聚磷酸铵在纺织品上的阻燃整理研究

本文介绍了阻燃剂聚聚磷酸铵的阻燃机理以及在麻布上的应用，并对阻燃麻布的阻燃性及物性进行了研究。     

聚磷酸铵阻燃剂的合成及阻燃机理

本文叙述了聚磷酸铵阻燃剂的合成方法及阻燃机理；并提出了一些改性处理办法。     

聚磷酸铵的微胶囊化与阻燃应用

研究了采用原位聚合法制备聚磷酸铵(APP)微胶囊的工艺条件及其应用于聚丙烯(PP)中的阻燃性能。分析表明，经微胶囊处理后，APP的溶解度降低，热稳定性提高，并应用扫描电镜测试了微胶囊APP的表面形态。阻燃性能测定表明在PP中，无论单独使用还是与其他阻燃剂复配使用，微胶囊APP的阻燃效果都好于普通APP。     

聚磷酸铵/聚酰亚胺微胶囊化改性阻燃聚丙烯薄膜性能研究

以聚磷酸铵(APP)为芯材、聚酰亚胺(PI)为囊材,通过低温喷雾干燥法制备微胶囊化改性APP阻燃剂。扫描电镜和红外光谱分析表明,改性后的APP分散性得到改善,并且PI较好地包覆在APP表面。将改性APP按照一定比例加入到PP树脂中制得薄膜,结果表明,改性APP的添加有提改善了薄膜的阻燃性能,极限氧指数比空白组最高提升了42.2%,UL-94达到V-0级,且热释放速率明显减缓,残炭量显著提升。此外,薄膜的机械性能、微观结构均未发生较大改变,可适用于物品的阻燃包装。     

聚磷酸铵/三聚氰胺/聚氨酯复合阻燃聚甲醛的研究

采用聚磷酸铵(APP)/三聚氰胺(ME)/聚氨酯(TPU)制成复合阻燃剂阻燃聚甲醛。研究了复合阻燃剂配比及用量对聚甲醛性能的影响。通过扫描电镜分析阻燃剂粒子均匀分散于分散相聚氨酯中,改善了POM的力学性能。由于TPU自身成炭作用,可进一步提高聚甲醛的阻燃性能,当阻燃剂用量为40份时,冲击强度可达4.84KJ/m2,氧指数为27%。热失重分析结果表明阻燃剂的加入使得POM分解温度提前,残炭量提高。     

聚磷酸铵/膨胀石墨协同阻燃EVA的阻燃机理

对聚磷酸铵(APP)和膨胀石墨(EG)协同阻燃乙烯-醋酸乙烯酯共聚物(EVA)及其阻燃机理进行了研究。结果表明,APP和EG对EVA具有良好的协同阻燃效果。通过热重分析(TG)、红外光谱(FT-IR)、扫描电镜(SEM)以及X射线光电子能谱(XPS)等手段对其阻燃机理进行了分析,认为在受热前期,主要是EG在凝聚相中的阻燃机理;在中后期,主要是APP在凝聚相发挥阻燃作用和部分的气相阻燃机理。     

膨胀石墨聚磷酸铵复合阻燃聚丙烯初探

以国产膨胀石墨为主阻燃剂，聚磷酸铵为协效剂，讨论了膨胀石墨复合阻燃剂两组分不同配比对阻燃聚丙烯燃烧性能和力学性能的影响。当膨胀石墨复合阻燃剂用量为30份、石墨与聚磷酸铵比为2：1时，材料的氧指数为21.7，拉伸强度为32，4MPa，缺口冲击强度为0.51KJ／m^2，力学性能和阻燃性能指标较好，材料的综合性能最佳，复合阻燃剂两组分在此配比时具有明显的协同效应。阻燃剂用量超过30份后。材料的拉伸强度快速下降，失去使用价值。     

