单组分室温硫化硅橡胶的配制(十四)

介绍了脱丙酮型单组分室温硫化(RTV-1)硅橡胶的特点,以及低挥发性、抗黄变性、耐油性和低模量脱丙酮型RTV-1硅橡胶的配制.     

单组分室温硫化硅橡胶的配制(九)

介绍了低拉丝性脱醇型室温硫化(RTV-1)硅橡胶密封剂的配制方法以及用α，w-二甲氧基聚二甲基硅氧烷、MDT硅油作增塑剂，酸性磷酸酯作催化剂，二烷氧基硅烷作扩链剂配制低模量脱醇型RTV-1硅橡胶密封剂的方法。     

单组分室温硫化硅橡胶的配制(八)

介绍了改进脱醇型单组分室温硫化(RTV-1)硅橡胶贮存稳定性的方法(包括采用六甲基二硅氮烷、三烷基硅酸酯、烷氧基硅酸酯、异氰酸根合烃基烷氧基硅烷、氯化钙、氯化镁作醇清除剂及选择适当的钛酸酯作催化剂）和采用双螺杆挤出机配制脱醇型RTV-1硅橡胶的方法。     

无机阻燃剂对单组分室温硫化硅橡胶性能的影响

试验研究氢氧化镁、氢氧化铝及其复合物对脱酮肟型单组分室温硫化（RTV-1）硅橡胶物理性能和阻燃性能的影响。结果表明，随着氢氧化镁用量的增大，RTV-1硅橡胶的硬度、拉伸强度和氧指数逐渐增大，拉断伸长率逐渐减小，氢氧化镁用量为50份时RTV-1硅橡胶具有阻燃性；氢氧化铝填充RTV1硅橡胶的硬度、拉伸强度和氧指数均高于相同用量氢氧化镁填充胶，氢氧化铝用量为40份时RTV-1硅橡胶具有阻燃性；氢氧化镁／氢氧化铝并用量为30份时RTV-1硅橡胶具有阻燃性，氢氧化镁／氢氧化铝质量比为1：4时其阻燃效果最佳。     

甲醇对脱醇型RTV-1硅橡胶性能的影响

通过添加无水甲醇模拟脱醇型单组分室温硫化(RTV-1)硅橡胶生产过程中产生的甲醇,研究了甲醇对脱醇型RTV-1硅橡胶性能的影响。结果表明:在配制脱醇型RTV-1硅橡胶时,甲醇的加入对密封胶力学和粘接性能无影响,但会影响部分施工性能。经70℃加速贮存5天后(相当于室温放置6个月),甲醇的存在会导致表干时间延长,力学强度和粘接性能均有一定幅度的下降;当甲醇质量分数为1%时,脱醇型RTV-1硅橡胶不硫化;若控制配制时甲醇的残留质量分数低于0.25%,则在加速贮存后,脱醇型RTV-1硅橡胶的施工性能略有下降,力学性能与粘接性能保持率达到80%以上。     

单组分室温硫化硅橡胶的配制(十二)

介绍了深层硫化型、消光型、抗菌防霉型、对铜无腐蚀型脱醇型单组分室温硫化(RTV-1)硅橡胶的配制。     

超细活性碳酸钙补强脱酮肟型RTV-1硅橡胶的制备及性能

以超细活性碳酸钙为补强剂制备脱酮肟型单组分室温硫化(RTV-1)硅橡胶,并研究了107胶黏度、碳酸钙用量、交联剂和偶联剂种类及用量等对RTV-1硅橡胶性能的影响。结果表明,采用黏度为50 000 mPa.s的107胶、80份超细活性碳酸钙、10份甲基三丁酮肟基硅烷、2份乙烯基三丁酮肟基硅烷及2份硅烷偶联剂KH560,可制备出综合性能较好的脱酮肟型RTV-1硅橡胶,拉伸强度达2.29 MPa,断裂伸长率达500%。     

渗油性低黏度RTV-1硅橡胶的研究

以黏度500~10 000 mPa·s的端羟基聚二甲基硅氧烷(107硅橡胶)为基础聚合物、超细白炭黑和其它粉料为填料,经过加热脱水处理后添加脱醇型交联剂、催化剂和助剂,配制成脱醇型单组分室温硫化(RTV-1)硅橡胶;再添加惰性硅油,制得系列渗油性低黏度RTV-1硅橡胶。考察了107硅橡胶的黏度,惰性硅油的黏度、用量、环境温度对RTV-1硅橡胶渗出性的影响,同时研究了惰性硅油的渗出性对输电线抗结冰性能的影响。结果表明。随着107硅橡胶黏度的减小、惰性硅油黏度的增加,惰性硅油用量的增多、环境温度的升高,RTV-1硅橡胶的渗油性增大,最后达到平衡;其质量损失越小,反之越大;聚二甲基硅氧烷的黏度越大、所占比例越大,渗油量越多、渗油速度也越快;其质量损失越大,且达到平衡所需时间越长;渗油性越好的RTV-1硅橡胶,其抗结冰性能好。     

