miPP与ziPP的可纺性比较

采用熔融纺丝法 ,比较了茂金属催化聚丙烯 ( mi PP)和齐格勒 -纳塔催化聚丙烯 ( zi PP)切片在相同纺丝条件下的可纺性 ,研究了纺丝条件对其初生纤维结构与性能的影响。研究发现 ,mi PP的可纺性受温度的影响比较大 ,在低温下纺丝性能较好 ;mi PP卷绕丝与 zi PP卷绕丝相比具有良好的可拉伸性能 ;m i PP的相对分子质量分布较窄 ,其初生纤维的取向度较高     

国产Z30S聚丙烯纺制细旦丙纶复丝的研究

研究了国产Ｚ３０Ｓ聚丙烯及其改性切片的分子量（ＭＷ）和分子量分布（ＭＷＤ）以及纺丝工艺对纺制细旦丙纶复丝可纺性和卷绕丝结构性质的影响。研究表明，采用Ｚ３０Ｓ切片即使纺丝温度高达２８０℃时，卷绕丝仍是α晶型结构，若添加少量降温母粒共纺或经改性后纺丝，卷绕丝可获得准晶型或混晶型结构，有较好的可纺性和后拉伸性；纺丝工艺条件，诸如纺丝温度、冷却条件、泵供量和纺丝速度等对卷绕丝的结构和性质虽起重要的影响，但ＰＰ的ＭＷ和ＭＷＤ则起首要的影响。     

熔体着色聚丙烯高速卷绕丝的结构与性能

由于聚丙烯缺乏染色席次,熔体着色成为工业化生产聚丙烯纤维普遍采用的办法。本文通过本色(纯PP)及着色聚丙烯高速卷绕丝的对比研究,揭示了聚丙烯着色熔体高速纺时纤维结构形成的基本规律。色母粒的加入改变了熔体冷却固化过程。使纺丝张力大大提高。在较低纺速下,着色卷绕丝结晶度增强主要归因于次晶的快速生长;在较高纺速下,结晶度增加主要归因于α晶的快速生长。同时,颜料颗粒的存在,不仅减弱了无定形区的大分子缠结和分子间力,而且使结晶区的折叠链结构更趋松散并使缚结分子易从晶片中滑脱。因此,相同纺速下制取的聚丙烯卷绕丝总是具有较低的强度、较低的屈服应力和较大的延伸度。     

聚丙烯/聚苯乙烯共混熔纺中分散相的形态演变

采用共混熔融纺丝法制备聚丙烯(PP)/聚苯乙烯(PS)共混纤维,在纺程上不同位置收集纤维,研究了纺程上分散相PS的形态演变以及共混组成和拉伸比对形态变化的影响。结果表明:纺程上分散相由挤出丝中的球形变为卷绕丝中的椭球形;随着分散相含量的增加,挤出丝中分散相数目增多,分散相之间发生聚并,直径增加,纺丝过程中在拉伸应力作用下,分散相发生形变;随着拉伸比的增加,卷绕丝中分散相长径比增加,分布变宽。     

高速往复槽筒设计与制造——涤纶高速纺丝研究之二

涤纶高速纺丝制予取向丝(POY)的技术是七十年代新技术,纺丝卷绕速度为3500～4000米/分时,要求导丝往复速度为450～600米/分。若取导丝行程为250毫米时,其往复次数高达800～1200次/分。因此对适应高速纺丝的卷绕机要求愈来愈高的导丝机构是实现高速卷绕的关键问题之一。对往复槽筒(或称圆柱凸轮)和导丝器的设计是十分重     

聚碳硅烷无卷绕纺丝及最小临界成形直径形成研究

通过纺丝动力学方程研究了无卷绕纺丝存在的最小临界成形直径及其产生的原因。单孔纺丝试验证实了无卷绕纺丝条件下存在的最小临界成形直径,并表明丝条成形直径总是大于临界成形直径,进而提出了补偿拉伸应力以降低丝条成形直径的方法。     

