Huang Shuhuai

Development of a polymer alloy of polystyrene (PS) and polyamide (PA) for building functional part based on selective laser sintering (SLS)

Abstract Polystyrene (PS) powder materials may be directly used for selective laser sintering (SLS). The part sintered with PS has high dimension precision, but its tensile strength is very low, only 5-6 MPa, and its solvent resistance capability is not good, which cannot meet the demands of the functional parts. The part sintered with polyamide (PA) has high mechanical properties and excellent resistance capability, so PA is suitable for building functional parts. However, the precision of the SLS part sintered with PA is low crystallinity. Also, PAs price is very high (relative to PS powder). Colligating the properties of the two materials, PS and PA, a polymer alloy of PS and PA for building functional parts is developped. Using this alloy as the sintering material, some parts are sintered successfully and the tensile strength of the parts increases to about 14 MPa, which can meet the demands of some functional parts.

Microstructure of Selective Laser Sintered Polyamide

The selective laser sintering (SLS) was used to prepare components from modified polyamide (PA) powder. The behaviour of the sintering process was analyzed. The influences of the fill laser power, powder bed temperature and powder thickness were discussed in detail. By means of SEM, the morphology and the heat influence were analyzed. Results show that the powders were fused thoroughly which allowed a more dense structure to be built at a powder bed temperature of 98°C, fill laser power 12W, slice thickness of 0.10 mm and a default scanning speed of 1700 mm/s.

Development of a Hybrid Photopolymer for Stereolithography

New liquid free radical-cationic hybrid photopolymer, consisting of acrylate-based photocurable resin and epoxy-based photosensitive resin for stereolithography by UV laser was developed. The experiment results indicated that the hybrid photopolymer exhibits advantages of both the acrylate-based photosensitive resin and the epoxy-based photosensitive polymer contained in the hybrid system with relatively high photospeed and low linear shrinkage. Stereolithography parts without obvious distortion were built on the stereolithography apparatus HRPLA-I from this hybrid resin successfully and efficiently.

Synthesis of a novel photosensitive prepolymer with trimethylolpropane triglycidylether and acrylic acid as starting materials

A novel photosensitive prepolymer of trimethylolpropane triglycidylether triacrylate was synthesized by utilizing trimethylolpropane triglycidylether and acrylic acid as two starting materials, triphenyl phosphine as catalyst and p-hydroxyanisole as inhibitor. The optimum synthesis conditions were that the concentration of triphenyl phosphine was 0.85wt% of reactants, the concentration of p-hydroxyanisole was 0.3wt% of reactants, and the reaction temperature was at 90–110°C. Benzil dimethyl ketal of a UV-cured initiator was added to the synthesized trimethylolpropane triglycidylether triacrylate to prepare a kind of UV-cured coating. The mechanical properties of the UV-cured films were determined, giving 28. 43 MPa of tensile strength, 965. 59 MPa of Young’s modulus and 4.10% of elongation at tear.

Synthesis and performance of transparent casting polyurethane resin

A series of transparent casting polyurethane resins (TCPU) were synthesized from cycloaliphatic diisocyanate (IPDI or H12MDI), polyol, chain extender, crosslinking agents, catalyst and special aids (T), which were characterized by FTIR. The thermal stabilities of the obtained TCPU were examined by DSC and TGA, the glass transition temperature (Tg) was in the range of 95–110°C, the initial decomposition temperature (5% weight loss) was 250–265°C, and 10% weight loss at the temperature was in the range of 260–286°C in nitrogen atmosphere. The morphologies of the fractured surfaces of TCPU were revealed by a scanning electron microscope (SEM). The crystalline-amorphous characters of TCPU were studied by WAXD, the result shows that TCPU possesses amorphous glassy characters. The optical properties of TCPU were studied by a UV-7500 visible light absorbance measurement. All the samples exhibited excellent optical properties and possessed light transmittance in the range of 91%–93%.

Regional adaptive delaminating algorithm for rapid prototyping

With the development of rapid prototyping (RP) technology, the contradiction fabricating speed and precision becomes more and more acute. In order to solve the contradiction, a regional effective adaptive delimitation algorithm is proposed in this paper. It is different from the traditional method that the regional adaptive delaminating adaptive method divides slicing contours into several regions and adaptively delaminates in respective region only according to the contours information. Namely, this method can not only adaptively delaminate at different height of CAD model but also adaptively delaminate different regions in one slicing layer. Furthermore, because the two-dimensional contours data adopted in this method are necessary for rapid prototyping system, the regional effective adaptive delaminating method is suitable for all RP systems. A comparative study is used to analyze the effectiveness of this method, which can demonstrate that this method can increase the fabricating speed and reduce the ...

Preparation of aryl-substituted sulfonium by condensation of biphenyl sulfoxides with aromatic compound

Three kind of aryl-substituted tri-benzyl sulfonium salts [(4-phX)phSph2]PF6[X=S,O] were prepared by the condensation of biphenyl sulfoxide with biphenyl sulfide, biphenyl ether or 1,1’-biphenyl in the presence of polyphosphoric acid which can be used as dehydrate agent. The reaction condition was mild, such as reaction temperature between 40–50 °C, reactive time 2–3 h, the yield of 4-(phenylthio)triphenylsulfonium hexafluorophosphate was 87.6%. The three kind sulfonium salts show better curing character to epoxy resin.