How should the development of general plastics engineering proceed?

How to get there? The bigger, the stronger, the better the technology, the stronger, the more reasonable the cost control, the stronger.

I think the prospects for general-purpose plastics are still very broad. The first reason is that they are widely used. Second, the current market demand is huge. I have also seen that many manufacturers require special resin raw materials. The raw materials they need are expensive and the quality is not very stable. On the contrary, they use general-purpose plastic resins, the quality of the products they produce is fully up to standard, and the price of general-purpose resin raw materials is relatively low. So general plastics are quite promising

Due to their large quantity and relatively low product performance, general plastics should be modified in the future.

As society becomes anti-war, the demand for general-purpose engineering plastics will increase. As the fourth floor said, product performance is low, so modification is an important aspect. As for the development of new plastic varieties, it is not mainstream!

Nowadays, the modification of general plastics seems to be mainly for this purpose.

For general plastics, it is necessary to continuously improve the process, reduce unit consumption, increase productivity and improve quality.

Research on toughened high-density polyethylene engineering plastics with excellent rigidity. Toughening high-density polyethylene (HDPE) so that this large variety of general-purpose plastics can be used as engineering plastics is an important direction for research and development of new engineering plastics at home and abroad. Judging from the current research and development situation at home and abroad, elastomer toughening has the best toughening effect. However, while general elastomer toughening greatly improves the toughness of HDPE, the rigidity (tensile yield stress, bending elastic modulus) is significantly reduced. ； Toughened with rigid particles (organic particles, inorganic particles), it has excellent rigidity, but the improvement in toughness is small, and it is mainly suitable for HDPE with already relatively good toughness. Therefore, how to significantly improve the toughness of elastomer-toughened HDPE while maintaining excellent rigidity is an urgent issue that has important scientific and technological significance and application value. Based on the analysis of the three structural reasons why general elastomer-toughened HDPE has a significant increase in toughness and a significant decrease in rigidity, this work has designed the structural characteristics that elastomer-toughened HDPE must have to exhibit excellent rigidity. ； In order to obtain a good technical/economic ratio, the design adopts the toughened masterbatch (TMB) process, that is, TMB with the designed structural characteristics is first prepared, and during the process of thermo-mechanically blending TMB and HDPE to prepare toughened HDPE, the structural characteristics of TMB are "transplanted" into the toughened HDPE. Based on this, the principles and techniques of "polymerization bridge connection, dynamic vulcanization, and micro-phase separation" developed in this work are used to prepare TMB, using 22∞JHDPE (denoted as E1) or 5∞OSHDPE (denoted as E2) as the matrix resin, ethylene-propylene elastomer and/or styrene-butadiene elastomer as the toughening agent, and adding bridging agents, etc. Different formulas of toughening masterbatch called E type (E-TMB, divided into E1-TMB and E2.TMB) were developed, and E. TMB is thermomechanically blended with HDPE to prepare various types of toughened HDPE (HDPE.TMB). E. was studied using graded extraction, IR, TEM, PLM, DSC, DTA, SEM, electronic universal testing machine, capillary rheometer, etc. TMB’s chemical and morphological structure, melt fluidity, HDPE/E_TMB's morphological structure, mechanical properties, brittle-ductile transition mechanism, thermal properties, melt rheological behavior, non-isothermal crystallization behavior, etc., and proposed and verified linear equations that characterize the relationship between the apparent viscosity (na) of the melt of polymers and polymer blends, the temperature (T) and the shear rate (r). The following main results and conclusions were obtained: l•Within the formula range studied, El-TMB and E2. The contents of elastomers in the form of graft copolymer and cross-linked polymer in TMB are 15.31% to 25.56% (accounting for 51.39% to 76.