山梨醇衍生物类成核剂是一种传统的等规聚丙烯（iPP）α成核剂，但是我们发现这类成核剂也可以诱导β晶结晶，是一种α-β双效成核剂。我们通过熔融共混法制备iPP/二（对甲基苯亚甲基）山梨醇（MDBS）和iPP/二（3,4-二甲基苯亚甲基）山梨醇（DMDBS）系列样品，并以相同条件处理过的纯iPP和添加高效β成核剂TMB-5的样品作为对比样品，利用广角X-射线衍射（WAXD）、小角X-射线散射（SAXS）和差示扫描量热分析（DSC）等实验手段研究含双效成核剂的iPP受到剪切外场和振荡外场后其晶型、取向结构及结晶度的变化。首先，我们研究了这类双效成核剂的成核效率。MDBS成核剂的成核效率（nucleating efficiency, NE）先随成核剂含量的增加而增加，在成核剂含量为0.4wt%时达到最高值18.3%，而后随着成核剂含量的继续增加，成核效率反而降低。DMDBS成核效率高于MDBS，在含量低于0.4wt%时NE随成核剂含量变化不大，均低于20%；当DMDBS含量达到1wt%时成核效率陡增至57.7%。iPP/MDBS和iPP/DMDBS系列样品在134℃静态等温结晶后，都是成核剂含量为0.2wt%的样品β晶结晶度Xβ最高，成核剂含量低于0.4wt%的样品中能同时生成α晶和β晶，此时山梨醇类成核剂为α-β双效成核剂；当成核剂含量为1wt%时，样品中无β晶生成，此时山梨醇类成核剂为α成核剂。施加剪切场后，iPP/MDBS和iPP/DMDBS系列样品的β晶结晶度Xβ均随着剪切速率的增加而增加，剪切与双效成核剂协同诱导β-iPP。固定成核剂含量，样品的取向度随着剪切速率的增加而增加。固定剪切速率，样品的取向度随着成核剂含量的增加而增加。剪切与双效成核剂协同增加iPP的取向程度。施加振荡场后，iPP/MDBS和iPP/DMDBS系列样品的β晶结晶度Xβ随振荡应变的增大而增大，振荡应变和双效成核剂对于诱导β-iPP晶呈现协同作用；我们固定振荡应变而改变振荡频率，发现振荡频率对样品的晶型、结晶度及取向程度均无明显影响。与剪切外场相比，振荡场下样品的取向程度较低，诱导的α排核长度较短，但是在振荡外场下更容易得到高含量β晶的样品。通过研究比较iPP/MDBS和iPP/DMDBS系列样品的结晶行为和取向行为可以发现，山梨醇衍生物类成核剂能在诱导α晶的同时诱导β晶结晶，充当α-β双效成核剂。外力场（剪切和振荡）对添加双效成核剂的iPP晶型、结晶度及取向行为等有较大影响，在一定条件下外力场和双效成核剂对iPP的β晶结晶和取向行为呈现协同作用。

Sorbitol derivatives, the traditional α-nucleating agent of isotactic polypropylene (iPP), are found to induce β-form iPP under normal crystallization conditions and act as versatile nucleating agent. iPP/1,2,3,4-bis(p-methylbenzylidene) sorbitol (MDBS) and iPP/1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS)blends were prepared by dissolved the desired ratios of iPP and sorbitol derivatives in melting, and pure iPP treated under the same condition is blank group. Wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) were used to study the crystallization behavior, the orientation structures and the variation of crystallinity of those three systems. Firstly, we studied the nucleating efficiency (NE) of sorbitol derivatives.NE of MDBS first increases to 18.3% and then decrease with the increase of MDBS content, while the most efficient concentration of MDBS is 0.4wt%. NE of DMDBS is lower than 20% when the content of DMDBS is less than 0.4wt% but steeps to 57.7% when it rises to 1wt%. When iPP containing sorbitol derivatives isothermally crystallized at 134℃, the highestcrystallinity of β-form crystal (Xβ) come up with the content of sorbitol derivatives is 0.2wt%. Sorbitol derivatives can induce both α- and β-form crystals simultaneously when the content is lower than 0.4wt% and act as versatile nucleating agents. But when the content rises to 1wt%, sorbitol derivatives lose the ability to induce β-form iPP and act as α-nucleating agents. After the application of shear, the β-crystal crystallinity Xβ of iPP/MDBS and iPP/DMDBS blends increase with the increase of shear rate, which means that the interaction between shear and versatile nucleating agents is synergistic on forming β-crystals. The orientation degree increases with the increase of shear rate when the content of nucleating agents is fixed and increases with the increase of nucleating agents when shear rate is fixed. Shear and versatile nucleating agents can induce oriented structures synergistically.After the application of oscillation, the β-crystal crystallinity Xβ of iPP/MDBS and iPP/DMDBS blends increase with the increase of oscillatory strain, which means that the interaction between oscillatory strain and versatile nucleating agents is synergistic on forming β-crystals. When oscillatory strain is fixed, the variation of oscillatory frequency has no obvious effect on crystallization behavior, crystallinity and orientation of all samples. Comparing with shear, the orientation degree is lower and the length of α-row nuclei is shorter under oscillatory flow. But the crystallinity of β-crystals is higher than shear under oscillatory flow.As the comparison of crystallization and orientation behavior between iPP/MDBS and iPP/DMDBS blends, we can find that sorbitol derivatives can induce α- and β-forms iPP simultaneously and act as versatile nucleating agents. Flow fields (shear and oscillation) have remarkable influences on crystallization types, crystallinity and orientation behavior of iPP. And the interaction between flow fields and versatile nucleating agents is synergistic under normal conditions.