Materials Literature
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The magnetic and structural properties of melt-spun Sm(FeT)12 alloys where T=Ti,V,Al,Cu,Ga,Si and with some containing small amounts of B and C have been studied. The samples are magnetically soft in the as-quenched state. High coercive fields are developed upon heating the samples at temperatures ranging from 750 to…
Polycarbosilane (PCS) is an organic polymer with a skeleton of Si-C bonds. SiC fiber (Nicalon) is produced from PCS in three steps: spinning, curing (rendering the material infusible), and heating. SiC fiber has high tensile strength, high elastic modulus, and excellent thermostability in high-temperature oxidizing at…
Abstract Dynamic mechanical techniques can be used for a rapid estimation of polymer crystallinity with an accuracy of better than ±20%. The advantage of our proposed procedure is that it is absolute and the crystallinity can be instantaneously estimated when the dynamic mechanical analysis (DMA) data is available. A…
Abstract An experimental procedure has been designed for the preparation of aqueous mesophases of (hydroxypropyl)cellulose (HPC) exhibiting a stable low turbidity Sandwich chiroptical filters have been made from these right‐handed cholesteric liquid crystals confined between two parallel glass plates. Their optical pr…
The major categories of homopolymers and copolymers are discussed. These include (1) linear siloxane polymers, [—SiRR'O—] n (with various alkyl and aryl R and R' side groups); (2) sesquisiloxane polymers possibly having a ladder structure; (3) siloxane—silarylene polymers, [—Si(CH 3 ) 2 OSi(CH 3 ) 2 (C 6 H 4 ) m —] n…
Abstract In an attempt to provide information for improving silk fiber and fabric properties including crease recovery and yellowing, silk modification has been studied by using succinic and glutaric anhydrides. Glutarylation has been found to protect silk fibers from yellowing caused by the high energy radiation and…
The electronic structures of mixed-valence heteropoly 12-molybdo-phosphate anions (heteropoly blues) were investigated by electronic absorption spectroscopy and by 17 O and 31 P NMR spectroscopy in aqueous and acetonitrile solutions. The one-, two-, and four-electron reduced forms of α-PMo 12 O 40 3 - (αI, αII, and αI…
Abstract Melting points of poly(vinyl alcohol) (PVA) gels obtained by repeated freezing/thawing cycles of the solutions in mixed solvents of water and dimethyl sulfoxide (DMSO) were measured. PVA solutions in 1–30 and 90 vol % DMSO froze at −40°C. The melting point of a gel increased with an increase in freezing/thawi…
Abstract Miscible blends from plasticized poly(vinyl chloride), and epoxidized natural rubber having 50 mol% epoxidation level were prepared in a Brabender Plasticorder by the melt‐mixing technique. Changes in Brabender torque and temperature, density, dynamic mechanical properties, and differential scanning calorimet…
This chapter surveys the possible ways to influence the molecular and morphological structures of rubber-toughened styrene polymers in industrial production processes. Two important types of production processes are used in industry. The first is polymerization of styrene monomer or its mixture with other monomers in…
Abstract Two kinds of polypropylene with different molecular weight (MI = 15 and 30) were melt‐spun at the spinning temperatures of 210–290°C and take‐up velocities of 0.15–3 km/min. In the cases of the spinning temperatures of 270 and 290°C for MI15 and 250 and 290°C for MI30, the density showed a minimum with increa…
Abstract Different formulations of rubber with chopped coconut fiber (treated and untreated) as reinforcing agent were prepared. These reinforced systems were vulcanized at 153°C and the properties of the vulcanizates were studied by stress–strain, shore A hardness, and abrasion loss measurements. The bonding between…
The use of brittle polymers, such as polyvinyl chloride (PVC) and polystyrene (PS), was limited prior to the development of rubber-toughened polymers in the 1930s and 1940s. PVC has been toughened by the addition of small amounts of acrylonitrile rubber (NBR) and other elastomeric materials. Over 1.5 million tons of r…
The structure, properties, and uses of poly(dimethylsiloxane) are surveyed in relation to its surface activity, with emphasis on the structural basis of this activity: the low intermolecular forces between methyl groups and the unique flexibility of the siloxane backbone. These basic attributes are used to explain the…
The use of brittle polymers, such as polyvinyl chloride (PVC) and polystyrene (PS), was limited prior to the development of rubber-toughened polymers in the 1930s and 1940s. PVC has been toughened by the addition of small amounts of acrylonitrile rubber (NBR) and other elastomeric materials. Over 1.5 million tons of r…
Gels are swollen networks possessing both the cohesive properties of solids and the diffusive transport properties of liquids. Elastically, they tend to be soft, and osmotically they are highly reactive. Gels based on water incorporate water's unique properties, in particular, the facility for ionization that an aqueo…
Abstract About 65 diverse phenyl benzoates incorporating a trans ‐1,4‐disubstituted cyclohexane ring and at least one lateral substituent have been synthesised. The dependence of the liquid‐crystal transition temperatures of these materials on various lateral substituents (F, Cl, CN, and Br) in different positions of…
A new activating reagent for amide condensation [(1,2,3-benzotriazine-4-one)-3-yl] diphenyl phosphate (BTDP), was prepared in good yield (88%) by the reaction of 3-hydroxy-1,2,3-benzotriazine-4-one with diphenyl phosphorochloridate in the presence of triethylamine (TEA) in tetrahydrofuran. Benzanilide was readily prep…
Si 3 N 4 test bars containing additions of BN, B 4 C, and C, were hot isostatically pressed in Ta cladding at 1900° and 2050°C to 98.9% to 99.5% theoretical density. Room‐temperature strength data on specimens containing 2 wt% BN and 0.5 wt% C were comparable to data obtained for Si 3 N 4 sintered with Y 2 O 3 , Y 2 O…
Abstract The crystallization of K 2 SO 4 from aqueous solutions of glaserite (a double salt of sodium and potassium sulphate) was investigated in an MSMPR cooling apparatus at 35 °C. The precipitation of K 2 SO 4 at an average purity of 93 wt.% was obtained and the crystallization kinetics were derived from the experi…