用Mark-Houwink方程描述环氧化天然橡胶复数粘度与相对分子质量的关系

研究橡胶加工分析仪测试的环氧化天然橡胶(ENR)复数粘度(η*)与凝胶渗透色谱(GPC)仪测试的相对分子质量(M)之间的关系.结果表明:用Mark-Houwink方程η=kMa可以描述ENR的η*与M的关系,二者之间有较好的线性相关性;随着试验频率的增大,Mark-Houwink方程常数k增大,a减小;用η*计算的ENR数均和重均相对分子质量与GPC仪测定结果的相对误差分别在0.401 8%～4.045 2%和1.009 6%～8.013 8%之间.     

用橡胶加工分析仪/凝胶渗透色谱仪测定NR的相对分子质量

研究橡胶加工分析仪测定的NR复数粘度(η*)与凝胶渗透色谱仪测定的NR相对分子质量(M)之间的关系。结果表明:用Mark-Houwink方程η=kMa可以描述NR的η*与M之间的关系,二者之间有较好的线性相关性;当试验频率增大,常数k增大,a减小;用η*计算的NR数均和重均相对分子质量与凝胶渗透色谱仪测定结果的相对误差分别在2.78%～5.45%和1.16%～2.82%之间。     

环氧化天然橡胶在阻尼材料中的应用研究

研究环氧化天然橡胶（ENR）用量对天然橡胶（NR）/ENR复合材料性能的影响。结果表明：ENR与NR并用后,NR/ENR复合材料的阻尼因子（tanδ）最大值和阻尼温域（tanδ＞0.3）增大,tanδ最大值对应温度向低温方向移动;随着ENR用量的增大,NR/ENR复合材料的邵尔A型硬度、拉伸强度和拉断伸长率呈减小趋势,100%定伸应力呈增大趋势;当ENR用量为10份,NR/ENR复合材料的tanδ最大值对应温度在25 ℃附近,其综合性能最佳。     

凝胶渗透色谱法测定辛基酚醛增粘树脂相对分子质量及其分布

采用凝胶渗透色谱（GPC）法测定辛基酚醛增粘树脂相对分子质量及其分布,并研究辛基酚醛增粘树脂相对分子质量对其软化点和增粘效果的影响。确定的测试条件为：流速　1.0 mL·min^-1,柱温　40 ℃,试样溶液质量浓度　（2±0.2） mg·mL^-1;辛基酚醛增粘树脂的软化点和增粘效果随着其相对分子质量的增大而提高。     

以硫化反应活化能评价胶料中 不溶性硫黄的热稳定性

利用胶料的硫化反应活化能（E_a）评价胶料中不溶性硫黄（IS）的热稳定性。结果表明：含有不同热稳定性的IS胶料的硫化曲线有细微差别,但IS的热稳定性对胶料的硫化速度的影响无明显规律;胶料的E_a大小顺序与IS的热稳定性高低顺序相反,热稳定越高的IS,其胶料的E_a越小,热稳定性越低的IS,其胶料的E_a越大;胶料的游离硫元素含量及表面粘性测试结果表明,胶料中IS的热稳定性与原材料IS的热稳定性和胶料的E_a测试结果相应,利用胶料的E_a与原材料IS的热稳定性之间的关系,可以评价胶料中IS的热稳定性。     

Determination of free fatty acids in crude palm oil and refined-bleached-deodorized palm olein using fourier transform infrared spectroscopy

A rapid direct Fourier transform infrared (FTIR) spectroscopic method using a 100 μ BaF₂ transmission cell was developed for the determination of free fatty acid (FFA) in crude palm oil (CPO) and refined-bleached-deodorized (RBD) palm olein, covering an analytical range of 3.0–6.5% and 0.07–0.6% FFA, respectively. The samples were prepared by hydrolyzing oil with enzyme in an incubator. The optimal calibration models were constructed based on partial least squares (PLS) analysis using the FTIR carboxyl region (C=O) from 1722 to 1690 cm⁻¹. The resulting PLS calibrations were linear over the range tested. The standard errors of calibration (SEC) obtained were 0.08% FFA for CPO with correlation coefficient (R ²) of 0.992 and 0.01% FFA for RBD palm olein with R ² of 0.994. The standard errors of performance (SEP) were 0.04% FFA for CPO with R ² of 0.998 and 0.006% FFA for RBD palm olein with R ² of 0.998, respectively. In terms of reproducibility (r) and accuracy (a), both FTIR and chemical methods showed comparable results. Because of its simpler and more rapid analysis, which is less than 2 min per sample, as well as the minimum use of solvents and labor, FTIR has an advantage over the wet chemical method.     

