纳米二氧化硅含量对微发泡高抗冲聚苯乙烯发泡行为的影响

将改性的纳米二氧化硅(nano-SiO2)以不同的含量加入到高抗冲聚苯乙烯(HIPS)中,在二次开模条件下制备微发泡HIPS/nano-SiO2复合材料,分析了不同含量的nano-SiO2对微发泡复合材料泡孔结构和发泡行为的影响规律。结果表明:随nano-SiO2含量的增加,泡孔平均直径逐渐减小,泡孔密度逐渐增加;当nano-SiO2含量为3%时,泡孔直径最小为19.15μm,泡孔密度最大达到1.71×107个/cm3,具有理想的发泡效果。     

模具温度对PP/SiO2发泡行为的影响

采用化学发泡法制备出聚丙烯/纳米二氧化硅(PP/nano-SiO2)微发泡复合材料,探讨了不同模具温度对PP/nano-SiO2发泡行为的影响。结果表明:模具温度对PP/nano-SiO2发泡材料发泡行为的影响主要体现在2个方面:一方面,影响PP/nano-SiO2复合发泡材料的泡孔结构参数,随模具温度升高,熔胶散热越慢,泡孔的直径越大,泡孔密度越小,分散状态越不稳定;另一方面,影响PP/nano-SiO2发泡材料制品内部区域面积,及随模具温度升高,发泡面积越大。发泡材料的冲击强度和拉伸强度随模具温度的升高明显下降。     

释压量对聚烯烃复合材料微发泡行为的影响

通过自行设计的模具,采用化学发泡法制备聚丙烯(PP)/纳米二氧化硅(nano-SiO2)与高抗冲聚苯乙烯(HIPS)/nano-SiO2微发泡复合材料。研究释压量对微发泡聚烯烃复合材料发泡行为的影响规律。结果显示:2种聚烯烃/nano-SiO2微发泡复合材料的泡孔平均直径、尺寸分散度,随着释压量的增大先减小后增大;泡孔密度则相反,随释压量的增大先增大后减小。在释压量为12%时,PP/nano-SiO2与HIPS/nano-SiO2的发泡效果最好。     

聚四氟乙烯原位纤维化对TPEE/PTFE复合材料发泡行为的影响

通过熔融共混法研究了不同加工工艺对聚四氟乙烯（PTFE）纤维化的影响,制备了热塑性聚酯弹性体（TPEE）/PTFE纳米纤维复合材料。在此基础上,研究了PTFE含量对TPEE的结晶行为、流变行为以及发泡行为的影响。结果表明,PTFE纤维可以促进TPEE结晶,改善TPEE的流变性能。纳米纤维的高比表面积为泡孔成核提供了大量成核位点,有效提高了泡孔密度,降低了泡孔尺寸;当PTFE含量为2份时,制备了平均泡孔直径为3.2 μm,平均泡孔密度为3.11×10¹⁰ 个/cm³的复合材料泡沫。     

微发泡PP/Nano-SiO_2复合材料泡孔结构与力学性能研究

采用化学注塑发泡法制备了微发泡聚丙烯/纳米二氧化硅(PP/nano-SiO2)复合材料,研究了发泡量对微发泡PP/nano-SiO2复合材料泡孔结构和力学性能的影响。结果表明:发泡量对微发泡PP/nano-SiO2复合材料的泡孔结构具有很大影响。随着发泡量的增加,微发泡材料逐渐呈现欠发泡、均衡发泡、过发泡状态,而且微发泡材料的拉伸强度逐渐降低,冲击强度则先增加后减小,并在发泡量为8%时达到最大值(5.398 kJ/m2)。另外通过非线性回归分析法对微发泡PP/nano-SiO2复合材料力学性能与相对密度之间的关系进行了预测,并获得了与其他相关研究一致的结论。     