提高RTV-1硅橡胶粘接性的方法

湖北回天胶业公司的杨敏等人发现,在脱酮肟型单组分室温硫化（RTV-1）硅橡胶中添加二乙氨基甲基三乙氧基硅烷能有效提高RTV-1硅橡胶的本体强度和粘接强度,并提高其耐机油性;     

单组分脱醇型密封胶的研制

以端羟基聚二甲基硅氧烷(107硅橡胶)为基胶、甲基三甲氧基硅烷和乙烯基三甲氧基硅烷为交联剂、纳米碳酸钙和气相法白炭黑为补强填料、硅烷偶联剂为增粘剂,有机钛为催化剂,制得单组分脱醇型室温硫化(RTV-1)硅橡胶。研究了基胶黏度,填料、交联剂、增粘剂的种类和用量对脱醇型RTV-1硅橡胶性能的影响。较佳配方为:100份黏度50 000 mm2/s的107硅橡胶、5份甲基三甲氧基硅烷与乙烯基三甲氧基硅烷按质量比7∶3复配的交联剂、0.4～0.6份自制氨基硅烷偶联剂。按此配方制得的RTV-1硅橡胶的性能较好。     

Process and fiber spinning studies for the cellulose/paraformaldehyde/dimethyl sulfoxide system

A cellulose pulp of about 550 D.P. was readily dissolved in a combination of (CH₂O)x/DMSO to afford an initial 6/6/88 cellulose/(CH₂O)x/DMSO composition solution. The concentration of formaldehyde was found to be a function of solution heating time and temperature. The solutions were microscopically free of gels and undissolved cellulose fibers. Cellulosic articles such as fibers and films are easily regenerated from these cellulose solutions in the presence of coagulants such as methanol or water. Fibers with high wet modulus, intermediate tenacity, and low elongations were produced from these regenerations systems. Fibers have been spun with conditioned and wet tenacities as high as 2.9 and 2.1 g/d, respectively, with wet modulus (at 5% elongation) as high as 1.3 g/d and solubility in 6.5% NaOH in the low range of 3.0%–15%. In many respects, these fibers are comparable to those produced in the viscose process. However, the low elongations of these fibers probably would not permit normal textile processing. The cellulose/(CH₂O)x/DMSO solutions were modified with compounds containing reactive N? H functional groups which are known to react with excess formaldehyde to yield the corresponding N-methylol derivatives. However, the resulting fiber physical properties were not significantly improved compared to those obtained from unmodified cellulose solutions. Addition of acrylic acid derivatives such as methyl acrylate, butyl methacrylate, or acrylonitrile to the cellulose solutions did not result in the formation of the expected 1,4-type adducts.     

PUR／PS间充复合弹性体的制备

本文报道了采用浇铸成型制备ＰＵＲ／ＰＳ间充复合弹性体的方法。考察了不同配方下的多元醇组分中各成分相容性及粘度与所含苯乙烯、预聚物中甘油相对含量的关系；浇铸过程中各类催化剂对工艺及制品性能的影响及ＮＣＯ／ＯＨ、交联密度与制品力学性能的关系。本方法获得的Ａ组分在常温下为稳定的溶体，粘度小，适用于室温下的浇铸成型，简化传统的聚氨酯浇铸成型工艺，并具有优良的脱模性能，所得弹性体的性能基本与市场上现有的中高模量聚氨酯弹性体相当。     

Effect of temperature and age on the relationship between dynamic and static elastic modulus of concrete

This study investigates the effects of cement type, curing temperature, and age on the relationships between dynamic and static elastic moduli or compressive strength. Based on the investigation, new relationship equations are proposed. The impact-echo method is used to measure the resonant frequency of specimens from which the dynamic elastic modulus is calculated. Types I and V cement concrete specimens with water-cement ratios of 0.40 and 0.50 are cured isothermally at 10, 23, and 50 °C and tested at 1, 3, 7, and 28 days.Cement type and age do not have a significant influence on the relationship between dynamic and static elastic moduli, but the ratio of static to dynamic elastic modulus approaches 1 as temperature increases. The initial chord elastic modulus, which is measured at low strain level, is similar to the dynamic elastic modulus. The relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic moduli for various cement types, temperatures, and ages.     

环氧-聚酰胺体系中增韧剂的研究

在环氧-聚酰胺体系中分别加入“海岛结构”QS-1、聚硫橡胶、液体丁腈橡胶增韧改性,通过对固化物剪切强度、弯曲弹性模量及断裂强度的对比,“海岛结构”QS-1增韧综合性能较好.     