Radiation-induced changes on beef fat-cephalin mixtures bygamma-radiation. Inhibition ofcis-trans isomerization

Ionizing radiation-inducedcis-trans isomerization of unsaturated bonds in beef fat was inhibited by the addition of phospholipid. Infrared absorption at 10.35μ (966 cm⁻¹) ofγ-irradiated beef fat-dl-a-cephalin dipalmitate mixtures was less than that of beef fat alone. These decreases were dose-dependent, but oxygen-independent. Reactions in the dose range 6 to 25 Mrad (see footnote 2) appear to differ from those in the dose range 25 to 100 Mrad. Some suggested explanations are offered for these phenomena.     

硫化机采用新型气动润滑装置

依据密炼机流变学理论,运用回归分析方法,从单台密炼机的角度,研究了混炼胶的粘度μ与排胶功率P、转速N和填充因数γ之间的关系,即μ= 2P/πN²A;建立了单台机粘度预测模型,即μ= P/N²×1 000 ×(-138 729 +151 444/γ^1/2-20 681.1/γ²)。此模型预测值与实测值之差的绝对值的平均值为1.410 5个门尼,且预测结果与按每种胶料所建模型的预测值非常接近。     

用门尼粘度仪测试天然橡胶的相对分子质量

研究了门尼粘度仪测试的门尼粘度和凝胶渗透色谱仪测试的相对分子质量的关系。结果表明,Mark-Houwink方程η=kMa可以描述复数粘度与相对分子质量间的关系,并有较好的相关性。用门尼粘度值计算的数均相对分子质量和重均相对分子质量与凝胶渗透色谱仪测试的相对分子质量的相对误差分别为11.3%和2.4%。     

全钢载重子午线轮胎胎面挤出热喂料自动供胶的改进

为提高全钢载重子午线轮胎胎面挤出过程能力,探讨建立胎面挤出机螺杆转速、供胶开炼机辊筒转速（ω_k）和破胶挤出机螺杆转速（ω_p）之间的关系模型,得到关系式ω_p＝4.758＋0.403 4ω_k。将挤出所需参数写入配方中,生产时调用对应规格,配方将自动下发。     

圆-椭圆垂直复合微孔织构对密炼机端面密封装置摩擦性能的影响

建立密炼机端面密封装置圆-椭圆垂直复合微孔织构（简称复合织构）的流体动压润滑模型,研究织构参数和工况参数对复合织构摩擦性能的影响。结果表明：当复合织构深度（h_p）为5 μm时,复合织构端面密封装置具有最好的减摩性能;当复合织构面积率（S_p）为43.96%时,复合织构的平均无量纲压力（P_av）最大和摩擦因数（μ）最小;复合织构的μ随着转子转速（n）和润滑油粘度（η）的增大而增大;密封间隙（h₀）为3和6 μm时,复合织构的P_av都随着n和η的增大而增大;在不同的n和η下,复合织构的P_av和μ随着h₀ 的增大而减小。     

炭黑主要理化指标对胶料硫化特性的影响

研究炭黑N234,N220,N375和N326的理化性质及其填充NR胶料的硫化特性。结果表明：同品种炭黑N234,N220和N375,随着压缩后DBP吸收值、STSA、氮吸附比表面积和着色强度的增大,胶料的门尼粘度、M_L、M_H增大,t90缩短,硫化速率提高;炭黑N326理化性质对胶料硫化特性的影响趋势与炭黑N234,N220和N375不同;与普通油炉法炭黑N220和N326相比,新工艺炭黑N234和N375能提高胶料的M_L、M_H和门尼粘度,缩短焦烧时间,提高硫化速率。     

