导　　师： 彭响方

学科专业： 080503

授予学位： 博士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 本文在自制的循环振荡推拉成型设备平台上，通过在成型过程中引入往复剪切动态力场和往复振荡剪切力场，对比系统研究分析了三种不同聚合物分别在不同动态力场作用下聚合物试样聚集态结构和性能变化的规律和响应机理。 1.选取常用高结晶型高密度聚乙烯HDPE，使用自制的聚合物熔体循环振荡推拉设备进行常规挤塑成型、循环推拉成型及循环振荡推拉成型实验，对比研究了不同力场下成型试样的力学性能变化规律，结果发现成型过程中引入往复剪切动态力场的循环推拉成型试样的拉伸强度、冲击强度和弹性模量相比没有引入动态力场属于静态成型的常规挤塑成型分别提高了85/%、113/%和48/%，实现了试样性能的自增强增韧；引入往复振荡剪切动态力场后的循环振荡推拉成型试样性能相比循环推拉成型又进一步提高了26/%、39/%和26/%。利用PLM、DSC、2D-WAXD及SEM微观结构表征手段对成型试样的聚集态微观结构进行表征，对比分析了静态力场（非动态力场）、往复剪切动态力场和往复振荡剪切复合动态力场作用下高结晶度聚合物聚集态结构及性能变化的响应机理，发现试样力学性能提高的原因在于动态力场形成了高度取向的串晶及串晶互锁结构，并提高了试样的取向度和结晶度；往复振荡剪切复合动态力场与往复剪切动态力场相比串晶数量增加导致取向层的增厚、串晶互锁紊乱区的减少及结晶度的进一步提高是其力学性能进一步提高的原因。使串晶数量增多取向层增厚大幅提高拉伸强度和冲击强度是往复振荡剪切复合动态力场成型HDPE试样时相比往复剪切单一动态力场的突出优点。 2.选取常用半结晶型等规聚丙烯iPP，使用自制的聚合物熔体循环振荡推拉设备进行常规挤塑成型、循环推拉成型及循环振荡推拉成型标准哑铃样条试样，研究了不同力场下成型试样的力学性能变化规律，结果发现成型过程中引入往复剪切动态力场的循环推拉成型试样的拉伸强度、冲击强度和弹性模量相比没有引入动态力场属于静态成型的常规挤塑成型分别提高了52/%、160/%和87/%，实现了试样性能的自增强增韧；引入往复振荡剪切动态力场后的循环振荡推拉成型试样相比循环推拉成型又进一步提高了19/%、79/%和12/%。利用PLM、DSC、2D-WAXD及SEM微观结构表征手段对成型试样的聚集态微观结构进行表征，对比分析了静态力场（非动态力场）、往复剪切动态力场和往复振荡剪切复合动态力场作用下半结晶聚合物聚集态结构及性能变化的响应机理，发现试样力学性能提高的原因在于动态力场使球晶尺寸减少且球晶密度增加，并提高了试样的取向度和结晶度。与往复剪切动态力场相比，往复振荡剪切复合动态力场使试样进一步自增强增韧的原因在于球晶尺寸的进一步减少和球晶密度的进一步增加，并进一步提高了试样的取向度和结晶度。球晶间形成高度取向的片晶、球晶的进一步细密化实现试样性能的增强增韧是往复振荡剪切复合动态力场作用下成型iPP试样相比往复剪切单一动态力场的突出特点。 3.选取常用高抗冲聚苯乙烯HIPS，使用自制聚合物熔体循环振荡推拉设备进行常规挤塑成型、循环推拉成型及循环振荡推拉成型，研究了不同力场下成型试样的力学性能变化规律，结果发现成型过程中引入往复剪切动态力场的循环推拉成型试样的拉伸强度、冲击强度和弹性模量相比没有引入动态力场属于静态成型的常规挤塑成型分别提高了56/%、263/%和80/%，断裂伸长率同时获得27/%的提高；引入往复振荡剪切动态力场后的循环振荡推拉成型比循环推拉成型试样的拉伸、冲击、弹性模量及断裂伸长率分别提高了8/%、56/%、8/%及22/%。利用SEM、SAXS及TEM微观结构表征手段对成型试样的聚集态微观结构进行表征，对比分析了静态力场（非动态力场）、往复剪切动态力场和往复振荡剪切复合动态力场作用下HIPS试样分层形貌的形成机理和试样聚集态结构、性能变化的响应机理，结果发现动态力场作用下PS基体的取向及在HIPS试样皮层形成了沿流动方向取向且平行排列的鹅卵石形状PB相是其HIPS试样力学性能增强增韧的主要原因，这种特殊相结构可以大幅提高试样的冲击强度，同时使拉伸强度获得一定提高；引入往复振荡剪切复合动态力力后使试样力学性能比循环推拉成型进一步获取提高，其原因在于复合动态力场使PB相变形程度增加，获得更多的变形且纤化增强的PB相使皮层增厚，且变形PB相的取向平行排列更为规整。通过形成变形更为剧烈、进一步纤化且取向平行排列的PB相是往复振荡剪切复合动态力场作用下成型HIPS试样相比往复单一动态力场的突出特点。 Our research based on the self-made loop oscillating push-pull molding equipment andintroducted reciprocating shear dynamic force field or reciprocating oscillating shear forcefield in the process, comparatively researched and analysised the change rule and mechanismof the aggregation structure and performance of three different types polymers under differentdynamic force field. 1.With selection of commonly used high crystallization type high density polyethylene/(HDPE/) and using self-made loop oscillating push-pull equipment for conventional extrusionmolding, loop push-pull and loop oscillating push-pull molding experiments,wecomparatively study the mechanical properties of the products under different force fields.The results showed the tensile strength, impact strength and modulus of elasticity of the looppush-pull molding products by introducing reciprocating shear dynamic force field increasedrespectively by85/%,113/%and48/%compared with conventional extrusion molding wichbelongs to static molding.After the introduction of reciprocating oscillation shear dynamicforce field the loop oscillating push-pull molding products performance is further increasedby26/%,39/%and26/%compared with loop push-pull molding process.By utilizing PLM,DSC,2D-WAXD and SEM microstructure characterization methods the aggregationmicrostructure of molding products was characterized, contrastly analysis the changemechanism of the performance and the aggregation structure of of high crystallinity polymerHDPE procducts under the action of the reciprocating shear dynamic force field andreciprocating oscillating shear composite dynamic force field.We found the reason ofimproving the mechanical properties of HDPE products was due to generate shish-kebeb andinterlocked shish-kebeb structure, and improved the orientation degree and crystallinity of theproducts under the action of dynamic force field.That reciprocating oscillating shearcomposite dynamic force field leaded to increase more shish-kebeb and thicken orientationlayer, reducing shish-kebeb inter-locked disorders and furtherly increase products crystallinityof is the cause of furtherly improving products mechanical properties compared withreciprocating shear dynamic force field. It is the prominent advantage of reciprocatingoscillation shear composite dynamic force field compared with single reciprocating shear dynamic shear force field that the tensile and impact strength of HDPE products weresignificantly improved by inductively generating multiply number shish-kebeb and thickenorientation layer. 