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作者:profed5ca94
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发布时间: 2021-02-02
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影响流动因素有分子链的柔韧性，分子量与分子量的分布，分子链的支化度、增塑剂和熔剂，树脂受热温度，剪切速率等。高聚物的成型加工一般是在粘流状态下进行的。Tf—Td之间温度越宽，越利于加工；Tf为粘流温度，Td为分解温度。
3.2流动性影响
3.2.1影响流动因素有分子链的柔韧性，分子量与分子量的分布，分子链的支化度、增塑剂和熔剂，树脂受热温度，剪切速率等。高聚物的成型加工一般是在粘流状态下进行的。Tf—Td之间温度越宽，越利于加工；Tf为粘流温度，Td为分解温度。溶融物料在螺槽内有正向流动、横向流动、逆向流动、漏流4种流动状态。
① 正流是促使物料沿螺槽向机头主要输送流；
② 横流是物料在螺槽内翻转运动，形成环流，对物料的混合、塑化有很大的影响，对生产率没影响；
③ 逆流与正流正好相反，速度分布呈抛物线关系变化；
④ 漏流是影响塑化质量及生产能力的主要因素，漏流不在螺槽中运动，而是在螺杆与料筒的间隙中运动，漏流的大小与机头阻力呈3次方倍数的关系，漏流大时生产力严重下降甚至不能正常生产。
由于这些运动的组合起到搅动、混炼、剪切、压缩物料的作用，使物料塑化均匀，以一定的压力连续成型。高分子链在原来的形态过渡到相适应的形状需要的时间为松弛过程，由于高聚物其链段长度不同，松弛过程与制件结构不符时产生的力为内应力。内应力对塑件有不良影响。
3.2.2塑胶的流变行为
聚合物在不同热力条件下，以3种形态存在：即固态（玻璃态）、高弹态、粘流态（液态）又称假塑性流体。下面分别对各种形态加以介绍：
处于固态下的塑料分子，链段运动基本上处于停止状态，分子在自身的位置上振动，分子链缠绕成团状或卷曲状，相互交错、紊乱无序，当受到外力作用时，链段仅作瞬间微小伸缩及键角的改变。在这种形态下，塑料的物理机械性能对环境的耐受性能取决于分子链的构成、形状、序列、柔顺性以及链间相互位置与堆砌密度。
高弹态下的分子单元，动能开始增加，链段展开成网状，但分子间的运动仍维持在小链段的旋转，链与链之间不产生位移，在较小的作用力下可产生较大的形变，但当外力解除后即恢复原状。其高弹形变并非瞬间发生，而是随着时间的增长应变增加，但达到一定量后，趋于稳定，达到平衡状态。
当塑料进入粘流状态（液态）时，网状结构已经解体，大分子链与链之间，链段与链之间都能自由滑移，当给予外力时，分子间易产生滑移（流动），造成塑胶熔体形变，除去外力也不恢复原状。塑料注射成型都是在粘流状态下进行，使分子单元能便利地通过各种形状结构的断面，充满模腔再经冷却回复转变为高弹态，最终在常温下以固态的形式保存下来。
3.2.3分子蠕变与应力松驰现象
玻璃态（固态）受到外力时产生的变量，随着时间的增加而增加,呈线性关系，直至断裂；当撤除外界应力时，应变力保持在当时所产生的变量状态.
高弹态受到外界应力时产生的变量，随着时间的增长应变增加,但达到一定量后，趋于稳定,达到平衡状态；应变力能在瞬间达到最大值，但照样能在瞬间又完全松驰（撤除外界应力）。
粘流态（液态）受到外界应力时产生的变量，随着时间的增加而呈线性 增加，类似于假塑性流体；应变力在随着时间的延长应力下降，呈一定倾向，随着时间的延长降为最低值，即没有应力。
3.2.4塑胶流动与冷却
①流动阻力：塑料在成型流动过程中，由固态转化为液态（粘流态），首先是表层开始软化熔融，形成半固体，经过混炼剪切，最终所有的固体床破裂直至全部熔融；流动所存在的阻力为固态时最大，半固态时次之，熔融状态时的阻力取决于温度/压力对粘度的影响，流动性质类似于假塑性流体。
②充模/压实阶段：熔融的物料按设定的工艺注入模腔，使熔料填满至模腔的个个角落，该阶段时间周期短，一般在（1-10）s内完成。物料的填充工艺过程决定了制品的主要品质，是注塑成型中要加以控制的主要过程。
③倒流阶段：塑胶熔体在充满模腔的瞬间，模腔内熔体压力达到最高峰，如此时浇口没完全封闭，而螺杆料筒已经卸压，会造成熔体倒流现象，在浇口附近产生收缩 痕，模塑成型时该避免此现象出现。
④冻结冷却阶段：冻结冷却阶段已进入了模塑过程的最后阶段，材料经熔融充满模腔再经过冷凝、结晶，转化为固态，完成了整个成型过程，控制冻结冷却速度及方向即能得到品质优良的产品。
3.2 Liquidity
3.2.1 The impact of mobile factors of molecular chain flexibility, molecular weight and molecular weight distribution, molecular chain branching degree, plasticizers and flux, resin heating temperature, shear rate and so on. Polymer molding process is typically carried out under viscous flow conditions. Tf-Td the temperature between the wider, more conducive to processing; Tf for the viscous flow temperature, Td is the decomposition temperature. Melting material has a positive flow in the spiral groove, lateral flow, reverse flow, leakage flow state 4.