可熔融加工的PAN树脂纺丝工艺及卷绕丝的结构与性能研究

研究了可熔融加工的聚丙烯腈 (MPPAN)树脂的非增塑熔融纺丝工艺 ,并应用 X光衍射、声速、应力 -应变等方法对卷绕丝的结晶和取向结构、力学性能和沸水收缩性进行了表征 ,结果表明 ,两种MPPAN样品均可进行熔融纺丝 ,其纺丝压力比常规聚酯纤维、聚酰胺纤维高 ;MPPAN卷绕丝的结晶及晶粒尺寸较低 ,具有一定的机械强度 ,热水收缩较大。     

涤纶高速纺丝工艺条件对POY性能的影响

<正> 为了弄清纺丝工艺条件的变化对高速纺丝过程影响的规律,以指导实际生产过程。本文研究了冷却吹风条件、纺丝集束位置变化以及卷绕有、无导丝盘等对高速纺丝以及POY(预取向丝)结构和性质的影响,并初步     

工艺条件对X形导湿透气功能聚酯预取向丝性能的影响

探讨了在纺丝成形过程中纺丝温度、侧吹风速度、卷绕速度等工.艺参数对X形导湿透气功能聚酯预取向丝截面形态、拉伸性能等的影响。研究表明,纺丝温度为291℃、侧吹风速度为0.40～0.45 m/s、卷绕速度为2800～2900m/min时得到的纤维综合性能较好。     

母粒注入法生产有色PTT全拉伸丝的工艺

利用原有的聚对苯二甲酸乙二酯(PET)纺丝及卷绕设备,采用前纺注入着色母粒的方法生产有色聚对苯二甲酸丙二酯(PTT)全拉伸丝(FDY)。结合PTT大分子的结构与性能,分析其特性,对有色PTT FDY生产过程中切片、色母粒的干燥,色母粒的加入量和纺丝、卷绕工艺等条件进行讨论,并对生产过程中易出现的色差问题提出了几点建议。     

Conducting bicomponent fibers obtained by melt spinning of PA6 and polyolefins containing high amounts of carbonaceous fillers

Melt spinning of conductive polymer composites (CPCs) is coupled with some difficulties such as a decrease of conductivity upon drawing and a reduced spinnability with increasing filler concentration. Applying bicomponent technology may provide the possibility to produce fibers from CPCs with a high filler concentration. A pilot‐scale bicomponent melt spinning set‐up was used to produce core/sheath fibers with fiber titers between 13 and 47 dtex. The sheath material was polyamide 6 (PA6) or polypropylene (PP) and the core material was a CPC. Two CPCs were used, polypropylene (PP) with carbon black (CB), denoted by PP/CB, and polyethylene (PE) with multiwalled carbon nanotubes (MWNT), denoted by PE/MWNT. The results showed that both materials could be used with a filler concentration of 10 wt % to obtain melt draw ratios up to 195. The volumetric fraction of core material in the bicomponent structure was 28%. A heat treatment of PP/CB fibers restored the conductivity to the level of the undrawn material, corresponding to an increase in conductivity by a factor 5. The same heat treatment had a positive effect on the conductivity of PE/MWNT fibers although the conductivity was not restored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

共混改性聚丙烯的研究

用双螺杆共混挤压机和熔融纺丝机,以PET、PE、EVA及另一牌号的PP对聚丙烯进行共混改性,讨论了这些共混物或共混纤维的相容性、流动性、可纺性和染色性。     

Annealing of polypropylene/poly(ethylene-co-propylene) blend. II. Influence of the structure and properties of poly(ethylene-co-propylene) and blended polyethylene on impact strength

