尼龙6在振动注塑中的力学性能和结晶形态

采用自行研制的压力振动注塑装置，在不同振动频率、振动压力下得到尼龙6注塑试样。结果表明，振动试样拉伸性能比静态试样有所提高，随振动频率或振动压力的提高，试样的拉伸强度发生变化。运用DSC（差示扫描量热分析）和SEM（扫描电镜）对试样结构进行了表征，测试结果表明，振动作用能使球晶数量增加，完善结晶，提高结晶度。     

高密度聚乙烯振动注射试样的结构与性能

为了研究高密度聚乙烯振动注射试样的晶体结构与性能．研制并采用压力振动装置进行振动注射实验一通过振动，高密度聚乙烯由常规注射试样的典型球晶结构转变为明显取向的片晶结构，在不同的振动条件下，片晶的尺寸和取向度都不同。振动试样的拉伸强度随振动频率和振动压力的提高而提高，最大增幅为41.0％。断裂伸长率随振动压力的增高而下降，随振动频率的增高开始时下降，然后开始回升。     

振动改善全同立构聚丙烯注塑试样的力学性能

为了研究振动场对全同立构聚丙烯力学性能的影响，研制了压力振动注射装置，研究了不同熔体温度下，振动频率、振动压力对iPP F401注塑试样的拉伸强度、冲击强度和断裂伸长率的影响，并进行了WAXD和DSC测试。结果表明：振动除了提高试样结晶度外，还会诱导晶型的变化，即除α晶，还有β晶生成。随着振动频率和振动压力的增加，振动试样的拉伸强度和冲击强度得到明显改善，其最大增幅分别为26．1％和168％。     

振动改善高密度聚乙烯注塑试样的力学性能

为了研究高密度聚乙烯在低频振动场中注塑试样的力学性能，研制了振动频率为0-1．5Hz、振动压力为0—75MPa的压力振动注射装置；研究了不同熔体温度下，振动频率、振动压力对HDPE DGDA6098注塑试样的拉伸强度、断裂伸长率的影响；并进行了WAXD的测试。结果表明，振动增强了试样的取向程度，改变了试样的微晶尺寸。随着振动频率和振动压力的增加，振动试样的拉伸强度得到明显改善，其最大增幅为41％。     

振动注射成型高密度聚乙烯的结构与性能

研究了高密度聚乙烯(HDPE)在压力振动场中的注射成型。结果表明：振动频率和振动压力对成型试样的拉伸强度有显著影响，振动注射成型试样的拉伸强度最大可提高28．7％；HDPE成型试样的晶体形貌由未振动时的球晶转变为特定振动条件下规整平行排列的片晶结构。     

全同立构聚丙烯振动注射试样晶体结构的变化

采用自行研制的压力振动注射装置，在不同熔体温度、振动频率、振动压力下成型了全同立构聚丙烯振动注射试样，并进行了WAXD、DSC和SEM测试。结果表明，当成型温度为190℃时，在高的振动频率下，有γ晶生成；在高振动压力条件下，有β晶生成。当成型温度为230℃，无论是在高频率，还是高压力振动，都有β晶生成。同时，振动还将改变试样的熔点，提高试样结晶度，细化晶粒。     

振动注塑PP/CaCO3的拉伸蠕变研究

采用自制的机械振动注塑机,在不同振动频率和振动压力下成型PP/CaCO3试样.考察了试样的拉伸蠕变.结果表明,当振动压力一定时,PP/CaCO3的拉伸应变随着振动频率的增加先增大后减小,当振动频率为15 Hz时达最大;而当振动频率一定时,材料的拉伸应变随着振动压力的增大而减小.通过对不同成型条件下注塑的PP/CaCO3材料进行了短时拉伸实验和动态力学性能测试,从材料柔性和刚性分析其蠕变原因.     