① now is to promote material flow along the spiral groove to head the main transport stream;
② cross flow is material in the spiral groove turning movement, the formation of circulation, mixing of materials, plastics have great impact, no impact on productivity;
③ countercurrent flow and are opposite parabolic relationship between velocity changes;
④ leakage affecting the plasticizing quality and productivity of the main factors, leakage does not screw slot movements, but the gap in the screw and barrel in the movement, size and head leakage resistance was a multiple of 3 power relationship, a serious leakage is large decline in productivity can not even normal production.
Because the combination of these campaigns play stirred, mixing, shear, compression material effect in that the plastics material evenly, forming a row to a certain pressure. Polymer chain in the original form to fit the shape of the transition time required for the relaxation process, due to polymer chain length of their different relaxation processes do not correspond with the workpiece structure of the forces generated by the internal stress. Internal stress has adverse effects on the plastic parts.
3.2.2 The rheological behavior of plastic
Polymer in different thermal conditions, the existence of three kinds of forms: the solid state (glassy state), high-elastic state, viscous flow (liquid), also known as pseudoplastic fluid. The following are to be introduced to various forms:
Plastic elements in the solid state, segment movement largely stagnated in their position of molecular vibration, molecular chain winding or coil-shaped lumps, intertwined, disorder disorder, when subject to external force, the chain is only for an instant small stretch and bond angle changes. In this form, the mechanical properties of plastics to the environment of tolerance performance depends on the composition of the molecular chain, shape, sequence, and the chain of mutual supple position and pile density.
Molecules under high-elastic state unit of kinetic energy began to increase, expand into a network segment, but the movement of molecules remain in the small segment of the rotation, between the chain and the chain does not produce displacement under a force in the smaller have a greater deformation, but when the external force to lift after restitution. The high-elastic strain is not instantaneous, but over time the growth of strain increased, but after a certain amount, become stable equilibrium.
When the plastic into the viscous flow state (liquid), the network structure has disintegrated, between the macromolecular chains and chain, chain segment and the chain can freely between the slip, when given external force, the molecules to slip easily between the (mobile ), resulting in deformation of the plastic melt, remove the external force is not restitution. Plastic injection molding are carried out in the viscous flow state, so that molecular unit to facilitate the structure through the cross section of various shapes, filled the cavity and then cooled back into a high-elastic state, the ultimate in solid form at room temperature to survive.
3.2.3 Molecular creep and stress relaxation phenomenon
Glass state (solid) when the external force generated by the variable increases with time, linear, up to fracture; when the removal of external stress, the strain will keep the state variables generated at the time.
High-elastic state of stress are generated when external variables, the growth of strain increases with time, but after a certain amount, become stable and balanced state; strain reached the maximum force and energy in an instant, but still loose in an instant they complete Chi (removal of the external stress).
Viscous flow (liquid) are generated when the external stress variables, as time increases linearly increased, similar to pseudoplastic fluid; adaptive stress in the fall with the time, was a certain tendency, as time extend the reduced minimum value, that is no stress.
3.2.4 Plastic flow and cooling
① flow resistance: plastic flow in the molding process, from the solid into a liquid (viscous flow), first began to soften the surface melting, forming semi-solid, after mixing shear, eventually all of the solid-bed break until all melting; flow the existence of resistance for the solid state the most, followed by semi-solid state, molten state, the resistance depends on the temperature / pressure on the viscosity, flow properties similar to pseudoplastic fluid.
② filling / compaction stages: melting of the material by the process set into the mold cavity to melt to the mold cavity to fill all corners of the stage a short time period, generally (1-10) s to complete. Process of filling materials determines the quality of products, mainly, is the injection molding of the main process to be controlled.
③ back stage: the plastic melt in a moment full of cavities, cavity melt pressure reached its peak, so when the gate is not completely closed, while the screw barrel has pressure relief can cause melt back phenomenon, the gate contraction near the mark, when the molding to avoid this phenomenon.
