结晶结构及固相热处理对聚苯硫醚摩擦性能的影响

通过对注塑聚苯硫醚(PPS)试样在不同条件下进行固相热处理,研究材料结晶结构对材料摩擦行为和性能的影响,利用差示扫描量热法及广角X射线衍射讨论了固相热处理对聚苯硫醚结晶行为的影响,利用环-块式摩擦磨损试验机研究了材料的摩擦磨损性能。结果表明,结晶结构对PPS摩擦性能具有重要影响,经固相热处理后PPS结晶度较未处理试样提高约118%,磨损率降低96.8%,摩擦系数由0.58降低至0.45,摩擦稳定性明显提高,且其磨损机理由非晶区软化造成的大面积粘着磨损较转变为以犁切和点蚀为主的磨粒磨损和疲劳磨损。     

多次DSC扫描对聚苯硫醚/尼龙6共混物中聚苯硫醚组分结晶行为的影响

用DSC研究了多次重复扫描对聚苯硫醚/尼龙 6(PPS/PA6)共混物中PPS组分结晶行为的影响.随扫描次数增加,熔融温度低时,PPS的结晶温度稍有提高;熔融温度高时,PPS的结晶温度逐步降低;而且出现2或3个结晶峰.共混物中PPS组分除结晶温度比纯PPS的高外,随熔融温度和扫描次数增加,仅有单一高温结晶峰 .以上结果可用自成核、异相成核和交联作用来解释.     

聚苯硫醚及其纤维增强复合材料的等温结晶形态

采用热台偏光显微镜技术观察了聚苯硫醚(PPS)及其玻璃纤维、 炭纤维及芳纶纤维增强复合材料等温结晶过程中球晶结构形态的变化。研究了等温结晶温度对PPS的晶体形态及球晶生长速率的影响。结果表明, 结晶温度对PPS的结晶影响非常明显。在235~265℃, 随着等温结晶温度的升高, 聚苯硫醚球晶形态发生了从细小而具有部分束状结构到大而完善再到细小而不完善的变化过程, 球晶的生长速率随着结晶温度的增大呈非线性下降。而纤维的存在使PPS的结晶形态发生了从球晶结构到横穿晶的变化, 且不同纤维诱导形成横穿晶的程度有所不同。其中玻璃纤维和芳纶纤维可以诱导形成较为明显的横穿晶形态, 而炭纤维则不能诱导形成明显的横穿晶。      

纳米填料改性聚苯硫醚及其纤维研究进展

聚苯硫醚(PPS)是一种耐高温、耐化学腐蚀、阻燃的高性能材料,其纤维制品可广泛应用于高温过滤、化学防护等领域。通过纳米填料熔融复合技术,可显著提高PPS材料及其纤维的综合性能。详细介绍了国内外纳米填料对PPS及其纤维紫外光稳定性、热氧稳定性、结晶和力学性能、以及耐磨性的改性研究,并进一步分析了纳米粒子对PPS的改性机理。详述了目前PPS纳米复合改性研究的不足,提出相应的解决方案。指出了纳米改性研究首先需要提高PPS纤维的紫外光稳定性、耐热氧化性能和最高使用温度,以扩展PPS纤维的应用范围。综合分析表明,PPS纤维的纳米改性研究仍处于起步阶段,需深入对不同形貌、尺寸纳米填料复合改性及纳米复合纤维成形机理的研究,并拓宽其研究范围。     

一种新的膜材料——聚苯硫醚

综述了聚苯硫醚 (polyphenylenesulfide简称PPS)的结构、性能和在制膜中的应用 .PPS是一种可在高温下连续使用 ,并拥有可与含氟材料相匹敌的耐酸、碱和有机溶剂的新型高分子工程材料 .用对二氯苯和硫化钠在合适的溶剂中经催化反应生成PPS ,目前已能规模化生产 .由于PPS具有多方面的优良性能 ,可用PPS或改性PPS通过熔融法或相转化法制备中空纤维膜、平板膜或管式膜 ,用于超滤、反渗透、渗透汽化、离子交换膜等 .     

熔融挤出制备PPS／PES共混物的研究

本文运用示差扫描量热分析(DSC)技术研究了经熔融挤出共混方法制备的PPS/PES共混物的熔融、结晶行为。结果表明,PES对PPS的熔融、结晶行为有深刻影响,混入PES使PPS的熔融行为发生了变化,使PPS的结晶能力提高;PPS和PES有一定的相容性,混入PES使PPS的玻璃化转变温度提高;不同的热历史对PPS/PES共混物的熔融行为有深刻的影响。     

PPS／PES共混体系热行为特征的研究

本文借用TBA、DSC技术,研究了聚苯硫醚(PPS)与聚醚矾(PES)共混的相容性,讨论了共混方法对两者相容性的影响,研究了无定形的聚醚矾对半结晶性的聚苯硫醚熔融、结晶和冷结晶行为的影响以及PPS/PES共混物的界面行为。结果表明:溶液共混较机械共混相容性好;且在PES含量为60～70％(重量百分比)时,两组份相容性得到提高并存在较强的界面效应,在DSC谱图上呈现界面相的玻璃化转变;PFS的加入,破坏了PPS原有的结晶聚集态结构,使PPS的熔融双峰变为单峰,并促进了PPS的冷结晶。     

