UFPSBR对NR胎面胶性能的影响

将超细全硫化粉末丁苯橡胶（UFPSBR）加入到常用的NR胎面胶体系中,研究其对NR胎面胶性能的影响。力学性能测试结果表明,添加5份经饱和食盐水处理的UFPSBR后NR拉伸强度最大（25．36MPa）,比空白试样提高了18．45％;磨耗量最小（0．1600cm^3／1．61km）,比空白试样减少了33．85％,耐磨耗性最好。定负荷压缩生热和DMA分析测试结果表明,UFPSBR的加入可以提高NR胎面胶的抗湿滑性能,同时,对滚动阻力及生热性能方面的负面影响不大。     

Effect of lactic acid on polymer crystallization chain conformation and fiber morphology in an electrospun nylon-6 mat

The role of lactic acid (LA) on the polymer crystallization chain conformation and the surface modification of the electrospun nylon-6 fibers were examined. The effect of different amounts of LA on the polymer crystallization chain conformation of nylon-6 mat was evaluated using XRD, FT-IR and Raman spectroscopy whereas the surface modification of the electrospun mats was examined by FE-SEM, contact angle and mechanical properties measurement. It was found that the transition of meta-stable γ-form into the thermodynamically stable α-form was achieved by increasing the amounts of LA in the blend mixture. The adhesive property of LA was found to be responsible for the transformation from non-bonded to the point-bonded structure of nanofibers in the electrospun nylon-6 mat. The resultant LA/nylon-6 hybrid mat with improved hydrophilicity and mechanical properties may be a potential candidate for tissue scaffold.     

超细全硫化粉末丁腈橡胶在聚氯乙烯改性塑料中的应用

介绍了超细全硫化粉末丁腈橡胶及其在硬质聚氯乙烯和软质聚氯乙烯两种材料共混增韧改性中的应用进展。与普通粉末丁腈橡胶P83的增韧性相比,采用少量的超细全硫化粉末橡胶即能够在保持较高强度和耐热温度的基础上,大幅度提高PVC改性材料的韧性。     

Crystallization of polyamides under elevated pressure: 2. Pressure-induced crystallization of nylon-6 (polycapramide) from the melt

A study has been made on the crystallization of nylon-6 from the melt under elevated pressures. Crystallization induced by pressures of up to 8 kbar at temperatures between 270° and 310°C did not lead to a significant increase of the melting temperature for nylon-6 containing 8% caprolactam. However, the melting peak temperature, as determined by differential scanning calorimetry was found to increase from 220° to 250°C for nylon-6 without caprolactam and crystallized under pressures exceeding 5 kbar for 50 h. The heat of melting of the nylon specimen crystallized under these conditions increased from 14 to 37 cal/g. Thermal decomposition of the polymer could be diminished by heating under pressure and extruding the nylon under vacuum prior to the high pressure crystallization experiments. The specific volume diminished gradually during isothermal crystallization and the melting temperature was found to increase with crystallization time. These observations point to a one stage process for the development of extended-chain crystals of nylon-6. The highest melting peak temperature of 256°C was recorded on nylon-6 which was crystallized at 315°C and 8 kbar for a period of 320 h.     

Toughening of polypropylene by combined rubber system of ultrafine full-vulcanized powdered rubber and SBS

A combined rubber system of ultrafine full-vulcanized powdered rubber (UFPR) and SBS was used for polypropylene toughening. The PP toughened with the combined rubber system shows not only higher impact strength as compared to each rubber component used alone but also good stiffness and heat resistance. Crystallization study shows that the UFPR is more efficient in promoting the crystallization of PP than SBS, leading to a higher crystallinity and an enhancement of stiffness and heat resistance of PP. The combined rubber system containing UFPR and a small amount of SBS still possesses a good nucleating ability. Transmission electron microscopy results indicate that the combined rubber system mostly forms an encapsulation structure of UFPR particles encapsulated by SBS phase. This morphology was also confirmed by scanning electron microscopy results through observing the fracture surfaces of toughened samples. A small amount of SBS was found to be helpful for a better dispersion of UFPR in PP matrix. The causes for the encapsulation morphology and the synergistic toughening effect were discussed. A tentative explanation was given by comparison of the solubility parameter of each component in the toughened samples.     