④ cooling phase of freezing: cooling phase of freezing into the molding process, the final stage of material by melting and then through the cavity filled with condensation, crystallization, into a solid, complete the entire molding process, the control and direction of the cooling rate freeze that will be quality excellent product.
3.2.1影响流动因素有分子链的柔韧性，分子量与分子量的分布，分子链的支化度、增塑剂和熔剂，树脂受热温度，剪切速率等。高聚物的成型加工一般是在粘流状态下进行的。Tf—Td之间温度越宽，越利于加工；Tf为粘流温度，Td为分解温度。溶融物料在螺槽内有正向流动、横向流动、逆向流动、漏流4种流动状态。
① 正流是促使物料沿螺槽向机头主要输送流；
② 横流是物料在螺槽内翻转运动，形成环流，对物料的混合、塑化有很大的影响，对生产率没影响；
③ 逆流与正流正好相反，速度分布呈抛物线关系变化；
④ 漏流是影响塑化质量及生产能力的主要因素，漏流不在螺槽中运动，而是在螺杆与料筒的间隙中运动，漏流的大小与机头阻力呈3次方倍数的关系，漏流大时生产力严重下降甚至不能正常生产。
由于这些运动的组合起到搅动、混炼、剪切、压缩物料的作用，使物料塑化均匀，以一定的压力连续成型。高分子链在原来的形态过渡到相适应的形状需要的时间为松弛过程，由于高聚物其链段长度不同，松弛过程与制件结构不符时产生的力为内应力。内应力对塑件有不良影响。
3.2.2塑胶的流变行为
聚合物在不同热力条件下，以3种形态存在：即固态（玻璃态）、高弹态、粘流态（液态）又称假塑性流体。下面分别对各种形态加以介绍：
处于固态下的塑料分子，链段运动基本上处于停止状态，分子在自身的位置上振动，分子链缠绕成团状或卷曲状，相互交错、紊乱无序，当受到外力作用时，链段仅作瞬间微小伸缩及键角的改变。在这种形态下，塑料的物理机械性能对环境的耐受性能取决于分子链的构成、形状、序列、柔顺性以及链间相互位置与堆砌密度。
高弹态下的分子单元，动能开始增加，链段展开成网状，但分子间的运动仍维持在小链段的旋转，链与链之间不产生位移，在较小的作用力下可产生较大的形变，但当外力解除后即恢复原状。其高弹形变并非瞬间发生，而是随着时间的增长应变增加，但达到一定量后，趋于稳定，达到平衡状态。
当塑料进入粘流状态（液态）时，网状结构已经解体，大分子链与链之间，链段与链之间都能自由滑移，当给予外力时，分子间易产生滑移（流动），造成塑胶熔体形变，除去外力也不恢复原状。塑料注射成型都是在粘流状态下进行，使分子单元能便利地通过各种形状结构的断面，充满模腔再经冷却回复转变为高弹态，最终在常温下以固态的形式保存下来。
3.2.3分子蠕变与应力松驰现象
玻璃态（固态）受到外力时产生的变量，随着时间的增加而增加,呈线性关系，直至断裂；当撤除外界应力时，应变力保持在当时所产生的变量状态.
高弹态受到外界应力时产生的变量，随着时间的增长应变增加,但达到一定量后，趋于稳定,达到平衡状态；应变力能在瞬间达到最大值，但照样能在瞬间又完全松驰（撤除外界应力）。
粘流态（液态）受到外界应力时产生的变量，随着时间的增加而呈线性 增加，类似于假塑性流体；应变力在随着时间的延长应力下降，呈一定倾向，随着时间的延长降为最低值，即没有应力。
3.2.4塑胶流动与冷却
①流动阻力：塑料在成型流动过程中，由固态转化为液态（粘流态），首先是表层开始软化熔融，形成半固体，经过混炼剪切，最终所有的固体床破裂直至全部熔融；流动所存在的阻力为固态时最大，半固态时次之，熔融状态时的阻力取决于温度/压力对粘度的影响，流动性质类似于假塑性流体。
②充模/压实阶段：熔融的物料按设定的工艺注入模腔，使熔料填满至模腔的个个角落，该阶段时间周期短，一般在（1-10）s内完成。物料的填充工艺过程决定了制品的主要品质，是注塑成型中要加以控制的主要过程。
③倒流阶段：塑胶熔体在充满模腔的瞬间，模腔内熔体压力达到最高峰，如此时浇口没完全封闭，而螺杆料筒已经卸压，会造成熔体倒流现象，在浇口附近产生收缩 痕，模塑成型时该避免此现象出现。
④冻结冷却阶段：冻结冷却阶段已进入了模塑过程的最后阶段，材料经熔融充满模腔再经过冷凝、结晶，转化为固态，完成了整个成型过程，控制冻结冷却速度及方向即能得到品质优良的产品。
3.2 Liquidity
3.2.1 The impact of mobile factors of molecular chain flexibility, molecular weight and molecular weight distribution, molecular chain branching degree, plasticizers and flux, resin heating temperature, shear rate and so on. Polymer molding process is typically carried out under viscous flow conditions. Tf-Td the temperature between the wider, more conducive to processing; Tf for the viscous flow temperature, Td is the decomposition temperature. Melting material has a positive flow in the spiral groove, lateral flow, reverse flow, leakage flow state 4.