电子封装用聚苯硫醚高性能复合材料的研制

微电子工业的快速发展迫切需要性能更为优异的封装材料.采用聚苯硫醚复合材料作为电子封装材料,具有使用温度高、热膨胀系数低、介电损耗低、电绝缘性能好等优异的性能,应用于现代微电子领域的前景良好.本文用国产商品PPS树脂经纯化处理后,与其它材料复合,成功制备出了聚苯硫醚高性能电子封装材料,制备的PPS电子封装材料具有低吸水性、低热膨胀系数、高强度以及优异的介电性能等综合性能,优于目前常用的环氧类电子封装材料.     

聚苯硫醚/羟基改性多壁碳纳米管复合材料的非等温结晶行为

采用差示扫描量热(DSC)法研究了羟基改性多壁碳纳米管(MWCNTs-OH)填充聚苯硫醚(PPS)复合材料的结晶过程,并利用莫志深方程研究了PPS/MWCNTs-OH复合材料的非等温结晶动力学。结果表明,莫志深方程能较好地描述该体系的非等温结晶动力学过程,在达到相同结晶度时,莫志深方程中的两个参数F(T)和α均明显随着MWCNTs-OH添加量的增加而下降,定量说明PPS/MWCNTs-OH复合体系的结晶速率明显高于纯PPS,且随着MWCNTs-OH添加量的增加,结晶速度提高。但是熔融热(ΔHm)和结晶热(ΔHc)随着MWCNTs-OH添加量的增加均呈现出下降趋势,说明MWCNTs-OH的加入使PPS/MWCNTs-OH复合体系的结晶度降低。     

中长纤维毡/高分子量PPS悬浮液含浸法热塑性复合材料工艺研究

本文对高分子量PPS的工艺性以及中长纤维增强高分子量PPS热塑性复合材料的制备方法进行了研究。确定了用PPS的悬浮液进行对中长纤维毡的含浸工艺是制造这种复合材料较为有效的方法。其中,环氧树脂作为胶粘剂来把PPS粉和纤维毡粘住。由于环氧树脂对PPS粉末的包覆作用,可以防止PPS的氧化交联。通过对材料机械性能的测试,并且运用“均匀设计”的试验方法,找出了最佳工艺条件。用这种方法制得的中长纤维增强PPS热塑性复合材料在性能上超出了美国DOW化学公司RFCI艺的类似产品。最突出的是这种材料的高温性能。在高达250℃的温度下,其抗拉强度仍可达到89MPa.     

Crystallization of polyphenylene sulfide

The properties of molded PPS parts are dependent on the crystalline morphology developed during processing. Even though processed under identical conditions, the crystalline morphology may differ owing to the differences in the crystallization process. The crystallization behaviour of a polymer is known to depend on its molecular architecture which in turn depends upon polymerization process. Thus the study of the crystallization behaviour of polymer with reference to its molecular architecture is essential for obtaining product with desirable properties. In the present paper, the crystallization behaviour of two grades of polyphenylene sulfide was investigated using differential scanning calorimetry (DSC). An attempt has been made to explain the differences in the crystallization behaviour of PPS samples on the basis of the differences in their molecular architecture. The structural differences of PPS manifest themselves in terms of the depression in the equilibrium melting point, retardation of nucleation and overall crystallization rate and coarsening of spherulitic texture.     

聚苯硫醚/尼龙6共混物的结晶与熔融行为

用ＤＳＣ研究了不同组成比的聚苯硫醚（ＰＰＳ）／尼龙６（ＰＡ６）共混物中ＰＰＳ和ＰＡ６组分的结晶与熔融行为及其相互作用的影响,结果表明,ＰＰＳ在ＰＡ６熔体存在下结晶温度明显提高,结晶峰形变窄;随ＰＡ６含量增加,ＰＰＳ的结晶温度移向高温,甚至ＰＰＳ成为分散相,这一作用还十分明显;而ＰＰＳ的熔融温度受共混影响较小,结晶了的ＰＰＳ也使ＰＡ６的结晶温度有所提高,但不如ＰＰＳ的结晶温度提高明显;当ＰＡ６为分散     

羟基及羧基改性多壁碳纳米管对聚苯硫醚结晶性能的影响

采用差示扫描量热法（DSC）考察了聚苯硫醚（PPS）和PPS/多壁碳纳米管（MWCNTs）复合材料的等温结晶过程,通过Avrami方程得到等温结晶动力学参数。结果表明,少量（1%）羟基改性多壁碳纳米管（MWCNTs-OH）和羧基改性多壁碳纳米管（MWCNTs-COOH）的加入不会改变PPS的成核方式,但能提高它的结晶速...     