聚乳酸扩链改性及其挤出发泡的研究

采用扩链剂对聚乳酸（PLA）进行扩链改性,研究了扩链剂对PLA流变性能的影响。采用3种不同类型的化学发泡剂：发泡剂A（发泡母粒）、发泡剂B\[自制复合发泡剂：偶氮二甲酰胺（AC发泡剂）/碳酸氢钠(NaHCO3)\]、发泡剂C(自制改性AC发泡剂),利用单螺杆挤出机对PLA进行挤出发泡。采用扫描电子显微镜观察分析了发泡材料的断面泡孔结构。结果表明,加入扩链剂可有效提高PLA的熔体强度和黏度及降低其熔体流动速率,改善PLA的发泡效果,扩链剂含量为0.8份（质量分数,下同）时,发泡材料的发泡效果最好;实验所用的3种发泡剂中,发泡剂C的发泡效果最好,发泡剂含量为1.5份时,发泡样品的表观密度较小（0.6 g/cm3）,泡孔直径最小(约为57 μm),泡孔密度最大（约为7.69×10^6个/cm3）,泡孔分布均匀,无明显泡孔破裂和连通现象。     

单甘脂对聚苯乙烯挤出发泡性能的影响

利用超临界二氧化碳挤出发泡法,研究了单硬脂酸甘油脂（GMS）母粒的添加量对聚苯乙烯（PS）发泡性能的影响。采用毛细管流变仪研究了GMS添加量对PS/GMS体系的流变特性的影响,观察并测试了发泡材料的微观泡孔结构。研究结果表明,GMS的添加会降低树脂的黏度。母粒中含有的多组分GMS和少组分乙烯-醋酸乙烯（EVA）共同影响制品的表观密度、平均泡孔直径和泡孔密度等参数。在GMS添加量为1.05%,EVA添加量为0.45%时,制品的平均泡孔直径最小,泡孔密度最大。     

PETA/St双单体聚丙烯挤出改性及其发泡性能研究

以季戊四醇三丙烯酸酯（PETA）和苯乙烯（St）为接枝单体,采用反应挤出改性制备具有长支链结构的聚丙烯（LCBPP）。使用红外光谱、差示扫描量热仪、流变测试等表征材料的可发泡性,并通过扫描电子显微镜观测发泡材料的泡孔形貌。并以CO₂为发泡剂进行了间歇熔融发泡实验以评估聚丙烯（PP）的熔融发泡性。结果表明,在未交联改性PP中,用2 %（质量分数,下同）PETA和3 %St改性的PP各项性能最好;改性PP具有不同程度的应变硬化现象,这归因于不同程度的长链支化结构;改性后具有长链支化结构的PP有较好的发泡效果,PP?g?PETA/St样品的发泡温度窗口为25 ℃,最高发泡倍率达到33倍,此时泡孔平均直径为36 μm,泡孔密度为3.17×10⁸个/cm³。     

环氧基POSS对PLA/PBAT共混材料发泡行为的影响

通过熔融共混法制备了聚乳酸/聚己二酸对苯二甲酸丁二酯/聚倍半硅氧烷(PLA/PBAT/POSS)复合材料,并利用超临界二氧化碳(CO_2)固相发泡法对复合材料进行发泡,通过差示扫描量热仪、高级动态流变仪和扫描电子显微镜等对复合材料的结晶行为、流变行为和发泡行为进行了研究。结果表明,POSS粒子对基体树脂具有增塑效应,PLA的冷结晶温度降低,结晶度提高;复合体系的流变性能明显提高,其发泡材料的泡孔密度和发泡倍率均随着POSS粒子含量的增加而增大,当加入7份(质量份,下同)POSS时,发泡材料的泡孔密度提高至8.25×10~7个/cm~3,发泡倍率达到13倍;POSS粒子对PLA泡沫的泡孔形态具有显著的调控作用。     

新型非对称双螺杆挤出制备PPC/PTFE共混物及其超临界CO_2发泡行为研究

采用新型同向非对称双螺杆挤出机制备了聚碳酸亚丙酯(PPC)/聚四氟乙烯(PTFE)共混物,分析了PTFE在PPC基体中的分散性,并通过超临界流体发泡技术,探讨了PTFE填料对PPC发泡材料泡孔结构的影响。结果表明,新型同向非对称双螺杆挤出机的高效混合特性有利于增强PTFE在PPC基体中的分散;PTFE作为成核剂,可减小复合材料微孔发泡的泡孔尺寸,增加泡孔密度,当PTFE含量为3%(质量分数,下同)时,泡孔密度比纯PPC大幅度提高,达到4.75×10~7个/cm~3,平均泡孔直径约为2μm。     