氢氧化铝包覆改性聚磷酸铵及其在阻燃聚丙烯中的应用研究

针对聚磷酸铵(APP)有一定的水溶解性和阻燃效率不高等问题, 提出了采用氢氧化铝(ATH)包覆改性APP的方法。X射线荧光光谱(XRF)和扫描电镜(SEM)分析结果显示, 在APP颗粒表面实现了ATH的包覆改性。测试表明, ATH包覆改性后的APP溶解度明显下降, 比表面大幅增加。将改性后的APP与双季戊四醇(DPER)复配, 作为膨胀阻燃剂添加到PP中, 阻燃PP的燃烧性能测试结果表明: 阻燃剂总添加量为25%时, 包覆ATH的APP使阻燃PP 3.2 mm样条的垂直燃烧级别从V-1提高到V-0, 氧指数(LOI)从26.6%增加到31.8%, 热释放速率峰值(PHRR)从475 kW/m²下降至308 kW/m², 下降了约35%。对阻燃PP的燃烧残炭研究说明, APP经ATH包覆改性后, 促进了阻燃PP在燃烧时形成更加完整均匀的炭层, 因而改善了阻燃性能。     

纳米材料改性聚磷酸铵在聚合物阻燃中的应用研究进展

综述了纳米材料改性聚磷酸铵(APP)的方法及其在聚合物材料中的协同阻燃作用。重点讨论了纳米二氧化硅(SiO2)、纳米碳酸钙(CaCO3)、海泡石、碳纳米管、纳米纤维素、纳米蒙脱土和可膨胀石墨改性APP协同阻燃聚合物材料方面取得的研究成果。提出了纳米材料改性APP在阻燃应用中存在的一些问题。     

Crazing behaviour in oriented poly(ethylene terephthalate)

A study has been made of the two types of crazes formed in oriented sheets of poly(ethylene terephthalate). The crazes have been termed tensile crazes and shear crazes. The tensile crazes formed parallel to the initial draw direction (IDD) whereas the shear crazes formed in a direction close to that of the deformation bands observed when the material yields.The possibility of applying a yield criterion to shear craze formation has been examined and there appears to be fairly good agreement between theory and experiment. Measurements of crazing stress on the tensile crazes indicated that the criterion for tensile craze formation is not purely dependent on the component of stress normal to the extended chains.It is concluded that the two types of crazes are formed by two quite different mechanisms, although the exact nature of these mechanisms is still uncertain.     

Physical ageing studies in semicrystalline poly(ethylene terephthalate)

The physical ageing of semicrystalline poly(ethylene terephthalate) (c-PET) of different crystallinities and morphological structures was studied using differential scanning calorimetry. Samples of c-PET of crystallinity content _c = 0.12, crystallized at low temperatures (105 °C for 13 min), submitted to physical ageing in a temperature range between 50 and 65 °C for different periods of time, showed two endothermic peaks. The first peak (P₁) of higher intensity, appeared at a temperature close to the glass transition temperature, T _g, of the amorphous PET, and the other peak (P₂) of lower intensity, merged as a shoulder of the first one, at a higher temperature. These peaks have been attributed to the enthalpy relaxation process of two different amorphous regions: one amorphous phase outside the spherulitic structure (interspherulitic amorphous region) and another amorphous phase inside the spherulites (interlamellar amorphous region). The separation between P₁ and P₂ indicates that DSC, via enthalpy relaxation, is a good technique to detect the real double glass transition of the semicrystalline PET. However, the physical ageing of a semicrystalline PET of _c = 0.32, crystallized at 114 °C during 1 h, showed a main endothermic peak shifted to a higher temperature, which probably corresponds to the enthalpy relaxation of the more restricted interlamellar amorphous region, and a small endothermic peak at lower temperature which could be a reflection of the hindered interspherulitic amorphous region.     