2.With selection of commonly used semicrystalline isotactic polypropylene /(iPP/) andusing self-made loop oscillating push-pull equipment for conventional extrusion molding,loop push-pull and loop oscillating push-pull molding experiments,we comparatively studythe mechanical properties of the products under different force fields. The results showed thetensile strength, impact strength and modulus of elasticity of the loop push-pull moldingproducts by introducing reciprocating shear dynamic force field increased respectively by52/%,160/%and87/%compared with conventional extrusion molding wich belongs to staticmolding.After the introduction of reciprocating oscillation shear dynamic force field the looposcillating push-pull molding products performance is further increased by19/%,79/%and12/%compared with loop push-pull molding process.By utilizing PLM, DSC,2D-WAXD andSEM microstructure characterization methods the aggregation microstructure of moldingproducts was characterized, contrastly analysis the change mechanism of the performance andthe aggregation structure of of high crystallinity polymer HDPE procducts under the action ofthe reciprocating shear dynamic force field and reciprocating oscillating shear compositedynamic force field.We found the reason of improving the mechanical properties of iPPproducts was due to reduce sphaerocrystal size and increase sphaerocrystal density, andimproved the orientation degree and crystallinity of the iPP products under the action ofdynamic force field.That reciprocating oscillating shear composite dynamic force field leadedto furtherly sphaerocrystal size and increase sphaerocrystal density and furtherly increaseproducts crystallinity of is the cause of furtherly improving products mechanical propertiescompared with reciprocating shear dynamic force field. It is the prominent advantage ofreciprocating oscillation shear composite dynamic force field compared with singlereciprocating shear dynamic shear force field that the mechanical property of iPP productswere significantly improved by furtherly reducing sphaerocrystal size, increasingsphaerocrystal density and the orientation of the lamella between the sphaerocrystals. 3.With selection of commonly used amorphous high impact polystyrene /(HIPS/) and using self-made loop oscillating push-pull equipment for conventional extrusion molding,loop push-pull and loop oscillating push-pull molding experiments,we comparatively studythe mechanical properties of the products under different force fields. The results showed thetensile strength, impact strength,elasticity modulus and elongation at break of the looppush-pull molding products by introducing reciprocating shear dynamic force field increasedrespectively by56/%,263/%,80/%and27/%compared with conventional extrusion moldingwich belongs to static molding.After the introduction of reciprocating oscillation sheardynamic force field the loop oscillating push-pull molding products performance is furtherincreased respectively by8/%,56/%,8/%and22/%compared with loop push-pull moldingprocess.By utilizing SEM,SAXS and TEM microstructure characterization methods theaggregation microstructure of molding products was characterized, contrastly analysis thechange mechanism of the performance, the aggregation structure and hierarchical morphologyof amorphous high impact polystyrene /(HIPS/) procducts under the action of the reciprocatingshear dynamic force field and reciprocating oscillating shear composite dynamic forcefield.We found the reason of reinforcing and toughening HIPS products was due to theparallel arrangement orientation pebble-like shape PB phase under the action of dynamicforce field. Reciprocating oscillating shear composite dynamic stress are introduced to makethe products further access to improve mechanical properties than loop push-pull molding, thereason for this is that the compound dynamic force field increase PB phase deformationdegree, deformation PB phase to thicken more skin layer, and the deformation of PB phaseorientation parallel arrangement more neat. It is the prominent advantage of reciprocatingoscillation shear composite dynamic force field compared with single reciprocating sheardynamic shear force field that the impact strength of HIPS products were slightly improvedthe tensile strength and significantly improve the impact strength by forming more dramaticdeformation fibrillating orientation parallel arrangement PB phase slightly improved andsignificantly improve the impact strength.

关 键 词： 循环振荡推拉 复合动态力场 聚集态结构 力学性能 自增强增韧

分 类 号： [TQ320.666]

领　　域： [化学工程]