引入PNA、1, 2-PG对聚氨酯胶粘剂微相形态及性能的影响

引入PNA、1; 2-PG对聚氨酯胶粘剂微相形态及性能的影响;聚氨酯胶粘剂;结晶;微相分离;软段;硬段     

4—苯甲酰氧基苯甲酸液晶性的研究

关于个苯甲酸氧基苯甲酸（BBA）的合成虽已有报道［‘j，但其双分子缔合物具有液晶性则属本文作者首次发现．一般认为在有机分子结构中引人不对称性及柔性基团对其液晶性的形成十分重要“‘．在不具备这两个条件时，当分子的长径比达到一定值（约l／d＞4）时也可能出现液晶性，但实例不多，且一般t。。很高．如聚合度为5的聚苯t。。一388”C［’j，而且难溶．这给此类液晶化合物的研究带来很大不便．BBA以双分子缔合物（BBA）。形式存在，结构对称，亦无柔性基团，但却具有液晶性，其t。。为230C．BBA与个乙酸氧基苯甲酸形成的低共熔…     

聚合物材料结晶度（下）

4.2 Ruland方法使用式(2)计算结晶度时,Ruland考虑了热运动及晶格畸变的影响,从而使算得的结晶度值较合理。在不失计算结晶度W_(c,x)数值精度的情况下,在Ruland方法的实验中可以只取具有较大衍射峰强度的S范围,就可提高计算结晶度的数值准确性,克服了其它方法必须收集尽可能大范围S内的衍射强度数据的限制。Ruland方法测定结晶度的基本公式:     

Ti－Al pentasil型分子筛的表征及其热稳定性能

用气固相同晶取代法合成了Ｔｉ－ＡｌＺＳＭ－５和Ｔｉ－ＡｌＺＳＭ－１１型分子筛，并测定了它们的ＩＲ光谱、ＵＶ－Ｖｉｓ光谱以及晶胞参数，证实Ｔｉ进入了分子筛的骨架．热稳定性能的研究表明，Ｔｉ进入骨架后，分子筛热稳定性基本不变．另外，当高温处理时，Ｎａ型含钛分子筛的结晶度下降，直至转化为方石英，９６０ｃｍ－１处钛的特征峰不会消失．     

Evaluation of compatibility and properties of biodegradable polyester blends

Three different biodegradable polyesters, namely, polycaprolactone (PCL), polybutylene succinate (BIONOLLE), and a copolyester of adipic acid, terephthalic acid, and 1,4‐butanediol (EASTAR) were melt‐blended using a twin‐screw extruder. The percentage composition of each of the aforementioned polymers was varied to obtain different blends, and the mechanical properties were evaluated. Selected blends showed significant improvement in tensile strength as compared with the individual polymers used to prepare the blend. The compatibility between the polymer phases was examined via Fourier transform infrared (FTIR) and nuclear magnetic resonace (NMR) spectroscopy as well as dynamic mechanical analysis. FTIR and NMR data confirmed the occurrence of hydrogen‐bonding and ester‐interchange reactions. Thermal properties and changes in crystallinity of the blends were examined with differential scanning calorimetry and X‐ray diffraction. A considerable increase in crystallinity was shown by the blend system containing BIONOLLE/PCL. The morphology of the blends was observed and correlated to the improved mechanical properties of the blend system. Results revealed an intermediate multiphase system in which a significant degree of mixing was achieved through the chemical interaction of the functional groups present, while using the twin‐screw extruder. Significant improvement in mechanical properties of some blends was observed, and information about the miscibility of these polyesters is provided. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2003–2014, 2002     

Use of thermal analysis techniques for examining blow-molded pet bottle specimens

Eight samples from different areas of stretch-blow-molded poly(ethylene terephthalate) [PET] bottles, including a PET resin control, were tested by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). The glass transition temperature (T _g) was found to linearly decrease about 6C from zero to 45 percent initial crystallinity. Measurements ofT _c (crystallization temperature, DSC) and film tension modulus (TMA) were related to crystallization rate during stretch-blow-molding. The TMA linear coefficients of thermal expansion and shrinkage were shown to be important for blow-molding temperature control.     

SYNTHESIS AND PROPERTIES OF NEW MESOGEN-JACKETED LIQUID CRYSTALLINE POLYMERS*

Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, andmesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of thesepolymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Theirliquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. Theresults show that 1) a more flexible polymer main-chain is more favorable to the formation of a liquid crystal phase, while 2)a flexible spacer will decrease the "Jacket Effect" and the liquid crystallinity and 3) a subtle modification of the terminalgroups on the mesogenic unit may also have a significant influence on properties of the polymers.     

碳酸根离子柱撑钴铝水滑石的合成与表征

水滑石类化合物近年来受到人们的广泛关注,它具有的独特的阴离子柱撑层状结构及独特的阴离子可交换性和阳离子可搭配性,使它成为一种多功能的新型催化材料［１］．本文报道的是钴铝水滑石类化合物（ＣｏＡｌＨＴ）的制备规律及其表征．１实验部分１．１ＣｏＡｌ?..     

Crystallinity and crystalline phase orientation of poly(1,4‐cis‐isoprene) from Hevea brasiliensis and Taraxacum kok‐saghyz

Crystallization is studied for poly(isoprene‐1,4‐cis) from Hevea brasiliensis (natural rubber [NR]) and from taraxacum kok‐saghyz, mainly by collecting wide‐angle X‐ray diffraction patterns after processing and stretching. Although rubber samples before stretching are generally fully amorphous, crystallization can be induced in NR samples by processing at room temperature under moderate pressure. This phenomenon is possibly associated with nucleation by saturated fatty acid components. For rubber samples being fully amorphous in the undeformed state, strain‐induced crystallization occurs only at high strain ratios (α > 4), leading to high degrees of crystalline phase orientation (f_c > 0.9 for α = 5). Rubber samples presenting some crystallinity already in the unstretched state, on the contrary, reach much lower degrees of axial orientation, even for high strain ratios (f_c < 0.7 for α = 5). These differences in crystallinity and in crystalline phase orientations produce large differences in stress–strain behavior of the rubber. By room temperature processing, the considered NR samples can also develop an unreported disordered crystalline modification, with low intensity of 120 and 121 reflections. This disordered crystalline modification, which is also maintained after axial stretching procedures, can rationalized by a structural disorder along the b axis, possibly associated with statistical sequences of A⁺TA^? or A^?T A⁺ conformations for poly(isoprene‐1,4‐cis) chains. Copyright © 2016 John Wiley & Sons, Ltd.     

结晶高聚物结晶度与密度关系公式的简易推导

结晶高聚物的结晶度与密度有密切关系,体积结晶度和重量结晶度与聚合物的非晶密度、结晶密度和实际密度之间都存在对应的关系,在一般的教学中,都是利用密度加和性和比容加和性来推导这2个关系公式的,本文以更加简洁易懂的体积加和性和重量加和性非常简单地推导出了这2个关系公式,便于学生掌握和理解。