BaSO₄/TPU型X射线摄影纤维的研究

【作者】 彭美桂；

【导师】 安树林；

【作者基本信息】 天津工业大学 ， 材料学， 2004， 硕士

【摘要】 本课题运用无机粒子硫酸钡（BaSO₄）填充改性热塑性聚氨酯（TPU），采用熔融纺丝技术纺制高性能X射线摄影纤维。用不同配比的BaSO₄/TPU共混切片进行熔融纺丝，将纺制的纤维进行后加工处理，以便获得综合性能较好的纤维。并对所纺制的纤维的结构和性能进行系统的研究。 研究了温度、剪切力和BaSO4含量对BaSO4/TPU共混体系流变性的影响。结果表明，随着BaSO₄粒子的加入共混体系的粘度增大，体系流动性变差；其中温度和剪切力对共混体系的流动性也有很大的影响，当温度升高或剪切力增大时共混体系的粘度大大下降，流动性变好，共混体系表现出对温度的依赖性和切应力变稀性；但当共混体系温度升高到200℃以上时，共混体系粘度的变化随温度变化不再明显，共混体系表现出具有良好的加工性能；在进行熔融纺丝时，共混体系也表现出随BaSO₄含量增加，BaSO₄/TPU共混体系的可纺性变差，要求适当升高纺丝温度并增大螺杆转速使纺丝正常。 研究了BaSO4/TPU共混体系的结构形态及二者的相容性。从SEM照片可以看出，BaSO₄在聚合物中有形成连续相的趋势，出现了典型的“混凝土结构”，并且随BaSO₄加入量增大，这种结构就越明显。另外从SEM照片分析得知BaSO₄/TPU为热力学不相容体系，两者之间相界面的清晰度与BaSO₄粒子表面是否加工改性有关。当BaSO₄表面未用偶联剂处理时，BaSO₄/TPU共混体系相界面清晰，界面粘合力较小；当BaSO₄表面用偶联剂处理后，BaSO₄/TPU共混体系相界面模糊，界面粘合力强。 研究了BaSO₄对BaSO₄/TPU共混体系Tg的影响。DMA测试结果表明：BaSO₄对聚合物Tg影响不大。这说明BaSO₄对聚合物大分子的单健内旋转运动阻碍性较小，并不影响聚合物大分子链段运动。 研究了BaSO₄对TPU纤维结构和性能的影响。加入BaSO₄对TPU纤维的影响较大，纤维的回弹性下降，纤维断裂伸长和断裂强度均大大降低。这是因为：①BaSO₄属于刚性粒子，阻碍TPU大分子链的回缩，降低了纤维的弹性；②BaSO₄与TPU相容性极差，共混时容易形成相界面，界面结合力小，受外力作用时相与相间容易发生分离，使纤维的力学性能下降；③BaSO₄在高含量下，纤维强度主要由聚合物的力学性能决定，随着BaSO4含量的增加，TPU所占比例下降，从而在宏观上表现出纤维的力学性能下降。可见BaSO;对改变纤维的综合性能起重要作用。 通过对BaSO4/T PU共混切片进行熔融纺丝实验，确定了纺丝工艺参数。纺丝温度控制在190一205℃之间，螺杆转速<70r/mln，卷绕速度则是随着BaSO4含量的升高而下降，实验中采取低速卷绕，纺丝理想环境温度控制在10¹5’C左右。 通过对60%，70%，75%，80%四种不同BaSO;含量的纤维进行后加工热定型处理，从纤维拉伸实验可以看出:不同BaSO;含量的纤维后加工工艺参数不同。其中对60%，70%的纤维后加工处理时，其拉伸率为200一300%，水浴拉伸温度为40℃时，纤维的拉伸性能最好，可得到加工性能比较理想的纤维。另外从60%一80%纤维的应力一应变曲线可知，纤维的拉伸性能随BaS认含量升高下降，应力一应变曲线也发生变化，由开始模量随应变增大而增大，逐渐转化为出现平台直至断裂。 通过选用不同品种的聚合物原材料和不同配比的BaSO4/T PU进行实验发现:原材料对纤维吸收X射线的性能影响不大;纤维对X射线的吸收性能只与BaSO;含量有关，且随着BasO;含量升高而增大，但二者并不呈线性关系;当BaSO;含量大于60%时，纤维对X射线具有很强的吸收性能，其吸收率可达95%以上。因此60%纤维基本达到医用摄影纤维的要求。更多还原