Properties of toughened poly(butylene terephthalate) by blending with reactive ultra-fine full-vulcanized acrylonitrile butadiene rubber particles (UFNBRP)

The nano-sized ultra-fine full-vulcanized acrylonitrile butadiene rubber particles (UFNBRP) functionalized with carboxyl groups were used to toughen poly(butylene terephthalate) (PBT) through compatibilization of the two components via reactive extrusion in a twin-screw extruder. The impact strength of PBT was greatly improved with the nano-sized UFNBRP which may be attributed to its small particle size and the reactive compatibilization. Reactions between carboxyl groups on the surface of UFNBRP and hydroxyl end groups of PBT were proved with FT-IR spectra. In addition, UFNBRP also exhibited good nucleation effect and promoted the crystallization kinetics of PBT. Incorporation of small amounts of UFNBRP was found to be enough to improve the thermal stability. The maximum temperature of decomposition was increased by 25 °C at 1 wt% UFNBRP in comparison with that of pure PBT.     

Crystallization of polyamides under elevated pressure: 5.Pressure-induced crystallization from the melt and annealing of folded-chain crystals of nylon-11, poly(aminoundecaneamide) under pressure

High pressure dilatometry, differential scanning calorimetry, electron microscopy, X-ray diffraction, and infra-red spectroscopy to study how the crystallization of nylon-11 from the melt, as well as annealing of the folded-chain crystals, are affected by pressure in the range from 1 to 10 kbar (1 kbar = 100 MN/m²) and temperature in the range from 200° to 320°C. Pressures exceeding 3 kbar and temperatures higher than 230°C are sufficient for growth of the chain-extended crystals of nylon-11 either by pressure-induced crystallization from the melt or by annealing of the folded-chain crystals. Crystallization from the melt or annealing at 320°C or higher, and 10 kbar, resulted in crosslinking of the polymer. The highest melting temperature and heat of melting found for the chain-extended crystals of nylon-11 were 226°C and 35 cal/g respectively, as compared to 190°C and 13.6 cal/g for the folded-chain material. The texture of the chain-extended crystals of nylon-11 was found to be spherulitic with well developed striations forming circle patterns, and polymer chains passing through several lamellae. No sharp boundaries were found between the chain-extended lamellae. The alpha-crystalline modification, found for the folded-chain crystals of nylon-11, was preserved in the high pressure crystallization and annealing experiments. Infra-red absorption bands at 1420 and 1225 cm^?1 seem to be associated with the presence of folds in the nylon-11 crystals. It is suggested that, during the initial stage of crystallization under pressure, folded-chain crystals are formed, with a crystalline order and long spacing larger than that of the starting nylon-11.     

Cold crystallization behavior of poly(lactic acid) in its blend with acrylic rubber; the effect of acrylic rubber content

Understanding the crystallization process of polymer blends is of great importance for designing their process conditions, especially when the crystallization occurs during heating, so‐called cold crystallization. In this paper, the cold crystallization behavior of poly(lactic acid) (PLA) in its blends with acrylic rubber (ACM) was studied as a function of ACM content, using various techniques including differential scanning calorimetry, polarized optical microscopy and rheological methods. It was found that the addition of 10 wt% ? 20 wt% ACM to the PLA accelerated its cold crystallization. However, on using a greater amount of ACM up to 30%, the rate of crystallization was not further increased. In the ACM‐rich blends, the crystallizable PLA domains were distributed inside the amorphous ACM matrix and consequently confined crystallization occurred. The observed effects are discussed in terms of the interplay between chain mobility enhancement and the influence of phase boundaries. © 2017 Society of Chemical Industry     

Kinetic studies of the crystallization of nylon-6 block copolymers

The crystallization kinetics of nylon-6 and nylon-6 block copolymers (NBC's) containing 1–3 mole % poly(ethylene oxide), PEO, were measured under isothermal and linear cooling conditions. The Avrami equation was used to fit the data. The range of the Avrami index n was from 1.5 to 2.2 for the system studied in the temperature range from 400–454 K. Maximum rate of crystallization was observed in the above temperature range. Nylon-6 block copolymers showed the maximum crystallization rate at a lower temperature than nylon-6. When the soft segment exceeded 3 mole %, no crystallization was observed. Cooling rate studies showed the same tendency. The crystallization rate behavior of nylon-6 block copolymers was similar to the pure nylon.     

