LLDPE/LDPE薄膜加工改性剂PPA

以LLDPE/LDPE共混树脂为基料,添加加工改性剂氟弹性体PPA,采用挤出吹塑成型加工薄膜制品。以LLDPE/LDPE质量比为1/2作空白样。按每克试样总量中含500μg PPA的比例添加PPA,当共混物中LLDPE含量为1/3时,挤出机电流下降,薄膜的透光率增加,雾度降低;LLDPE含量为60％时,挤出机电流未变而产量提高,薄膜的透光率和雾度变化不大;继续增加LLDPE比例时,挤出机电流和雾度增加。薄膜的拉伸性能随LLDPE比例增大显著提高,且纵横向的取向度变小。

LLDPE／LDPE共混体系的相容性与性能

ＬＬＤＰＥ／ＬＤＰＥ共混体系的相容性与性能杨毓华，花荣，白春霞，于旻李三喜，葛铁军（中国科学院长春应用化学研究所长春１３００２２）（沈阳化工学院高分子系沈阳）关键词ＤＳＣ，ＷＡＸＤ，力学性能，ＬＬＤＰＥ，ＬＤＰＥ，共混，相容性非晶－非晶－结晶共混体系...

EFFECT OF GAMMA-RADIATION ON DYNAMIC VISCOELASTIC PROPERTIES AND THERMAL-BEHAVIOR FOR LDPE

The effect of gamma-radiation on dynamic viscoelastic properties and thermal behavior for low density polyethylene(LDPE) have been investigated. The store energy modulus (E) of the samples increased after radiation. The beta and alpha transition temperature shifted to higher temperature with increasing irradiation dose. The results of thermal analysis show that crystal melting temperature (Tm), enthalpy(DELTAHm) and crystal disapperance temperature(Td) for irradiated samples decreases with increasing of dose.

THE EFFECT OF RADIATION-INDUCED CROSS-LINKING ON THE RELAXATION OF TAUT TIE MOLECULES DURING ANNEALING OF DRAWN LDPE

Shrinkage, retractive stress, and infrared dichroism of the drawn low-density polyethylene (LDPE) as-drawn and irradiated by Co-60-ray have been measured under different annealing conditions. The shrinkage and the disorientation of the irradiated sample was undergone more rapidly than that of unirradiated one as the temperature was continuously increased, surpassing a certain value, and a higher degree of shrinkage and disorientation was achieved finally for the irradiated sample when the samples were annealed with free ends. For the samples heated isothermally with fixed ends, the retractive stress went through a maximum and then attenuated to a limited value, and the degree of such a stress attenuation for the unirradiated sample was much more than that for the irradiated sample. These results show that the taut tie molecules (TTMs) in drawn PE can relax by the pulling of chain segments out of crystal blocks that they anchored in at elevated temperatures higher than the a transition and also by the displacing of microfibrils if the samples were annealed with free ends. The cross-links produced by irradiation prohibit the former process. It was further observed that the dependence of the average extinction coefficient of the band at 2016 cm-1 on that of the band at 1894 cm-1 is related to irradiation and annealing conditions, which has also been explained by the relaxation of TTMs and the function of irradiation-induced cross-linking on the relaxation.

LDPE/EVA共混体系的结晶行为

本文通过DSC、WAXD、偏光显微镜、DMA等方法,对LDPE/EVA共混体系进行了研究。结果表明,EVA可使LDPE的熔融峰温提高15℃。并在LDPE结晶过程中起稀释剂作用。LDPE/EVA共混体系为非晶相相容。

LDPE/iPP复合膜的附生结晶研究

附生结晶(epitaxy)是指结晶物质在结晶基质上的取向成核和生长。聚合物-聚合物的附生结晶揭示了聚合物间新的结构关系,在高分子物理领域引起了极大兴趣和广泛关注。根据结构关系,聚合物附生结晶主要分为两类,即均相附生结晶(homoepitaxy)和异相附生结晶(het-eroepitaxy)。在异相附生体系中,大多数研究工作集中在全同立构聚丙烯(iPP)与一些锯齿链

