凝胶丁腈共聚弹性体增韧聚甲醛的加工流变行为及力学性能

研究了聚甲醛(POM)/凝胶丁腈共聚弹性体(GNBE)共混物的熔体流动指数(MFI)、高压毛细管流变行为和力学性能。结果表明,共混物MFI随GNBE用量的增加下降较大。聚酰胺(PA)对POM/GNBE共混体系的MFI影响较小,而热塑性酚醛树脂(PFR)的影响显著。当PFR的质量份为4时,POM共混物的MFI达最小值(0.053g/min),约为未加增容剂POM共混物MFI的1/6。随着剪切速率的提高,共混物剪切黏度迅速与POM接近。这种黏度变化行为说明共混物比GNBE对剪切速率更敏感,共混物的黏度受POM的影响较大。随着剪切速率的提高,POM与GNBE的黏度比迅速减小,并接近1,说明POM和GNBE在高剪切速率下共混时,GNBE的液滴能够在POM连续相中分散达到最小。含20份GNBE的POM共混物在高剪切速率下的熔体表观黏度与POM相当;在PFR质量份为6时,POM共混物的缺口冲击强度达到21.6kJ/m2,超过了GNBE质量份为40的POM共混物。当PFR质量份为4时,共混物的缺口冲击强度为对应的不加增容剂共混物的冲击强度的2倍多,扯断伸长率提高了55.4%。     

POM／COPA二元及POM／COPA／EVA三元共混物的研究

研究了聚甲醛供聚酰胺（POM/COPA）二元及聚甲醛／共聚酰胺／乙烯-醋酸乙烯酯共聚物（POM／COPA／EVA）三元共混物，探讨了COPA、EVA用量对共混体系性能的影响。结果表明，C1DPA的加入使共混物的熔融温度（Tm）增大；当COPA含量为4％（质量分数，下同）时，00PA能够较均匀地分散于POM基体中，共混物缺口冲击强度出现最大值，比纯聚甲醛提高了约63．3％，而拉伸强度变化不大，POM／COPA共混物具有较理想的综合力学性能。EVA的加入使共混物缺口冲击强度和拉伸强度均呈下降趋势。     

POM／TPU共混物的力学性能和摩擦磨损性能研究

采用双螺杆挤出熔融共混的方法制备了聚甲醛(POM)和热塑性聚氨酯弹性体(TPU)/增容剂Z共混物.考察了共混物的力学性能、摩擦磨损性能,并通过扫描电子显微镜(SEM)观察其微观形态结构以及磨损表面形貌.结果表明:加入增容剂z可以使共混体系的相容性得到改善,提高了缺口冲击强度;当TPU的质量分数为30份时,缺口冲击强度达到13.8 kJ/m2,比纯POM提高了126%;共混物的摩擦磨损性能下降,随着TPU的用量的增加共混物的摩擦因数呈现先减小后增大趋势,而磨损量随之增大.     

聚甲醛/丙烯酸酯弹性体共混物的性能研究

采用双螺杆挤出机共混的方法制备了聚甲醛(POM)/丙烯酸酯弹性体(ACR)共混物,通过力学测试、差示扫描量热仪(DSC)、热重分析仪(TG)和扫描电子显微镜(SEM)等手段研究了POM/ACR共混体系的力学性能、结晶性能和热稳定性等。结果表明,POM的简支梁缺口冲击强度和断裂伸长率均随ACR含量的增加而提高,ACR含量为16%时,缺口冲击强度达到15 k J/m2,比纯POM提高了158%,断裂伸长率为80.5%,比纯POM提高了90%;DSC分析显示该弹性体影响了POM分子链段的运动,使POM的相对结晶度和结晶速率均降低;TG分析也显示氮气条件下,共混物的热分解温度和降解活化能均高于纯POM。     

不同弹性体增韧聚甲醛的研究

以丙烯酸酯类弹性体(KT–28)和热塑性聚氨酯(PUR-T)为增韧剂,通过熔融共混法对聚甲醛(POM)进行增韧改性,研究了这2种增韧剂含量对POM熔体流动速率(MFR)、韧性和拉伸强度的影响。结果表明,随KT–28和PUR-T含量的增加,POM的MFR和拉伸强度逐渐降低,缺口冲击强度和断裂伸长率逐渐升高;KT–28增韧POM的MFR低于PUR-T增韧POM,表明KT–28与POM的相容性比PUR-T更好;POM/KT–28的缺口冲击强度和断裂伸长率均高于POM/PUR-T,且当增韧剂质量分数低于12%时,KT–28对POM拉伸强度的劣化影响比PUR-T的小,同时KT–28具有比PUR-T更低的价格成本,是一种增韧效果好且价格低廉的POM增韧剂。     