纳米SiO_2对微发泡聚丙烯复合材料发泡行为的影响

将改性的纳米二氧化(硅SiO2)以不同含量加入到聚丙(烯PP)中,在二次开模条件下制备微发泡PP/纳米SiO2复合材料,分析了纳米SiO2含量对微发泡复合材料发泡行为的影响。结果表明:随着纳米SiO2含量的增加,复合材料的平均泡孔直径减小,泡孔密度增加,当纳米SiO2含量为4%时,复合材料的泡孔直径为16.3μm泡,孔密度达1.41×109个/cm3具,有理想的发泡效果。     

Preparation of poly(propylene carbonate)/nano calcium carbonate composites and their supercritical carbon dioxide foaming behavior

Biodegradable polymer foams are attracting extensive attention in both academic and industrial fields. In this study, an emerging biodegradable polymer, poly(propylene carbonate) (PPC), was compounded with nano calcium carbonate (nano‐CaCO₃) and foamed via supercritical carbon dioxide for the first time. Four concentrations of nano‐CaCO₃, 1, 3, 5, and 10 wt %, were used and the thermal properties of PPC/nano‐CaCO₃ composites were investigated. The glass‐transition temperature and thermal decomposition temperature of the PPC/nano‐CaCO₃ composites increased with the addition of nano‐CaCO₃. The morphologies of the PPC/nano‐CaCO₃ composites and the rheological results showed that homogeneous dispersions of nano‐CaCO₃ and percolated nano‐CaCO₃ networks were achieved at a nano‐CaCO₃ content of 3 wt %. Therefore, the finest cell diameter (3.13 μm) and highest cell density (6.02 × 10⁹ cells/cm³) were obtained at the same nano‐CaCO₃ content. The cell structure dependences of PPC and PPC with a nano‐CaCO₃ content of 3 wt % (PPC‐3) foams on the foaming pressure and temperature were investigated as well. The results suggested that the cell structure of PPC‐3 was more stable at different foaming conditions due to the networks of nano‐CaCO₃. Moreover, the change in pressure was more influential on the cell structure than the temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42248.     

Rheological and mechanical properties of thermoplastic polyurethane elastomer derived from CO2 copolymer diol

CO₂ copolymer diol‐based thermal polyurethane elastomers (PPC‐TPU) were prepared by the reaction of CO₂ copolymer diol and methylene diphenyl diisocyanate and chain extender (ethylene glycol/1,4‐butanediol/1,6‐hexanediol) (EG/BDO/HG). The rheological and mechanical properties of PPC‐TPU were analyzed. The effects of shear rate, shear temperature, hard segment content, and variety of chain extender on the properties of PPC‐TPU were studied. The results showed that the apparent viscosity (η) of PPC‐TPU decreased with the increasing shear rate (τ), and the non‐Newtonian index (n) was less than 1. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. The degradation during the processing was obviously inhibited by adding plasticizer and antioxidant. It was also discovered that the apparent viscosity varied with the content of hard segment and chain extender. Under the same temperature (185 °C) and shear rate (50 s^?1), the apparent viscosity increased considerably with the raise of hard segment content, and the apparent viscosity and tensile strength of PPC‐TPU with EG as chain extender was the maximum. It can be seen that with the apparent shear rate increasing, the variation tendency of apparent shear stress levels off, and the nonlinear relationship of τ–γ curve tended to be obvious. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45974.     

Thermal, mechanical, and rheological properties of poly(propylene carbonate) cross-linked with polyaryl polymethylene isocyanate

In this study, cross-linked poly(propylene carbonate) (PPC) was prepared using polyaryl polymethylene isocyanate (PAPI) as a cross-linking agent. The gel content, thermal behaviors, mechanical and rheological properties of the cross-linked PPC were investigated. FTIR results showed that the chemical reactions took place between PPC and PAPI and the interactions demonstrated that PPC may be cross-linked with the PAPI. The results of gel content revealed that PPC was partially cross-linked with the PAPI. The cross-linked PPC showed higher glass transition temperature and decomposition temperature compared with pure PPC. Accordingly, the melt flow index gradually decreased and complex viscosity increased with increasing PAPI content. Moreover, the mechanical properties proved also to be enhanced as evidenced by tensile tests. The introduction of small amount of cross-linkable moiety provides an efficient and convenient method to improve the properties of PPC and extend its application area.     