∞% of the total elastomer) and 9·99% to 12.85% respectively. (Accounting for 29.60% ~ 36.83% of the total elastomer), the content of HDPE in the form of graft copolymer and cross-linked polymer is 2.4l% ~ 11.51% respectively (accounting for 5.27% ~ 1 of the total HDPE 9.10%) and 4·09% ~ 11.36% (accounting for 7.98% ~ 19.17% of the total HDPE), because the content of the graft copolymer is only 0.5l% ~ 4.49% and 1.74% ~ 2.34 respectively %, therefore, the vast majority of the elastomers and HDPE that exist in the form of graft copolymers and cross-linked polymers in these two types of E-TMB mainly exist in the form of HDPE and elastomer cross-linked polymers connected through polymeric bridge chains. Make E. The formula of TMB, such as the ratio of ethylene-propylene elastomer to styrene-butadiene elastomer, etc., is very important for E. The composition of TMB has an impact. The morphological structure of E-TMB is: HDPE is the continuous phase, and the elastomer is the dispersed phase. The dispersed phase has a cellular (sausage-like) structure containing a considerable amount of HDPE. ； HDPE crystallization refinement. 2． E. The structural characteristics of TMB are "transplanted" into HDPE/E-TMB, HDPE. TMB has the designed toughness to be greatly improved while maintaining high rigidity. HDPE is a continuous phase. The elastomer is a dispersed phase, has a certain degree of cross-linking, and is chemically bonded with HDPE. The dispersed phase has a cellular (sausage-like) structure that contains a considerable amount of HDPE, and the structural characteristics of HDPE crystallization refinement. The degree of crystallization refinement of HDPE is related to E. It is related to the formula of TMB and other factors. 3. HDPE/E-TMB shows the excellent performance of significantly improving the toughness compared to the raw material HDPE while maintaining the rigidity of HDPE at a relatively high level. For example, for 29¨HDPE with relatively poor toughness and toughness, when the Izod notch impact strength is increased to 16 times that of 29¨HDPE, the tensile yield stress and bending elastic modulus are still maintained at 78% and 63.5% of 29¨HDPE respectively, which is impossible to achieve by general elastomer-toughened 29¨HDPE. The toughening effect and rigidity retention rate of HDPE E-TMB are the same as those of E. It is related to the formula of TMB and other factors. E. suitable for toughening different types of HDPE were screened out. The best recipe for TMB. 4. The brittle-to-tough transition behavior of HDPE E1-TMB is significantly different from that of general elastomer-toughened HDPE (HDPE/elastomer). For example, at 17°C, the 22∞JHDPE/E1-TMB toughened system undergoes a brittle-to-ductile transition when the elastomer mass content is 3% to 10%, while the 22∞IIIDPE/elastomer toughened system only undergoes a brittle-to-ductile transition at 6% to 16%. It is revealed that the brittle-ductile transition mechanism of the HDPE E-TMB toughened system changes from the craze-crack deformation and fracture mechanism to the deformation and fracture mechanism of fracture after large deformation in shear and tension. 5. The thermal and thermal oxidative stability of HDPE/E-TMB is greatly improved compared to the raw material HDPE. For example, the thermal decomposition and thermal oxidation onset temperatures of 22∞JHDPE/E1-TMB (1∞/0) are respectively 20.4℃ and 25.5℃ higher than that of 2200JHDPE. The melting point (DSC endothermic peak peak temperature) of most HDPE/E-TMB compositions is higher than that of the raw material HDPE to a certain extent. 6． Under the shear flow conditions studied, the HDPE/E-TMB melt exhibits the rheological behavior of a pseudoplastic fluid, and the degree of pseudoplasticity is greater than that of the corresponding raw material HDPE. The ηa of HDPE/E-TMBs is larger than that of the corresponding raw material HDPE to varying degrees, but it has a melt viscosity suitable for molding and processing. 7. The ηa=A+KT linear equation proposed in this work to characterize the relationship between polymer and polymer blend melt ηa, T and •r has two outstanding advantages compared with the Arrhenius-type equation lnηa=lnA+△Eη/RT.: First, it can intuitively reflect the amount of change in eta caused by temperature changes. ； Secondly, it can truly reflect the difference in the degree of change of eta caused by T under different γ, and the difference in the degree of change of eta caused by γ under different T. 8. The crystallization of HDPE in HDPE/E-TMB has a heterogeneous nucleation mechanism, and the crystallization starting temperature is higher than that of the corresponding raw material HDPE to varying degrees, with the maximum amplitude of 23°C. The influence of the formula of E-TMB on the crystallization behavior of HDPE in HDPE/E-TMB is relatively complex.

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It is a development trend to replace engineering plastics with general plastics, and modify them to use them in a wider range of fields, such as flame retardancy, toughening, etc.