石蜡/丙烯酸核壳聚合乳液特性粘数的研究

采用半连续单体乳液滴加法聚合法,以石蜡(PF)为种子、丙烯酸(AA)为壳,制备石蜡/丙烯酸(PFAA)核壳聚合乳液。以乳液特性粘数([η])为评价指标,利用正交实验L9(34)筛选最佳工艺条件。考察了反应温度θ、反应时间t、引发剂K2S2O8用量和单体AA用量对PFAA乳液[η]的影响。结果表明,影响乳液[η]因素的大小顺序为θ>t>w(K2S2O8)>w(AA),较优的工艺条件:θ=70～75℃,t=2h,w(K2S2O8)=0.16%～0.20%,w(AA)=16.5%～18.0%。     

淀粉与丙烯酰胺接枝共聚物性质的研究

研究了小麦淀粉与丙烯酰胺的接枝共聚物的物理特性和结构特征,实验结果表明:该接枝共聚物在热性质上与原淀粉有明显的区别,其糊化温度比原淀粉略低,粘度热稳定性及溶解度较原淀粉均有提高。接枝共聚反应不仅发生在淀粉颗粒的表面上,而且也发生在颗粒结构的内部,但反应仅发生在淀粉的无定型区。     

Synthesis of Poly(∊-caprolactam) and Poly(ethyleneterephthalate) Star Polymers

Abstract

Two kinds of condensation-polymerization star polymers were prepared. One kind is star nylon-6 and the other is star PET. In both star polymers the arms are flexible and the cores are rigid aromatic fractal polyamides (FPs). The FPs are porous and of size comparable to the size of the flexible arms of the stars. The FPs are decorated with reactive sites appropriate for the grafting or growing of star arms. In the case of star nylon-6, two preparation methods are described: grafting of pre-existing nylon chains onto FPs, and growing nylon-6 arms from the FPs by polymerization of caprolactam in the presence of FPs. In the case of star PET, grafting of pre-existing PET chains was employed in order to create the star polymers. Various characterization techniques indicated that in the grafted star polymers up to 10 arms could be attached to each FP core. The results indicate, however, that fine control of the star formaton was not achieved yet. The required conditions to reach this target are spelled out.     

反式聚异戊二烯橡胶/NBR并用胶性能的研究

研究了反式聚异戊二烯橡胶（ＴＰＩ）／ＮＢＲ并用胶的耐油性能手力学性能,以及用ＴＰＩ接枝－甲基丙烯酸酯（ＴＰＩ－ｇ－ＭＭＡ）对并用胶进行的相容改性。研究结果表明,ＴＰＩ／ＮＢＲ并用胶耐油性能很好,但力学性能较差,ＴＰＩ－ｇ－ＭＭＡ可明显改善ＴＰＩ和ＮＢＲ两相之间的相容性,加入ＴＰＩ－ｇ－ＭＭＡ相容的ＴＰＩ－ＮＢＲ并用胶保持了很好的耐油性能,力学性能明显改善。     

紫外辐射法制备聚羟基丁酸酯/聚乙二醇接枝共聚物

利用紫外辐射法制备了聚羟基丁酸酯/聚乙二醇(PHB/PEG)接枝共聚物,共聚物中聚乙二醇接枝含量分别为1.7%、2.6%、3.8%、6.4%和10.1%.利用红外光谱(FT-IR)、差示扫描量热(DSC)、广角X射线衍射(WAXD)、表面接触角及力学性能测试对不同聚乙二醇接枝含量的共聚物进行了分析研究.结果表明,接枝聚...     

Mercerization of Flax Fiber Improves the Mechanical Properties of Fiber-Reinforced Composites

In this article, modification of mercerized flax (MFx) through graft co-polymerization with methylmethacrylate (MMA) using ferrous ammonium sulphate–potassium per sulphate (FAS–KPS) redox initiator has been reported. Water uptake and moisture absorbance properties of methylmethacrylate grafted mercerized flax (MFx-g-MMA) and mechanical behavior of raw flax, mercerized flax, and MFx-g-MMA fibers reinforced—polystyrene matrix–based composites also have been evaluated. Four reaction parameters, reaction temperature, reaction time, initiator molar ratio, and monomer concentration, have been optimized to get maximum graft yield. Maximum graft yield of 138.35% has been obtained at optimum reaction conditions. The graft co-polymers thus formed were characterized by FTIR, TGA, and SEM techniques. Mercerized flax fiber reinforced showed better results than raw flax and MFx-g-MMA fibers reinforced composites.