Effect of poly(styrene-co-maleic anhydride) on physical properties and crystalline behavior of nylon-6/PEBA blends

This study investigated the effect of blending poly(styrene-co-maleic anhydride) (SMA) on the mechanical and thermal properties of nylon-6/polyether block amide (PEBA) blend. In these blends, nylon-6 was toughened with PEBA using SMA as the compatibilizer. All the blends were prepared via direct melt compounding using a co-rotating twin screw extruder. The amount of PEBA added affected the crystallization characteristics and the relative ratio of γ and α crystalline phases of Nylon 6. The crystallization rate of Nylon 6 was also affected by the cooling rate and the amount of PEBA added. The results of mechanical tests showed that the tensile properties, flexural properties, and impact strengths of the nylon-6/PEBA were all increased when blended with 1 wt% of SMA, at both 23 and ?20 °C. However, for neat nylon-6, the impact strength was not affected despite that both tensile and flexural properties were increased by the blending of SMA. The results indicated that SMA can increase the compatibility between nylon-6 and PEBA, thus expanding the usage of nylon-6/PEBA blend in low-temperature applications.     

超细全硫化粉末丁腈橡胶/二元共聚氯醚橡胶共混物的结构与性能

采用熔融共混工艺制备了超细全硫化粉末丁腈橡胶(UFPNBR)/二元共聚氯醚橡胶(ECO)共混物,研究了共混物的相态结构、动态力学性能、物理机械性能及老化性能,并与丁腈橡胶(NBR)/ECO共混物进行了对比.透射电镜观察表明,在UFPNBR/ECO体系中,UFPNBR为分散相,ECO为连续相;而在NBR/ECO体系中,ECO为分散相,NBR为连续相.动态力学性能分析结果显示在共混质量比不超过50/50时,UFPNBR/ECO共混物只存在1个玻璃化转变温度;当共混质量比超过50/50时分散相尺寸较大,出现2个玻璃化转变温度,而NBR/ECO始终存在2个玻璃化转变温度.加入适量的UFPNBR(不超过50份,质量)能降低UFPNBR/ECO共混物的压缩永久变形.与NBR/ECO共混物相比,UFPNBR/ECO共混物的脆性温度较低,耐老化性能更好,但物理机械性能稍差.     

A study on blends of nylon-6 and nylon-66

Blending of nylon-6 and nylon-66 was carried out by coextrusion in the whole range of compositions with particular emphasis on small amounts of one polymer in the other. Most significant improvement in properties is achieved at low blend compositions in which the minor component remains amorphous while severely affecting the crystallization behavior of the major component. The nylon-6-rich blends crystallize predominantly in the γ-crystalline form, whereas the nylon-66-rich blends exhibit low crystallinity. Because of this property, the blends are more easily drawable, giving rise to a more highly oriented structure with improved tensile properties and uniformity. High tenacity and modulus are observed in drawn blends containing 70% nylon 6 and 30% nylon-66.     

Thermal properties and crystallization behavior of ultrafine fully‐vulcanized powdered rubber particle toughened polypropylene

Thermal properties and crystallization behavior of ultrafine fully‐vulcanized powdered rubber (UFPR) toughened polypropylene (PP) were studied by Differential scanning calorimetry (DSC) and Wide angle X‐ray diffraction (WAXD) measurements. It was found that the fraction of β‐form in the PP crystal increased at first, then sharply deceased up to zero with increasing UFPR content. This trend did not rely on isothermal crystallization temperature. Moreover, DSC measurements implied that UFPR particles addition affected both isothermal and nonisothermal crystallization behaviors, including the crystallization temperature and the half‐time of crystallization. Furthermore, WAXD test results indicated that the addition of UFPR induced the orientation of the crystallites more or less. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of ultrafine,fully vulcanized acrylate powdered rubber on the mechanical properties and crystallization behavior of nylon 6

Nylon 6 (PA6) is a widely used engineering plastic. However, its poor toughness limits its applications. Therefore, toughening PA6 has been a point of interest in the field of PA6 modification. Generally, toughening a plastic with an elastomer reduces the stiffness and heat distortion temperature of the matrix. It has been an important goal of polymer researchers to find a way of toughening PA6 without reductions in its stiffness and heat distortion temperature. In this study, a new kind of material—an ultrafine, fully vulcanized acrylate powdered rubber (UFAPR)—was used to toughen PA6 through melt blending. The influence of UFAPR on the isothermal crystallization kinetics and nonisothermal crystallization behavior of PA was studied with differential scanning calorimetry. The results showed that, with the addition of a little UFAPR, the crystallization rate of PA could be increased, the crystallization temperature could be augmented, and the crystal size distribution of the crystal grain could be narrowed. The changes in the free energy perpendicular to the crystal nucleus were consistent with the results of an Avrami equation according to the theory of Hoffman. The unit surface free energy of the radially developing crystal spherulites decreased with an increasing amount of UFAPR. The results for the mechanical properties, crystalline structure, and crystallization kinetics of PA6/UFAPR composites showed that UFAPR was not only a good toughening agent for PA6 but also an excellent nucleation agent for PA6. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3503–3511, 2003     