振动注塑对IPP力学性能和晶型的影响

主要对比了普通注塑等规聚丙烯(IPP)试样和振动注塑IPP试样晶型及力学性能的差别,研究了高模温条件下振动频率、振动压力对IPP样条力学性能和晶体形态的影响.结果表明,IPP样条的冲击强度比未振动试样有所提高;较高的模温则有利于β晶的生成.通过广角X射线衍射分析发现,在高温下,高频、低振动压力注射有利于IPP中β晶含量的增加,实现注射IPP试样的自增强和自增韧.     

振动注射成型对等规聚丙烯的结构和静态力学松弛行为的影响

采用自行研制的机械振动注塑装置,在不同振动频率和振动压力下制得等规聚丙烯(IPP)振动注塑试样。结合试样的广角X射线衍射(WAXD)、差示扫描量热(DSC)测试结果发现,与常规注塑试样相比,振动应力场促进了PP的结晶,振动试样的结晶度明显提高,晶粒明显细化。在0～15MPa范围内增加振动压力能明显减小试样的蠕变和应力松弛;在0～2.3Hz范围内随着振动频率的增加,试样的蠕变和应力松弛先减小后增大,在振动频率为1Hz时其静态力学松弛性能达到最佳。     

振动注塑对IPP/HDPE共混物力学性能和凝聚态结构的影响

研究了振动频率、振动压力对等规聚丙烯/高密度聚乙烯(IPP/HDPE)共混物力学性能和凝聚态结构的影响。结果表明,与未施加振动的静态试样相比,振动试样的力学性能得到提高。随着振动压力的提高,低频率振动试样的力学性能呈明显上升趋势;振动频率对低振动压力试样的力学性能影响较小。在试样的表层及次表层,聚合物晶体沿熔体流动方向均有明显的取向。而对于试样芯层,则只有在成型温度为190℃、振动频率为0.23 Hz、振动压力为90 MPa的条件下才能观察到明显的晶体取向。     

Vibration-Induced Self-Reinforcement of Injection Molding Samples of High-Density Polyethylene

A pressure vibration injection machine with vibration frequency of 0–1.5 Hz and vibration pressure of 0–75 MPa was developed to investigate self-reinforcement of high-density polyethylene (HDPE). The effect of vibration frequency and vibration pressure on tensile strength and elongation of HDPE DGDA6098 vibration molding samples, which were obtained at different melt temperatures, was studied, and SEM and WAXD measurements were conducted. Experimental results showed that vibration changed the crystal structure of vibration samples and enhanced their orientation. Instead of spherulites of static samples, crystal structure of vibration samples was lamellae that was orientated along melt flow direction. When vibration frequency was high, lamella size was small and orientation degree was low. When vibration pressure was high, lamella size was large and orientation degree was high. Therefore, vibration samples were self-reinforced with increasing vibration frequency and vibration pressure, where the maximum increment of tensile strength was 41.0 %.     

Mechanical Property, Thermal Property and Crystal Structure of Isotactic Polypropylene Samples Prepared by Vibration Injection Molding

Summary A self-designed pressure vibration injection device was used to study the effect of vibration frequency and vibration pressure on tensile strength and impact strength of iPP F401 vibration injection molding samples. Furthermore, vicat softening temperature, WAXD measurements and polarized microscopic observation were conducted. According to the results, tensile strength and impact strength increase with increasing vibration frequency and vibration pressure. The maximum increment of tensile strength is 26.1%. Under certain process conditions, there is a transition of the impact strength, whose maximum increment is 85%. The vicat softening temperatures have a significant increase of 6∼8 °C for the samples obtained at high vibration frequencies compared with that of static samples. According to pole figures, α-PP of vibration samples orientates much stronger than that of static samples. PM micrograghs show that vibration changes the crystal structure of samples and enhances their orientation.     