甲基乙烯基硅橡胶溶解度参数的测定

采用平衡溶胀法和粘度法分别测定了甲基乙烯基硅橡胶(MVQ)的溶解度参数。采用平衡溶胀法测定时,交联高聚物的溶解度参数与溶剂的溶解度参数相等时,交联高聚物的溶胀比Q^v值最大,其所对应溶剂的溶解度参数即为高聚物的溶解度参数,求得MVQ的溶解度参数δ^Q为15.65 (J·mL_-1)_1/2。采用粘度法测定时,不同溶剂溶解高聚物所得溶液的特性粘度最大值所对应溶剂的溶解度参数即为高聚物的溶解度参数,求得MVQ的溶解度参数δ^Q为15.78 (J·mL_-1)_1/2。可以看出,两种方法测得的数据十分相近,说明这两种测定方法实用可行。     

Inhibition of aflatoxin production inAspergillus flavus by cotton ovule extracts

The effect of cotton ovule extracts onAspergillus flavus growth and aflatoxin biosynthesis was investigated. Extracts derived from either noninoculated cotton ovule tissue or cotton ovule tissue challenged withA. flavus inhibited aflatoxin (B₁) synthesis by fungal cultures ofA. flavus. When added to fungal cultures in concentrations of 50 μg per mL of medium, extracts derived from fungus-challenged ovule tissue inhibited aflatoxin synthesis by as much as 93%. The ED₅₀ for this type of extract was 18 μg per mL of medium (P < 0.01; r²=0.46). Similar experiments with a noninoculated ovule extract (50 μg/mL medium) produced aflatoxin inhibition levels of up to 77%. The ED₅₀ for noninoculated extracts was 35 μg per mL of medium (P < 0.01; r²=0.66). These extracts did not inhibit the growth ofA. flavus in culture. Cultures ofA. flavus that contained pure gossypol (10–50 μg/mL medium) also showed significantly reduced levels of aflatoxin production. Gossypol may account for the aflatoxin-inhibitory activity observed in the extracts derived from noninoculated cotton ovule tissue.     

纳米SiOx改性6109硅橡胶研究

以纳米S_iO_x取代6109硅橡胶用料沉淀法白炭黑，采用传统的硅橡胶混炼方法进行纳米S_iO_x在其中的分散，可使6109硅橡胶在其他性能数据变化不大的情况下，拉伸强度由原来的4.5MP_a提高到6.7MP_a，即提高55%。     

Wetting of fat crystals by triglyceride oil and water. 2. adhesion to the oil/water interface

Fat crystals influence the stability of food emulsions, such as margarine, butter, or cream, if adsorbed to the oil/water interface. During the adsorption process, a new fat crystal/water interface is created, while the oil/water interface is lost. The driving force for adsorption is therefore the difference between the interactions between fat crystal/water and oil/water. In this work, we have estimated this interaction difference and compared it to the displacement energy for fat crystals from the oil/water interface to the oil. Our calculations have shown that fat crystal adsorption to the oil/water interface (expressed by contact angle ϑ) is determined by polar energy, excess of fat crystal/water over oil/water (I _sw -I _ow ). The interfacial tension constitutes the resistance force for crystal adsorption to the interface. Polar interaction energy for fat crystal/water is stronger than the polar interaction energy for oil/water in all cases examined (I _sw -I _ow >0). The difference corresponds to about 10⁴–10⁶ hydrogen bonds for a hypothetical fat crystal with a diameter of 1 μm. The displacement energy for fat crystals to oil is lower than the polar energy excess in most cases examined. Thus, an additional interaction between fat crystals and oil makes it easy to displace the crystals to the oil. There is also a relationship between the adhesion tension (-γ _ow • cos ϑ) for the crystals at the oil/water interface and the interfacial tension γ _ow . A straight line of slope -1 is achieved for systems with low interfacial tensions (γ _ow ) and low polar energy excess (I _sw -I _ow ).     