The effect of annealing on the impact strength of PP/poly(ethylene-co-propylene) (PEP) and PP/PEP/PE blends was studied with regard to the structure of PEP and the polyethylene crystallinity. The tensile impact strength of annealed blends was remarkably affected by the PEP structure such as molecular weight and comonomer composition and the annealing temperature, while the brittle temperature was scarcely affected. For the PP/PEP/PE blends, annealing at temperatures above the melting point of PE lowers the tensile impact strength in a similar manner as the PP/crystalline PEP blend. These phenomena were explained on the basis of the deformation mechanism presented in the previous article, that is, a thicker interfacial layer of PP and PEP forms by means of annealing to increase the energy needed to deform the interface. By using a scanning electron microscope, the transition layer was observed at the interface between amorphous PEP and PE in the PP/amorphous PEP/PE blend after etching with nitric acid. The formation of a thicker transition layer between amorphous PEP and PE and a sizeable increase in PE particle size by annealing was observed. The phenomena should be correlated with the impact sensitivity, especially tensile impact strength, in the PP/crystalline PEP and PP/amorphous PEP/PE blends. A reasonable explanation of the microstructure in PP/PEP blends has been developed in terms of comonomer composition and melting property of PEP.     

Microcellular foaming of PE/PP blends

Three different polyethylene/polypropylene (PE/PP) blends were microcellular foamed and their crystallinities and melt strengths were investigated. The relationship between crystallinity, melt strength, and cellular structure was studied. Experimental results showed that the three blends had similar variation patterns in respect of crystallinity, melt strength, and cellular structure, and these variation patterns were correlative for each blend. For all blends, the melt strength and PP melting point initially heightened and then lowered, the PP crystallinity first decreased, and then increased as the PE content increased. At PE content of 30%, the melt strength and PP melting point were highest and the PP crystallinity was least. The blend with lower PP crystallinity and higher melt strength had better cellular structure and broader microcellular foaming temperature range. So, three blends had best cellular structure at PE content of 30%. Furthermore, when compared with PE/homopolymer (hPP) blend, the PE/copolymer PP (cPP) blend had higher melt strength, better cellular structure, and wider microcellular foaming temperature range, so it was more suited to be microcellular foamed. Whereas LDPE/cPP blend had the broadest microcellular foaming temperature range because of its highest melt strength within three blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4149–4159, 2007     

Structure and morphology of polyethylene/polypropylene in‐reactor alloys synthesized by spherical high‐yield Ziegler–Natta catalyst

A series of spherical polyethylene/polypropylene (PE/PP) in‐reactor alloys were synthesized with spherical high‐yield Ziegler–Natta catalyst by sequential multistage polymerization in slurry. The morphology of PE/PP alloy granule was evaluated by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show PE/PP in‐reactor alloy with excellent morphology, high porosity, and narrow distribution of the particle size. The PE/PP in‐reactor alloys show excellent mechanical properties with good balance between toughness and rigidity. It was fractionated into five fractions by temperature‐gradient extraction fractionation, and every fractionation was analyzed by FTIR, ¹³C‐NMR, DSC, and WAXD. The PE/PP in‐reactor alloy was found to contain mainly five portions: PP, PE, segmented copolymer with PP and PE segment of different length, ethylene‐b‐propylene copolymer, and an ethylene–propylene random copolymer. The characteristic chain structure leads to good compatibility between the fractions of the alloy that shows a multiphase structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2075–2085, 2007     

Mechanical properties and morphology of polyethylene–polypropylene blends with controlled thermal history

The effect of time–temperature treatment on the mechanical properties and morphology of polyethylene–polypropylene (PE–PP) blends was studied to establish a relationship among the thermal treatment, morphology, and mechanical properties. The experimental techniques used were polarized optical microscopy with hot‐stage, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and tensile testing. A PP homopolymer was used to blend with various PEs, including high‐density polyethylene (HDPE), low‐density polyethylene (LDPE), linear low‐density polyethylene (LLDPE), and very low density polyethylene (VLDPE). All the blends were made at a ratio of PE:PP = 80:20. Thermal treatment was carried out at temperatures between the crystallization temperatures of PP and PEs to allow PP to crystallize first from the blends. A very diffuse PP spherulite morphology in the PE matrix was formed in partially miscible blends of LLDPE–PP even though PP was present at only 20% by mass. Droplet‐matrix structures were developed in other blends with PP as dispersed domains in a continuous PE matrix. The SEM images displayed a fibrillar structure of PP spherulite in the LLDPE–PP blends and large droplets of PP in the HDPE–PP blend. The DSC results showed that the crystallinity of PP was increased in thermally treated samples. This special time–temperature treatment improved tensile properties for all PE–PP blends by improving the adhesion between PP and PE and increasing the overall crystallinity. In particular, in the LLDPE–PP blends, tensile properties were improved enormously because of a greater increase in the interfacial adhesion induced by the diffuse spherulite and fibrillar structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1151–1164, 2000     