聚苯硫醚与聚四氟乙烯共混物的研究 Ⅰ.结晶形态与界面相互作用

PPS 的结晶形态与其树脂的处理、结晶条件及成型条件有关。在 PPS/PTFE 共混物中,PTFE 的织态结构及其热力学性质与其是否预烧结有关。表面张力及结晶动力学测定结果表明,PPS 与 PTFE 的界面存在一定的相互作用。在界面上两者相互向对方表面转移,使对方表面能发生变化。PPS 的存在对 PTFE 结晶有一定的成核作用,而 PTFE 的存在对 PPS 的结晶并无促进作用。     

Preparation and properties of electrically conductive PPS/expanded graphite nanocomposites

Nanocomposites based on poly (phenylene sulfide) (PPS) and expanded graphite (EG) or ultrasonicated EG (S-EG) were prepared by melt blending. Morphologies of the nanocomposites were examined using both SEM and TEM. Electrical conductivity and thermal stability of PPS were notably enhanced by the introduction of EG. The percolation threshold values are 1 wt% (S-EG) and 2 wt% (EG) for PPS/S-EG and PPS/EG nanocomposites, respectively. The variation of mechanical strength with the weight fraction of EG and S-EG in the nanocomposites showed somewhat correlation with the threshold filler concentration. The crystallization behavior of PPS matrix in the nanocomposites was investigated using DSC, and the results indicated that the crystallization process was significantly accelerated, leading to an increase in crystallinity.     

LDPE熔融接枝纳米SiO2协同增韧PPS的研究

采用熔融接枝共混法制备PPS基纳米复合材料。熔融接枝改性的纳米S iO2粒子在PPS中形成界面粘接较好的S iO2-LDPE核壳包覆结构以及微纤网络结构,使PPS结晶温度显著提高、晶粒细化、结晶度降低。包覆结构、微纤网络结构的形成和结晶特性的变化对PPS的增韧效果显著,使复合材料冲击强度高达85.1 kJ/m2(纯PPS的3.7倍)。     

热塑性树脂增韧聚苯硫醚的结晶行为

用DSC研究了高性能热塑性树脂聚砜(PSF)、酚酞型聚醚酮(PEK-C)与聚苯硫醚(PPS)共混物的结晶熔融行为,结果表明,PSF、PEK-C主要起阻碍PPS结晶的作用,使Avrami指数n值和冷却结晶函数m值下降;热塑性树脂的T_g越高和熔融温度提高,影响更大。     

Preparation and properties of poly (p-phenylene sulfide)/multiwall carbon nanotube composites obtained by melt compounding

In this paper, electrical and mechanical properties of Poly (p-phenylene sulfide) (PPS)/multi-wall carbon nanotubes (MWNTs) nanocomposites were reported. The composites were obtained just by simply melt mixing PPS with raw MWNTs without any pre-treatment. The dispersion of MWNTs and interfacial interaction were investigated through SEM &TEM and Raman spectra. The rheological test and crystallization behavior were also investigated to study the effects of MWNTs concentration on the structure and chain mobility of the prepared composites. Though raw MWNTs without any pre-treatment were used, a good dispersion and interaction between PPS and MWNTs have been evidenced, resulting in a great improvement of electrical properties and mechanical properties of the composites. Raman spectra showed a remarkable decrease of G band intensity and a shift of D bond, demonstrating a strong filler–matrix interaction, which was considered as due to π–π stacking between PPS and MWNTs. The storage modulus (G′) versus frequency curve presented a plateau above the percolation threshold of about 2–3 wt% with the formation of an interconnected nanotube structure, indicative of ‘pseudo-solid-like’ behavior. Meanwhile, a conductive percolation threshold of 5 wt% was achieved and the conductivity of nanocomposites increased sharply by several orders of magnitude. The difference between electrical and rheological percolation threshold, and the effect of critical percolation on the chain mobility, especially on crystallization behavior of PPS, were discussed. In summary, our work provides a simple and fast way to prepare PPS/MWNTs nanocomposites with good dispersion and improved properties.     

Various curing conditions for controlling PTFE micro/nano-fiber texture of a bionic superhydrophobic coating surface

A simple and conventional coating-curing process to fabricate superhydrophobic coating surface with both the micro-nano-scale binary structure (MNBS) roughness, and the lowest surface energy hydrophobic groups (?CF₃) on engineering materials of stainless steel or other metals was developed by control of curing conditions. Results show that higher temperature and longer cooling time resulted in longer crystallizing process, and the forming PTFE aggregates could slowly produce the crystallization and create the willow-leaf-like or wheat-haulm-leaf-like polymer micro/nano-fiber on the atop surface. The curing temperature dramatically influences the micro/nano-fiber texture of the PTFE/PPS superhydrophobic coating surface, leading to the excellent superhydrophobicity at higher temperature. An increase of the curing temperature is beneficial to fluorine gradient-distribution, PPS thermal-oxidative cross-linking and oxidative reaction, resulting in the enhancement of adhesive strength and mechanical properties of the PTFE/PPS superhydrophobic coatings. A bionic superhydrophobic surface with porous gel-like network and PTFE micro/nano-fiber textures could be created by natural cooling in air, whereas PTFE nano-sphere/-papillates textures could be fabricated by hardening in H₂O.