硫黄对杜仲橡胶形状记忆材料性能的影响

研究硫黄用量对杜仲橡胶形状记忆材料性能的影响。结果表明：随着硫黄用量的增大,胶料的ML变化不大,MH增大,t⁹⁰先缩短后延长;硫化胶的交联密度总体呈增大趋势,定伸应力和拉伸强度先减小后增大,热刺激响应回复温度呈减小趋势,最终形变回复率先增大后减小;动态力学性能测试发现,存在多相转变峰;当硫黄用量为1份时,硫化胶的物理性能和热致形状记忆性能最佳。     

矿用12.00R20 18PR全钢载重子午线轮胎的设计

介绍矿用12.00R20 18PR全钢载重子午线轮胎的设计。结构设计：外直径 1 134 mm,断面宽 310 mm,行驶面宽度 240 mm,行驶面弧度高 10.5 mm,胎圈着合直径 512 mm,胎圈着合宽度 230 mm,断面水平轴位置(H₁/H₂) 1.052 8,采用以横向花纹为主的混合花纹,花纹饱和度 62.72%,花纹深度 24.5 mm,花纹周节数 35。施工设计：胎面上层胶和基部胶采用机内复合挤出,1^#和2^#带束层采用39＋15×0.22＋0.15钢丝帘线,3^#带束层采用3×4×0.22HE钢丝帘线,0°带束层采用3×7×0.20HE钢丝帘线,胎体采用0.25＋6＋12×0.225HT钢丝帘线,采用一次法三鼓胶囊成型机成型、B型双模定型硫化机硫化。成品轮胎性能试验结果表明,轮胎的充气外缘尺寸、强度性能和耐久性能均符合相应设计和国家标准要求,胎圈耐久性能符合企业标准要求。     

A new class of poly(1,6-heptadiyne)-based photorefractive materials by metathesis polymerization

SUMMARY: We utilized the first metathesis reaction to synthesize a new type of photorefractive polymers that contain both a carbazole moiety as a hole transporter and NLO chromophores. These polymers have a long tail band at above 700 nm, indicating the formation of intramolecular charge transfer complexes between the carbazole groups and the conjugated double bonds in the polymer backbone. Also, these polymers show two maximum values of photocurrent around 350 and 700 nm. The electro-optic coefficient (r ₃₃) at the wavelength of 1.3 μm for polymer thin films poled around the 85°C were in the range of 1.6 ∼6.3 pm/V. The hyperpolarizabilities, <γ>, of the resulting polymers were ca. 2.9 × 10⁻³² esu. at the incident wavelength of 1.907 μm. Received: 1 June 1998/Revised version: 27 July 1998/Accepted: 5 August 1998     

Determination of (+)-, (−)-, and total gossypol in cottonseed by high-performance liquid chromatography

Gossypol, a pigment in cottonseed, is a polyphenolic, binaphthyl dialdehyde. Due to steric hindrance between the functional groups of the molecule at the bond connecting the two naphthyl rings, gossypol exists as (+)- and (−)-isomers. Gossypol is physiologically active with the (−)-isomer appearing to be more active and causing temporary infertility in males. It is thus important to know the amounts of isomers in livestock feeds. A quantitative high-performance liquid chromatography (HPLC) procedure was developed for the separation of (+)- and (−)-gossypol contained in cottonseed. This method involves derivatization of gossypol with (R)-(−)-2-amino-1-propanol followed by HPLC separation employing either a Phenomenex Prodigy (5 μ, ODS-3, 100 × 3.2 mm) or a MetaChem Inertsil (5 μ, ODS-3, 100 × 3.0 mm) reversed-phase column eluted with 80% acetonitrile and 20% 10 mM KH₂PO₄ adjusted to pH 3.0 with H₃PO₄ at 1.0 mL/min. The (+)- and (−)-gossypol-2- amino-1-propanol complexes eluted at roughly 1.4 and 2.6 min, respectively. It was found that gossypol from Upland (Gossypium hirsutum) seed was rich in the (+)-enantiomer, with the (+)- and (−)-enantiomers in a ratio of about 65:35, respectively, while gossypol from the seed of a Pima (G. barbadense) cultivar (S-6) was slightly richer in the (−)-enantiomer (46.8:53.2). Deceased.