低模量硅酮建筑密封胶的研究进展

简要介绍了低模量硅酮建筑密封胶的制备方法,综述了低模量硅酮建筑密封胶的种类、性能及应用。     

一种新型碳纤维复合材料绳索的研制

碳纤维复合材料绳索具有重量轻，比强度高，比模量高等优异性能，笔者以环氧树脂E51，甲基四氢苯酐（METHPA），三叔胺基苯酚DMP－30和活性增韧剂6350组成的树脂体系为基体树脂，以碳纤维为增强材料，以聚氨酯为保护涂层，采用独特的制绳工艺，制成了高性能的碳纤维复合材料绳索。     

Modulus recovery kinetics and other insights into the payne effect for filled elastomers

The nonlinear viscoelastic behavior of filled elastomers is examined in detail using a variety of samples including carbon‐black filled natural rubbers and fumed silica filled silicone elastomers. New insights into the Payne effect are provided by examining the generic results of sinusoidal dynamic and constant strain rate tests conducted in true simple shear both with and without static strain offsets. The effect of deformation history is explored by probing the low amplitude modulus recovery kinetics resulting from a perturbation by a large strain deformation such as a sinusoidal pulse or the application or removal of a static strain. It is found that a static strain has no effect on either the fully equilibrated dynamic (storage and loss) moduli or the incremental stress‐strain curves taken at constant strain rate. The reduction in low amplitude dynamic modulus and subsequent recovery kinetics due to a perturbation is found to be independent of the type of perturbation. Modulus recovery is complete but requires thousands of seconds, and is independent of the static strain. The results suggest that deformation sequence is as critical as strain amplitude in determining the properties, and that currently available theories are inadequate to describe these phenomena. The distinction between fully equilibrated dynamic response and transitory response is critical and must be considered in the formulation of any constitutive equation to be used for design purposes with filled elastomers.     

Resonant frequency study of tensile and shear elasticity moduli of carbon fibre reinforced composites (CFRC)

The dynamic elastic properties are important characteristics of composite materials. They control the vibrational behaviour of composite structures and are also an ideal tool for monitoring of the development of CFRCs’ mechanical properties during their processing (heat treatment, densification). The present studies have been performed to explore relations between the dynamic tensile and shear moduli and some structural features (viz., fibre fraction, fibre type, porosity, weave pattern of woven reinforcement) of various unidirectional or bi-directional fibre reinforced carbon/carbon composites, made out of PAN- or pitch-based fibres as reinforcements and phenolic resin or coal tar pitch as matrix precursors. The dynamic tensile and in-plane shear moduli were determined from resonant frequencies of a beam with free ends. The longitudinal dynamic Young’s modulus of unidirectional CFRC composites – besides its dependence on the original fibre modulus and fibre volume contents – also reflects changes induced in matrix and fibres by heat treatment. The in-plane shear modulus does not depend on the fibre type but there exists its distinct tendency to increase with increasing fibre fraction. For bi-directionally reinforced composites, the longitudinal tensile modulus is more sensitive to the fabric weave pattern than to the fibre type. Tensile modulus of diagonally cut specimens and in-plane shear modulus of longitudinally cut ones are mutually correlated and, therefore, simultaneously controlled by densification steps and graphitisation heat treatment.     

Glass fiber reinforced polyamide‐6 nanocomposites

Polyamide 6 nanocomposites (PA6/NC) are novel type of composite materials comprising extremely thin, “nanometer scale” dispersions of smectitic silicate platelets. We prepared such PA6/NC materials via a melt compounding technique using suitably organomodified montmorillonite or hectorite type clays. The high surface to volume ratio of such thin silicate dispersions in PA6/NC leads to a high reinforcement efficiency even at 2 to 5 wt% of clay, achieving high specific modulus, strength and heat distortion temperature under load (DTUL). In addition, the platelet orientation and their surface nucleation effects seem to promote a faster crystallization and higher crystallinity in PA‐6/NC (particularly at the surface and in thin‐wall injection moldings), as compared to the standard PA‐6. Such morphological features in PA‐6/NC also result in improved moisture resistance. Recognizing these benefits, we investigated the use of PA‐6/NC as a matrix for making both short and long glass fiber (GF) reinforced composites. Significant improvements in modulus were achievable in both the dry and the moisture conditioned state for PA‐6/NC compared to standard PA‐6, at any given level of glass fiber reinforcement. In general a small amount (3‐4 wt%) of the nanometer scale dispersed clay is capable of replacing up to 40 wt% of a standard mineral filler or 10‐15 wt% of glass fiber in PA‐6 composites to give equivalent stiffness at a lower density or a lower part weight advantage. In addition, improved moisture resistance, permeation barrier and fast crystallization/mold cycle time contribute to the usefulness of such composites.     

热塑性聚氨酯弹性体与乙华平橡胶共混物的性能

将聚酯型和聚醚型聚氨酯弹性体(TPU385E,TPU8685)分别与不同乙酸乙烯酯含量的乙华平橡胶(EVM400,EVM700)进行共混,考察了原料种类、共混比对共混物力学性能和耐磨性的影响。结果表明,随着TPU用量的增加,EVM/TPU共混物的拉伸强度、邵尔A硬度、100%定伸应力和300%定伸应力均提高,扯断伸长率下降;随着EVM用量的增加,EVM/TPU共混物的拉伸强度、邵尔A硬度、100%定伸应力和300%定伸应力均降低,扯断伸长率增大;随着TPU用量的增加,EVM/TPU共混物的耐磨性提高;TPU8685/EVM400共混物具有最大的拉伸强度,TPU385E/EVM700共混物具有最大的扯断伸长率,TPU8685/EVM700共混物具有最好的耐磨性;当2种TPU与EVM400质量比都为50/50时,TPU385E/EVM400的耐磨性最差。