The Synthesis Technology ￡ Rheology Study Of Heat-resistant Macromolecule Modified By N-phenyl Maleimide

Material is a foundation of the development of science and industry. The research of novel material with high-performance and functions become a hot point in material science field recently. With the polymeric material widely used, the performance of heat-resistance is paid more and more attention. For its outstanding heat-resistance polyimide resin, especially N-phenyl maleimide (NPMI) is the best choice and has been studied from 80's twenty century.The thermal stability of polymer material can be understood from two directions. One is revolves in the physical changes such as deformation, specific volume, strength. These changes usually induced by macromolecule and/or chain movement are testified with heat deformation temperature, softening point, glass transition temperature (Tg) and melt point. Another one is the chemical changes, for example, material decomposition, degradation, depolymerization which are demonstrated by decomposition temperature, weight loss temperature and solvent-resistance.The heat-resistance of polymer determined by its own molecular structure can be improved through three methods: The introduction of polarity groups and aromatic ring structure to the main chain or crosslinking; the compounding or blending; grafting NPMI, maleic anhydride to vinyl polymers. The later is the most promising method in producing high heat-resistance polymer material. (1)In this paper, NPMI-g-styrene(St)-acrylonitrile(AN) (SMIA) copolymer is synthesized by suspension polymerization. The upper limit temperature in the reaction is defined at 75℃. The following equations show the relation between Tg and the ratio of NPMI to St. Tg(SMIA- NPMI)=105.3+1.27*NPMI(%) Tg(SMIA-St)= -0.0743*[St(%)]2+6.5714*St(%)-15.4The following equations show the relation between the Vicat softening point and the ratio of NPMI to St. Vicat(SMIA- NPMI)=98.357+1.3286*NPMI(%) Vicat(SMIA-St)= -1.514*St(%)+197.07The following equation shows the relation between the melt index(MI) and the ratio of NPMI to St. MI(SMIA-St)= 0.69*St(%)-24.21 The purity of NPMI> 97%.(2)T he pilot test of SMIA copolymerization was conducted. The propeller type was pitched-blade turbine and the speed was at 160, 170 r/min. Amplification test criteria was defined at power in volume Pv. The temperature control method was determined. The copolymer SMIA was successfully carried out in pilot test and two brands of ABS products(N-I and N-II) were produced in 1500 t/a industry production line.(3)Industrial pilot test of SMIA copolymerization was carried out. During the study, it is found that the conversion arrived up to 26.6% in the initial unit reaction time. Theoretically, the initial reacting temperature is 36℃, higher than that of internal jacket water. So when the polymerization temperature is 70℃, the water temperature in internal jacket is only required about 34℃. In 30m3 reactor, seven batches of copolymer SMIA were produced. The N-I,N-II were produced and acquired application.(4) The synthetical technology of St-NPMI (SMI) was studied. By using conventional suspension polymerization, when the content of St is higher than 55%, there are two Tg peak in differential scanning calorimetry(DSC) curve. Adopting the method in which adding AN during the later reaction state and varying St content in a wider scope, two Tg peak also appeared clearly. When the content of St is up to 65%, two Tg peak also can be appeared.In this paper, SMI firstly synthesized used by suspension-solution polymerization. At a wide varying scope of St content, the content of monomers in SMI is even and homogeneous, for only one Tg peak appeared in the DSC curve. Based on orthogonal test method, the optimized recipe and reacting conditions were determined. The obtained softening point of ABS is 154℃.(5) The polymerization method for SMIA is systematically studied. a. SMIA is prepared by using conventional polymerization method. The emulsion system is stable. However, the colour of the emulsion turns to pink in static state for 10h. After drying the polymer, it is pink.b. SMIA emulsion is prepared with organic initiator by conventional process. The reaction could be conduct successfully, but some agglomeration could be produced (1.0~3.0%). The colour of the emulsion unvaried.c. Basing on pre-emulsification process and using organic initiator, SMIA emulsion is obtained. The reaction is successful and the system stability of the emulsion is highly enhanced. During the reacting, the little agglomeration is produced and the colour is good.d. The above polymerization method is easily controlled and the reacting is extremely stable. The agglomeration is very few. The reacting process is further optimized in the reacting temperature, agglomerating process and other aspects.(6)The rheological properties of SMIA with different content NPMI were investigated at different temperature (190, 200, 210, 230℃) and different shear rate(10-103 s-1). a. When the content of NPMI and the temperature remain the same, the copolymer melt shear stress climbs up with the increase of the shear rate, and the logarithms of them exhibit approximately linear relationship that can be stimulated via linear equations. The slope of the linear is the non-Newton melt index n. The copolymer melts are pseudoplastic fluid, and the non-Newton index varies due to temperature varies at a certain range. At the NPMI content and shear rate are the same, the shear stress fall down with the temperature increasing. The logarithm value of the shear stress decrease is nearly linear to that of the increase of temperature.b. At the same temperature and the content of NPMI, apparent viscosity decrease with the shear rate increase, and the logarithms of both of them exhibit linear relationship approximately, the slope n-1 varies at a certain range when the temperature fluctuate. At the same NPMI content and shear rate, apparent viscosity decrease with the temperature. The logarithm value of the apparent viscosity decrease is nearly linear to that of the increase of temperature.c. At the same NPMI content and shear rate, apparent viscosity decrease with the temperature increase and 1000/T is linear to the logarithm value of the apparent...