Detailed interpretation of wood plastic production formula

Detailed interpretation of wood plastic production formula

Wood plastic products are much lower in cost than pure plastics or pure wood, etc. You can use recycled plant fibers, waste wood flour in wood processing and used recycled plastics, which is conducive to the full use of the environment and resources. The advantages of wood and plastic, low density, low cost, water resistance, and moth resistance.

The wood powder used for wood plastic includes wood powder, bamboo powder, rice husk powder, wheat straw, peanut shell, bagasse, etc. The resin used for wood plastic includes PVC, PE, PP, of which PE accounts for 70% and PVC accounts for 13 %, PP accounts for 17%. As the price of oil rises, the prices of PE and PP, which are made of petroleum, increase, while the price of PVC is stable, which gives PVC-based plastic-wood composites a development opportunity. Of course, it is not low cost. We can ignore these and have a great impact on the physical and mechanical properties of the product. We can analyze it through actual production.

First of all, we need to know that the main ingredients of wood flour are cellulose + lignin + hemicellulose. In addition, other organic matter and moisture must be added with resin powder in real life.

Mix the mixture of plant fibers such as PVC + wood flour and so on for 5 minutes on a 170 ℃ double-roll plastic mixer, take tablets, tablet, sample preparation, notch impact strength according to GB1843-80 standard in ZBC-25B pendulum impact test It is carried out on the machine; the tensile properties are carried out on the CMT6104 universal electronic testing machine according to the GB / T1040-92 standard. The bending performance is tested according to GB1042-79 standard. The impact spline is cooled with liquid nitrogen, then brittlely broken, vacuum gold-plated on the cross-section, and scanned by a scanning electron microscope.



1. The influence variable of wood flour's moisture in production

Through experiments, we found that when wood flour is heated, the water evaporates first, and then the easily decomposable part of lignin decomposes, further heating the cellulose to oxidative decomposition, and finally the lignin decomposes. When the modified plastic is filled with wood powder that has not been dried or dried in place, due to the presence of residual water in the wood powder and the low-boiling volatile substances in the wood powder, there are considerable bubbles in the sample, so The mechanical properties of the material are obviously affected; at the same time, proper heating treatment can also avoid the phenomenon of "burning" during the processing, and ensure smooth processing, bright products and normal color. Therefore, wood flour must be dried before filling.

At the initial stage of heating, the weight loss value of wood and bamboo powder is relatively large, because the moisture of bamboo powder evaporates during heating. After 1 hour, the weight loss value of bamboo powder is basically unchanged. The weight loss of wood powder at 110 ℃ and 130 ℃ is mainly Water evaporates. At a temperature of 150 ° C, the weight loss value of bamboo flour is relatively large at the initial stage of heating, mainly due to the loss of moisture, but as the heating time is extended, the weight loss value of bamboo flour becomes relatively smooth. Low boiling point volatile substances. When heating, if the temperature is low, the time is short, the wood powder loss is less than 3%. If the temperature is high, the heating time is long, the wood powder is infinitely reduced, which is meaningless and uneconomical. Considering the combination of performance and economy, the heating temperature of wood flour is 110 ℃, 130 ℃, and the reduction range is 5-10%.



Second, the influence of the choice of resin on the mechanical properties of the product

The high filling of wood powder will affect the plasticizing performance and processing fluidity of PVC. The resin type must be selected according to the melt flow rate (MFR) of the resin. MFR also has a certain influence on the performance of the composite material. Under the same processing conditions, The MFR of the resin is higher, the overall wettability of the wood powder is better, and the distribution of the wood powder is more uniform, and the wettability and distribution of the wood powder affect the mechanical properties of the composite material, especially the impact strength.

The smaller the polymerization degree of polyvinyl chloride, the higher the MFR of the resin. The parameters we provide through PVC resin manufacturers are not difficult to see. The viscosity number of PVCSG-7 or PVCSG-8 is lower, and the MFR is higher. Therefore, PVCSG-7 or PVCSG-8 is more suitable for matrix resin of PVC / wood plastic composite material.

3. The influence of wood flour selection on the mechanical properties of products

Wood powder is made by mechanical crushing. The force of wood powder of different particle size in the crushing process is different. Therefore, the wood powder of different particle size has different surface roughness and length-to-diameter ratio. The degree of damage suffered by the "microbubble structure" is different. The larger the particle size of wood powder, the greater the roughness of its surface. The effect of the roughness of the surface of the wood on performance is:



① Good impregnation of wood and plastic;

② Deep interface diffusion and mechanical interlocking are formed at the interface.

If a deep interface diffusion and mechanical interlock cannot be formed at the interface, it means that a cavity is formed at the interface, resulting in a decrease in material performance. We use 60 mesh, 100 mesh, 300 mesh wood powder to fill PVC, with the following formula

PVC powder SG-7 100
Stabilizer 3.5
Internal and external lubricant 0.5 ~ 2.0
AC foaming agent 0.3 ~ 0.5
ACR foam processing aid 5.0 ~ 8.0
Packing 4.0 ~ 6.0
Flame retardant 2.0 ~ 3.0
Nucleating agent 0.2 ~ 0.7
Plasticizer 5.0 ~ 10.0
Modified wood powder 20.0 ~ 30.0
Internal and external lubricant 0.5 ~ 2.0
AC foaming agent 0.3 ~ 0.5
ACR foam processing aid 5.0 ~ 8.0
Packing 4.0 ~ 6.0
Flame retardant 2.0 ~ 3.0
Nucleating agent 0.2 ~ 0.7
Plasticizer 5.0 ~ 10.0
Modified wood powder 20.0 ~ 30.0
We found that with the change of the particle size of the filled PVC wood powder, the impact strength and bending strength of the PVC / wood powder composite material first increased and then decreased. This trend was confirmed by the PVC / wood powder composite material electron microscope. Powder, high surface roughness, loose structure, PVC resin failed to penetrate wood powder, more exposed particles, more voids around wood powder; 300 mesh wood powder, small particle size, wood powder is easy to agglomerate; these defects form Stress concentration, easy to break under a small force. The 100-mesh wood powder has a moderate particle size and good compatibility between the PVC resin and the wood powder interface. Therefore, the maximum impact strength and bending strength appear.

Through experiments, we concluded that: PVCSG-7 or PVCSG-8 is more suitable for the matrix resin of PVC / wood-plastic composite materials; 100-mesh wood powder, moderate particle size, good compatibility with PVC resin, and the greatest impact strength and bending strength. Value; wood powder filled PVC prior to drying temperature of 110 ℃ is better.If you want to know more about it please do not hesitate to contact me. WhatsApp:+86-15966835076.