This paper investigates the influence of molecular properties (molecular weight, polydispersity (PDI) and molecular weight distribution (MWD)) on the mechanical fatigue of model systems of anionic synthesized polystyrene (PS, low PDI), their blends (bimodal MWD) and commercial PS (broad PDI) under strain-controlled oscillatory shear (torsion). A power-law relation between lifetime N_f and strain amplitude γ₀ (Wöhler curve) was found, with the exponent independent, but the pre-factor highly dependent on molecular characteristics. Additionally, nonlinear changes of the stress response, due to ongoing fatigue, were quantified via Fourier Transform (FT), to analyze besides the storage modulus G′, the intensities of the second (I₂) and third (I₃) harmonics over the fundamental one (I₁). The behavior of G′ and I_3/1 was found to depend on molecular properties, with I_3/1 being more sensitive to failure onset than G′, while an increase of I_2/1 above the noise level could be correlated with the occurrence of macroscopic cracks.

本文研究了分子性能（分子量，多分散性（PDI）和分子量分布（MWD））对阴离子合成聚苯乙烯（PS，低PDI），其共混物（双峰MWD）和商业化模型系统的机械疲劳的影响。应变控制的振荡剪切（扭转）下的PS（广义PDI）。寿命之间的幂律关系Ñ _˚F和应变振幅γ ₀（沃勒曲线）被发现，与指数独立的，但预因子高度依赖于分子的特性。另外，由于疲劳的存在，应力响应的非线性变化通过傅立叶变换（FT）进行了量化，除了储能模量G'之外，还分析了第二个（I₂）和三次谐波（I ₃）超过基波一次（I ₁）。的行为G'和余_3/1被发现依赖于分子的特性，与我_3/1是要失败的发病比更敏感G' ，而增加了我_{2 / 1}中的噪声电平以上可与相关联宏观裂纹的发生。