硅灰石填充尼龙-6复合体系的非等温结晶行为及动力学研究

用差示扫描量热法(DSC)考察了硅灰石填充尼龙-6复合体系的非等温结晶行为,并用Avrami以及Mo法研究了其非等温结晶动力学。结果表明,随着降温速率的增加,复合体系的结晶峰变宽并向低温方向移动,结晶速率增加。通过对比,Mo法能很好地描述硅灰石填充尼龙-6复合体系的非等温过程。     

Change of thermal properties of polyamide-6,6/glass fiber composite by the addition of nigrosine

Effects of nigrosine content on the thermal behavior of nylon-6,6/glass fiber composite were investigated. Differential scanning calorimetry was used to analyze the thermal behaviors. The onset crystallization temperature and peak crystallization temperature were shifted to lower temperature by the addition of nigrosine, which indicated that nigrosine suppressed the crystallization of nylon-6,6 molecules. Higher value of effective activation energy by the addition of nigrosine was obtained using Friedman isoconversion method and it also indicated the restriction of nylon-6,6 molecules to form crystals. Liu–Mo method was applied to characterize the non-isothermal crystallization kinetics, and Liu–Mo model was suitable to represent the non-isothermal crystallization kinetics of nylon-6,6 containing nigrosine.     

粉末橡胶的开发与研究进展Ⅱ.研究及应用

综述了凝聚共沉法粉末橡胶与粉末接枝橡胶的制备及应用进展,介绍了超细粉末橡胶的开发与应用,并对粉末橡胶的发展前景作出了展望.     

不相容聚合物共混物受限结晶行为的研究进展

不相容聚合物共混是一种获得综合性能优异的高分子材料的有效途径。当结晶聚合物作为分散相均匀地分布在不相容聚合物基体相中,并且其分散相数目大于活跃的异相成核物质数目时,在冷却过程中会发生受限结晶(分级结晶)现象。分散相中缺少活跃的异相成核物质是不相容共混物发生受限结晶的关键因素。从受限结晶的产生总结了近年来不相容共混物中受限结晶的研究进展,并概述了增容剂、填料、退火、分散相尺寸及其分布和结晶温度等因素对受限结晶行为的研究。     

Nylon-6/liquid natural rubber blends prepared via emulsion dispersion

Nylon-6 is widely used as engineering plastic because it is easy to process, high tensile properties, resistant to chemical and abrasion. However, poor impact strength at low temperature makes it limitedly used in some applications. Nylon-6/liquid natural rubber (LNR) blends were prepared via emulsion dispersion with composition of 100nylon-6/0LNR, 95nylon-6/5LNR, 90nylon-6/10LNR, 85nylon-6/15LNR, 80nylon-6/20LNR and 75nylon-6/25LNR. Nylon-6 was dissolved in a 2,2,2-trifluoroethanol and chloroform mixture (1:1 TFE/CHCl₃) and emulsified with hexadecyltrimethylammonium bromide (HTAB). LNR was dispersed into the nylon-6 emulsion to form homogeneous nylon-6/LNR emulsions and the emulsions were de-emulsified with methanol, filtered and dried. High impact behaviour was achieved at 85nylon-6/15LNR composition. DSC thermogram indicated a single glass transition temperature, T _g and SEM images showed no phase separation between blend components implying homogeneous blends were obtained.     

A possible mechanism of chain extension in nylon-6 during crystallization under pressure

The effect of pressure on crystallization from the melt and annealing of nylon-6 fractions has been investigated. Pressures exceeding 5 kbar and temperatures 40°C below the final melting temperature of the fractions under pressure, were sufficient to produce the extended-chain crystals by an isothermal crystallization from the melt as well as by annealing of the chain-folded material. Crystalline structure and the thermal characteristics of the extended-chain crystals formed from the fractionated nylo?n-6, were identical to those of unfractionated polymer. G.p.c. analysis of the extended-chain material formed from the fractions of narrow molecular weight distribution showed that this material most probably had a wide molecular weight distribution, similar to that of unfractionated nylon-6. Based on a change in the molecular weight distribution and decrease in the molecular weight, concurrent with the extended-chain crystallization it is suggested that on the thermal treatment of polyamides under pressure a transamidation reaction occurs between the CONH groups of the broken folds of adjacent lamellae, which may lead to the chain extension.