含异氰酸酯基的低聚物和聚醚增容改性POM/TPU共混物

利用双螺杆挤出机制备了聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)、POM/TPU/含异氰酸酯基的低聚物(Z)以及POM/TPU/Z/聚醚3种共混物。采用力学性能测试、差示扫描量热分析(DSC)、偏光显微镜(PLM)、傅里叶转换红外线光谱 (FTIR)、扫描电子显微镜(SEM)、动态力学性能分析(DMA)等,研究了3种共混物的力学性能、结晶行为及形态结构。结果表明：共混物的缺口冲击强度和断裂伸长率随TPU含量的增加而提高;异氰酸酯基低聚物（Z）和聚醚在促进分散相分散、增强两相间的相容性方面发挥重要作用,降低了聚甲醛的结晶度,能够有效地提高共混物的缺口冲击强度和断裂伸长率。     

乙烯-乙酸乙烯酯共聚物增韧改性聚甲醛的研究

通过熔融共混的方法制备了聚甲醛(POM)/乙烯-乙酸乙烯酯(EVA)共混物,并对共混物的力学性能、结晶性能以及形貌进行了研究。结果表明,纯POM的缺口冲击强度只有7.6 kJ/m2,加入EVA橡胶后,共混物的缺口冲击强度得到了明显提高,但随着橡胶用量的增加,材料的弯曲模量与拉伸强度不断下降;EVA 的存在影响着POM的结晶性能,使结晶度下降;POM与EVA的两相界面比较清晰,表明两者的相容性不好,但合适的分散相粒径分布有利于EVA增韧POM。     

TPU增韧改性POM的研究

利用双螺杆挤出机制备了聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)和POM/TPU/异氰酸酯预聚物(Z)共混物.采用力学性能测试方法、偏光显微镜(PLM)、傅立叶转换红外线光谱 (FTIR)、扫描电子显微镜(SEM)等研究了共混物的力学性能、结晶行为及形态结构.结果表明,不同种类TPU增韧的共混物的缺口冲击强度和断裂伸长率都随TPU含量的增加而增加,TPU(95A)增韧的POM/TPU共混物的刚性较好,TPU(250)增韧的POM/TPU共混物的韧性较好;Z能促进TPU在基体树脂中的均匀分散,增强两相界面的粘结力,并能细化球晶.     

不同摩尔质量聚碳酸酯的增韧改性

研究了弹性体SEBS（苯乙烯-乙烯/丁烯-苯乙烯共混物）和SEP（苯乙烯-乙烯/丙烯共混物）的加入对不同摩尔质量聚碳酸酯（PC）力学性能的影响.对于通用级PC及低摩尔质量的PC,其缺口冲击强度随样品厚度增加大幅度降低,而少量弹性体（SEPTON 1003、SEPTON 8006）的加入使其6.4 mm厚样品缺口冲击强度有大幅度的提高,其它的力学性能如拉伸强度等变化不大.SEM和DSC分析表明：SEPTON与PC的相容性较好,共混物由PC明显的脆性断裂转变为韧性断裂.     

硅灰石填充改性聚丙烯体系结构与性能的研究

采用机械共混的方法制备了聚丙烯(PP)/硅灰石共混体系,并对共混体系的拉伸强度、冲击强度、断口形貌进行了测试与分析。在共混体系中加入弹性体乙烯-醋酸乙烯共聚物(EVA)和苯乙烯-丁二烯-苯乙烯(SBS),以增加体系的韧性;添加马来酸酐(MAH),以提高组分间的界面结合力。结果表明:EVA对共混体系增韧效果不明显,SBS能够增加体系韧性,MAH能够提高体系强度;当硅灰石质量分数为30%,SBS和PP-g-MAH的质量分数均为15%时,体系的力学性能最佳。     

聚甲醛合金的增容改性研究进展

介绍了不同增容剂增容聚甲醛(POM)/热塑性聚氨酯、POM/丁腈橡胶、POM/凝胶丁腈共聚物、POM/(乙烯/辛烯)共聚物、POM/(乙烯/丙烯/二烯)共聚物、POM/(甲基丙烯酸酯/丁二烯/苯乙烯)共聚物、POM/聚丙烯、POM/高密度聚乙烯合金体系的研究进展,并对其增容效果做了比较。     