Morphology and properties of microfibrillar composites based on recycled poly (ethylene terephthalate) and high density polyethylene

Microfibrillar composites (MFCs) from recycled high density polyethylene (R-HDPE)/recycled poly (ethylene terephthalate) (R-PET) (75/25 w/w) were made through reactive extrusion and post-extrusion strand stretching. The resultant MFCs could be processed at HDPE processing temperature. The compatibility between microfibers and R-HDPE matrix was improved through compatibilizers. Of the three compatibilizers evaluated, ethylene glycidyl methacrylate copolymer (E–GMA) performed the best. The addition of compatibilizers did not obviously change the size of R-PET fibers in MFCs. The toughness of MFC was significantly enhanced, and R-PET phase did not crystallize when 5% E–GMA was used. The process of manufacturing MFCs provides a way to recycle commingled plastics, and MFCs would be potential matrices for natural fiber polymer composites.     

Assessing changes on poly(ethylene terephthalate) properties after recycling: Mechanical recycling in laboratory versus postconsumer recycled material

Keeping rheological, mechanical and thermal properties of virgin poly(ethylene terephthalate), PET, is necessary to assure the quality of second-market applications. A comparative study of these properties has been undertaken in virgin, mechanical recycled and commercial recycled PET samples.     

Nonisothermal crystallization kinetics of poly(ethylene terephthalate) nanocomposites

This article reports the nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) nanocomposites. The non-isothermal crystallization behaviors of PET and the nanocomposite samples are studied by differential scanning calorimetry (DSC). Various models, namely the Avrami method, the Ozawa method, and the combined Avrami-Ozawa method, are applied to describe the kinetics of the non-isothermal crystallization. The combined Avrami and Ozawa models proposed by Liu and Mo also fit with the experimental data. Different kinetic parameters determined from these models prove that in nanocomposite samples intercalated silicate particles are efficient to start crystallization earlier by nucleation, however, the crystal growth decrease in nanocomposites due to the intercalation of polymer chains in the silicate galleries. Polarized optical microscopy (POM) observations also support the DSC results. The activation energies for crystallization has been estimated on the basis of three models such as Augis-Bennett, Kissinger and Takhor methods follow the trend PET/2C20A < PET/1.3C20A < PET, indicating incorporation of organoclay enhance the crystallization by offering large surface area.     

Structural changes during photodegradation of poly(ethylene terephthalate)

An investigation has been conducted into the effects of photodegradation on the structure of poly(ethylene terephthalate) (PET). Films, with and without ultraviolet absorbers and prepared by biaxial orientation after extrusion, have been exposed in the laboratory for periods of up to 1020 hours. The samples were investigated by differential scanning calorimetry (DSC), X-ray diffraction and size exclusion chromatography. The appearance of a cold crystallization peak during DSC heating scans was noted for exposed samples and this was considered to be a result of released molecules in the amorphous region that could rearrange into a crystalline phase. From X-ray analysis, a loss of crystalline orientation was observed after degradation and an interpretation was given based on relaxation in the mesophase region. In samples containing the photostabilizer additive the magnitude of changes in structure was lower, possibly due to segregation effects during film production making the non-crystalline region relatively immune to degradation effects.     

Novel biocomposites from poly(trimethylene terephthalate) and recycled carbon fibres

Biobased composites from recycled carbon fibre and poly(trimethylene terephthalate) (PTT) were fabricated by extrusion followed by injection moulding. The mechanical, thermal and morphological properties of the composites were investigated as a function of recycled carbon fibre content. The mechanical properties such as tensile, flexural and notched impact strength as well as tensile and flexural modulus of the composites increased with increasing recycled carbon fibre content. The improvement of stiffness and toughness of composite materials is one of the important findings of this investigation. Experimental values of tensile strength and modulus were compared with parallel, series and Hirsch’s models. The morphology of the composites was analysed by scanning electron microscopy. Differential scanning calorimetry, thermogravimetric analysis and dynamic mechanical analysis were used to measure the thermal properties of the composites. Recycled carbon fibre loading appreciably improved the storage modulus of PTT. Thermal stability and crystallization temperature of PTT also improved with the recycled carbon fibre content.