流动改性剂PSAM/ZrP的制备及其对PC性能的影响

利用自由基共聚制得(苯乙烯/丙烯酰胺)寡聚体(PSAM),将其与磷酸锆(简称ZrP)熔融共混刺得流动改性剂PSAM改性磷酸锆(PSAM/ZrP),再将PSAM/ZrP和ZrP分别与聚碳酸酯(PC)熔融共混制得PC/PSAM/ZrP复合材料和PC/ZrP复合材料.利用傅立叶变换红外光谱(FTIR)仪、熔体流动速率(MFR)仪和凝胶色谱(GPC)仪对两种复合材料进行了表征,并考察了其流动性能和力学性能.结果表明,PSAM/ZrP和ZrP均能明显改善PC的流动性能,其中PSAM/ZrP的改善效果更为明显,并且ZrP用量不大于3份时,其并未引起PC相对分子质量或相对分子质量分布的变化;随着ZrP用量的增加,复合材料的拉伸弹性模量和弯曲弹性模量不断升高,弯曲强度和拉伸强度有所提高,冲击性能有所下降.当ZrP用量为1份时,PC/PSAM/ZrP复合材料的综合性能较佳.     

PC/改性ABS复合材料的制备与性能

在传统的丙烯腈-丁二烯-苯乙烯共聚物(ABS)乳液接枝聚合中加入甲基丙烯酸甲酯(MMA),制得了改性ABS,然后与聚碳酸酯(PC)共混挤出，制得了PC/改性ABS复合材料。研究了MMA用量对PC/改性ABS复合材料的熔体流动速率(MFR)、维卡软化温度、力学性能的影响。结果表明：随着MMA用量的增加，PC/改性ABS复合材料的MFR、拉伸强度、弯曲强度和缺口冲击强度均先升高后降低。当MMA质量分数为20%时，PC/改性ABS复合材料的拉伸强度和弯曲强度均达到最大，分别为48.9 MPa和63.2 MPa;当MMA质量分数为30%时，PC/改性ABS复合材料的缺口冲击强度为41.0 kJ/m²;当MMA质量分数不高于30%时，与PC/ABS复合材料相比，PC/改性ABS复合材料的维卡软化温度更高。     

CPVC／PVC与CPVC／ABS合金加工性能研究

研究了聚氯乙烯(PVC)与丙烯腈-丁二烯-苯乙烯共聚物(ABS)用量对氯化聚氯乙烯(CPVC)/PVC、CPVC/ABS合金最低塑化温度Tmin、塑化时间t、平衡扭矩TQ等加工性能以及体系的热稳定性的影响;同时对合金的耐热性能进行了分析.结果表明,随着体系中PVC、ABS用量的增加,CPVC/PVC、CPVC/ABS合金的Tmin、t和TQ降低,而体系的热稳定性增加.     

PC/ABS共混改性研究

研究了甲基丙烯酸甲酯/丁二烯/苯乙烯共聚物(MBS)作为相容剂对聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯共聚物(ABS)共混体系相容性、力学性能、形态结构以及动态力学性能的影响.结果表明,随着MBS添加量的增加,PC/ABS的缺口冲击强度和断裂伸长率呈先增大再减小的趋势,拉伸强度和弯曲强度都呈下降趋势;加入MBS后,PC/ABS的分散相粒径明显减小,PC与ABS两相的玻璃化转变温度相互靠拢,因而PC/ABS的相容性得到显著改善.     

BDP阻燃PC/ABS及其纳米复合材料的阻燃性和热降解动力学

采用双螺杆挤出机挤出造粒制备了苯基双酚A二磷酸酯(BDP)阻燃的聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯(ABS)、PC/ABS有机蒙脱土(OMMT)和PC/ABS有机改性纳米二氧化(SiO2)3种复合材料,采用热重分析探讨了PC/ABS/BDP , PC /ABS/BDP/OMMTPC/ABS/BDP/SiO2复合材料的热降解动力学行为,以此分析其阻燃性能与热降解行为的关系。结果表明,加入纳米材料后,在质量损失8%以前,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2纳米复合材料的活化能均低于PC/ABS/BDP的活化能,但质量损失8%以后,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2复合材料的活化能均高于阻燃PC/ABS。在质量损失5%-75%范围内,PC/ABS/BDP/OMMT和PC/ABS/BDP/SiO2平均活化能分别为139.39KJ/mol和144.17KJ/mol,均高于PC/ABS/BDP的平均活化能(104.87 kJ /mol),说明添加纳米材料后,由于BDP与OMMT或SiO2的协同阻燃作用,降低了材料的热降解速率,增大了材料的热稳定性,这与氧指数测试、UL94V阻燃性能及热重分析得出的结沦一致。     