Aggregation structure development and mechanical properties of biodegradable poly(butylene succinate-co-terephthalate) fibers

Biodegradable poly(butylene succinate-co-terephthalate)(PBST) copolyester, with 70 mol % butylene terephthalate (BT), was melt-spun into fibers at various take-up velocities ranging from 2.0 to 4.0 km/min. The structure development and mechanical properties of the as-spun PBST fibers were intensively investigated via birefringence, wide angle X-ray diffraction (WAXD) measurement, tensile test, and cyclic stretch test. With increasing the take-up velocity, the initial tensile modulus and breaking strength of PBST fibers increased, while elongation at break decreased. These were attributed to the increasing degree of orientation and crystallinity, which were resulted from the elevating tension of spinning line at higher take-up velocity. To elucidate the effects of soft butylene succinate (BS) unit on the tensile and elastic properties of PBST fibers, poly(butylene terephthalate) (PBT) fibers were adopted as a comparison sample. The results showed that the combination of soft BS unit and hard BT unit for PBST fibers made contribution to the lower initial modulus, higher elongation at break and better elastic recovery than those of PBT fibers. Moreover, PBST fibers were found to undergo PBT-like crystal form transition from α-form to β-form crystal structure under tension load through the measurement of WAXD. A relatively wider strain region for the crystal transition of PBST fibers also endowed them with higher elastic recoverability than PBT fibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

载体包裹填料提高PE/PP/EPDM/BN材料导热性

以三元乙丙橡胶(EPDM)/氮化硼(BN)复合材料为母料,通过熔融共混EPDM/BN复合材料与聚乙烯(PE)、聚丙烯(PP),制备PE/PP/EPDM/BN复合材料。采用PE∶PP的比例为5∶5,以使复合材料形成共连续结构;通过EPDM包裹BN的方法,实现BN在PE/PP/EPDM/BN复合材料共连续结构的相界面处分布,以形成导热通路,从而提高PE/PP/EPDM/BN复合材料的导热性能。通过接触角测试和扩散系数公式计算预测了EPDM会选择性分布在PE/PP/EPDM复合材料共连续结构的相界面处。通过连续度计算结果得出,EPDM为PE和PP总质量的15%时,EPDM的连续度为85.3%。由扫描电子显微镜分析表明EPDM在PE/PP/EPDM/BN复合材料中连续贯通。由导热测试分析知,随着BN含量的增加,PE/PP/EPDM/BN复合材料的热导率逐渐增加。这项研究提高了PE/PP复合材料的热导率,此材料在电子工业中可能具有潜在应用。     

PP/HDPE/EPDM复合体系微孔发泡实验

聚丙烯(PP)是结晶性聚合物,熔体强度低,发泡性能差.为了提高PP的微孔发泡性能,首先将PP和聚乙烯(PE)共混,然后在PP/PE共混体系中加入少量EPDM,研究EPDM的质量含量对PP/PE共混体系熔体强度和最终泡孔结构的影响.分析机理,寻找能够提高PP熔体强度和改善发泡性能的材料.     

Effects of spinning conditions on morphology and properties of polyethylene terephthalate fibers spun at high speeds

Fiber spinning of polyethylene terephthalate (PET) was studied at take-up speeds ranging from 2000 m/min to 7000 m/min under various spinning conditions. Effects of changes in process variables on the molecular orientation, crystallinity, and properties of as-spun PET fibers are reported. Conventional cross-flow quench in high-speed spinning yields fibers with undesirable crimp and asymmetric structure with respect to the fiber axis. Radial-flow quench eliminates these problems. Changes in other spinning conditions, such as extrusion temperature, throughput or take-up denier, and molecular weight, may also affect the development of PET fiber structure in the high-speed threadline.