【Abstract】 In this paper, high performance x-ray developing filament were fabricated from thermoplastic polyurethane (TPU) filled with inorganic particles of Barium Sulfate (BaSO4) by melt spinning. The structure and mechanical properties of the filament with the different content of Barium Sulfate were discussed roundly.The effects of temperature, shearing force and the content of BaSO4 on the rheological behaviours were investigated. The results showed that BaSO4 filler obviously enhanced the viscosity and lower the flowability of BaSCVTPU. Temperature and shearing force strongly affected on the viscosity of BaSCVTPU, in that with the increase of temperature or the increase of shearing force, the viscosity of the blend could decrease significantly, the flowability and the processability of the blend were highly improved; BaSCVTPU blend was a kind of temperature-sensitive and shear thinning resin. While the viscosity of the blend changed little up to 200℃, and had an good processability. During the melt-spinning process, the spinnability became bad with BaSO4 adding.The morphological structure of BaSCVTPU blend system and the compatibility of BaSO4 and TPU were studied by SEM. The SEM results showed that BaSO4 particles in TPU had a trend to form a continuous phase, which appeared a typical concrete structure; and with the increase of content of BaSO4 the above structure became more evident. Also showed the SEM result that BaSCVTPU blend was a thermodynamic incompatible system. The distinctness of the phase interface formed by BaSO4 and TPU depended on the surfaces of BaSO4 particles. If the surfaces of BaSO4 particles were not modified with couplant, the interface was clear with a very small adhesive force; while the surfaces modified, the interface was fuzzy with a strong adhesive force.The glass transition temperature (Tg) of BaSO4 /TPU blend was obtained by DMA. The results showed that BaSO4 particles had not big influence on Tg of TPU. The above phenomena could be explained from the following reasons: (1) BaSO4 particles didn’t hinder macromolecular single bonded internal rotation. (2) BaSO4 particles hadn’t effect on the action of macromolecular chain segment.The studies on influence of the addition of BaSO4 particles on structure and properties were carried out. The results showed that elastic recovery, breaking length and breaking tenacity decreased considerably deeply. This was due to three reasons: (1) BaSO4 particles were rigid inorganic particles, which could hinder the retraction of polymer molecules and decreased the elasticity. (2) A bad compatibility between BaSO4 and TPU, small interface adhesive force and the phase interface ready to separate. (3) During high content of BaSO4, the tenacity of filament mainly depended on TPU, so that the strength decreased with the content of TPU in filament down.The process parameters of melt spinning were decided. Spinning temperature were controlled ranging from 190℃ to 205℃, rotate speed of the screw was less than 70r/min,the ideal room temperature was 10~15℃, and the winding speed decreased with the increase of content of BaSO4 .Four kinds of filament with different content of BaSO4, 60%, 70%, 75%, 80%, were heat- treated. Post-treatment process parameters of the filament were different with the concentration of BaSO4 changing. Drawing behaviours reached the best value when the draw rate, draft temperature in bath and the content of BaSO4 were 200%~300%, 40℃, 60%~70%, respectively. From the stress-strain curves of the filament, with the increase of content of BaSO4, drawing behaviours of the filament declined and the stress-strain curves of the filament changed from the modulus increasing with strain enlarging at first to appearing a platform up to break.Polymers had a small effect on the performance of absorping X-ray, the filament’s performance of absorping X-ray depended on the content of BaSO4. The property of absorping X-ray was stronger with the increase of content of BaSO4, but the relation was not linearity. When the content of BaSO4更多还原