MBS对CPVC/ABS体系性能的影响

在氯化聚氯乙烯(CPVC)与丙烯腈-丁二烯-苯乙烯共聚物(ABS)复合体系中添加甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物(MBS),制备了MBS/CPVC/ABS复合材料。通过SEM观察和力学性能测试研究了MBS用量对复合体系力学性能及加工流变性能的影响。结果表明:适量的MBS可以提高体系的韧性,改善体系的加工性能。     

PLA/ABS复合材料的制备与性能研究

选取丙烯腈-丁二烯-苯乙烯共聚物(ABS)接枝马来酸酐(ABS-g-MAH)、聚苯乙烯接枝马来酸酐(PS-g-MAH)和苯乙烯-丙烯腈-甲基丙烯酸缩水甘油酯共聚物(SAG)等界面相容剂,改进聚乳酸(PLA)/ABS复合材料的界面相容性。结果表明：SAG能够有效改善复合材料的界面相容性,提高复合材料的力学性能、热稳定性和耐热性,同时使PLA/ABS的储能模量(G’)、损耗模量(G’’)和复数黏度(η^*)增大。SAG添加量为3%时,复合材料的拉伸强度和无缺口冲击强度分别为57.3 MPa和35.4 kJ/m²,相比未添加界面相容剂分别提高87%和116%。     

硼酸锌在膨胀型无卤阻燃ABS中的协同作用

采用熔融共混法制备了丙烯腈-丁二烯-苯乙烯共聚物(ABS)/膨胀型阻燃剂(IFR)/硼酸锌(ZB)无卤阻燃复合材料。利用热重分析仪、氧指数测定仪、扫描电子显微镜等研究了ZB对复合材料热失重行为、阻燃性能、微观结构及力学、加工性能的影响。较低含量的ZB与IFR存在较好的阻燃协同作用,且ZB可促进IFR成炭,使ABS/IFR复合材料的氧指数及其残炭量分别由未加ZB时的27.4%、21.29%提高到30.1%和23.05%。ZB的加入能够提高ABS/IFR复合材料的弯曲性能和加工性能,但对复合材料的冲击、拉伸性能产生了不利影响。     

弹性体对废旧PS/废旧ABS/HDPE/木粉复合材料性能影响

探讨了苯乙烯-丁二烯-苯乙烯共聚物热塑性弹性体(SBS)、三元乙丙橡胶(EPDM)、丁苯橡胶(SBR)3种弹性体对废旧聚苯乙烯(PS)/废旧丙烯腈-丁二烯-苯乙烯共聚物(ABS)/高密度聚乙烯(HDPE)/木粉复合材料物理及力学性能影响.结果表明,3种弹性体不但不会导致废旧PS/废旧ABS/HDPE/木粉复合材料密度的增加,而且有利于降低复合材料的吸水率,改善复合材料的冲击韧性;添加SBS的废旧PS/废旧ABS/HDPE/木粉复合材料综合性能最优,密度为0.90 g/cm3,冷、热水中的吸水率分别降至0.87％,1.32％,冲击强度增至3.1 kJ/m2.     

超细粉末羧基丁苯橡胶增韧PC/ABS性能研究

研究了超细粉末羧基丁笨橡胶(UFPR)对聚碳酸酯(PC)/丙烯腈-丁二烯-苯乙烯三元共聚物(ABS)合金机械性能的影响.结果表明:随着UFPR用量的增加,PC/ABS合金的拉伸强度、弯曲强度有所降低,断裂伸长率明显提高,悬臂梁缺口冲击强度先升高后明显降低.当UFPR用量为0.5～2.0 phr时,PC/A BS合金悬臂...     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.