抗静电聚甲醛的制备及性能

以聚乙二醇/季铵盐基甲基丙烯酸酯共聚物(DC3)为复合抗静电剂,乙烯–丙烯酸甲酯–乙酸乙烯酯无规三元共聚物(AX8)为增容剂,通过熔融挤出制备永久型抗静电改性聚甲醛(POM)材料。分别研究了DC3和AX8含量对POM表面电阻率和体积电阻率及力学性能的影响。结果表明,当DC3质量分数为1%,AX8质量分数为5%时,POM的表面电阻率降到2.7×10~9Ω,体积电阻率降到4.2×10~(10)Ω·cm,拉伸和弯曲强度略有下降,断裂伸长率略有提高,冲击强度则比纯POM提高了25.35%,且水洗30 d后,抗静电性能和力学性能均未发生明显的变化,达到了POM抗静电标准要求。     

乙烯–丙烯酸甲酯对聚甲醛热氧老化性能的影响

采用挤出成型制备出了具有优异韧性的乙烯–丙烯酸甲酯共聚物(EMA)改性聚甲醛(POM),研究了EMA对POM热氧老化性能的影响。采用万能拉力机、广角X射线衍射仪和蠕变仪对不同老化时间的纯POM和EMA改性POM的力学性能、结晶性能及蠕变性能进行了对比分析。结果表明,EMA的加入明显提高了POM的韧性,当EMA质量分数为9%时,其改性的POM冲击强度和断裂伸长率分别比纯POM提高了13%和97%,而拉伸和弯曲强度仅下降了4.5%和8.0%,结晶度和耐蠕变性也略有下降。EMA的加入并没有劣化POM的热氧老化性能,随老化时间的增加,EMA改性POM的拉伸和弯曲强度、结晶度、蠕变性能变化趋势与纯POM基本相同,在30 d老化时间内,其冲击强度和断裂伸长率的下降幅度较大,但仍高于相同老化时间下的纯POM,且在老化早期,EMA改性POM的韧性仍高于未老化时的纯POM,表明其可应用于汽车方向盘轴承链等需要材料具有较好韧性的零件部位。     

Thermal stability of polyoxymethylene and its blends with poly(ethylene‐methylacrylate) or poly(styrene‐butadiene‐styrene)

Polyoxymethylene (POM) copolymer and its blends with poly(ethylene‐methylacrylate) (EMA) or poly(styrene‐butadiene‐styrene) (SBS) up to 5 wt % were conducted to thermooxidative ageing in oven at 140°C for 111 days. POM showed continued degradation as seen from the gradual decrease in the crystallization temperature from differential scanning calorimetry (DSC) study, while no change in Fourier transform infrared spectra (FTIR) and low weight loss were observed (2.5% after 111 days' ageing). The POM degradation was characterized by the initial increase of crystallinity due to crystal perfection, which then kept nearly unchanged until 35 days' ageing, and lastly increased again to result in embrittlement and decrease in tensile strength. Increase in the tensile stress and strain was observed up to 35 days' ageing. POM blends with SBS or EMA had similar degradation behavior as POM, but addition of SBS accelerated the POM degradation significantly, while POM blend with 1 or 3% EMA just showed slightly lower thermal stability than POM. Degradation in POM and SBS/POM occurred in amorphous phase while EMA/POM degraded in both amorphous and crystal phase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

共聚尼龙增韧改性聚甲醛的研究

本文采用共聚尼龙，用机械共混的方法对聚甲醛进行增韧改性，并对共混物的形态，结构与力学性能进行测试与分析。研究发现，在ＰＯＭ／ＣＯＰＡ共混体系中，存在着氢键的相互作用，且氢键的相对强度随ＣＯＰＡ含量的增加而增加。ＣＯＰＡ的加入，使得ＰＯＭ的熔融温度Ｔｍ和结晶温度Ｔｃ均增加，ＣＯＰＡ含量在１０％以下质量范围内，ＣＯＰＡ对ＰＯＭ具有增韧改性作用。     

Polyoxymethylene/ethylene butylacrylate copolymer/ethylene‐methyl acrylate‐glycidyl methacrylate ternary blends

