)固定復(fù)合材料,并對(duì)其彎曲強(qiáng)度、剪切強(qiáng)度和沖擊韌性等力學(xué)性能及其鎂片微弧氧化處理(MAO)的影響進(jìn)行了研究,最后,探索了復(fù)合材料在模擬體液中的降解性能,研究表明：隨鎂片體積含量的增大,鎂片未MAO處理的復(fù)合材料(un-MAO-復(fù)合材料)的彎曲強(qiáng)度、剪切強(qiáng)度和沖擊韌性均逐漸增大,體積分?jǐn)?shù)為60%時(shí),分別為229.3MPa、 84.5MPa和222.4 kJ/m2。鎂片MAO處理有效改善了復(fù)合材料(MAO-復(fù)合材料)的界面結(jié)合,彎曲過(guò)程中兩相界面沒(méi)有發(fā)生脫粘現(xiàn)象,沖擊韌性有顯著提高。復(fù)合材料制備過(guò)程中,粘流態(tài)聚乳酸進(jìn)入鎂片MAO陶瓷層表面微孔中,冷卻后產(chǎn)生機(jī)械鎖合作用,同時(shí),兩相熱膨脹性能差別較大,制樣冷卻過(guò)程中產(chǎn)生的殘余熱應(yīng)力會(huì)進(jìn)一步增大復(fù)合材料兩相界面機(jī)械鎖合效果。理論計(jì)算表明,在三點(diǎn)彎曲試驗(yàn)過(guò)程中復(fù)合材料外表面聚乳酸受到的最大拉應(yīng)力約為35MPa,與純聚乳酸的抗拉強(qiáng)度接近(約40MPa),可認(rèn)為拉應(yīng)力是造成最外層聚乳酸彎曲斷裂的主要原因。復(fù)合材料彎曲過(guò)程中兩相界面處受到的最大切應(yīng)力理論值約為0.4MPa,而復(fù)合材料中un-MAO鎂片與聚乳酸界面剪切強(qiáng)度實(shí)測(cè)值為1.08MPa,說(shuō)明界面處切應(yīng)力只是界面脫粘的重要原因之一。在37℃模擬體液浸泡實(shí)驗(yàn)過(guò)程中,隨浸泡時(shí)間的延長(zhǎng),un-MAO-復(fù)合材料彎曲強(qiáng)度快速下降,浸泡28天后聚乳酸與鎂片分離；MAO-復(fù)合材料試樣彎曲強(qiáng)度逐漸降低,浸泡28天后仍能保持完整,其剩余彎曲強(qiáng)度為64.9MPa,表明了鎂片MAO處理能顯著提高復(fù)合材料在模擬體液中的強(qiáng)度維持能力。純聚乳酸浸泡液pH值逐漸降低,而MAO-復(fù)合材料在浸泡5天后浸泡液pH值才發(fā)生變化,逐漸升高。un-MAO-復(fù)合材料在常溫浸泡7天后就開(kāi)始釋放氫氣,而MAO-復(fù)合材料在浸泡28天后仍未釋放氫氣,說(shuō)明鎂片表面氧化層可以在較長(zhǎng)時(shí)間內(nèi)保護(hù)復(fù)合材料中的鎂合金不被浸泡液腐蝕。MAO-復(fù)合材料中聚乳酸分子量在浸泡過(guò)程中逐漸降低,浸泡3周后,鎂片表面有“龜裂狀”裂紋產(chǎn)生。
[Abstract]:In order to overcome the shortage of poly (lactic acid) or magnesium alloy used as bone fixation material alone, a kind of absorbable bone fixation composite with magnesium alloy sheet as reinforcement and poly (lactic acid) as matrix was prepared by hot pressing method in this paper. The mechanical properties, such as bending strength, shear strength and impact toughness, as well as the effect of micro-arc oxidation (MAO) on magnesium sheet were studied. Finally, the degradation properties of the composites in simulated body fluid were explored. The results show that the bending strength, shear strength and impact toughness of the untreated MAO composites (un-MAO-) increase with the increase of the volume content of magnesium sheets, and the volume fraction of 60kJ / m ~ (2) is 229.3 MPA, 84.5MPa and 222.4 KJ / m ~ (2), respectively. The MAO treatment of magnesium sheet can effectively improve the interfacial bonding of the composite (MAO- composite). During the bending process, there is no debonding phenomenon at the interface of the two phases, and the impact toughness is improved significantly. During the preparation of the composites, the viscous polylactic acid (PLA) enters the micropores on the surface of the MAO ceramic layer of the magnesium sheet, and after cooling, the mechanical locking cooperation occurs. At the same time, the thermal expansion properties of the two phases differ greatly. The residual thermal stress in the cooling process will further increase the mechanical locking effect of the two-phase interface of the composite. Theoretical calculations show that, During the three-point bending test, the maximum tensile stress of polylactic acid on the outer surface of the composite is about 35 MPA, which is close to the tensile strength of pure PLA (about 40MPa). It can be concluded that the tensile stress is the main reason for the bending fracture of the outermost polylactic acid. The maximum shear stress at the interface of two phases is about 0.4 MPA, while the measured value of shear strength at the interface of un-MAO magnesium sheet and polylactic acid is 1.08 MPA, which indicates that the shear stress at the interface is only one of the important reasons for the debonding of the interface. During the immersion experiment of simulated body fluid at 37 鈩，

本文編號(hào)：2182859