γ辐照LDPE/EPDM共混物的动态力学性能和热行为

本文报道了~(60)Coγ辐照LDPE/EPDM共混物的动态力学性能和热行为。在动态力学性能谱上出现两个转变,-20℃左右的转变是LDPE的β转变和EPDM玻璃化转变相叠加的转变,其峰温简称T_(βg),转变峰较平坦,表明LDPE/EPDM具有一定相容性;在69℃附近的另一个转变是LDPE的结晶预熔温度,随辐照剂量的增加而下降。未辐照的α转变活化能为106kJ/mol,辐照后活化能下降至80kJ/mol左右。用DSC法在所利用的剂量范围内,EPDM的T_g随剂量变化甚微,共混物的T_(βg)则不明显。LDPE的T_m辐照后有所下降,结晶度略有改变。

HDPE/LDPE共混体系的晶性研究

用DSC和WAXD方法考察了高密度聚乙烯和低密度聚乙烯共混体系(HDPE/LDPE)的结晶性能。结果表明,在共混物中HDPE含量大于50%时,共混物只出现HDPE的熔融峰,且熔融温度随HDPE含量减小而降低;LDPE含量大于50%时,DSC图上只出现熔点介于HDPE和LDPE之间的新熔融峰。DSC和WAXD法所测结晶度均偏离共混物的线性加和值,而晶胞参数则随共混物组成变化出现最小值,表明HDPE和LDPE可以形成共晶相容体系。Raman光谱测得介晶相αb值的膨胀,支持这一观点。

低密度聚乙烯/乙丙烯三元共聚(LDPE/EPO)共混体系的结晶动力学

用DSC方法研究了LDPE/EPO共混体系的等温及非等温结晶动力学,对LDPE/EPO共混体系的等温结晶动力学研究表明,共混物是三维生长的异相成核,共混物在各个结晶温度下的结晶过程都是以方式K_g(Ⅱ)进行的.采用联系Avrami方程和Ozawa方程导出的新非等温结晶动力学方程,处理了LDPE/EPO共混体系,得到了非等温结晶过程的一些基本参数,新方程很好地描述了此共混体系的非等温结晶动力学过程.

低密度聚乙烯/乙丙烯三元共聚(LDPE/EPO)共混体系的相容性及其结晶结构

DDV、DSC、WAXD、萃取和Raman光谱实验表明,在所有组成下,LDPE/EPO共混体系共晶相容.WAXD法测定表明,LDPE/EPO共混体系的结晶度随EPO组分含量的增加而降低,EPO未能进入LDPE晶胞中.

EPDM对PP/LDPE共混物力学阻尼及结晶行为的影响

用动态粘弹谱仪和DSC研究了聚丙烯/三元乙丙橡胶(PP/EPDM)的动态力学性能,考察了EPDM对PP/LDPE(低密度聚乙烯)的力学行为的影响。结果表明,EPDM对PP有增塑作用,在PP/LDPE/EPDM共混物中,PP和LDPE的非晶部分与EPDM具有部分相容性;PP有两个结晶温度(T_c),较低的一个T_c随共混物中EPDM含量(5～25质量份)的增加逐渐向更低温度区迁移,说明EPDM具有加快冷却速率的作用。

HDPE,LLDPE或LDPE高取向薄膜微结构的电子显微学研究

木工作用透射电子显微术及电子衍射技术研究3种PE(HDPE,LLDPE或LDPE)均聚物高取向薄膜的微结构。定量测定了它们的结晶尺寸。通过倾斜样品电子显微学研究确定了不同种PE纤维结构的对称性。

γ射线辐射交联LDPE/CSM共混物的结构和性能

本文研究了~(69)Cγ射线辐照对LDPE/CSM共混物红外光谱和结晶度的影响。讨论了辐射交联LDPE/CSM共混物的力学性能、介电性能及热性能。

γ—辐射交联LDPE的物理性能(摘要)

本文研究γ—辐射交联LDPE的力学、介电和热性能,同时讨论其动态力学性能。结果表明:经250KGy剂量辐照后,抗张强度接近极大,约20Pa,而伸长率在50KGy左右剂量出现极大值,辐照交联后,tanδ略有增加,但在1kHz以内,室温下仍为10~(-4),ε在22左右,热学参数随剂量增加而下降。辐照交联后LDPE的贮能模量增加,多重转变温度Tα、Tβ和Tγ向高温方向移动,松弛强度有一定变化。图3表2参4