Blends of compatibilized polyoxymethylene (POM)/ethylene butylacrylate copolymer (EBA)/ethylene‐methyl acrylate‐glycidyl methacrylate copolymer (EMA‐GMA) and uncompatibilized POM/EBA were investigated. The notched impact strength of the compatibilized blends was higher than that of their uncompatibilized counterparts. The toughness of the POM blends was improved obviously with relatively low loading of EBA. Fourier transform infrared spectroscopy (FTIR) spectra of EMA‐GMA, pure POM, and POM/EBA/EMA‐GMA blends indicated that epoxy groups of EMA‐GMA reacted with terminal hydroxyl groups of POM molecular chains. The glass‐transition temperature (T_g) values of the POM matrix and the EBA phase were observed shifted to each other in the presence of EMA‐GMA compatibilizer indicating that the compatibilized blends had better compatibility than their uncompatibilized counterparts. With the addition of EBA to POM, both the compatibilized and uncompatibilized blends showed higher onset degradation temperature (T_d) than that of pure POM and the T_d values of the compatibilized blends were higher than those of their uncompatibilized counterparts. The scanning electron microscopy showed better EBA particles distribution state in the compatibilized system than in the uncompatibilized one. The compatibilized blend with an obvious rougher impact fracture surface indicated the ductile fracture mode. POLYM. ENG. SCI., 58:1127–1134, 2018. © 2017 Society of Plastics Engineers     

The effect of interface modification between POM and PTFE on the properties of POM/PTFE composites

A plasma technique was applied to modify the surface of polytetrafluoroethylene (PTFE) fiber to improve the compatibility between PTFE and polyacetal (POM). This technique used argon (Ar) plasma to treat PTFE fiber first and then grafting the fiber with acrylic acid (AAc) by peroxidation. The Ar plasma‐treated PTFE (PPTFE) fiber and AAc‐grafted PPTFE (AAc‐g‐PPTFE) fiber were added into POM to increase the wear resistance and to decrease the friction coefficient of POM. The variables of the experiments were plasma treatment time, monomer concentration of AAc, and grafting time. The graft copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The stress–strain behavior, impact strength, Taber wear factor, friction coefficient, and morphology of composites were also investigated. The properties of POM/PTFE composites could be successful modified by surface modification of PTFE in this investigation. The impact strength of POM/AAc‐g‐PPTFE composites was more than twice of that of POM/PTFE composites. The Taber wear factor and friction coefficient of POM/AAc‐g‐PPTFE composites decreased markedly. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 800–807, 2000     

共聚聚甲醛的增韧研究

本研究以国产共聚甲醛(POM)为原料,以硅橡胶和纳米硫化丁苯橡胶为增韧剂,改性聚甲醛。通过万能强力仪、热重分析仪、差示扫描量热分析仪、偏光显微镜、X射线衍射仪、扫描电镜等测试方法,分析和研究了改性聚甲醛的结晶行为以及力学性能。结果表明：硅橡胶的最佳用量为总质量的3%,纳米硫化丁苯橡胶的最佳用量为总质量的1%。增韧剂可以使POM的球晶得到细化,POM的抗冲击性能提高30%以上的同时,几乎不影响拉伸强度。     

Modification of aromatic diamine-cured epoxy resins by poly(oxymethylene) or hybrid modifiers containing poly(oxymethylene)

A copolymer comprising poly(oxymethylene) (POM, polyacetal) was used to improve the fracture toughness of a resin based on diglycidyl ether of bisphenol A (DGEBA) cured with 3,3′-dimethyl-5,5′-diethyl-4,4′-diaminodiphenyl methane. POM was a less effective modifier for epoxies and a third component was used as a toughener or a compatibilizer for POM. The third component includes polypropylene glycol-type urethane prepolymer (PU) and aromatic polyesters. The hybrid modifiers composed of POM and PU were more effective as modifiers for toughening epoxies than POM alone. In the ternary DGEBA/POM/PU (90/10/10wt ratio) blend, the fracture toughness, K_IC, for the modified resin increased 50% with retention of flexural properties and a slight decrease in glass transition temperature (T_g) compared with those of the unmodified epoxy resin. The aromatic polyesters include poly(ethylene phthalate) (PEP), the related copolyesters and poly(butylene phthalate). PEP was most effective of them as a third component in the hybrid modifier. In the ternary DGEBA/POM/PEP (85/15/10) blend, K_IC for the modified resin increased 70% with medium loss of flexural strength and retention of T_g. The toughening mechanism is discussed in terms of morphological and dynamic viscoelastic behaviour of the modified epoxy resin systems. ©1997 SCI