BCE/BMI/Nano-SiO_2复合材料的性能研究

采用熔融共混法制备了氰酸(酯BCE/)双马来酰亚胺预聚(体BMI)/纳米二氧化(硅nano-SiO2)复合材料,研究了nano-SiO2用量对复合材料耐热性能、静态力学性能和动态力学性能的影响,并利用扫描电镜分析了nano-SiO2在聚合物基体中的分散情况。结果表明:随着nano-SiO2用量的增加,BCE/BMI/nano-SiO2复合材料的冲击强度和弯曲强度均是先升后降,冲击强度、弯曲强度和储能模量均在nano-SiO2含量为2%时达到最大值;nano-SiO2的加入可以提高复合材料的耐热性,但随其用量的增加,nano-SiO2在基体中的分散性逐渐变差。     

PPC/PBAT共混复合材料性能的研究

采用双螺杆挤出机制备了聚碳酸亚丙酯/聚对苯二甲酸-己二酸丁二酯共混复合材料(PPC/PBAT)。考察了PPC、扩链剂和增塑剂用量对该共混材料力学性能和流变性能的影响。研究结果表明:在PPC/PBAT共混体系中,随PPC用量的增加,拉伸强度逐渐提高,而断裂伸长率和熔体流动速率(MFR)不断降低;而扩链剂二苯基甲烷二异氰酸酯(MDI)的引入,改善了PPC与PBAT的相容性,且随着MDI用量的增加,共混材料的拉伸强度和断裂伸长率呈增加趋势,而MFR则持续降低;另外,当体系中加入增塑剂柠檬酸三丁酯后,随其用量的增加,PPC/PBAT共混材料的拉伸强度降低,而断裂伸长率和MFR持续提高。     

共混方法对PP/纳米Si02复合材料性能的影响

分别采用溶液共混法、熔融共混法以及二阶共混法来制备PP纳米SiO2复合材料,探讨了不同共混方法时,纳米SiO2含量对复合材料力学性能及微观结构的影响。结果表明,从纳米SiO2的分散来说,溶液共混最好、二阶共混次之、熔融共混最差;当纳米SiO2含量超过3%时,二阶共混法制备的复合材料具有复相结构;而纳米SiO2用量超过5%时,3种共混方法制备的复合材料都出现层状结构;因此,纳米SiO2含量为3%时的二阶共混法制备的复合材料既形成了复相结构又还未出现层状结构,其综合力学性能优异,拉伸强度提高了21. 3%,断裂伸长率增加了27.6%,冲击强度提高了131. 1%。     

纳米SiO2改性PVC／MPC共混膜的研究

采用浸入沉淀相转化和铸膜液光透射测试相结合的方法,考察了纳米SiO2对PVC／MPC铸膜液扩散性质及膜性能的影响。分析测试了不同配方体系的相分离动力学曲线、膜的性能及微观结构。结果表明,PVC／MPC共混膜体系中加入纳米SiO2后,PVC／MPC铸膜液体系分相速度加快。膜性能测试结果表明,体系中SiO2含量对PVC／MPC共混膜的纯水通量和截留率有影响,加入的纳米SiO2质量分数为2％～4％时,该膜在保持较大的截留率的情况下,水通量有较大幅度的提高。膜断面的SEM照片表明,PVC／MPC／SiO2共混膜有更大、更短的指状孔。     

CE/nano-SiO_2复合材料的韧性和耐磨性研究

采用模塑成型法制备CE/nano-SiO2复合材料,通过冲击强度和磨损率测试、透射电子显微镜(TEM)和扫描电子显微镜(SEM)表征,分别考察了nano-SiO2及其表面处理对氰酸酯树脂韧性和耐磨性的影响。结果表明,nano-SiO2经偶联剂SEA-171表面处理后其改性效果明显优于未表面处理的nano-SiO2;相对纯CE,含3.00%nano-SiO2时,未表面处理和表面处理的nano-SiO2复合材料的冲击强度提高率分别为61.28%和83.58%;耐磨性提高率分别为51.16%和77.05%。