Effect of vibration on rheology of polymer melt

In this article, under shearing vibration and pressure vibration, the rheological behavior of HDPE, ABS, and PS melts and the mechanical properties of molded parts are studied. The experimental results show that, under the vibration condition, the apparent viscosity of the polymer melt decreases with an increasing of the vibration frequency and amplitude applied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1587–1592, 2002     

动态塑化过程振动参数对聚丙烯性能的影响

采用新型液压脉振式注射机成型聚丙烯(PP)试样,探讨了塑化过程中振幅和频率对PP物理力学性能和成型过程整机能耗的影响。结果表明:保持其他工艺参数不变,在塑化过程中施加振动后,PP试样的拉伸强度提高9.8%,冲击强度提高13.8%,密度提高0.3%,整机加工能耗降低6.6%。     

振动参数对HDPE注塑件力学性能的影响

采用自制的振动注射试验装置注射成型高密度聚乙烯(HDPE)制件,探讨振动频率、振动压力幅度对HDPE注塑件屈服强度、断裂伸长率、拉伸弹性模量和冲击强度的影响。结果表明,振动使得注塑件的综合力学性能得到改善;不同温度下振动频率或振动压力幅度对注塑件力学性能的影响程度不同,但其影响趋势是一致的。     

Influence of Recycled ABS Added to Virgin Polymers on the Physical,Mechanical Properties and Molding Characteristics

Reuse of recycled polymers is steadily increasing. In this study, two different ABS virgin materials are considered. Then, blends of varying proportions of ABS recycled resins (0–50%), obtained from the gate and runner materials of products, was added to virgin resin to investigate the effect of various compositions of virgin ABS and recycled polymers on the physical and mechanical properties of the final blend. Three different rib and closure organization of boss of the reinforcement structures were designed and injection molded under blends of varying proportions of the ABS recycled resins to do the torsion test by Air-Torsion tools. In addition, molding characteristics were also examined. The results show that there is no obvious effect of recycled ABS percentage (by weight) on the tensile strength, elongation at yield, flexural strength, flexural modulus, and impact strength. However, the torsion strength for rib and closure organization of boss of the reinforcement structures decrease with increasing recycled ABS weight percentage. On the other hand, hardness, glass transition temperature, and melting flow index of recycled ABS increase with as the percentage (by weight) of recycled material increase. The impact strength was found to vary with the recycled ABS loading. The injection pressure decreases with increasing the content of recycled resin under some specified molding conditions.     

Effect of nanoparticles on the mechanical properties of acrylonitrile–butadiene–styrene specimens fabricated by fused deposition modeling

Acrylonitrile–butadiene–styrene (ABS) nanocomposite filaments with different inorganic nanofillers for fused deposition modeling (FDM) were prepared by melting extrusion and printed via a commercial FDM three‐dimensional printer. The effects of the nanoparticles on the mechanical strength, anisotropy, and thermal properties of the ABS specimens were evaluated. The performances of the virgin ABS samples manufactured by FDM and injection molding were also studied. The results show that the tensile strength (TS) of the pure ABS made by FDM was just up to 70% of the value obtained from the injection‐molded specimens. The mechanical anisotropy of the pure ABS samples was very evident when the building orientation was changed. However, we found that the addition of nanofillers significantly reduced the mechanical anisotropy and improved the mechanical strength and thermostability of the ABS samples fabricated by FDM technology. The TS and flexural strength of the ABS samples increased by 25.7 and 17.1%, respectively, with the introduction of nanomontmorillonite. The addition of nano calcium carbonate lowered the mechanical anisotropy of ABS from 42.1 to 23.9%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44470.     

Mechanical properties and structure of high‐density polyethylene samples prepared by injection molding with low‐frequency vibration

To better understand the formation of different crystal structures and improve the mechanical properties of high‐density polyethylene samples, melt vibration technology, which generally includes shear vibration and hydrostatic pressure vibration, was used to prepare injection samples. Through melt vibration, the crystal structure changed from typical spherulites of the traditional injection sample to obviously orientated lamellae of vibration samples. Sizes and orientation degrees of lamellae were different according to different vibration conditions. Crystallinity degrees of vibration samples increased notably. Therefore, the tensile strength of vibration samples increased with increasing vibration frequency and vibration pressure, whereas elongation of vibration samples decreased during the first stage and then continued to increase as the vibration frequency increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 818–823, 2005