① now is to promote material flow along the spiral groove to head the main transport stream;
② cross flow is material in the spiral groove turning movement, the formation of circulation, mixing of materials, plastics have great impact, no impact on productivity;
③ countercurrent flow and are opposite parabolic relationship between velocity changes;
④ leakage affecting the plasticizing quality and productivity of the main factors, leakage does not screw slot movements, but the gap in the screw and barrel in the movement, size and head leakage resistance was a multiple of 3 power relationship, a serious leakage is large decline in productivity can not even normal production.
Because the combination of these campaigns play stirred, mixing, shear, compression material effect in that the plastics material evenly, forming a row to a certain pressure. Polymer chain in the original form to fit the shape of the transition time required for the relaxation process, due to polymer chain length of their different relaxation processes do not correspond with the workpiece structure of the forces generated by the internal stress. Internal stress has adverse effects on the plastic parts.
3.2.2 The rheological behavior of plastic
Polymer in different thermal conditions, the existence of three kinds of forms: the solid state (glassy state), high-elastic state, viscous flow (liquid), also known as pseudoplastic fluid. The following are to be introduced to various forms:
Plastic elements in the solid state, segment movement largely stagnated in their position of molecular vibration, molecular chain winding or coil-shaped lumps, intertwined, disorder disorder, when subject to external force, the chain is only for an instant small stretch and bond angle changes. In this form, the mechanical properties of plastics to the environment of tolerance performance depends on the composition of the molecular chain, shape, sequence, and the chain of mutual supple position and pile density.
Molecules under high-elastic state unit of kinetic energy began to increase, expand into a network segment, but the movement of molecules remain in the small segment of the rotation, between the chain and the chain does not produce displacement under a force in the smaller have a greater deformation, but when the external force to lift after restitution. The high-elastic strain is not instantaneous, but over time the growth of strain increased, but after a certain amount, become stable equilibrium.
When the plastic into the viscous flow state (liquid), the network structure has disintegrated, between the macromolecular chains and chain, chain segment and the chain can freely between the slip, when given external force, the molecules to slip easily between the (mobile ), resulting in deformation of the plastic melt, remove the external force is not restitution. Plastic injection molding are carried out in the viscous flow state, so that molecular unit to facilitate the structure through the cross section of various shapes, filled the cavity and then cooled back into a high-elastic state, the ultimate in solid form at room temperature to survive.
3.2.3 Molecular creep and stress relaxation phenomenon
Glass state (solid) when the external force generated by the variable increases with time, linear, up to fracture; when the removal of external stress, the strain will keep the state variables generated at the time.
High-elastic state of stress are generated when external variables, the growth of strain increases with time, but after a certain amount, become stable and balanced state; strain reached the maximum force and energy in an instant, but still loose in an instant they complete Chi (removal of the external stress).
Viscous flow (liquid) are generated when the external stress variables, as time increases linearly increased, similar to pseudoplastic fluid; adaptive stress in the fall with the time, was a certain tendency, as time extend the reduced minimum value, that is no stress.
3.2.4 Plastic flow and cooling
① flow resistance: plastic flow in the molding process, from the solid into a liquid (viscous flow), first began to soften the surface melting, forming semi-solid, after mixing shear, eventually all of the solid-bed break until all melting; flow the existence of resistance for the solid state the most, followed by semi-solid state, molten state, the resistance depends on the temperature / pressure on the viscosity, flow properties similar to pseudoplastic fluid.
② filling / compaction stages: melting of the material by the process set into the mold cavity to melt to the mold cavity to fill all corners of the stage a short time period, generally (1-10) s to complete. Process of filling materials determines the quality of products, mainly, is the injection molding of the main process to be controlled.
③ back stage: the plastic melt in a moment full of cavities, cavity melt pressure reached its peak, so when the gate is not completely closed, while the screw barrel has pressure relief can cause melt back phenomenon, the gate contraction near the mark, when the molding to avoid this phenomenon.
④ cooling phase of freezing: cooling phase of freezing into the molding process, the final stage of material by melting and then through the cavity filled with condensation, crystallization, into a solid, complete the entire molding process, the control and direction of the cooling rate freeze that will be quality excellent product.
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