热处理对尼龙6及其与聚酰胺嵌段共聚物共混体系晶体熔融行为和结晶结构的影响

采用溶液共混-共沉淀的办法获得尼龙6及聚酰胺嵌段共聚物/尼龙6共混体系粉末,样品在260℃下熔融之后经程序降温的方法得到非淬火样品,然后分别在190℃下高温退火不同时间(0~48 h),采用示差扫描量热仪(DSC)、广角X射线衍射仪(WAXD)、偏光显微镜(POM)等表征手段研究热处理对体系晶体熔融行为和结晶结构的影响.结果表明,(1)在相同的热历史条件下,嵌段共聚物的存在影响了尼龙6的结晶行为及结晶结构;(2)退火处理对两种样品有着不同的影响,对于尼龙6体系,退火处理促进了非晶相向晶相的转变,大大提高样品的结晶完善程度和结晶度;对于共混体系,退火处理同样促进了非晶相向晶相的转变,同时形成新的α型和γ型结晶,体系的结晶完善程度明显提高,退火48 h后,结晶度比原始样品提高约84%.

INFLUENCE OF THERMAL TREATMENT ON CRYSTAL MELTING BEHAVIOR AND CRYSTAL STRUCTURE OF NYLON 6 AND POLYAMIDE BLOCK COPOLYMER/NYLON 6 BLENDS

Nylon 6 and its blends with a polyamide block copolymer were prepared by solvent blending and co-precipitation process.The samples were melted at 260℃ and then cooled at a rate of 30 K/min to obtain the controlled cooling samples(CCS).Investigations were carried out on the influence of thermal treatment on crystal melting behavior and crystal structure of nylon 6 and the blends by differential scanning calorimetry (DSC),wide-angle X-ray diffraction(WAXD)and polarized optical microscopy(POM).Measurements were taken after annealing at 190℃ with varied time from O h to 48 h.The resuhs indicated that the existing of the polyamide block copolymer affected the crystal behavior and the crystal structure of nylon 6,comparing to those of pure nylon 6 under the same thermal conditions.The pure nylon 6 tends to form α crystals,but it in the blends forms γ crystals.It was also found that annealing treatment had different effects on these two kinds of samples.For Nylon 6,annealing treatment only promoted the transformation of nylon 6 from amorphous to crystal phase,improved the crystalline structure and increased the crystal degree greatly without crystal form change.The crystal degree increased by about 61% after annealing for 48 h.For the blends.annealing treatment not only promoted the transformation from amorphous to crystal phase,improved the γ form crystalline structure and increased the crystal degree,but also resulted in the formation new α crystals.Compared with the original sample,the crystal degree increased by about 84%after annealing for 48 h.